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

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.