Tuning the Reactive Species in Oxidant Activation by Single-Atom Catalysts: Mechanisms, Manipulations, and Perspectives

Precise control over the reactive species generated in oxidant activation systems—specifically hydroxyl radicals (⋅OH), sulfate radicals (SO4⋅–), singlet oxygen (1O2), and high-valent metal-oxo (HVMO) species—is of paramount importance for advancing environmental remediation and selective oxidation. Single-atom catalysts (SACs) have emerged as a powerful and tunable platform to govern this process at the atomic scale. This review systematically elucidates the fundamental mechanisms governing reactive species generation at isolated metal sites, focusing on the key processes of oxidant adsorption, electron transfer, and intermediate transformation. We critically analyze how these elementary steps dictate selective production of target radical and non-radical reactive species and comprehensively discuss the state-of-the-art design strategies—including coordination engineering, defect modulation, and bimetallic site construction—that enable the rational manipulation of these pathways. Finally, we provide a forward-looking perspective on challenges and opportunities, guiding the development of next-generation SACs for sustainable oxidation processes.