Advances in single/dual-atom catalysts for activating persulfate applied to organic pollutant degradation: the critical role of active site configuration

Single-atom catalysts (SACs) and dual-atom catalysts (DACs) have emerged as promising materials for activating persulfate (PS) in advanced oxidation processes (AOPs) aimed at degrading organic pollutants. This review systematically summarizes recent advances in the design, synthesis, characterization, and application of SACs and DACs for peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation. Special emphasis is placed on the critical role of active site configuration—including coordination number, heteroatom doping, and metal–metal interactions—in governing the oxidation mechanisms, which encompass both radical and nonradical pathways. While SACs and DACs exhibit exceptional atomic utilization and catalytic performance, challenges such as low metal loading, structural instability, and limited recyclability hinder their large-scale application. The review also highlights the potential of machine learning and electro-assisted systems in optimizing catalyst design and improving stability. Finally, future perspectives are provided to guide the development of efficient, stable, and scalable SAC/DAC-based PS-AOPs for environmental remediation.