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

Abstract

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 g_catalyst⁻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.