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.

Graphical Abstract

In this work, a novel detection of Au³⁺ based on heterogeneous catalytic activation of peroxymonosulfate by Ag@Cu₂O NPs was raised, and proposed the mechanism in detail.

Keywords:

• Ag@Cu₂O NPs
• colorimetric detection
• Au³⁺
• peroxymonosulfate
• catalytic synergy effect

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We gratefully acknowledge financial support by the Natural Science Foundation of China as general projects (grant Nos. 21722702 and 21874099), the Natural Science Foundation of Tianjin City of China (grant Nos. 17JCJQJC45000), the Tianjin Commission of Science and Technology as key technologies R&D projects (grant Nos. 18YFZCSF00730, 18YFZCSF00770, 18ZXSZSF00230, 19YFZCSF00740, and 20YFZCSN01070), the National Key Basic Research Program of China (2017YFA0403402), the National Innovation and Entrepreneurship Training Program for College Students (grant No. 202010056072).