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.