Novel multinary nanocomposite of GO/AlCrO₃/SiO₂/Mn₃O₄/SnO₂: synthesis and electrochemical performance for energy storage system

Abstract

A unique nanocomposite GO/AlCrO₃/Mn₃O₄/SiO₂/SnO₂ synthesized through hydrothermal method serves as an electrode material for electrochemical supercapacitors. The material structural and optical characteristics were studied using various techniques. Interestingly, the average crystallite sizes were 16.88, 21.2, 20.81 nm for AlCrO₃, GO, and GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite, respectively. The nanocomposite displayed 16 nm spherical grains due to particle aggregation on the graphene oxide surface causing structural deviations evident in the Raman spectrum slope around 1578 cm⁻¹. FTIR spectra revealed distinctive bands at 2097 cm⁻¹ and 1523 cm⁻¹ indicating metal–oxygen bonds. UV-Vis spectra disclosed a band gap of 2.85 eV and a zeta potential of 27.9 mV signifying stability. The hybrid electrode exhibited remarkable electrochemical performance boasting a specific capacitance of 2495 Fg⁻¹ for scan rate of 10 mVs⁻¹. Given its robust performance under high current densities, enduring stability and energy efficiency the material holds significant promise as an energy storage material particularly for supercapacitors.

GRAPHICAL ABSTRACT

KEYWORDS:

• Multinary nanocomposite
• sol-gel method
• nano-electrode fabrication
• energy storage application

1. Introduction

Due to the surging demand for electronic devices, energy storage has become a crucial focus alongside energy conversion [1]. With the need for alternative energy sources and higher energy consumption, improving energy storage technologies is vital given their dual optimization and high-power density. Supercapacitors, known for their impressive charge/discharge rates and long-lasting power have emerged as a significant solution [2,3]. These devices bridge the gap between rechargeable batteries and electrolytic capacitors due to their superior capacitance values. To achieve cost-effective high energy storage, environmentally friendly transition metal oxides with abundant availability and strong redox activity have been explored [4]. In recent times efficient oxide spinel-based materials have been synthesized for the supercapacitor applications [5–9]. The nano-flower and nano-plates like structures has also gained high attention for the supercapacitor applications [10].

Utilizing two-dimensional (2D) structures, extensive electronic diversity have been achieved. In light of escalating ecological concerns and the need for clean water and efficient energy storage, advanced energy storage devices with high energy and power density and prolonged cycle life have gained worldwide significance. Particularly in 2D edge environments, massive materials exhibit distinctive physical and chemical properties tied to electron and phonon confinement effects [11].

Graphene oxide characterized by its 2D nanostructure, exceptional electrical properties and large surface area has emerged as a prominent material in various applications. Its potential spans gas absorption, transistors, lithium-ion batteries, supercapacitors, lithium-air batteries, and drug delivery, garnering global attention. Introducing nanocrystals between layers of graphene oxide nanosheets enhances electrochemical characteristics making graphene oxide a compelling subject of research despite its relatively short history [12,13]. As a palpable semiconductor with substantial surface area, charge mobility, optical transparency, mechanical strength, thermal conductivity, and electrical conductivity graphene oxide holds promise [14,15] (Figure 1).

Figure 1. Graphene mechanical and electrical properties.

ABO₃-type perovskites, a class of compounds with diverse structures, have garnered interest [16]. Investigating chemical interactions between aluminium and chromium nitrate has revealed reaction products formed at varying temperatures [17,18]. Amid extensive research on chromium-aluminium compounds and their physicochemical properties, interactions between chromium nitrates and aluminium have been explored [19,20]. Anticipating the need for sustainable energy, catalysts like tri-manganese tetroxide (Mn₃O₄) play roles in methane and carbon monoxide oxidation and nitrobenzene reduction. Manganese oxides serve in energy storage, catalysis, sensing, and electrodes [21–23]. Mn₃O₄, an efficient and cost-effective catalyst, stands out [24,25]. SnO₂ with its theoretical capacity of 782.0 mAhg⁻¹ holds potential as a lithium-ion battery electrode material but its bulk counterparts face capacity degradation [26,27]. Nanostructured SnO₂ materials dispersed on graphene nanosheets using various methods exhibit improved capacity and stability [28]. Silicon dioxide nanoparticles valued for biomedical applications are functionalized due to their consistency and low toxicity [29–31].

Addressing graphene oxide aggregation challenges AlCrO₃, Mn₃O₄ and Na₂SnO₃.3H₂O are introduced onto graphene oxide sheets forming a stable 3D conductive network and hydrogen bonding configuration [32,33]. Electrochemical investigations confirm the potential of the synthesized multinary composite as a high-performance electrode for supercapacitors [34,35]. While the GO/multinary nanocomposite shows promising performance in energy storage and water treatment detailed studies on chemical reactions between chromium carbonate and aluminium nitrate at elevated temperatures are lacking [36–38]. The research introduces a novel multinary nanocomposite composed of graphene oxide (GO)/AlCrO₃/SiO₂/Mn₃O₄/SnO₂ representing a distinctive combination that offers unprecedented advantages in the realm of energy storage. This unique composite structure harnesses the synergistic effects of multiple materials potentially enhancing electrochemical performance for energy storage systems such as increased capacity and cycling stability. The significance of this work lies in its ability to address specific challenges within the energy storage field and contribute to the advancement of energy storage technologies positioning it as a noteworthy addition to the ongoing research in this domain.

2. Preparation methods

2.1. Synthesis of aluminium perovskite

To initiate the synthesis, combine 3.7 grams of aluminium nitrate and 7 grams of chromium nitrate in 50 ml of ethanol. The aluminium and chromium nitrates dissolve in the ethanol solution. After a period of time, introduce an appropriate quantity of citric acid into the mixture while continuously stirring. Continue to heat and stir the solution consistently for around 2 h until a gel-like substance is formed. Subsequently, dry the gel at a temperature of 75 ˚C. Then, subject it to annealing for a duration of 6 h in an oven at varying temperatures ranging from 600 ˚C to 1100 ˚C. Once this process is complete, grind the resultant material using an agate mortar. Store the ground powder in sample bottles for subsequent characterization [39].

2.2. Synthesis of trimanganese tetroxide

Commence the synthesis by combining 7 grams of chromium nitrate and 2.87 grams of manganese oxide within a beaker containing 50 ml of de-ionized water. Apply heat to the solution on a hot plate, maintaining a temperature range of 40–50 ˚C, and sustain continuous stirring for a duration of 20 min. Once homogeneity is achieved, gradually introduce 20 ml of ethanol into the mixture as a chelating agent. Subsequently, initiate the evapouration process by elevating the temperature to a range of 60–70 ˚C while consistently stirring until a gel with the desired brown hue forms. Proceed to desiccate the gel in a DHG-9202 oven at 105 ˚C for a period of 2 h. Following thorough desiccation, a brown powder is obtained. To further enhance the material, subject the Mn (NO₃)₂ powder to sintering in a VULCAN-D550 furnace at 800 ˚C for 3 h. Ultimately, utilize an agate motor to grind the sample into a finely powdered state [40].

2.3. Synthesis of graphene oxide

Graphene oxide (GO) is typically produced from pure graphite powder using a modified version of Hummer’s approach [41,42].

2.4. Preparation of GO@AlCrO₃ @SiO@ Mn₃O₄@SnO₂ nanocomposite

Graphene Oxide (GO) is synthesized using natural graphite flakes following the methodology described in the literature. To create GO@AlCrO3@SiO2@Mn3O4@SnO2, the process involves introducing GO into a reduction procedure alongside AlCrO3 and diethylene glycol (DEG) [43,44]. Moving on, the next phase involves combining the prepared GO@AlCrO₃@Mn₃O₄ composite with 40 mL of ethanol, 10 mL of water, and 5 mL of ammonia as per the as-prepared form (1 mL). Subsequently, 0.2 mL of tetraethyl orthosilicate (TEOS) is meticulously added drop by drop, and the reaction continues for a duration of 10 h under constant stirring. Following this, the dispersed GO@AlCrO₃@SiO₂@SnO₂ composite is introduced into a solution comprising 60 mL of ethanol/water, with ethanol making up 37.5% by volume. In this solution, 0.2 g of sodium tin oxide (Na₂SnO₃·3H₂O) and 0.36 g of urea are added while stirring. The amalgamated solution undergoes 10 min of continuous stirring before being transferred to a Teflon-lined stainless-steel autoclave. Subsequently, the autoclave is heated to a temperature of 200 °C and maintained at this temperature for a duration of 24 h. Upon completion of the reaction, the final product undergoes a sequence of procedures. It is subjected to four rounds of washing with ethanol and subsequently undergoes vacuum drying for 12 h at a temperature of 60 °C [45].

2.5. Preparation of working electrode

1 milliliter of ethanol is employed to dissolve 0.25 mg of the nanocomposite material. The mixture is subsequently subjected to sonication for a duration of 20 min. The resulting solution is then delicately deposited onto a glassy carbon electrode using a micropipette. The electrode with the solution is allowed to air-dry for approximately 15 min. Following this, the prepared electrode is subjected to vacuum drying for a period of 20 min at room temperature. To act as a binder, a small droplet of Nafion solution is applied. The proportion of the binder in relation to the total mass of the active substance is 5%. After the vacuum drying process, the overall mass of the active ingredient on the electrode is 0.25 mg/cm².

3. Instrumentation

For X-ray diffraction investigation, Brucker D-8 X-ray diffractometer equipped with a 40 VK X-ray source operating at a current of 40 mA and a step size of 0.02 was employed. Morphological and elemental analyses were conducted using the 20 kV TESCAN VEGA 3. Raman spectroscopy was performed by the high-resolution DONGWO OPTRON system from Korea, using 532 nm wavelength with a power output of 150 mW.

Cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy within the frequency range of 0.1 Hz to 1 MHz were conducted using the Gamry Potentiostat Interface 1000. The reference, counter and working electrodes employed were silver chloride (AgCl), silver wire and modified glass carbon electrode (GCE) respectively. The electrolyte used was 1M KOH and the results were recorded using a DELL laptop. For the electrochemical calculation of the active surface area at a scan rate of 100 mV s⁻¹ a standard redox solution was employed.

4. Results and discussion

4.1. XRD analysis

In Figure 2 the X-ray diffraction patterns of the cleaned and dried samples are presented. Notably, the presence of oxygen-based functional groups contributes to a distinct peak at 2θ = 11.5° in GO, corresponding to an interlayer spacing of 0.94 nm between the GO layers (JCPDS NO.75-2078). Figure 2(a) displays diffraction peaks at 2θ values of 20.37°, 24.94°, 34.15°, 36.84°, 42.15°, 51.10°, 55.70°, 59.24°, 66.15°, 74.54°, and 78.23°. These peaks align well with the (200), (211), (220), (321), (330), (510), (521), (530), (600), and (611) space groups, indicating a strong correspondence to the hexagonal AlCrO₃ with the p63/mmc space group (JCPDS card No.00-021-109). The diffraction pattern signifies the hexagonal structure of the material, with 2θ values consistent with those expected for AlCrO₃. In Figure 2(b) the GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite demonstrates diffraction peaks at 2θ values of 26.28°, 27.65°, 30.05°, 31.60°, 35.44°, 36.62°, 37.95°, 41.04°, 44.35°, 53.80°, 56.08°, 62.3°, and 65.76°. These peaks are all indexed as cubic. Additionally, the absence of other discernible peaks indicates that the SiO₂ in AlCrO₃@SiO₂ is in an amorphous state. The diamond-shaped peaks observed in GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ can be attributed to the (211), (200), and (220) reflections of hexagonal AlCrO₃ nanocrystals. Meanwhile, the broader peak around 11.5° corresponds to GO. Peaks corresponding to SnO₂ and SiO₂ are less conspicuous due to their lower concentration and amorphous nature within the material [46]. To explain this variance in lattice parameter values, we must look at the discrepancy in the size of ionic radii between the three metal ions, Mn ^+ 2, Al ^+ 3 and Si ^+ 2 [47]. If the spinel crystal lattice parameter is affected by a new phase of Al when it comes to the dielectric constant, AlCrO₃ has a higher value than Mn₃O₄. Each sample is determined using Scherer equation, and the results are displayed in Table 1 for each diffraction peak [48]. According to this study, the crystallite sizes of multinary metal oxides were smaller than those of metal oxides [49].

Figure 2. XRD pattern of (a) GO, (b) AlCrO3 and (c) GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite.

Table 1. Lattice parameters, particle, crystalline size and strain values of compound.

Sample	a (Å)	c (Å)	c/a	Crystal size (nm)	Strain from WH plot	Particle size (nm)
AlCrO3	9.089	9.089	1.000	16.88	0.800	07
GO	2.461	6.708	0.366	21.20	0.042	20
GO@AlCrO3@SiO2@Mn3O4@SnO2	8.320	8.320	1.000	11.81	0.0167	16

Figure 3 depicts the results of a Williamson-Hall (WH) analysis of the full width at half maximum (FWHM) (β) of different Bragg peaks used to determine the influence of strain. The coordinates of the y-axis are $\text{β}\mathrm{cos\theta }/\lambda$ and the x-axis is $4\mathrm{sin\theta }/\lambda$. Each sample strain is calculated from the slope of the linear line fitted to the data, and each sample crystallite size is calculated from the intercept on the y-axis. Table 1 displays the computed values of strain and crystallite size. Table 2 shows the miller indices and peak lists for the parent and composite materials.

Figure 3. WH plot curves of (a) AlCrO₃ and (b) GO@AlCrO₃@SiO₂@Mn₃O₄ nanocomposite.

Table 2. Miller indices and peak lists of AlCrO₃ and GO/AlCrO₃/SiO₂/Mn₃O₄/SnO₂ nanocomposite.

2$\mathit{\theta }$AlCrO3	$\mathit{\theta }$	hkl	2$\mathit{\theta GO}$@@AlCrO3@SiO2@Mn3O4@SnO2	$\mathit{\theta }$	hkl
20.738	10.369	200	26.085	13.0425	111
24.943	12.4715	211	27.655	13.8275	220
34.145	17.0725	220	30.046	15.023	311
36.837	18.4185	321	35.441	17.7205	222
42.145	21.0725	330	37.951	18.9755	400
51.108	25.554	510	44.347	22.1735	331
55.708	27.854	521	53.809	26.9045	422
59.238	29.619	530	56.080	28.04	511
66.149	33.0745	600	62.631	31.3155	440
74.541	37.2705	611	65.759	32.8795	531
78.225	39.1125	611	71.790	35.895	622
			74.121	37.0605	533

4.2. SEM analysis

Figure 4(a) shows SEM image of graphene oxide as due to the presence of functional groups primarily oxygen. GO was found to be a two-dimensional material with a sheet-like lamellar structure and increased sheet thickness near the edges. Due to their firmly suspended morphology, GO sheets did not exhibit bending behaviour [50]. The aluminium chromite nanoparticles maintained their nearly spherical morphology, while the graphene oxide (GO) nanoparticles were effectively incorporated onto the surface of the aluminium chromite resulting in the formation of a nanocomposite as depicted in Figure 4(b). The subsequent visualization of GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ reveals a complex, layered structure as illustrated in Figure 4(c). The image exhibits a relatively high aspect ratio suggesting that the quasi-spherical agglomerated morphology is attributed to the presence of approximately 127 spherical particles (depicted as lighter areas). Degradation of the GO layer became evident due to structural imperfections, aligning with findings from XRD measurements. Furthermore, the interplanar distance of 16 nm can be attributed to the (222) plane of α-MnO₂ within the Mn₃O₄ crystals. The grain size evaluation using the Image J. program yielded dimensions of 22 nm for the graphene oxide, 7 nm for the aluminium chromite and 20 nm for composite. Additionally, the cumulative frequency and per-count histograms of the composite are illustrated in Figure 5 for further characterizations.

Figure 4. SEM images of (a) GO (b) GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ (c) AlCrO₃.

Figure 5. Grains diameter variation and Histogram distribution of GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite.

4.3. FTIR spectroscopy

For each nanomaterial molecular bonding investigation, we plotted out its FTIR spectrum evaluation as shown in Figure 6. The FTIR spectra of GO give you an idea about absorption peaks at 766, 1253, 1570 cm⁻¹ and 2093cm⁻¹. In addition to sort of absorption bands, metal–oxygen stretching is responsible for both tetrahedral and octahedral sites [51]. The angular distortion of water molecules absorbed is believed responsible for the band at 1253 cm⁻¹. The C – H stretching vibrations cause a tiny bar at 2093cm⁻¹ [52,53]. The band represents the bending vibrations of O-H groups at 1570 cm⁻¹ [54]. The bending sensations of OH groups were a symbol of bands at the same position, while the band signified the stretching feelings of OH groups at 2097cm⁻¹. The perovskites lattice octahedral and tetrahedral aluminium or manganese ions are responsible for these two bands vibrations [55]. Absorbed water molecules bend their vibrations at 1523 cm⁻¹, which is the source of the band Al³⁺ O^{2 –} in the octahedral sites and Mn^2 +O^{2 –} in the tetrahedral sites in synthesized Mn₃O₄ [56]. This indicates that spinel Mn₃O₄ is present in the material. There is no change in the absorption band despite a secondary phase (Al), suggesting that Al²⁺ and Mn³⁺ occupy the tetra and octahedral sites respectively [57]. Perovskite structure had an effect on wavenumber peculiar to these two bands, which lies between the ethics of ternary oxides analogous to Al and Mn ions in spinel structure about GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ [58]. The vibration wavenumbers are somewhere between ternary metal oxides and multinary oxide samples. At the same time AlCrO₃ (8.11) and Mn₃O₄ (8.19) have the highest lattice parameter values. All peaks shift due to structure change varying ionic radii of different metals and various cation distributions.

Figure 6. FTIR spectra of (a) GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ (b) GO (c) Mn₃O₄ and (d) AlCrO₃.

4.4. Energy dispersive spectroscopy

Figure 7 showing EDS spectra of AlCrO₃ with maximum intensity peak of aluminium accompanied by low intensity peaks of chromium and oxygen. Nanocomposite EDS spectra is visible in Figure 8 with an impurity peak of sodium is visible in minor concentration might be due to beaker impurities existence [13,59]. AlCrO₃ elements weight ratios are mentioned in Figure 7 whereas nanocomposite elemental percentage can be seen in Figure 8 respectively.

Figure 7. EDs spot and spectra of AlCrO3.

Figure 8. Energy dispersive spot and spectra of GO@AlCrO3@SiO2@Mn3O4@SnO2 nanocomposite.

4.5. Raman spectroscopy

The Raman spectra spanning wavelengths from 1200 cm⁻¹ to 1600 cm⁻¹ are presented in Figure 9 illustrating the Raman spectrum of GO (Figure 9(a)) alongside the Raman spectrum of the GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite (Figure 9(b)). Within the spectrum of GO, two distinct peaks are observed at 1352 and 1578 cm⁻¹ corresponding to the D band and the G band of GO respectively. The Raman-active E_2g mode at 1578 cm⁻¹ confirms the presence of a graphite structure, while the pronounced D band suggests sp³ defects within the graphene sheet [60]. The introduction of oxygen functionalities enhances the number of edge sites, subsequently amplifying the intensity of the D band in GO. The intensity ratio between the D and G bands (ID/IG) serves as a measure of structural deviations. This ratio increases from 0.83 for GO to 0.95 for the GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite. This elevation can be attributed to the hydrothermal process ability to restore the sp² network upon reduction [61]. In the case of the nanocomposite, the D band undergoes a red shift to 1351 cm⁻¹, while the G band experiences a blue shift to 1589.90 cm⁻¹ compared to GO. This phenomenon can be attributed to the presence of nanoparticles within the nanocomposite and the charge transfer between GO and SnO₂ [62,63].

Figure 9. Raman spectra of (a) GO and (b) GO@AlCrO3@SiO2@Mn3O4@SnO2 nanocomposite.

4.6. Ultra-Visible spectroscopy

For the nanocomposite GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ there are metallic absorption peaks at 260 and 630 nm but none can be identified [64]. Another name given to absorption spectroscopy is UV-Visible spectroscopy related to UV (ultraviolet) light absorbance in nanomaterial as shown in Figure Figure10 [65]. No obvious absorption edge is shown by GO confirming graphene oxide metallic nature. In case of GO@AlCrO₃@SiO₂@Mn₃O₄@SiO₂@SnO₂ nanocomposite, absorption edges shifted to longer wavelengths. Bandgap energies of nanocomposite is determined by drawing plot between (αhʋ)^1/2 versus hʋ as 2.85 eV. Obviously quantum size effect and bandgap narrowing are due to GO hybridization within nanocomposite [66–68].

Figure 10. Band Gap of GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite.

4.7. Zeta measurements

Surface charge stability investigations necessitate Zeta potential measurements. These measurements have revealed a significant relationship between the rate at which the negatively charged electrode attracts the positively charged electrode and a potential difference of approximately 100 volts [69,70]. Remarkably, the GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite demonstrates a remarkable capability to uphold a stable colloidal solution. This stability is achieved through the augmentation of electrostatic repulsion forces among the nanoparticles, as visually depicted in Figure 11.

Figure 11. Zeta potential of GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite.

4.8. Electrochemical measurements

The Gamry potential state interface 1000 instrument was utilized to perform the electrochemical analysis using an Ag/AgCl type reference electrode, also platinum wire using counter electrode and a glassy carbon electrode as the working electrode [71]. Before fabricating using the powder-produced materials, the working electrode was always washed with alumina slurry and Ethanol. For GCE preparation 0.02 g of powdered electrode material was put on the surface, and 5% Nafion solution was added [72]. It took 20 min in a 50${}^{\circ }C$ in an oven to dry the nano – electrode material after it was produced.

4.8.1. CV measurements

Cyclic voltammetry was employed to analyse the electrode potential in alkaline electrolytes using the modified working electrodes. As illustrated in Figure 12, cyclic voltammograms were captured using a GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ electrode immersed in 1M KOH solution with scan rates varying from 10 to 100 mVs⁻¹. Notably, the nanocomposites exhibited capacitive behaviour, where the forward scan corresponded to anodic peaks (oxidation) and the reverse scan to cathodic peaks (reduction). This behaviour provided further evidence of surface redox processes occurring. The specific capacitance of the working electrodes (GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite) was determined using the equation $\mathrm{Cp}=A/2\left(\mathrm{mkV}\right),$ where Cp represents specific capacitance in F/g, m signifies the electrode mass in mg (0.02 mg), and k is a constant. The estimated electrochemical capacitance parameters are summarized in Table 3. Notably, the capacitance exhibited an inverse relationship with the scan rate. At a scan rate of 20 mVs⁻¹ in 1M KOH solution, a substantial specific capacitance of 2495 Fg⁻¹ was recorded. However, the specific capacitance declined as the scan rate increased, since the penetration of electrolyte ions into the interior of the electrode material decreased, consequently reducing its charge storage capacity [73]. Reduced scan rates allow electrolyte ions to use less surface area, leading to higher specific capacitance [74]. Diffusion coefficient (D°) values for 1M KOH Pseudo capillary capacitance at the electrode inner surface can be explained by a diffusion seeing controlled process as shown by a linear type relationship between peak current (Ip) and the square root of scan rate (1/2) in a Randles–Sevcik plot (Figure 13).

Figure 12. Cyclic voltammetry at various scan rates GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite.

Figure 13. The specific capacitance of nanocomposite at various scan rates.

Table 3. Measurements of specific capacitance of GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ at various scan rates.

Scan rate (mVs^−1)	Specific capacitance (Fg^−1)
10	2495
20	2342
30	2042
50	1933
100	1814

Capacitive energy storage applications are commonplace in the graphene oxide composites with heteroatom incorporation [75–77]. The successful fabrication of nanomaterials has yielded an electrode material with a notably enlarged surface area, contributing to its robust electrochemical activity. This enhanced performance is attributed to the nanocomposite larger diffusion coefficient and reduced charge transfer resistance at the electrode–electrolyte interface, making it particularly proficient in basic solutions. Additionally, the heightened apparent rate constant underscores the enhanced utility of the synthesized capacitive material for on-site power applications in alkaline electrolytes. Furthermore, the nanocomposite outperforms certain previously reported capacitive materials by demonstrating substantially elevated capacitance values. This characteristic positions it as an effective medium for energy storage. Remarkably, the GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite exhibits significantly superior capacitance performance, even when operating with lower electrolyte concentrations.

4.8.2. Galvanostatic charge-discharge (GCD) measurements

Figure 14 shows that the galvanostatic charge–discharge type analysis curve exhibits a non-linear behaviour during charging and discharging, which is indicative of the redox-active nature of the material and helps to explain the presence of oxidation and reduction peaks in the CV curve. Discharging times are reduced when current density increases [78–80]. Maximum capacitance and prolonged discharge time are realized at the lowest current density form of special value due to the electrode long residence time for hydroxyl ion insertion into electrode-type material [81]. Energy density and power density are two metrics where an inverse relationship can be shown when defining relations between them $E=\mathrm{\Delta V}\times Q/3.6\times 2$ and $P=E3600/\mathrm{\Delta t}$, correspondingly [82]. Density of power increases from 1092 to 2495.5 W/kg; density of energy decreases from 67.388–48.611 Wh/kg. Nanocomposite electrode material is suggested as a promising electro-based active one for supercapacitor based devices [83–85].

Figure 14. (a) GCD curves and Ragone plot of GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite in IM KOH electrolyte (b) Cycling performance.

4.8.3. Electrochemical impedance spectroscopy

Modified electrode using glassy carbon electrode (GCE) electron transfer capacity analysed via EIS in both 1M KOH electrolytes by drawing Nyquist plot as shown in Figure 15. The prepared electrode EIS parameters are shown in Table 4 whereas the electron transfer rate is evaluated using the formula $\mathrm{kapp}=\mathrm{RT}/F2.\mathrm{Rct}.C.$ In this equation C is electrolyte molar concentration, R is the universal gas constant, T is standard temperature, F is Faraday's constant, and R_ct is charge transfer resistance [86–88]. Charge transfer resistance (Rct) decreased value for 1M KOH confirms the maximum electron transfer rate (K_app) resulting in maximum conductivity. It is worth noting that electrode modification affects R_ct as it represents active material conductive behaviour [89,90]. The roughness parameter α value of the modified electrode ranges between 0.92-0.64, indicating fair roughness [91]. The highest electron transfer rate constant value for 1M KOH is an indication of reaction facilitation [92–94]. The compassion of the current work with the existing literature is depicted in Table 5.

Figure 15. EIS spectra of GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite in IM KOH electrolyte solution.

Table 4. GO@AlCrO₃@SiO₂@Mn₃O₄@SnO₂ nanocomposite electrode material parameters.

Electrolyte	Rct (Ω)	α	kapp × 10^−9 (cms^−1)
1M KOH	64.99	0.92	4.806

Table 5. Comparison of multinary composite with previous literature.

Electrode Material	Capacitance (F/g)	Electrolyte	Reference
Quaternary NiCuCo2S4 thin film	159	5 M KOH	[95]
Cu2FeSnS4/PVP/rGO composite	328	2 M KOH	[96]
CuFeS2 nanoflakes	219	2 M KOH	[97]
GO/LiCr2O4 nanocomposite	321	0.1 M H2SO4	[71]
GO@AlCrO3@SiO2@Mn3O4@SnO2	2495	1M KOH	This Work

4. Conclusion

Exploring the potential advantages of a novel electrolyte formed through the amalgamation of distinct nanostructured components holds significant importance. The primary objective here is to comprehensively assess the capabilities and performance attributes of the inventive multinary nanocomposite based on GO@AlCrO₃@Mn₃O₄@SiO₂@SnO₂ as an electrode material within an electrochemical supercapacitor. To achieve this goal, an extensive array of analytical techniques was employed encompassing XRD, SEM, EDS, Raman, UV-visible, FTIR, Zeta measurements, and cyclic voltammetry. Electrochemical impedance spectroscopy, the electrochemical active surface area, as well as power densities were also scrutinized. The FTIR spectra delineate noteworthy bands at 2097cm⁻¹ and 1523 cm⁻¹ signifying stretched vibrations indicative of the metal–oxygen interactions. EDs spectra affirm the presence of aluminium, silicon, tin, chromium and manganese in addition to oxygen. UV-Vis spectra shows the energy bandgap value of approximately 2.85 eV. The material stability is confirmed by a zeta potential value of 27.9 mV. The findings demonstrate remarkable power density ranging from 1710 to 2495.5 W/kg and energy density spanning from 67.38–48.61 Wh/kg. These outcomes underscore the nanocomposite-based material pronounced performance, particularly at heightened current densities displaying commendable stability and impressive energy efficiency. As a result, this material holds significant promise for utilization as an energy storage medium especially within the domain of supercapacitors.

Acknowledgement

We are thankful to National Institute of Lasers and Optronics (NILOP) College PIEAS, NILORE, Islamabad for provision of characterization facilities. This work was funded by the Researchers Supporting Project Number (RSP2024R243) King Saud University, Riyadh, Saudi Arabia.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

We acknowledge Higher education of Pakistan for funding NRPU grant to Malika Rani from department of physics. The Women University Multan. This work was funded by the Researchers Supporting Project Number (RSP2024R243) King Saud University, Riyadh, Saudi Arabia.