From Interfacial Adsorption to Decontamination Fate: Adsorption-Regulated Electron-Transfer Pathways in Peroxymonosulfate-Based Fenton-Like System

Nonradical electron-transfer processes (ETPs) based on peroxymonosulfate (PMS) have attracted increasing attention for removing emerging contaminants from wastewater. However, these processes are strongly governed by adsorption, and the role of adsorption type in regulating electron-transfer pathways, product fate, and environmental risks remain fragmented. This review examines adsorption-regulated electron transfer in peroxymonosulfate-based system by linking physisorption and chemisorption with direct and mediated electron transfer pathways. Chemisorption promotes inner-sphere complexes, orbital coupling, and multi-electron oxidation, thereby favoring aromatic ring cleavage and deep mineralization. In contrast, non-specific physisorption tends to induce outer-sphere electron transfer, rapid desorption of single-electron oxidation intermediates, and subsequent radical coupling or polymeric deposition. An appropriate adsorption free energy window is essential to balance interfacial electron flux and catalytic turnover, whereas under- or over-adsorption may cause poor selectivity, catalyst deactivation, metal leaching, or toxic byproduct accumulation. We further discuss the collective role of catalyst electronic structure, geometric configuration and pollutant molecular properties in reshaping adsorption-electron transfer coupling. Finally, this review proposes a balanced adsorption regulation strategy, encompassing catalyst-interface modulation and pollutant-specific adsorption matching. This review provides a mechanistic basis and practical recommendations for guiding PMS-based ETPs from efficiency-oriented contaminant removal toward pathway control, risk mitigation, and environmentally responsible water treatment.