High-Efficiency Photooxidation of Methane to the C1 Product

Abstract

The efficient conversion of methane (CH₄) to high-value-added chemicals using a photocatalyst at room temperature and pressure faces great challenges compared to harsh reaction conditions. However, achieving this efficient conversion would yield substantial cost advantages and hold immense potential for development. Here, we demonstrate the enhanced photocatalytic conversion efficiency of CH₄ at room temperature and pressure conditions without requiring any oxidant through the construction of a bimetal Ag–Cu-loaded brookite TiO₂ photocatalyst. The C1 products were ultimately obtained with 100% selectivity and a yield of 936 μmol·g^–1·h^–1. The performance exceeds that of similar research by tens of times. The high selectivity of this system is attributed to the optimal number of ·OH, which strikes a balance between excess and deficiency. Ag effectively enhances electron transport in the photocatalytic reaction process on a dual active site photocatalyst, while Cu significantly improves the selectivity of the C1 products. In this system, the hydroxyl radical (·OH) activates CH₄ to generate the methyl radical (·CH₃), which then binds with the lattice oxygen of TiO₂, breaking the Ti–O bond and resulting in the formation of *OCH₃. The *OCH₃ undergoes further conversion to CH₃OH, which is subsequently oxidized to HCHO by ·OH. This work presents a cost-effective and highly efficient approach for directly oxidizing CH₄ into valuable chemicals, ensuring superior selectivity.