Heterogeneous catalytic activation of peroxymonosulfate by Ag@Cu2O composite for Au3+ detection

Abstract

Although gold (Au) plays an important role in many fields, the residual Au3+ ion in our natural environment is one of the most noxious heavy metal ions for animals and plants. It is of great significance to develop an efficient and simple detection method for Au3+. Based on heterogeneous catalytic activation of peroxymonosulfate (PMS) by Ag@Cu2O nanoparticles (Ag@Cu2O NPs), a novel, visible and convenient strategy for Au3+ detection was developed. The well-dispersive Ag@Cu2O NPs could catalyze PMS to produce sulfate radicals (SO4 •−) and hydroxyl radicals (·OH) which could oxide 3, 3′, 5, 5′-tetramethylbenzidine (TMB) into oxidized TMB (oxTMB) in colorimetric detection. The introduced Au3+ could effectively enhance catalytic activation of PMS to produce more SO4 •− and ·OH. This was because there was the synergistic effect of Au and CuO, which reduced the charge transfer resistance and promoted electron transfer. This method had good specificity against 22 types of cationic or anionic interfering ions and the detection limit of Au3+ was about 290 nmol·L−1. In this study, a new substrate of PMS was used for colorimetric detection of heavy metal ions, and the catalytic synergy of Au and CuO in PMS/Ag@Cu2O NPs/Au3+ colorimetric detection system was analyzed in detail.