Highly efficient light-driven methane coupling under ambient conditions based on an integrated design of a photocatalytic system

Direct non-oxidative coupling of methane (NOCM) is an effective way to produce hydrocarbons. However, this process usually requires a high temperature (≥1100 °C) to break the C-H bond of CH4 and suffers catalyst deactivation due to coke formation. Photocatalytic NOCM is an ideal strategy to solve these issues. Herein, we designed a novel photocatalytic methane coupling system consisting of a continuous flow reactor and metal-loaded TiO2 photocatalysts with light-diffuse-reflection-surfaces. It was found that Au/TiO2 was the best catalyst for the system due to the easy transport of photoelectrons from TiO2 to Au particles to inhibit the photoelectron-hole recombination. The yield of C2H6 reached 81.7 μmol gcatalyst-1 h-1 with higher than 95% selectivity over Au/TiO2 under simulated 1.5G sunlight irradiation and ambient conditions (room temperature and 1 atm), which is 174% larger than the highest reported value. Furthermore, DFT calculation results revealed that the methyl anion is a possible intermediate species for the formation of ethane