Activating C–H Bonds by Tuning Fe Sites and an Interfacial Effect for Enhanced Methanol Oxidation

Abstract The interaction mechanism between the reacting species and the active site of α‐Fe₂O₃‐based photoanodes in photoelectrochemical methanol conversion reaction is still ambiguous. Herein, a simple two‐step strategy is demonstrated to fabricate a porous α‐Fe₂O₃/CoFe₂O₄ heterojunction for the methanol conversion reaction. The influence of the electronic structure of active site and interfacial effect on the reaction are investigated by constructing two different FeO₆ octahedral configurations and heterogeneous structures. The optimal sample ZnFeCo‐2 affords high photocurrent density of 1.17 mA cm⁻² at 0.5 V vs Ag/AgCl, which is 3.2 times than that of ZnFe (0.37 mA cm⁻²). Meanwhile, the ZnFeCo‐2 also exhibits 97.8% Faraday efficiency of CH₃OH to HCHO, and long‐term stability over 40 h. Furthermore, density functional theory calculations reveal that the heterostructured α‐Fe₂O₃/CoFe₂O₄ with favorable electron transfer effectively lowers methanol adsorption, C–H bond activation, and HCHO desorption energy relative to the pristine α‐Fe₂O₃, resulting in excellent methanol conversion efficiency.