A comprehensive review on photocatalytic degradation of organic pollutants and microbial inactivation using Ag/AgVO₃ with metal ferrites based on magnetic nanocomposites

Abstract

Recent reviews have given a lot of attention to semiconductor photocatalysts’ applicability in environmental applications. These reviews are largely concerned with the geometry, layout, and manufacturing of semiconductors. However, it is necessary to evaluate recent studies on semiconductor photocatalysis. The new study focuses on crucial topics that have received scant consideration in past studies. It provides essential knowledge on microbial and pollutant exposure as well as the pros and downsides of conventional, pharmaceutical, and microbiological methods for removing them. The photocatalyst dose, starting initial concentration, acidity liquid, ambient lighting, oxygen concentration, Hydroxyl radicals’ addition, instant photolysis, and catalyst loading were a few of the operating factors that were briefly discussed. This in-depth analysis provides examples of the different semiconductor substitution techniques. Heterogeneous nanoparticles with a supported or core/shell structure have also been thoroughly investigated. The types of heterojunctions photocatalysts like “p-n, type I, type II, and Z-scheme heterojunctions” and others. Additionally, the Ag-AgVO₃ nanoparticles employed for bacterial degradation are addressed. Moreover, the application of the nanocomposites is discussed too with the adsorption kinetics in which its efforts express the parameters in progress.

Keywords:

• Photo-catalytic
• catalysts
• metal ferrites
• degradation activity
• microbial inactivation

1. Introduction

Human survival and societal growth are both threatened by water contamination. Solar energy has made remarkable progress in research to address environmental challenges. Semiconductor photocatalysis, which uses solar energy to remove organic contaminants and dangerous microorganisms from wastewater, is gaining popularity (Al-Husseiny et al., 2021). However, widespread usage is challenging due to the enormous band gap and quick recombination of photoinduced charges in TiO₂ or ZnO. As a result, producing visible light active photocatalysts is crucial for environmental cleanup (Peng et al., 2020; Rotjanasuworapong et al., 2021).

“Advanced oxidation processes” (AOPs) are treatments that regularly utilize hydroxyl radicals, the harshest oxidants, for the treatment of organic pollutants in wastewater. These cutting-edge techniques for accelerating oxidation have been very successful. AOP can be used with ozone (O₃), a catalyst, or ultraviolet (UV) irradiation to provide a potent wastewater treatment. Future research should focus mostly on enhancing the features of heterogeneous catalysts in AOPs. The multiple AOPs employed to eliminate various phenolic compounds and textile colors from wastewater are summarized in this publication (Abazari & Mahjoub, 2017; Al-Husseiny et al., 2021).

On the percentage of dyes in sewage that is decolored, the effects of ferric iron and oxidant dosage have been documented. The use of several customized photocatalysts for the reaction of photosynthesis is also included in the debate. Future difficulties are explored, including adopting tactics for process integration and lowering the operational cost of AOPs. The use of various heterogeneous catalysts is discussed as well as ways to reduce the amount of energy and chemical input required for the processes (Ahmed Al-Lhaibi & Mazin Al-Shabander, 2022).

To increase photocatalytic activity, a number of effective Ag-nanocomposite systems have recently been created. In contrast to conventional heterojunctions, the Z-scheme charge carrier pathway may hasten the separation of photo-induced electron pairs while maintaining their strong redox capacity. Ag-containing photocatalysts have been found to significantly increase the photocatalytic activity of Ag-nanocomposite with Z-scheme. It is important to discover how effective the Z-scheme g-C₃N₄@Ag/AgVO₃ is against bacteria because there has not been much research on it (Faraji et al., 2021). Studies that demonstrate the impact of nanocomposites on the photocatalytic process are discussed (Kosslick et al., 2021).

In addition, the nanocomposite in which “ternary hybrid g-C₃N₄@Ag-ZnO NCs” demonstrated exceptional durability and degradability with a significant level of photocatalytic methylene blue (MB) degradation. The experiment further demonstrated that the primary species responsible for MB degradation were the superoxide (*O₂) and hydroxyl (*OH) radicals. The “tripartite hybrid g-C₃N₄@Ag-ZnO NCs’” higher photocatalytic activity and noticeably increased antibacterial performance are due to the synergistic interaction between Ag-ZnO NPs and g-C₃N₄ NSs at the interface. As a result, present studies indicate that the synthetic “g-C₃N₄@Ag-ZnO NCs” may prove to be an effective photocatalyst technology for the reduction of organic pollutants and disinfection for the elimination of dangerous bacterial species from wastewater. In addition, polymers could be effective in photocatalytic degradation in some research studies (Liu et al., 2019).

However, hydrogels, which have a multi-network structure and functional compounds in the polymer backbone, are among the most often used adsorbents in the sewage treatment sector. “Chitin, glycolate, lignin, and xylose” are all biopolymers that can be used to make hydrogels. However, due to their ability to degrade, cytocompatibility, non-toxicity, relatively inexpensive, and favorable adsorption, natural polysaccharide-based hydrogels have recently attracted extraordinary attention (Liu et al., 2019).

Another study has concentrated on the bio-adsorption of MB using batch studies with manufactured CA/CNC hydrogel. The impacts of acidity, contact time, adsorbent dosage, and MB concentration on the adsorption were examined. Separate studies of the isotherm and kinetic models of adsorption were also conducted. On the biopolymer CA/CNC hydrogel, the adsorption capacity has been investigated using both ANN models and RSM (Farhan et al., 2022).

Another example for promising photocatalysts is studied while having certain distinctive qualities such as a high degree of stability, strong capacity, and ability to function in visible light. The g-photocatalytic C₃N₄‘s activity underneath visible light is constrained by a high rate of reactive charge recombination. In order to address this problem, g-C₃N₄ is coupled with GaN-ZnO in this study to increase the active sites and decrease the rate at which charge carriers recombine. The composite with exceptional qualities also functions well in visible light; as a result, it is anticipated to be widely used in environmental remediation, particularly in antibiotic residue where more than 90% of the tetracycline broke down after 3 hours (Gao et al., 2017; Liu et al., 2019).

Using a simple solvothermal technique, a unique tripartite composite photocatalyst (g-C₃N₄/BiOI/BiOBr) was created. The photocatalyst showed more photocatalytic activity for the degradation of MB when exposed to visible light than pure g-C₃N₄ and BiOI/BiOBr. The hybrid photocatalyst with the greatest photocatalyst for MB degradation comprised 3% g-C₃N₄/BiOI/BiOBr. These findings imply that a synergistic effect is produced by the heterostructure of g-C₃N₄, BiOI, and BiOBr via an effective charge transfer process (Kokkinos et al., 2020).

Cellulose nanocrystals (CNCs) are one of the best materials that have recently been used in a variety of fields (CNCs). The focus of this study is on using sulfuric acid to hydrolyze cotton fibers waste to release CNCs. The physicochemical characterization of the manufactured CNCs was examined by utilizing a variety of techniques. The findings demonstrate the performance and quality of synthesized CNCs. An X-ray diffraction (XRD) analysis showed that the crystallinity index increased from 79.87% to 88.37% as WCFs were converted into CNCs. Microscopy techniques were employed to validate CNC’s rod-like shape. Moreover, DLS (dynamic light scattering) tests showed that CNCs in aqueous solution were quite stable. Additionally, the material displayed less thermal stability as a result of the introduction of 0.74 weight percentage (SM, 2018).

Finally, the aim of this research was to review different processes related to oxidation process, photocatalytic process, degradation mechanism, types of semiconductors, the application of photocatalysts, adsorption kinetics, and others.

2. Photocatalytic advanced oxidation process

(AOPs) are prospective methods for mineralizing both some inorganic pollutants that are hard to decompose and extremely stable organic pollutants such insecticides, additive pollutants, and dye chemicals. AOPs may directly use solar energy to clean and purify the water, which makes them effective for wastewater treatment. Photocatalytic degradation strategies have gained a lot of interest due to their potential to generate “photo-generated electron-hole pairs” (Abazari & Mahjoub, 2017; Al-Husseiny et al., 2021; Baqi and Ebrahim, 2020).

AOPs are extremely reactive and susceptible to reactive oxygen species (ROSs), which seem to be mechanisms in which pollutants are oxidized largely by hydroxyl radicals. They are created when electron–hole pairs are created. “The hydroxyl radical (OH⁻) is a potent oxidizing agent with an oxidized form of 2.8 eV and a powerful electron donor that interacts non-selectively with nearly all organic compounds rich in electrons”. Depending on how OH⁻ is produced, AOPs can be categorized as biochemical, electrochemical, or biological processes (Al-Mahmoud, 2019; Alshabander & Bassim Abd-Alkader, 2023).

On the other hand, AOPs can vary based on the response mixture and the phase of the catalysts being used. The division of processes into two categories: homogeneous and heterogeneous. Based on the following criteria, categorization was made in the absence of light and when using strong oxidizing agents like H₂O₂ and O₃. The benefits of heterogeneous catalysis are numerous, despite the fact that the word “heterogeneous” has a bad reputation. The main difference between heterogeneous and homogeneous catalysts is that recovering catalysts from homogeneous solutions is difficult for catalysis. Additionally, heterogeneous catalysis is a quick, accessible, and affordable technique that can be used in large-scale water purification plans (Al-Husseiny et al., 2021; A. Singh et al., 2014).

3. Values of heterogeneous photocatalytic oxidation

The varied “photocatalysis,” which also has the potential to be a “low-cost process” and ought to be solar energy-efficient, inexpensive, non-toxic, and photoactive (Jing et al., 2016). The aqueous phase is the usual setting for heterogeneous advanced oxidation processes, with adsorbed water molecules oxidizing to the OH⁻ radical on the catalyst surface. The study was carried out in aerobic settings, oxygen must be lowered, which results in the “production of the superoxide (O₂) radical.” Nanocomposites require a quantity of a good valence band redox potential in order to be photochemically active (Shakil et al., 2022).

Unfortunately, normal restrictions were put in place. Fenton methods have a number of AOPs that prevent their widespread application, including fossil fuel consumption, costs of production, and the production of waste iron sludge. Traditionally, photocatalytic decontamination is a method that uses light to eradicate microorganisms. Physicochemical characteristics of inorganic materials have made them useful for many centuries. Several inorganic nanoparticles, comprising silver, copper, titanium dioxide, zinc dioxide, cadmium oxide, manganese metal ferrite, nickel metal ferrite, zero valent metals and bimetallic nanoparticle, have been proposed for photocatalytic water disinfect (Karnaji & Nurhasanah, 2017). The AOPs offer a superb alternative to hydroxyl radical-based water filtering. The photocatalytic reaction, according to Brunet et al., is initiated when two semiconductors strike the surface, prompting electron promotion from the v band to the c band (Fatima et al., 2022).

By oxidatively withdrawing electrons from hydroxyl ions or water, the hole can generate a hydroxyl radical (OH⁻). Lin and Associates (2005) Numerous organic, inorganic, and biomolecules, including carbohydrates, enzymes, lipids, nucleic acids, and other biomolecules, can suffer structural damage from strong, non-specific oxidants like the superoxide radicals and the hydroxyl radical. They can also be used to purify and deodorize water, air, and other things. In order to avoid recombination and extend the lifespan of holes, the O² molecule in oxygenated aqueous scavenge electrons from of the bandgap (Kefeni & Mamba, 2020).

4. Restrictions of conventional photocatalysts

Reactive oxygen species (ROSs), notably peroxide (O₂) and hydroxyl free (OH⁻) radicals, which are produced by and, respectively, under UV irradiation, are linked to the ability of inorganic nanoparticles, such as TiO₂, to photocatalytically kill bacteria (P. Singh et al., 2020).

Despite being a novel technique with numerous applications in the areas of energy, medicinal chemistry, and environmental treatment, heterogeneous photocatalysis has significant limitations. Using a bare photocatalyst has the disadvantages of aggregation, instability, and the ability to considerably improve the performance by loading or doping with exotic plants, which frequently serve as recombination sites. The high incidence of recombination of photo-induced pairs of electrons (D. Chen et al., 2019) is another problem. These imperfections reduce the quantum yield, which decreases the photocatalyst efficiency. Due to these faults, the majority of photocatalysts are unable to mineralize the starting material, even if many of them are successful at photo-decomposing a variety of contaminants (M, Aksoy et al., 2020)

Although inorganic metal oxides are a significant class of photocatalysts, Menard et al. (2011) and Han et al. (2009) have pointed out that employing them has some disadvantages. These limitations include: (i) the inability to immobilize powder inorganic material oxides, such as TiO₂, on some supports; (ii) The fast recombination of photoinduced electron–hole pairs; (iii) The minimal activity in the visible region;

Due to a number of restrictions, including poor contaminant adsorption, partial porphyry, high destabilization and propensity to coalesce, less reusability, tough detachment, and nanotoxicity, the use of bare bitwise, nested loops. Due to these restrictions, scientists have experimented with defect-induced photocatalysis, assisted photocatalysis, metal, dye desensitization, linked transistor, and metal doping (Ajormal et al., 2020). If the right support material is utilized, aided photocatalysis can be an effective technique to get around the drawbacks of bare nanoparticles. NPs, supported on other materials, can be used to remove organic or inorganic components from wastewater as an example of this method of green technology (Kokkinos et al., 2020). In this regard, the constancy and photocatalytic action of metal photocatalysts have been improved by using support materials. Modified nanomaterials and carbon-based materials have displayed impressive antibacterial activity in a number of environments (Yousif, 2018).

5. Degradation mechanism

Photodegradation is a process in which it occurs to degrade the pollutants, whatever the pollutant might be. In the presence of semiconductor, the e- is excited from the valence band to the conduction band by this leaving a hole h⁺ for the semiconductor. The oxygen reactive free radical also creates an active free hydroxyl radical when it interacts with a hydrogen ion as well as the hydroxyl ion (reaction 2). The reaction of the photogenerated hole (h⁺) is performed in order to produce active hydroxyl-free radicals with water (Baqi and Ebrahim, 2020). Thus, several parameters enhanced energy level at which the band gap, utilizing visible light, increase stability, reaction separation is easy to occur and others (Ebrahim et al., 2019).

6. Ag-AgVO₃ nanocomposites and its application for degradation

It has recently become a huge hazard for organic pollutants and pathogenic bacteria to become a major concern in the environment, and it is seen as a problem. As a result, green technology has evolved into a viable technique capable of degrading contaminants and bacterial inactivation (Ajormal et al., 2020). Ag₂S (silver sulfide), this semiconductor is deemed desirable. Despite this, the high recombination rate of photoelectron–hole couples has a substantial influence on Ag₂S applications. Understanding how a Z-scheme heterojunction can enhance charge transfer and oxidative durability can help (Jamil, 2021). Adding a redox mediator to Z-scheme photocatalysts reduces charge recombination, increases electron–hole utilization efficiency, according to new research (Nguyen et al., 2022).

Duong et al. (2020) were able to create a special Z-scheme heterojunction CdS/Fe₃O₄/g-C₃N₄ catalysts that demonstrated considerable photocatalytic activity for the elimination of different antibiotics by including Fe₃O₄ as a reaction center point between CdS and g-C₃N₄. Due to its high visible light usage, good crystallization, and appropriate band gap, silver metavanadate (AgVO₃) is also acknowledged as one of the best alternatives for microbial inactivation and ecological pollutant degradation in wastewater treatment. Even inVO₄/AgVO₃ and AgI/AgVO₃-based Z-scheme heterostructures, the inclusion of AgVO₃ considerably enhanced the photoactivity of the 12 composites (Al-Alawy et al., 2018).

Using the capillary effect in conjunction with the hydrothermal technique, a structured Z-scheme Ag₂S/Fe₃O₄/AgVO₃ graphene quality and unique photocatalyst was originally developed. A permeable glass tube was initially filled with a copper wire. Then, graphene oxide was electrostatically modified using chitosan (CS) (GO). Using the capillary effect along with the hydrothermal 1 technique, a structured Z-scheme Ag₂S/Fe₃O₄/AgVO₃ graphene performance and innovative photocatalyst “Ag₂S/Fe₃O₄/AgVO₃ @GM” was first created. A copper wire was inserted into a tubular glass tub. After that, graphene oxide’s electrostatic characteristics were altered using chitosan (CS) (GO) (Gupta et al., 2020; Jabbar, Ammar, et al., 2021).

The Ag₂S/GO functions as a unifying method was then generated by precipitating AgNO₃ on the GO interface using Na₂S solution. Through capillary action, the Ag₂S/GO solution was absorbed and held in a glass tube with a copper wire. The eight layers of Ag₂S graphene gel (Ag₂S@graphene gel) on copper wire were produced by a hydrothermal technique. A prototype of the Ag₂S/Fe₃O₄/AgVO₃ @graphene gel composite was created by covering the Ag₂S@graphene gel with Fe₃O₄ graphene gel and the AgVO₃ graphene gel using in vivo depositing, total porosity, and chemical treatment. The Ag₂S/Fe₃O₄/AgVO₃ @graphene solution was allowed to spontaneously cure after the interior copper was removed by etching. This resulted in the compound (Ag₂S/Fe₃O₄/AgVO₃ @GM) with geographically 15 separated microtopography (Ali et al., 2018).

In this Z-scheme system, Fe₃O₄ serves as a redox center, obtaining and utilizing holes from Ag₂S and AgVO₃ to produce more active radicals and advance photoinduced charge separation, both of which are useful for boosting photocatalytic performance. Furthermore, the electrical conductivity of the hollow graphene microtube carrier can improve the Ag₂S/Fe₃O₄/AgVO₃ @GM electron–hole pair separation. Ag₂S/Fe₃O₄/AgVO₃ @GM is therefore expected to have better photocatalytic performance and rate capability in its application (Alkurdy & Ebrahim, 2020). These five fundamental traits offer fresh perspectives and opportunities for developing photocatalytic models for wastewater treatment (Boris et al., 2019).

The p-type solid—state AgVO₃ is one of these Ag-based photocatalysts that has generated a lot of controversy because of its good photoelectrochemical and catalytic capabilities, and it is widely employed in contaminants poverty, decontamination, and H₂S sensors. In addition, single AgVO₃ has a limited photocatalytic activity, limiting its practical applicability. More work must be put into enhancing the photocatalytic performance of the system by using the proper nanostructure. This can aid in the quick disconnection of “photogenerated charge carriers” and the range of applications, particularly the range of consumption of a large amount of noble metals. A promising method to increase photocatalytic performance is to use (Au, Ag, and Pt). Noble metals can contribute to the expansion of the photo absorption effect due to the vibrational modes of the surface electrons (Bayantong et al., 2021). Noble metals are also renowned for their superior properties and positive impact on performance to trap electrons, which facilitates electron transit even more. In order to significantly enhance AgVO₃‘s photocatalytic property, adding noble metals can significantly increase the photocatalytic performance. For instance, these nanowires showed good photocatalytic capability in the degradation and eradication of Rh B (Al-Mahmoud, 2019).

When subjected to visible light, Zhao and colleagues’ highly effective and stable Ag/AgVO₃ nanorods exhibit improved photoactivity. However, photocorrosion is a constant problem for Ag-based photocatalysts, which has a major impact on their photocatalytic activity and stability. As a result, more stable constructions are still needed urgently. BiVO₄@AgVO₃, Ag₃PO₄/AgVO₃, Ag/AgVO₃/C₃N₄, and other heterojunction structures have been designed to be consistent with single AgVO₃. By dramatically accelerating the detachment of photoinduced electron–hole pairs, heterojunction devices can enhance photocatalytic performance by permitting more charge carriers to produce reactive species. In addition to having improved photocatalytic activity and stabilities, Z-scheme photocatalytic devices provide good anti-photocorrosion properties for Ag-based materials. This is because photogenerated electrons electron and holes are effectively separated (Alshabander & Bassim Abd-Alkader, 2023).

Chen et al. (2020) used in situ deposition to create a new “Ag₃PO₄/Ag/BiVO₄/RGO Z-scheme” heterojunction that demonstrated exceptional “visible-light-driven photocatalytic performance” for the breakdown of tetracycline. As a result of previous research, it is desirable and predicted that AgVO₃‘s photocatalytic performance will be greatly enhanced by creating a Z-scheme structure with nanomaterials and adding Ag NPs for SPR effect. However, a semiconductor with the proper band strength and band gap combining with AgVO₃ should be utilized as a replacement of that disinfection and photoanodes as a semiconductor with a tiny band gap (approximately 2.30 eV), outstanding durability, low toxicity, and sun damage. Recently, BiVO4 has been used to make heterojunctions like “Bi₂WO₆/BiVO₄, BiVO₄/Bi₂S”, and others (A. Singh et al., 2014). “BiVO₄@b-AgVO₃, BiVO₄/Ag/AgCl, BiVO₄@b-AgVO₃”, and additional BiVO₄@b-AgVO₃ combinations. In particular, Yang et al. (2020) have discussed in-situ preparation.

Therefore, this study supports the notion that BiVO₄ is a helpful dietary supplement. AgVO₃ is a suitable option for composites because of the matching energy. Techniques that produce effective heterojunctions, such as band levels, are seen to be efficient (Anchieta et al., 2014). It goes without saying that as photogenerated charge carriers move, AgVO₃‘s photocatalytic performance increases. Although the photocatalytic activity of AgVO₃ has increased, there is still opportunity for improvement.

Therefore, it is postulated that a plasmonic Z-scheme system can be created by synchronously growing BiVO₄ over 1D AgVO₃ and decreasing Ag NPs, showing improved photocatalytic activity, as well as recycling the noble metal (Aparna et al., 2018).

In light of the aforementioned context, we describe in this study a simple and eco-friendly technique for controlling the synthesis of new Ag@AgVO₃/BiVO₄ nanostructures using an in situ top method ion exchange-reduction method. First, uniform AgVO₃ NBs were created by hydrothermal means, which produced highly noticeable AgVO₃ NBs having exceptional stability, huge surface areas, and catalytic activity Bi (NO₃)₃. The AgVO₃ dispersion was then supplemented with 5 H₂O (Azzaz et al., 2021).

H⁺ and BiONO₃ were produced as a result of hydrolysis. Additionally, PVP may promote the SPR effect and enable the reuse of the palladium Ag (Boris et al., 2019).

7. The photocatalytic mechanism of nanocomposites

It is well known that a wide range of active species, including OH⁻, O^2-, and h⁺, are supported by photogenerated electrons and holes. Trapping studies were carried out in interaction with Ag@AgVO₃/BiVO₄ utilizing a variety of decomposing organic matter in order to determine the primary hydroxyl radicals in the photocatalysts antibacterial process (IPA as OH scavengers and TEMPOL as O^2- scavengers). The outcome shows that adding IPA had little to no impact on Ag@AgVO₃/antibacterial BiVO₄‘s rate, proving that the oxidizing ion promoters were not the main source of the photocatalytic activity (Boris et al., 2019).

The antibacterial effectiveness of E. coli was significantly reduced in both reaction systems after TEMPOL and sodium oxalate were added to the reaction system. The most effective activators of the Ag@AgVO₃/BiVO₄ photocatalytic process were found to be the h⁺ ion and the O^2- radical. Control trials have shown that scavengers are only somewhat effective against E. coli, as they barely affect the antibacterial property (Qin et al., 2020).

The bands of AgVO₃ and BiVO₄, which were essential in controlling the direction of photogenerated charge carriers in the heterojunction, were discovered in order to further investigate the photocatalytic performance of the “Ag@AgVO₃/BiVO₄” heterostructure. The empirical equation can be used to determine the conduction band (CB) and valence band (VB) potentials of a semiconductor, where X is a statistical representation of the atoms’ absolute electronegativity (5.860 eV). Eg is the energy of the material’s appropriate band (2.10 eV/NHE for AgVO₃ and 2.26 eV/NHE for BiVO₄), and EC is the quantity of unpaired electrons at the hydrogen level (4.5 eV/NHE). A heterojunction structure is created when AgVO₃ and BiVO₄ come into contact. This structure could speed up the separation of photogenerated charge.

With improved photocatalytic performance, a possible Ag@AgVO₃/BiVO₄ heterostructure plasmon Z-scheme photocatalytic activity method was created. Visible light simultaneously activated the Ag, AgVO₃, and BiVO₄ in the Ag@AgVO₃/BiVO₄ heterojunction. The AgVO₃ and BiVO₄ ions excited to CB left exactly the same number of holes (h⁺) on VB. The photogenerated electrons in AgVO₃‘s CB will subsequently move to BiVO₄‘s CB due to the more negative ECB of p-AgVO₃, mimicking the conventional separation of the electron−hole pair in p-n heterojunction. Nevertheless, since the potential of O²/redox O² (_0.046 eV/NHE) is lower than that of the ECB (0.405 eV/NHE), O² cannot be produced by reducing O² with the electron in BiVO₄‘s CB. As a result, research on oxygen-based radical trapping yields unfavorable findings. Ag@AgVO₃/BiVO₄ inhibits electrons from conveniently traveling from AgVO₃ to BiVO₄, where they would engage in plasmonic Z-scheme activity, in accordance with classic p-n heterostructure theory. Due to the greater negative CB value of BiVO₄ compared to the Fermi energy of Ag NPs, photoinduced electrons in the CB of BiVO₄ after being exposed to visible light can easily pass across the buffer layer into Ag NPs and rejoin the plasmon-induced holes (Cuong, Trang, Ha, Viet, Phuong, & Cuong, 2021).

Due to the different Fermi potentials of Ag NPs and AgVO₃, holes on the VB of AgVO₃ can easily travel to Ag NPs and interact with electrons there. Due to their outstanding electron transport capacities, Ag NPs can act as a charge separation and separation center during the photocatalytic activity. This significantly speeds up the charge recombination process or the separation of holes from VB of AgVO₃ and electrons from CB BiVO₄ (W. Zhao et al., 2015).

Since BiVO₄ has a greater negative CB potential than Ag NPs, photo-induced electrons in its CB can easily pass the Schottky barrier when exposed to visible light (Dumitru et al., 2021). Plasmon-induced holes in Ag NPs’ Fermi level will soon start to emerge. Potentially, the Fermi is likewise more advanced than the VB development due to the enhanced for Ag NPs (Duong et al., 2021; Zuliani & Cova, 2021).

The holes readily attack the Ag NPs on the VB of AgVO₃, letting them to move about and interact with the electrons there. Ag NPs can frequently end up acting as an electron–hole replication motivator in a photocatalytic reaction due to their strong electron transport and disconnection core, which significantly helps in faster electrical conduction through the interaction and particulate disconnection of the CB of BiVO₄ and holes from VB of AgVO₃ (Dutta et al., 2021).

Moreover, the simultaneous conveyance of electrons and holes in Ag@AgVO₃/BiVO₄ boosts the yield and lifetime of the material due to the enhanced separation and reduced recombination of charge carriers. As a result, AgVO₃ CB produces more charge carriers, such as electrons and holes (a material with high reductive power).

BiVO₄ has a higher positive EVB value than the conventional OH⁻/OH⁻ oxidation state (1.99 eV/NHE), which enables the photoengraved holes (h⁺) on the VB of the composite to target living things, dye, or water molecules right away and produce a small number of OH⁻ radicals in the photocatalyst. When the silver nanoparticles’ carrying electrons underwent a collective oscillation, they were able to effectively absorb visible light and generate split electrons and holes as a result of the SPR effect that the light’s impinging electric field’s pulsating electric field caused. Thus, O⁻² can be produced and captured using the AgVO₃ CB’s electrons’ plasmon-enhanced, inadequate reductive capability (0.405 eV/NHE) (L. Zhao et al., 2004).

Highly oxidizable O^2-radicals will continue to disintegrate dye and bacterial cells, causing more oxidation. After constructing the Z-scheme Ag@AgVO₃/BiVO₄ heterostructure, the induction of Ag NPs successfully limits the photo-corrosion of pure AgVO₃ because the photo-induced electrons can be absorbed by Ag NPs rather than fed into Ag⁺ in the AgVO₃ structure. By successfully improving the splitting of photo-generated electrons, the SPR effect of Ag NPs in combination with the Z-scheme of a composite ternary heterostructure increases the efficiency and effectiveness of the photocatalytic process (Y. Chen et al., 2019).

8. Organic pollutant degradation via photocatalysis

The photocatalytic efficiency of the created photocatalysts was measured using Rh B’s photoactivity when subjected to visible light. With Ct standing for both the initial concentration of Rh B and the percentage of Rh B at various points during the photocatalytic activity. Rh B was severely damaged by the blank control, which is essentially dismissible. Due to the enormous precise surface area of the generated photocatalysts, there was a tiny amount of Rh B degradation in the dark test with photocatalysts, but it was negligible when subjected to daylight.

The formation of a persistent nanocomposite that made it easier for photogenerated carriers to be separated was the reason why the Ag@AgVO₃/BiVO₄ composites outperformed other photocatalysts in terms of photocatalytic performance. Ag@AgVO₃/BiVO₄ exhibited 100% Rh B degradation within 30 min for the nanocomposite with improved performance, however when the molar ratio was more than 0.2, it showed a significant drop. The various photocatalytic activities are strongly influenced by the heterostructure’s shape. AgVO₃ NBs were damaged by too much Bi (NO₃)₃.5 H₂O reacting with them during the reaction phase (Ebrahim, 2019a).

The nano composite also showed a higher photocatalytic performance than control materials, suggesting that the SPR effect of Ag NPs significantly facilitated the migration of photo-induced electrons, leading to increased photocatalytic activity. Due to the addition of silver nanoparticles and BiVO₄ NSs to silver metavanadate NBs, a reliable and assimilated heterostructure, the SPR effect of Ag NPs, and a significant increase in the specific surface area of the nanocomposite, the photocatalytic property of the material was significantly enhanced. In order to evaluate the reaction process, it was also decided to look at the kinematics of the degradation reaction. When Rh B concentrations are in the millimolar range, pseudo-first-order kinetics frequently governs how the initial Rh B concentration affects the rate of degradation. Based on the kinetics modeling, it showed that the nanocomposite had an excellent performance of photoactivity processes (Y. Chen et al., 2019; Ebrahim, 2019a).

TOC tests were also carried out to verify the final products and delve deeper into the AgVO₃/BiVO₄ combination’s photocatalytic activity. After 30 min of photocatalyst, the mineralization output of the AgVO₃/BiVO₄ composite for Rh B breakdown may achieve 81.6%, which is lower than the dissolving rate of the other nanocomposite (Ebrahim Shahlaa, 2020a). This discovery showed that some Rh B molecules only deteriorated to particular intermediates within 30 min, whereas others were completely obliterated into carbon dioxide and water during in the photocatalytic reaction. In order to completely eliminate all Rh B molecules, the reaction’s photocatalytic rate must be increased (Rasheed and Ebrahim, 2020). Each sample had a distinct photocurrent response to visible light at regular intervals.

The photocurrents were measured to confirm the improved photocatalytic activity of the heterojunction and to obtain insight into the kinetics of interfacial production and segregation of photoinduced charges. Ag@AgVO₃/BiVO₄ composite has a markedly higher current responsiveness than both AgVO₃ and Ag@BiVO₄ due to the creation of heterojunctions between AgVO₃ and BiVO₄. This discovery increases the separation effectiveness and lengthens the lifetime of photoinduced electron–hole pairs, which improves the photocatalytic performance of the AgVO₃/BiVO₄ composite (Ebrahim Shahlaa, 2020b).

9. Photocatalytic antibacterial performance

For photocatalytic antibacterial tests using generated photocatalysts in disinfection, E. coli and S. aureus were employed as models. After 30 min, the quantity of E. coli was essentially unchanged, which can be disregarded. Additionally, the dark control (photocatalysts in the dark) demonstrated that the photocatalysts alone have a negligibly negative impact on E. coli with little difference in the number of living cells (Ebrahim, 2019b).

Ag-containing compounds have been shown to release Ag⁺ throughout the reaction process. However, our experiment did not find any Ag⁺ in the reaction mixture, demonstrating that Ag⁺ leakage in “Ag@AgVO₃/BiVO₄” composites was negligible.

In terms of photocatalytic antibacterial activities, the ternary composite significantly outperformed nanocomposite, Ag NPs in conjunction with the development of heterostructure, which promotes the segregation of photo-generated charge carriers (Duong et al., 2021). The electrocatalytic antimicrobial effects of the nano-composites steadily increased as the semiconductor molar ratio in the composite grew from 0.05 to 0.2, but they appeared to decline after this value, which was in good accord with the Rh B photocatalytic degradation results. It demonstrates that due to NBs structure breakdown, composite barium metavanadate would have reduced photocatalytic antibacterial efficacy (Dutta et al., 2021). As a consequence, in terms of photocatalytic antibacterial performance, nanocomposite with a steady and interconnected heterostructure outperformed other amalgams (Ebrahim et al., 2019).

Bacterial inactivation was shown for these nanocomposites based on this method. In contrast, nanocomposite demonstrated enhanced photocatalytic antibacterial activity S. aureus, demonstrating its broad-spectrum antibacterial efficiency with an antibacterial rate of 99.99% in a 15-min reaction (Farhan et al., 2022). The unmodified E. coli and S. aureus cells had distinctive, full cellular components and strictly delineated cell walls, demonstrating that the cells were thriving normally and had not had any intervention. After 15 h of exposure to visible light in the absence of nanocomposite, the cytomembrane and epithelial tissue in both E. coli and S. aureus experienced severe damage, resulting in internal component leak and cell death (Farhan et al., 2022). These findings support the hypothesis that the oxidative active species produced during the photocatalytic reaction attacked bacteria, causing cell walls and other cellular components to be destroyed first. The cytoplasmic membrane and cell wall of bacteria would be the initial targets of these species, which would then rupture the compartment partition and let intracellular components flow out.

According to Jue et al. (2020), the oxidative active species would subsequently break down the leaky internal components and cell fragments, producing CO₂ and H₂O, before the cell was totally dissolved. The Ag@AgVO₃/BiVO₄ composite, a promising material, was discovered to be extremely effective, broad-spectrum antibacterial, and ecologically benign (Farhan et al., 2022).

10. Examples of magnetic nanocomposite degradation with their application

The hydrothermal method’s ability to manufacture metal ferrite nanoparticles (10.5–14.8 nm in size) was examined using the example of methyl blue dissolution in aqueous solution. It was discovered that methylene blue’s unfavorable oxidation state in aqueous solution worsened with increasing Zn content, ferrite nanoparticle presence, pH = 7, and exposure to natural sunlight. With increasing Zn content, the rate of methyl blue degradation slows (Fatima et al., 2022). The photooxidation of methylene blue using these core-shell nanoparticles was carried out under UV light. Magnetic separation can still have major effects on the nanoparticles in the reaction medium, even if non-magnetic coatings are used to lower the magnetic moment.

Co-precipitation was utilized to make a variety of materials, including pure cobalt ferrite CoFe₂O₄ (50 nm in size), “CoFe₂O₄ and TiO₂” nano catalysts, and others. The visible light was absorbed by the Co²⁺ and Fe³⁺ cations on the TiO₂ substrate between 550 and 650 nm. In order to achieve maximum degradation, the concentration and usage rate of the nano catalyst were varied for the photodegradation of Reactive Red 120 (RR120) (Gupta et al., 2020).

The main effect of the reaction medium was to transform ferrites into a complex mixture of different iron-containing phases. Iron-nickel alloys made up the majority of the samples made using thermal synthesis, but iron carbide Fe₃C was more likely to be present in samples made using SPS. The obtained ferrites’ current-phase composition, which was shaped by the reaction medium, significantly affected their catalytic activity and selectivity during the microbial conversion of methanol to CO and methane in a flow reactor (as well as for the pure nickel ferrite previously mentioned, which was made by chemical precipitation) (Jabbar, Ammar, et al., 2021).

These ferrites were utilized as catalysts in the alkylation of aniline, with a maximum conversion of 80.5% for aniline and a selectivity of 98.6% for N-methylaniline. The yield was discovered to be 2:1 at 673 K, with a molar ratio of 5:1 between methanol and aniline. CuFe₂O₄ is present in the highest concentration there. The catalyst’s performance is also very important. The relationship between the acidity and surface area of ferries was also discovered (Jabbar, Ebrahim, et al., 2021).

To produce carbon nanotubes, these nano catalysts underwent chemical vapor deposition (CNTs). It was discovered that structural isotropy, cationic catalytic characteristics, and cation concentrations in the octahedral and tetrahedral positions all that have an impact on the catalytic activity of these nanocrystals on CNT synthesis. Since Ni has a higher catalytic activity than Co, the catalytic activity of Ni/Co ferrites increases as Ni concentration does. The structural isotropy of Ni/Zn ferrites has a major impact on their catalytic activity. Due to its inverted spinel structure, ferrite has a higher catalytic activity than Ni/Zn ferrites, although Ni/Co ferrites have a lower catalytic activity due to safety measures (Jabbar, Ebrahim, et al., 2021).

According to Liu et al. 2019‘s article, the “g-C₃N₄@Ag/AgVO₃” composite was successfully synthesized and investigated using “XRD, FESEM, TEM, XPS, and UV-DRS”. Comparing ternary “g-C₃N₄@Ag/AgVO₃” composites to bare g-C3N4, Ag/AgVO₃, and “g-C₃N₄@AgVO₃” composites, the former showed greater photocatalytic activity for Rh B degradation. The “g-C₃N₄@Ag/AgVO₃” composite has a greater photocatalytic disinfection efficacy, with “3.05 log of E. coli” inactivated after 100 min of exposure to visible light, according to antibacterial testing (SM, 2018). As a charge transmission bridge, Ag nanoparticles are essential for Z-scheme charge transfer, which significantly boosts photocatalytic activity. After three cycling studies, the composites still exhibit exceptional stability and reusability (Gao et al., 2017; Liu et al., 2019).

Merely refluxing 19.1 nm ZnFe₂O₄ nanoparticles (NPs) with graphitic to the successful creation of magnetic ZnFe₂O₄-C₃N₄ hybrids. In order to determine if heterogeneous ZnFe₂O₄-C₃N₄ catalysts had any catalytic activity. Comprehensive research has been done on the photocatalytic degradation rates, catalytic durability, and functionalities of ZnFe₂O₄ and C₃N₄ (SM, 2018). The composite catalysts were demonstrated to exhibit outstanding catalytic efficacy in neutral circumstances, in contrast to the conventional Fenton system (Fe^2+/H₂O₂). The p-conjugated substance g-C₃N₄ was utilized as a catalyst for the breakdown of hydrogen peroxide into •OH radicals in addition to its role as a component in the creation of heterojunctions with ZnFe₂O₄. After five trials, the multifunctional ZnFe₂O₄-C₃N₄ hybrid maintained its effectiveness without decreasing, indicating that it might be used to photo-oxidatively eliminate organic pollutants (SM, 2018).

11. Fundamental of semiconductors (photocatalysts)

It explores the core principles of the different approaches after introducing various sorts of implementations. Electromagnetic materials all need to be effective at absorbing light, separating charges, facilitating charge migration, and transferring charges quickly. The particular processes, however, vary greatly. There are various approaches to light absorption. The photogenerated charges are also separated by other systems. The photo—induced lifetimes range through several orders of magnitude, from 100 fs in plasmonic materials to picoseconds to microseconds in semiconductors. These life lengths need to be contrasted with the typical duration of a chemical reaction (usually microsecond to millisecond).

A significant challenge in the study of photocatalysis is matching the charge lifetimes of various processes. Based on the materials used, we split the sections below into four groups: “semiconductors, QDs, 2D materials, and plasmonic materials” (Kosslick et al., 2021; N & Kumar, 2017).

11.1. Semiconductor-based photocatalysis

As the most established of the materials were discussed, semiconductor-based photocatalysis’ governing principles are reviewed in this section. A Schottky junction forms in an “n-type semiconductor when the flat band” potential is lower than the electrode reaction of the electrolyte. In a nutshell, electrons’ flow from an n-type semiconductor to an electrolyte when they come into contact in the dark, creating an equilibrium condition at the interface (Gao et al., 2017).

Regularly seen diagrams of band patterns are employed in particle systems, which shows a “flat” band. This is an illustration of a standard convenience method. The small size of the semiconductor, however, may mean that the level of band bending is not particularly high. It is possible that the entire particle is already close to the photo—generated charge diffusion distance (i.e., particle size LD) (Gao et al., 2017)

The following scenario to take into account is the semiconductor with hidden interconnections. This is intended to lessen the vulnerability of the Schottky junction on the semiconductor/electrolyte interface, which is in turn dependent on a wide range of hard-to-control interface properties.

11.2. QD-Based photocatalysis

Quantum dots (QDs) are semiconductor nanocrystals, according to Farré et al. (2011)having a reactive core that controls their optical properties. Zinc selenide (ZnSe), indium phosphide (InP), cadmium selenide (CdSe) are some examples of the semiconductors used to build these cores.

QDs are colloidal fluorescent semiconductor nanocrystals with a size range of 2 to 10 nm with narrow emission spectra and broad absorption spectrum. The principal used for this substance is the creation of imaging probes (Thakre et al., 2021). One distinct advantage of QD displays over conventional LCDs is their superior color accuracy. Other benefits include their higher energy efficiency and lifetime, as well as their wider range of potential applications.

Many applications for quantum dots (QDs) with special features can be found in the fields of energy, environment, and medicine. Due to their abundant availability, durability, availability, accessibility, and environmental friendliness, green natural resources are suitable for the synthesis of a range of nanoarchitectures. This critical review highlights recent advances in the environmentally friendly and sustainable synthesis of carbon, graphene, and metal-based QDs in addition to their important environmental applications, such as the creation of photocatalyst hydrogen, the deterioration of detrimental contaminants/pollutants, and the slight decrease in CO₂. It also underlines the principal difficulties and opportunities that remain (Z. H. Jabbar & Ebrahim, 2022; Jabbar, Ebrahim, et al., 2021), (SM, 2018).

The unique quality of QD-based technology using a CdSe quantum dot as an illustration. In comparison to the typical calomel electrode (SCE), the QD shows a VBM at +0.75 V and a VBM at V. When molecules are exposed to light, photogenerated ions can enter the molecules’ antibonding orbitals.

The same reduced target molecule or a molecular electron donor can be used to recombine with electrons from either a positive or negative charge to remove holes. When the same source provides the electrons for hole annihilation. The development of things to reduce the oxidation of the newly reduced target molecule may be challenging. A synchronisation of photoinduced charges with molecular energy orbitals of substances under investigation. There have been many responses (Liu et al., 2019). The initial research on charged kinetics at the meeting point of quantum dots and superconducting materials charge collectors was done by the Kamat group. The bandgaps increase from 1.9 to 2.4 eV and the QDs decrease when the CdSe crystals have varied diameters.

Unexpectedly, the valence band of QDs has mostly stayed intact. The potential grows as the CBM turns more adverse. TiO₂ and CdSe have different characteristics. The key findings demonstrate that smaller QDs have faster charge transfer rates to TiO₂. Ni²⁺ co-catalysts assist in this process, injection of 150 surface charges into, by altering the driving force, molecular substrates have been examined (e.g., Schottky barrier height) (Liu et al., 2019).

11.3. 2D layered materials-based photocatalysts

Similar to how QDs are related to compound semiconductors, 2D materials have developed into an entirely distinct subclass of materials with novel, distinctive properties lacking in bulk semiconductors. A 2D material’s bandgap could shift as a result of the quantum confinement impact when its thickness is reduced. Because of their layered topologies, two-dimensional materials like QDs display anisotropy in their physical characteristics. It was also demonstrated that differential charge separation takes place in layered BiOCl nanosheet formations, with the charge gap distance along the [001] direction being considerably lower than the typical separation distance along the [010] direction. The anisotropy was confirmed by various crystal orientations and the photocurrent response of BiOCl nanosheets to the breakdown of methane orange (MO). Due to the fluctuating surface potentials, the results are comparable to those obtained when experiments were done on BiVO₄ or TiO₂ with different exposed facets (Nguyen et al., 2022).

2D composite materials have been revealed to have superior charge transfer than single-phase 2D substances. To create 2D nanocomposites, Zn_0.8Cd_0.2S silicon particles were combined with reduced graphene oxide, and it was found that photogenerated electrons could flow from the “Zn_0.8Cd_0.2S bandgap to the RGO” layer more readily. It is assumed that the reduction of Cd²⁺ and Zn²⁺ is hampered by the gap between electrons and holes created by photons. For usage in similar applications, carbon materials, and/or carbon materials matrix composites with efficient charge separation have also been studied. For example, g-C₃N₄ has been utilized in single- or ultrathin-layered forms for reasons other than its semiconducting capabilities.

11.4. Plasmonic photocatalysts

One of the methods explained, and maybe the most unusual, is the way in which ions are isolated in plasmonic materials. This is due to the fact that the majority of plasmonic materials, except for the ones that are heavily doped, are metallic in composition, chalcogenides). The separation of electrons in plasmonic photocatalysts is therefore not adequately explained by the band theory (Yuan et al., 2016).

On an electronic energy scale, SPR activity would drive electrons to the plasmonic regions, making gaps at lower energies I. Landau damping (1100 fs) of electron injection away from the surface causes a Fermi-Dirac distribution. Landau households are instances of damping. Molecules that catalyze chemical reactions could directly transfer electrons from surface-absorbed plasmonic bands to the LUMO in photocatalysis (Yongsheng & Wang, 2011), and (Xian et al., 2020).

To improve charge separation, semiconducting current collectors are used. This method involves injecting electrons into the semiconductor’s CB after the plasmon thermal injection phases. At the metal/semiconductor contact, charge separation depends on the “Schottky barrier height ((ϕ))” in which states that lowering allows more electrons to get through “(QY(ω)=(ℏω − ϕ)2/(4EFℏω))”.

Lowering enables for more back electrostatic interaction while also allowing for more electrons to pass from the material to the semiconductor’s CB. On the other hand, a value that is too high might stop electrons from moving from a semiconductor to a metal. Plasmonic photocatalysts and particle or QD photocatalysts may have similar charge transfer mechanisms. For example, species electrons could move from microelectronics to a material (which has a higher Eg) through a Föste (with lower negative plasmon band energy) r). Dipole–dipole coupling is an energy transfer method used during resonance (Jabbar, Ebrahim, et al., 2021).

A plasmonic metal can also transfer electrons to a non-plasmonic metal. Heterojunctions SiO₂@Cu₂O could use a thin insulating layer for interface softening and dispersion reduction to prevent this energy transfer. To help semiconductor photocatalysts capture more light outside of their bandgap for visible and near-infrared light, PIRET was created as an illustration (Liu et al., 2019).

12. Semiconductor heterojunction photocatalysts

The heterojunction system utilizes methods for producing photocatalysts because of its viability, visible light sensitivity, photocatalytic activity, and accuracy in spatially charged particle pair separation with reduced recombination rate (Faraji et al., 2021). In semiconductors, heterojunctions come in two varieties in which “p-n heterojunctions and non-p-n heterojunctions” (Z. H. Jabbar & Ebrahim, 2022), (W. Zhao et al., 2015).

In a nutshell, this system is one of the most extensively utilized methods for producing photocatalysts because of its viability, visible light sensitivity, photocatalytic activity, and accuracy in spatial charged particle pair separation with reduced recombination rate (Faraji et al., 2021). In semiconductors, heterojunctions come in two varieties: The binary kinds of semiconductor heterojunctions are “p-n heterojunctions and non-p-n heterojunctions”.

12.1. P-n heterojunction

In a p-n heterojunction, two semiconductors are combined, with one being p-type (like Sb₂S₃) whereas the other being n-type (like Ag₂WO₄). The pathways taken by the transferred electrons after heterojunction are altered, causing the locations of the zones in the metal and semiconductor to change. This causes the n-type Fermi energy level (EF,n) to form at its CB and the p-type Fermi energy level (EF,p) to form nearby its VB. Due to electron/hole transportation during semiconductor heterojunction, the p-type Fermi energy level rises while the n-type Fermi remnant energy falls (Kefeni & Mamba, 2020).

12.2. Type I and type II heterojunctions

Electrically conducting photocatalysts of type I have semiconductors 1 and 2, with semiconductor 1 having a lower VB and a higher CB. The ions and holes from the CB and VB of semiconductor 1 would concentrate in semiconductor 2 as a result of the potential difference. Due to the different photogenerated electrons’ electron and hole transmission rates, radicals become more intense and last longer. The decreased oxidation number of the transmitted holes and electrons in semiconductor 2 will drastically lower the heterostructure’s capacity to redox a photocatalysts process (Manikandan et al., 2021).

Frequently, photocatalytic processes employ Type II heterojunctions. This technique moves semiconductor 1‘s CB and VB positions closer to semiconductor 2 than they would otherwise be. The detachment of electron–hole pairs occurs when photogenerated holes are transported to the VB of transistor 1 and photoinduced electrons are sent to the CB of transistor 2. The redox potential of the type II heterostructure photocatalytic activity will also be lowered by Lv and colleagues (2012) because of the diminished redox potential of transistors 2 and semiconductor 1, respectively (Z. H. Jabbar & Ebrahim, 2022).

12.3. Z-Scheme heterojunction

According to this type, the two main parts of the photosynthetic system are PS I and PS II. PS I was in charge of CO₂ fixation, whereas PS II was in charge of oxygen release. In response to exposure to visible light, excited electrons from PS II’s highest occupied molecular orbital (HOMO) travel to PS I’s lowest unoccupied molecular orbital (LUMO), which is excited to PS I’s highest occupied molecular orbital (HOMO) (Jabbar, Ebrahim, et al., 2021).

A heterojunction is created when “photogenerated holes on PS I and electrons on PS II” combine after migrating over conductive materials or the interfacial phase. Despite the fact that fewer people are carrying. Increasing the redox ability requires more holes and the holes concentrated in g-VB C₃N₄‘s (+1.4 eV) lack the necessary oxidizing strength to convert OH into •OH (+2.38 eV). The Z-scheme heterojunction has developed considerable oxidation and reduction capabilities as a result of the usage of silver nanoparticles as a link for recombination “between electrons in the CB of Ag₂CO₃ and holes in the VB of Ag₂CO₃”. The process will involve a larger number of participants, boosting the redox capacity. It was kept photogenerated holes and electrons at lower levels. Greater PS I and VB CB and VB of PS II, respectively (Gao et al., 2017).

12.4. Core/Shell nanocomposites

Biphasic materials with an inner core structure and an exterior shell formed of various materials are known as core–shell-type nanoparticles. These particles have attracted attention because they can display distinctive characteristics resulting from the combination of the material, shape, and design of the core and shell.

Core-shell nanoparticles for microfluidic drug delivery. Because of their improved healing and diminished negative effects, biodegradable nanoparticles are used for drug delivery. Moreover, a number of conventional methods can increase the lower drug loading efficacy.

The main advantages of core-shell nanomaterials are the lowered reactivity and modified thermal stability of the core material, which improves the core particle’s proper functioning and degradability (Jeseentharani et al., 2013).

These nanostructures are heterogeneity nanoparticles made of different nanomaterials, such as alloys and metal oxides, as well as elements and other compounds. Biphasic nanomaterials with an interior phase (such as Fe₃O₄, Ni, Fe₂O₃, etc.) and an exterior shell made of various elements are known as core/shell nanostructures. Biphasic nanomaterials with an inner phase include core/shell nanostructures in general. Fe₃O₄, Ni, Fe₂O₃, and other materials, as well as an exterior shell constructed from other components (Qin et al., 2020).

Based on the characteristics of these nanocomposites, the types are defined or defined in such categories. It could be a core or shell with two types of particles in which the particles could be organic and inorganic. Core/shell NCs that are both inorganic and inorganic in which they typically consist of an organic layer polymeric and an organic layer on top of such a core. The polymer coating has several benefits (Kosslick et al., 2021).

Additionally, offering this type of characteristics is enhanced by such compatibility with NCs in organic and inorganic cores and shells. They are made of an inorganic shell. Double organic and inorganic properties in general are advantageous for organic/inorganic core/shell NCs. Abrasion resistance, colloidal and thermal strength, oxidation resistance, and refining the forte of conservative core/shell nanocomposites are only a few of the functions of the inorganic shell. A Type-II heterojunction was produced by consistently dispersing Ag₂ZrO₃ nanoparticles onto the g-C₃N₄ sheet (Liu et al., 2019).

12.5. Supported nanocomposite structure

These are considered to be existing in recent years as photocatalysts. Nano TiO₂, ZnO, and Ag₂WO₄ are a few examples of nanomaterials used in photocatalysis. Due to their robust UV photocatalytic activity, chemical stability, affordability, and nontoxicity, many photocatalysts have stimulated a lot of study into their practical uses. There are disadvantages in which having lower band gap, large surface area, recombination rate recovery and wide band gap energy aggregation effects. The prevalence of photocatalytic reactions has increased as a result, clusters of TiO₂ and Ag₂WO₄ impeded the procedure (Thakre et al., 2021).

Clusters of TiO₂ and Ag₂WO₄ impeded the procedure. As a vital response to these problems, photocatalysts with a supported nanocomposite structure have been created. It is proper as a crucial response to these problems to create nanocomposite in which a special characterization is provided. Benefits such as sizable specific surface area and non-degradability should be present in supporting strong photocatalytic adherence to photocatalysts and chemical inertness (Fatima et al., 2022).

A supported heterogeneous nanocomposite (g-C₃N₄/Ag₂WO₄/AgBr/GO) was fabricated by Wang et al. (2019) using a co-deposition technique assisted by hexadecyl trimethyl ammonium bromide CTAB. A straightforward in-situ deposition procedure was used to create the g-C₃N₄/Ag₂WO₄ (suspension (A)) composite by depositing Ag₂WO₄ nanorods in the shallows of nanorods. The “g-C₃N₄/Ag₂WO₄/AgBr/GO” displayed remarkable photocatalytic activity toward tetracycline (TC) degradation after 100 min of simulating sunlight exposure (91.64% elimination). Zou et al. (2022) talked about the use of aluminosilicate clay minerals (ACM) like kaolinite and montmorillonite as photocatalysts (Soraya1 et al., 2022).

13. The recycling and reusing of AgVO₃ nanocomposites

Reusing waste materials is commonly referred to as recycling, though occasionally special techniques are needed for trash recovery or conversion into finished goods or raw resources. Zero-waste production or the circular economy is an industrial system that permits remanufacturing and reuse. In the modern world, closed-loop recycling is the primary industry strategy for developing the architecture of a circular economy. Additionally, recycling is effective, particularly for composite materials because of how easily their physical qualities may be changed. In conclusion, a circular economy helps to create goods that have the right mechanical qualities as well as reduce harmful materials and trash (Nguyen et al., 2022).

This is despite the fact that numerous published studies discuss composite material recycling methods. Few of them deal with the methods for recovering in materials at the end of their useful lifespans. In addition, information on polymer composite recycling methods, notably the computation of energy requirements in each recycling step, is confusing and lacking. The recycling and reusing of AgVO₃ can be utilized for other purposes (Liu et al., 2019).

In-situ bio-nanocomposite beads made of recyclable chitosan (Cs) and silver (Ag) nanoparticles are described in the research for use in catalytic processes. For the first time, Ag@Cs nanocomposite hydrogel beads were created using an alkaline ethanol solution as a physiological bridging and reducing agent. Prior to and following the incorporation of varied Ag concentrations through the hydrogenation of harmful nitro group to glutamic acid, as a safer structure, the produced beads’ catalytic activity was assessed.

According to HRTEM, the developed Ag atoms have an average size of around 6.7 nm and are distributed evenly throughout the Cs. The optimum Ag@Cs combination beads have significant catalytic performance with a kinetics constant of 0.143 min1, Ag hypersensitive and a vast surface area working together in a synergistic way. In order to confirm the catalyst’s stability during the nitrophenol elimination process, regeneration tests were also performed.

14. Kinetic adsorption for photocatalytic

The kinetics regarding the photocatalytic process can be calculated using the following formula:

-LN(C/Co) = t*K app

where the C is considered to be the original attentiveness and the C is the dosage of the solution in mg/L, while it is considered to be the time dependent and the amount K is a constant for the application. The model provides the equations for the kinetics’ dependency on environmental factors such as photocatalysts concentration and light intensity (Jabbar, Ammar, et al., 2021).

In addition, initiatives have been taken to investigate the photocatalytic oxidation reaction kinetics and intermediates (Anchieta et al., 2014). Visible-light responsive Titanium dioxide has been demonstrated to be affected by a number of kinetic and environmental factors, including starting dosage, light levels, and moisture content (Aparna et al., 2018; Azzaz et al., 2021). Understanding the photodegradation reaction in both dark and light circumstances may benefit from a thorough investigation of the sorption processes occurring on Titanium dioxide. The adsorption kinetics of a visible-light-active and the successive photocatalyst photodegradation process of pollutants under visible-light irradiation and in the absence of light were studied.

It is well acknowledged that the most significant reaction pathways in the elimination of organic contaminants from water are adsorption and photocatalytic degradation. It is preferable for the treatment catalyst to have both photocatalytic and adsorption capabilities. For the adsorption kinetics, the two most important ones are Langmuir and Fredundlich isotherms (Swady and Jawed, 2021).

Some of researches expressed such experimental data were interpreted using a variety of models to identify the governing mechanisms. The “pseudo-second-order model” and the Rhodamine B (Rh B) dye’s adsorption kinetics were in agreement (R² = 0.992). The observed findings are consistent with the Fredundlich and Langmuir isotherm models (R² = 0.937 and 0.993, respectively), and Rh B’s maximum capacity for adsorption is 7.26 mg/g. The Langmuir model offers the best fit to the adsorption experiment datasets examined in this study. Investigations on Rhodamine B (Rh B) dye destructive over nanocomposite produced 90.4% of Rh B degradation, which was significantly higher than that of PgCN and CZTS. After three runs of recycling, the nanocomposite still exhibited 75.3% of its original concentration. Finally, a viable method for Rh B degrading over “CZTS@PgCN” composites was discovered.

15. Application related to metal ferrites and AgVO₃ nanocomposites

The different type’s metal ferrites are used for catalytic purposes. Without losing their magnetic characteristics, silica and titania core-shell nanostructures are also employed. Decomposition (especially photocatalytic) and there are only a few of the activities that use ferrite nanoparticles as catalysts. It is simple to remove ferrite nanocatalysts from reaction systems and re-use them for up to many runs almost without losing any catalytic activity (Gupta et al., 2020). The results showed that the geomorphology and characteristics of the nanocomposites are meaningfully influenced by the concentration of oleic acid (Jabbar, Ammar, et al., 2021).

The best nanostructures for targeted medication delivery are thought to be metal ferrite nanocomposites. In addition, the modification of metal ferrites in their structures improves the activity of their performance in such applications. Finally, various obstacles that still stand in the way of getting the targeted medicine to people were emphasized. The biggest problem is that there aren’t enough research using people as subjects. Still dependent on animals, scientists are reluctant to experiment with humans.

Spinel ferrites have drawn a lot of attention from all around the world due to their appealing prospective applications. The study focused on various spinel ferrites synthetic protocols, each of which can affect the ferrite’s characteristics. The effectiveness of metal ferrites depends on visible-light production, band gap, and particle size of the nanoparticles. Ferrites have a great deal of latent for dye degradation in an advanced oxidation process when H₂O₂ is present and creates a Fenton-type system (Z. H. Jabbar & Ebrahim, 2022). Metal ferrites have good electrochemical characteristics. Ferrites of metal were discovered to form crystals. CoFe₂O₄ has the highest specific capacitance when compared to other metals ferrites (SM, 2018).

Utilizing visible-light active photocatalytic materials has the potential to alter our world’s energy landscape and open the door to a carbon-neutral civilization. Currently, the majority of photocatalysts are made using a low-ecologically sound, energy-dispersive, and fossil-based synthesis method. Recently, research has concentrated on the creation of novel heterogeneous photocatalysts created using environmentally friendly and sustainable synthetic methods. These tactics span the wide use of plant extracts, valuing and reusing the metals found in industrial sludges, or from the development of synthetic tools for mild reaction conditions to the application of solventless procedures (SM, 2018). Based on two distinct strategies: developing sustainable synthetic techniques and using trash and biomass as a sources of chemical in the photoactive materials thetic textile effluents frequently contain significant amounts of processed dyes, some of which may be quite dangerous. In this study, the production process for ZnFe₂O₄@ZnO is explained. By applying photocatalytic methods to eliminate Rhodamine B using a simple solution combustion, evaluations were made into the potential of nanocomposite materials. The research showed that Rhodamine B degradation was more successful. Using a catalyst which gives a removal efficiency 91.87% of the time, “Reactive oxygen species’ (O⁻² and OH) impact” on the excitation of electrons was the main mechanism for photocatalysis that was put forth (Dong et al., 2015) (Soraya1 et al., 2022).

The ZnFe₂O₄ catalyst could be recycled in more than three cycles. In a comparison study, ZnFe₂O₄-50 percent @ZnO demonstrated the best photocatalytic performance in comparison to other nanocomposites. In order to handle organic dyes, it can be expected to be a promising photocatalyst (Al-Husseiny et al., 2021). To choose the photocatalyst in which is effective in heterogeneous photocatalysis has been extensively investigated in many applications. The catalysts widespread use is due to their high photocatalytic activity, robust, cost-effectiveness, and photosensitivity (Al-Husseiny et al., 2021).

The magnetic and physical attributes of exploring the most common ferrite compounds are better strength than the commercial material. Researchers have devised a number of techniques overcoming these constraints. The coupling of various semi-conductors ranks first among these substances to create nanocomposite materials in which they are readily recoverable. The development of magnetic materials has advanced, and that is what this review is focused on. Nanocomposites of zinc oxide and titanium oxide with ferrite are considered to be the most used as the foundation (Abazari & Mahjoub, 2017).

The (Cu_xNi_1-xFe₂O₄) nanocomposite has been made and is the subject of the current study. (CNTs) were created using a wet-chemical process. The composite that was created and the synthesis of “NiFe₂O₄ and Cu_xNi_1-xFe₂O₄” with XRD data was validated using tetragonal lattice composition by substituting (Kokkinos et al., 2020). Cu⁺² ions in NiFe₂O₄ had a “moderate crystallite size of 32 nm”, while Cu_xNi_1-xFe₂O₄/CNTs did not. SEM analysis revealed spherical Cu_xNi_1-xFe₂O₄ nanoparticles with aggregated blocks when combined with CNTs with a high surface. Pure NiFe₂O_4’s conductivity increased and the S/m values were 0.028 and 0.22. For CV, which was 1.4, Cu_xNi_1-xFe₂O₄/CNTs demonstrated maximum degrading efficiency (92.9%) compared to NiFe₂O₄ and Cu_xNi_1-xFe₂O_4, respectively, and 1.8 times higher.

Chemical precipitation and hydrothermal methods were used to successfully create Ag₃VO₄/b-AgVO₃ nanocomposites. In comparison to pure materials, the composites attributed to the coordinated energy structures. The sample with the uppermost photocatalytic action for Rh B degradation displayed the removal efficiency of about 2.4 times when compared to nanocomposites. Active species for the destruction of Rh B include holes and hydroxyl radicals, and a potential mechanism for increased photocatalytic activity was put forth (Kosslick et al., 2021).

Spinel ferrite properties and the manner of manufacture are important in discussing. Our findings demonstrated that MFe₂O₄‘s M-site metal substantially impacted the organic persulfate oxidation catalytic process. The effectiveness of the removal followed the order of CuFe₂O₄, employing several MFe₂O₄ persulfate systems CoFe₂O₄, MnFe₂O₄, and ZnFe₂O₄. In addition, it was discovered that the hydroxyl group on a surface was not the primary factor regulating the reactivity of in a persulfate solution, MFe2O4. Furthermore, artificial techniques (solvothermal, sol-gel, further compared were the coprecipitation and) for MFe₂O₄. As a result, the as-produced CuFe2O4 displayed better acid orange was around (96.8%) and 62.7% for comparing results from solvothermal methods (diclofenac) and good reusability coprecipitation routes, etc. This study deepens our understanding of spinel ferrite (Kosslick et al., 2021).

Gupta et al. (2017) describes the use of surfactants to synthesize metal ferrites using the co-precipitation method, and a total of all four ferrites demonstrated outstanding dye degradation rates between 2.065 and 2.417 min1 at neutral pH. When NiF was operating at its peak efficiency, it was discovered that methylene blue and methyl. Within 1 min of UV exposure, the colors changed. The amount of total organic matter examined was found to be around 40% after 5 min and around 60% after 50 min. Scavenger test was performed and seven consecutive cycles were made too through this experiment. Consequently, it was determined that these photocatalysts are extremely well suited for cleaning up wastewater that has been tainted with dye (Gao et al., 2017).

In the current investigation, metal-loaded Mo-BiVO₄ was photocatalysts loaded with metal oxide “MO: Ag₂O_x, CoO_x, and CuOx” were produced by a wet impregnation process and used to dye under visible light during microbial inactivation (VL). The outcomes of the bacterial inactivation indicate that the CuO_x-loaded Compared to CuO_x/BiVO₄, Mo-BiVO₄ nanostructure has much better antibacterial properties. Additionally, throughout the bacterial inactivation, it showed bacterial inactivation producing reactive oxygen species which cause cell death and cause troublesome and the ROS can kill bacteria by damaging their metabolic processes and the plasma membrane. Consequently, a fresh thought for a photocatalytic antibacterial method activated by visible light for upcoming disinfection applications (Peng et al., 2020), (Azzaz et al., 2021).

In order for a semiconductor photocatalyst to effectively purify water, effective charge extraction and cycle stability are essential. A number of characterization findings demonstrated the Ag₂S/AgVO₃@GAs’ synergistic effects. Adapt the superior characteristics of the macroscopic porous Ag₂S and AgVO₃ airborne graphene. In addition, because chitosan (CS) was chelated for AgVO3, it was utilized to stop the agglomeration/shedding of Ag₂S and AgVO₃. Thus, the photocatalytic activity and reaction stability occurred. The nanocomposite was examined to be having advantage in stability and remarkable photodegradation effectiveness. Escherichia coli disinfection activity for methyl orange was found to have 97% in 40 min and later which becomes 100% of antibacterial effectiveness (Nguyen et al., 2022), (Rotjanasuworapong et al., 2021).

Comprehensive research has been done on the kinetics of the reaction, the mechanism of catalyst degradation, the stability of the catalyst, and the functions of “ZnFe₂O₄ and C₃N₄” in the photoreaction. The “ZnFe₂O₄/C₃N₄” photocatalysts were examined in this experiment, and it was found to be outstandingly catalytic under neutral conditions. The degradation is considered to be excellent about two times greater than the control nanocomposite. The results exhibited a stable performance for photooxidant for organic pollutant (Lu et al., 2015). Findings demonstrate that the photoinduced carriers’ separation rate in Ag/AgVO₃/BiVO₄ heterojunctions can be strongly advertised. Abatement was used to gauge the sample’s photocatalytic activity of organic pollutant. The findings show Ag’s photocatalytic activity. AgVO₃/BiVO₄ heterojunctions perform better photocatalytically for the destruction of Rh B. Trapping Measuring results show that separation of holes and radical groups are key players in the deterioration of Rh B, which is related to in the samples to the presence of Ag. Using all of the information from the characterization, a Z-scheme mechanism of it was suggested to separate and transfer photogenerated charges. Additionally, the improvement in photocatalytic affect the performance of Ag/AgVO₃/BiVO₄ heterojunction carriers (Lu et al., 2015) (Sher et al., 2021).

Ag@AgVO₃/BiVO₄ heterostructure’s shape and photocatalytic activity were greatly influenced by the composite’s BiVO₄ concentration. Additionally, Ag@AgVO₃/BiVO₄ was found to be a good photocatalyst which enhanced removal efficiency for pollutants. Based on the results, it was found that the mechanism examined between two semiconductors play an effective role in the effectiveness of degradation. This characterization was found to be effective due to the photogeneration and recombination processes. This effort is anticipated to motivate other initiatives for the construction and enhanced photocatalytic performances for the application of energy (Shakil et al., 2020).

Results showed that the composites had improved surface characteristics and increased absorption of visible light. This synthetic SnO₂/g-C₃N₄ nanocomposites with varying SnO₂ concentrations are used to break down tetracycline. They exhibited good deterioration efficiency when exposed to visible light. The effectiveness of tetracycline’s degradation by 1%, 2%, 3%, and 5% SnO₂. The removal efficiency reached 90% or higher. Thus, the material itself has 40 or less percent removal (Lu et al., 2015). The nanocomposite innovated displayed perfect performance in the decomposition of some antibiotics into aqueous liguids and in other pharmaceuticals having the same chemical structures (Shakil et al., 2020).

Technologies for wastewater cleanup have advanced. The creation of nanomaterials has made it possible for mankind to take various approaches of treating the many types of pollutants that are present in waste products from various sources. Among the various substances, semiconductor substances have found various uses in the environment because of their exceptional photocatalytic abilities (Tanveer et al., 2022).

TiO₂ and ZnO work better than other materials such as photocatalysts or adsorbents and are considered excellent materials in removing organic and inorganic pollutants. Graphene, on the other hand, Graphene nanocomposites have exceptional physical, optical, thermal, and electrical properties. Nanocomposites made of TiO2 with grapheme or zinc oxide with graphene have been evaluated for treatment of wastewater using photocatalysis. These applications showed good performance in water purification process and photo activity development (Tanveer et al., 2022).

A significant portion of pretreatment dyes is frequently present in synthetic textile effluents, which may be highly hazardous. The creation of ZnFe₂O₄@ZnO in this study was done. We demonstrate the easy solution combustion of nanocomposite materials and its promise for Rhodamine B elimination using photocatalysis using LED lights for visible light. The outcomes showed the greatest efficiency of Rhodamine B degradation with a catalyst and removal efficiency was at 91.6%. The principal suggested at least four photocatalytic reusing cycles were possible for the ZnFe₂O₄-50%@ZnO catalyst. The ZnFe₂O₄-50%@ZnO composite exhibit better performance than others as it is considered to be a promising photocatalyst (Mapossa et al., 2021).

This brief review describes the usage of using zinc ferrites and composites made of ZnFe₂O₄ to photocatalytically break down organic dye. Ferrite of zinc is considered to be the most common, thermal techniques and solid-state or water-thermal route. These ferrites resulted in an improvement in photocatalytic efficiency. ZnFe₂O₄ is a crucial magnetic material (Mapossa et al., 2021).

A straightforward preparation procedure was used to create ZnFe₂O₄/TiO₂ nanoparticle-induced visible-light-active photocatalysts picture catalyst, demonstrating that the TiO₂ nanoparticles and ZnFe₂O₄ nanoparticles were mixed together with TiO₂ and the amount of hydroxyl on their surfaces was greater than that on TiO₂‘s surface. The findings of the photocatalytic experiments showed that ZnFe₂O₄/TiO₂ could successfully photodegrade methyl orange and this ferrite had a noticeable role brought on by light (Tanveer et al., 2022). In this research, some measurements have been done like TOC “total organic carbon” to determine the degree of decompositions. It demonstrated that the nanocomposite expresses a degradation in what is considered a superior photocatalytic activity. Based on the scavenger tests, it was shown that the superoxide radials were the one that is dominant as a primary component in the photocatalytic.

(MB) removal via the photocatalytic method was researched. TiO₂ was used as the catalyst and external UV radiation (UV) was present. According to the relevant data, dye mineralization was more favorable at high pH stages and low salt attention, and it reduced as dye concentrations increased. Additionally assessed was the coexistence of organic and inorganic pollutants (Zinc). The matching experimental findings demonstrated that it slowed down for greater concentrations at low quantities of metal ferrites. As the solutions degraded, the carbon contents were measured and revealed complete mineralization (Sher et al., 2021).

The preparation of a simple one-step hydrothermal ZnFe₂O₄graphene nanocomposite photocatalyst with various graphene contents was accomplished. Methylene blue’s rate of photodegradation was discovered to increase in the presence of H₂O₂. After only 5 min of exposure to visible light, (MB) was 88%, and after 90 min, it reached up to 99%. As a pure ZnFe₂O₄ catalyst, ZnFe₂O₄graphene performs a dual function. The hydroxyl radical irradiation is produced when H₂O₂ undergoes photoelectrochemical breakdown under visible light. The ZnFe₂O₄ combination contains grapheme because of the magnetic characteristics of the ZnFe₂O₄ nanoparticles (N & Kumar, 2017).

In other studies, ZnFe₂O₄ nanocomposite was established and used as a photocatalyst. At the calcining facility, the precipitate for 3 h, a temperature of 600°C, 700°C, and 800°C was used to produce crystal nature. The consequences of the effects of calcination temperature on ZnFe₂O₄ nanoparticle characteristics were examined. The outcomes indicate that the ZnFe₂O₄ phase, crystallite size, and energy gap are all affected by the calcination temperature particles of ZnFe₂O₄. The best photocatalytic performance is demonstrated by 700 °C-calcined ZnFe₂O₄ nanoparticles smaller crystallite size and higher absorption contribution to Rhodamine B degradation.

In order to create ZnFe₂O₄ nanoparticles, zinc nitrate and ferric nitrate were combined in an aqueous solution. The particles generated by both solvents have a cubic spinel shape. These nanoparticles produced microporous and mesoporous structures, respectively. When 1,4 butanediol was utilized as the solvent, more pore volume, surface area, and catalytic action for contaminant squalor were discovered (Azzaz et al., 2021; Soleimani et al., 2023).

Rhodamine B (Rh B) degradation served as a measure of the ferrite samples’ photocatalytic activity. Our findings show that compared to pure ZnFe₂O₄ ferrites, the ZnNd_xFe2_xO4 samples had better removal efficiencies. The ZnNd_0.03Fe_1.97O₄ sample produced a degradation efficiency of 98.00% after 210 min. It was made clear how many variables, including catalyst loading and H₂O₂ oxidant concentration, affected the degradation of Rh B dye. The separation occurs based on a doping mechanism in which the separation between electron and holes occurs (Cuong, Trang, Ha, Viet, & Phuong, 2021).

By increasing the separation of charge carriers produced by photons, it has been demonstrated that heterostructure creation can increase photoactivity. The synthesized NFO/AVO/AVPO composites exhibit enhanced visible-light performance when compared to control metal ferrites. Photoactivities improved photodegradation efficiency for methylene blue compared to control pollutants. The creation of conjunction between two semiconductors is responsible for this improvement but also lays the door for heterojunction photocatalysts which improves photoactivity (Nguyen et al., 2021).

Ag/AgVO₃ nanowires and silver meta-vanadate nanorods were fabricated in a simple sonochemical process in aqueous media. The outcomes show that the development of Ag/AgVO₃ nanowires is encouraged by an inert environment. According to investigations of the catalytic process, the Ag/AgVO₃ nanowires were completely degraded by photocatalysis of Rhodamine B in 45 min when exposed to visible light. Ag/bacteriophage AgVO₃‘s activity Bacillus subtilis and Escherichia coli were used as test subjects for nanowires with the least growth-inhibiting (Kelebogile Mmelesi et al., 2021). The concentration value for the antibiotic ciprofloxacin for E. coli was discovered to be 50 and 10 times lowerو respectively, and B. subtilis. The “b-AgVO₃ nanorods’” antibacterial characteristics demonstrate that in the event of the improved antibacterial effect it is also due to contribution from the Ag scattered “Ag/AgVO₃ nanowires” the AgVO₃ backing (Qin et al., 2020).

AgVO₃ crystallization is required for the first-ever successful manufacture of the innovative photocatalyst employing a straightforward one-step in-situ hydrothermal method. According to the photocatalytic studies’ findings, CoFe₂O₄/Ag/Ag₃VO₄ composites have higher photocatalytic activity that causes Escherichia coli, MO, and TC to be destroyed (E. coli) (Nguyen et al., 2022), (Oluwole & Olatunji, 2022). The two are crucial reactive species for the CoFe₂O₄, Ag, and Ag₃VO₄ photocatalytic system. In addition, the produced “CoFe₂O₄/Ag/Ag₃VO₄” composite is simple to extract from the solution. It is regarded as a photocatalyst that promotes the treatment of wastewater. More organic pollutants are degraded by the nanocomposite of “CoFe₂O₄@Ag@AgVO₃” than by pure AgVO₃ or metal ferrites. The hydrothermal method has been utilized for the production of such “plasmonic photocatalyst” such as crystallized AgVO₃. Five items and intermediaries produced in the breakdown of Bisphenol A by photocatalysis were also discovered (Kefeni & Mamba, 2020).

Dye is a dangerous substance that is frequently found in industrial wastewaters. The effectiveness and low cost of adsorption techniques in the elimination of organic molecules (Aparna et al., 2018). After the pollutant has been treated, magnetic nano-composite was utilized for the treatment and the nanocomposite was for the removal of dyes and the characterization of the composite was perfect, such as surface area and diameter and others. The Langmuir isotherm was followed by batch adsorption data. The MFe₂O₄@GO’s maximum adsorption capacity. There were 25.81, 50.15, and 76.34 mg g1 copper, cobalt, and Nickel (Peng et al., 2020).

Composition was looked at in this review due to their distinctive qualities, such as their superior photocatalytic and antibacterial activities, high pollutant adsorption capabilities, and utilization of methylene blue as cobalt ferrite nanoparticles and nanocomposites, these materials have attracted the attention of scientists. Several nanocomposites and their semiconductors are discussed here, such as silver meta-vanadate, metal ferrite, and nanocomposite of both of which enhance the photo-catalysis process with maximum removal of pollutant degradations (Faraji et al., 2021).

As a result, several recently released research reports on nanocomposite and accessible nanocomposites that merit review. Metal ferrites with silver metavanadates are the subject of the review methods for creating nanoparticles, accessible surface stabilization for enhancing photocatalytic capabilities, and potential ways to improve antibacterial action. Additionally, potential methods of recovery and reusability after use are discussed, which are essential for the cost-effectiveness and sustainability of those nanocomposites as shown in the Table 1. Several examples of nanocomposites are indicated by their mechanism and their pollutant degradation process (Faraji et al., 2021). Table 1 demonstrates all the studies related to the photocatalytic process with their application (Yao, et al., 2014).

Table 1. Several examples of nanocomposite with their characteristic

Materials	Method of treatment	Pollutants	Removal efficiency	Concentration	Type of photolysis	References
NiFe2O4/Ag3VO4/ Ag2VO2PO4	Z-scheme heterostructure heterojunction photocatalysts	MB	90%	0.15 mol/L	Visible light irradiation	Changhua Su et al. (2021)
AgVO3 and Ag/AgVO3 nanowires	photocatalysts	antibacterial activity	94%			Anamika Singh et al. (2013)
AgVO3 and Ag/AgVO3 nanowires	photocatalysts	Rhodamine B	93%		Visible light	Anamika Singh et al. (2013)
Ag-AgVO3/g-C3N4 composite	photocatalysis	Antibiotics tetracycline	83.6%.		Visible light	Danyao Chena et al. (2019)
Ag/AgVO3/RGO	ternary plasmonic photocatalyst	Bisphenol A.	90%		Visible light	Wei Zhaoa, et al. (2015)
MgFe2O4, CaFe2O4, BaFe12O19, CuFe2O4, and ZnFe2O4)	photocatalysts	methylene blue	96 and 85%		UV-visible light	Ali et al. (2018)
CoFe2O4, NiFe2O4, MnFe2O4, CuFe2O4, ZnF2O4	photocatalysis	ethylene glycol	80%			Aparna et al. (2018)
ZIF-8/NiFe 2 O 4	photocatalysis	methylene blue			visible-light irradiation	Faraji et al. (2021)
CoFe2O4/Ag/Ag3VO4	photocatalysis	MO, TC and killing Escherichia coli (E. coli).	degradation efficiency of 94% in 120 min	5 % CoFe2O4/Ag/Ag3VO4	visible-light irradiation	Jing et al. (2016)
Ag/AgVO3/RGO	plasmonic photocatalyst photocatalysis	Bisphenol A	96.2%		visible-light irradiation	Zhao et al. (2015)
MFe2O4, M: Mn, Fe, Co, Ni	photocatalysis	HER	90%		visible-light irradiation	Aksoy et al. (2022)
MFe2O4@GO (M ¼ Cu, Co or Ni)	photocatalysis	methylene blue	90%	25.81, 50.15 and 76.34 mg g_1	visible-light irradiation	Rhay B. et al. (2020)
Cobalt ferrite nanoparticles	photocatalysis	antimicrobial activity	90%		visible-light irradiation	Mmelesi et al. (2020)

16. Conclusion

The usefulness of semiconductor photocatalysts in environmental applications has established a focus in current reviews. The geometry, arrangement, and production of semiconductors are the main topics of this review. So, it is important to assess current semiconductor photocatalysis research. The current study focuses on important issues that were barely touched upon in other studies. It offers crucial information about pollutant and microbiological exposure, as well as the benefits and drawbacks of traditional, pharmacological, and microbiological approaches for removing them. A few of the operating characteristics that were briefly reviewed included the photocatalyst dose, starting initial concentration, acidity of the liquid, ambient lighting, oxygen concentration, addition of hydroxyl radicals, immediate photolysis, and catalyst loading. Examples of several semiconductor substitution methods are provided in this in-depth analysis. Heterogeneous nanoparticles with a supported or core/shell structure have also been thoroughly investigated. In terms of photocatalysis, it was also described how “heterojunction photocatalysts such p-n, type I, type II, and Z-scheme heterojunctions” work. The use of Ag-AgVO₃ nanoparticles for bacterial breakdown is also discussed.

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Nuralhuda Aladdin Jasim

Nuralhuda Aladdin Jasim use of various metal ferrites in the photocatalytic process for degradation to remove organic contaminants. This research also seeks to confirm the effectiveness of several synthetic metal ferrites in the removal of organic contaminants using photocatalysis. The author’s activities involve developing nanotechnology. Papers based on nanoparticles that investigate how the characteristics of organic natural matter affect the impact of nanoparticles on plants, the dispersion of nanoparticles and their impact on plants, and other papers based on research in the nanoparticles field, have been published. The author is also interested in how different coagulants, either natural or synthetic, are utilized to treat water. She has a keen interest in GIS methodology by doing spatial analysis of forest biomass in some state located in different areas.