Simultaneous Ag⁺ and Hg²⁺ colorimetric sensors based on graphene oxide/Au-Pt nanoparticles

ABSTRACT

With the development of society and the increasing frequency of heavy metal pollution accidents, there is an urgent need for real-time on-site detection technology for heavy metals to control pollution and protect the environment. Therefore, in this paper, a colorimetric sensor was constructed based on the peroxidase-like nature of graphene oxide/nano-gold platinum composites (GO/Au-PtNPs), and a colorimetric sensor was constructed to achieve simple and rapid on-site simultaneous detection of Ag⁺ and Hg²⁺. This is mainly because GO/Au-PtNPs can catalyse the oxidation of the chromogenic agent 3,3‘,5,5’-tetramethylbenzidine (TMB) to blue in the presence of H₂O₂. Additionally, Ag⁺ and Hg²⁺ can selectively inhibit the catalase activity of GO/Au-PtNPs. This inhibition causes the system colour to lighten, which can be observed by the naked eye. The simultaneous visual detection of Ag⁺ and Hg²⁺ is achieved by the change in absorbance value of the system before and after the addition of EDTA. Under the optimal detection conditions, the colorimetric sensor had a detection range of 1 –10,000 nM for Hg²⁺, with a detection limit of 1 nM. For Ag⁺, the detection range was 50 –100,000 nM, with a detection limit of 50 nM. The colorimetric sensing method has high sensitivity, and a wide detection range, and is not affected by other interfering ions. It also exhibits good specificity. In addition, the method achieved a recovery rate of 92–104% for Ag⁺ and Hg²⁺ in spiked campus lake water, tap water, and serum. We envision that this material will have a wide range of potential applications in biomedical and environmental chemistry.

KEYWORDS:

• Graphene oxide
• colorimetric sensor
• Ag⁺ detection
• Hg²⁺ detection

Acknowledgments

The authors would like to express their gratitude to the Ministry of Higher Education Malaysia for providing research funding through the Fundamental Research Grant Scheme (Grant Number: FRGS/1/2020/WAB02/UNIMAS/03/1) and Research Program of Qilu Institute of Technology (No.: QIT23NK002). The authors also thank Universiti Ma laysia Sarawak and Qilu Institute of Technology for their support in this work.

Disclosure statement

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