Fe-Enhanced Proton Capture on Boron Nitride Surfaces for Improved Photocatalytic Methane Conversion to C1 Chemicals

The direct solar-driven conversion of methane (CH₄) into oxygenated liquid compounds has emerged as a promising approach for achieving high-value utilization of natural gas. Here, an Fe/boron nitride (BN) catalyst system was constructed. Mechanistic investigations demonstrate that Fe acts as an acceptor of photogenerated electrons, promoting charge-carrier separation and transfer and thereby accelerating H₂O dissociation to generate ·OH radicals. These reactive oxygen species facilitate CH₄ activation, leading to a notable enhancement in CH₄ conversion. In addition, Fe sites strengthen proton capture by adjacent N atoms, promoting the formation of N-H bonds. The resulting N-H bonds can provide protons in situ, effectively suppressing the dehydrogenation of key reaction intermediates. As a result, over 1 wt% Fe/BN, the production rate of liquid oxygenates (CH₃OH and HCHO) reaches 321.1 µmol·g^-1·h^-1, which is 2.3 times higher than that of pristine BN, with an overall selectivity of up to 94.2%. The synergistic interaction between Fe and BN transcends conventional electron transfer: Fe not only promotes photogenerated charge separation but, more importantly, alters the reaction pathway by modulating surface proton chemistry. This work provides a useful reference for regulating and optimizing two-dimensional, non-noble-metal semiconductor materials.