Facilitating Redox Cycles of Copper Species by Pollutants in Peroxymonosulfate Activation

Abstract

The redox behavior of metal active sites determines the rate of heterogeneous catalysis in peroxymonosulfate activation. Previous reports focused on the construction of catalysts for accelerating interfacial electron transfer. In this work, a new strategy was proposed for facilitating valence cycles of Cu⁺/Cu²⁺ by using pollutants. The 2.5Cu/CeO₂/PMS system was capable of achieving the efficient removal of pollutants, including tetracycline, oxytetracycline, and rhodamine B, in a wide pH working range. In the presence of tetracycline, a Cu-N bond was formed between the -NH₂ group of tetracycline and the Cu site of the catalyst, showing that the coordination of Cu active sites changed to CuO₄N₁. The charge of CuO₄N₁ active sites rearranged, making it easier to obtain electrons and promote the PMS oxidation, thereby accelerating the reduction of Cu²⁺ to Cu⁺ and PMS activation. The PMS activation system showed excellent sustainability and selectivity for the removal of organic pollutants. This study provides a novel routine to promote peroxymonosulfate activation by utilizing pollutants to accelerate the redox behavior of metal species.