Photo‐Self‐Fenton Reaction Mediated by Silver Single Atom and Cluster Photocatalysts for Highly Selective Generation of Singlet Oxygen Toward Efficient Organic Wastewater Treatment

via the intermediate *OOH at the Ag SA sites for ring-opening reaction and reactive H* at the Ag clusters sites for dechlorination reaction, respectively. This discovery gives the deep understanding of the high-performance photo-self-Fenton reaction through in situ cycles of variable metals for the organic contaminants treatment.