Generating dual-active species by triple-atom sites through peroxymonosulfate activation for treating micropollutants in complex water

Abstract

The peroxymonosulfate (PMS)-triggered radical and nonradical active species can synergistically guarantee selectively removing micropollutants in complex wastewater; however, realizing this on heterogeneous metal-based catalysts with single active sites remains challenging due to insufficient electron cycle. Herein, we design asymmetric Co-O-Bi triple-atom sites in Co-doped Bi₂O₂CO₃ to facilitate PMS oxidation and reduction simultaneously by enhancing the electron transfer between the active sites. We propose that the asymmetric Co-O-Bi sites result in an electron density increase in the Bi sites and decrease in the Co sites, thereby PMS undergoes a reduction reaction to generate SO₄^•- and •OH at the Bi site and an oxidation reaction to generate ¹O₂ at the Co site. We suggest that the synergistic effect of SO₄^•-, •OH, and ¹O₂ enables efficient removal and mineralization of micropollutants without interference from organic and inorganic compounds under the environmental background. As a result, the Co-doped Bi₂O₂CO₃ achieves almost 99.3% sulfamethoxazole degradation in 3 min with a k-value as high as 82.95 min^-1 M^-1, which is superior to the existing catalysts reported so far. This work provides a structural regulation of the active sites approach to control the catalytic function, which will guide the rational design of Fenton-like catalysts.