Asymmetric active-site on heterogeneous single-atom alloy metallene boost fenton-like reaction for sustainable water purification.

A precise modulation of heterogeneous catalysts in structural and surface properties promises the development of more sustainable advanced oxidation water purification technologies. However, the poor catalyst stability due to covering of surface-active sites by oxidation intermediates remains a key bottleneck to their practical applications. Herein we propose a simple defect-induced in-situ single-atom anchoring strategy to overcome this challenge by creating unique asymmetric active-sites on the catalyst surface. The single-atom-anchored asymmetric coordination sulfide (Ce-CoS) offers a highly active surface rich in sulfur vacancy defects, displaying excellent affinity for peroxymonosulfate (PMS) binding and charge transfer capabilities, along with a strong pollutant adsorption capacity, and initiates synergistic free radical and non-radical reactions, achieving nearly complete degradation of recalcitrant pollutants within 15 min, thereby alleviating the catalyst passivation by oxidation intermediate accumulation. Theoretical calculations unveil that the optimized configuration enhances the strength of the asymmetric Ce-S-Co sites by adjusting the E orbital, consequently reducing the energy barrier for the pivotal *O intermediate responsible for active oxygen species generation. This work provides a broader perspective for regulating the electronic structure of the single-sites at the atomic level and precisely designing efficient Fenton-like catalysts to alleviate water pollution dilemmas.