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

Abstract

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.