Microenvironment modulation of single-atom sites and its applications in Fenton-like reactions.

Single-atom catalysts (SACs) featuring ultrahigh atom utilization, tunable coordination environments, and distinct structure-activity relationships have emerged as a prominent class of catalysts in heterogeneous Fenton-like reactions. Precise modulation of microenvironments around active single-atom sites offers a promising avenue to enhance catalytic activity, direct reaction pathways, and elucidate underlying mechanisms; however, achieving such control remains a significant challenge. This review systematically delineates the microenvironment modulation strategies of SACs in heterogeneous Fenton-like systems, encompassing coordination environment engineering, support/ligand-mediated electronic regulation, spatial confinement regulation, and external field effects. By manipulating ligand properties, modifying supports, altering electronic structures, controlling the local environment and introducing an external field, these strategies synergistically enhance the catalytic performance and regulate the underlying reaction mechanisms. Moreover, analysis of correlations among active-center microenvironment structures, Fenton reactivity, and reactive oxygen species (ROS) generation pathways offers valuable insights for future research and development in this domain. Finally, by addressing the critical challenges in SAC design and nascent microenvironment engineering, this review delineates future research directions for SACs in Fenton-like systems and analogous catalytic processes.