Proton-Coupled Electron Transfer Governs Heterogeneous Fenton-like Reactivity: Modulation of Surface O–H Bond Dissociation Free Energy and Proton Activity

Fenton-like reactions are fundamental to environmental remediation, yet conventional electron-centric frameworks overlook critical proton transfer contributions. Here, we demonstrate that strategic modulation of proton transfer enhances heterogeneous Fenton-like reactivity by two orders of magnitude through validated proton-coupled electron transfer (PCET) mechanisms. Two complementary strategies emerged: modifying catalyst surface hydroxyl density and tuning solution pH. Mechanistic investigations revealed that hydroxyl modifications alter the surface O–H bond dissociation free energy (BDFE), while pH adjustments follow Brønsted–Evans–Polanyi (BEP) relationships. We developed electrochemical methods for quantifying BDFE alongside techniques for measuring net H• transfer rates involving surface hydroxyl groups. This paradigm transcends electron-centric approaches by establishing comprehensive theoretical frameworks for reaction enhancement and by providing transformative proton-transfer-based modulation strategies to overcome inherent activity limitations in practical Fenton-like applications.