In this review, SACs with different metal species and substrates are summarized to investigate the metal−support interaction effects on the persulfate oxidation reaction for water treatments. Abstract With maximum utilization of active metal sites, more and more researchers have reported using single atom catalysts (SACs) to activate persulfate (PS) for organic pollutants removal. In SACs, single metal atoms (Fe, Co, Cu, Mn, etc.) and different substrates (porous carbon, biochar, graphene oxide, carbon nitride, MOF, MoS2, and others) are the b...