Methane is the main component of natural gas, combustible ice, biogas, etc. It is widely distributed in nature. How to convert methane resources with huge reserves into fuels or chemical products with higher economic added value is of great scientific significance and application prospects.

The photocatalytic methane anaerobic coupling method, which can directly convert methane under mild conditions while obtaining polycarbon hydrocarbons and hydrogen, is an attractive pathway.

On the one hand, the photocatalytic methane anaerobic coupling method does not require the two-step indirect conversion method via the well-established methane reforming and Fischer-Tropsch synthesis, avoiding the disadvantages of complex processes, high energy consumption and high production costs," said Yujie Xiong. On the other hand, the method does not require the use of harsh reaction conditions and avoids excessive oxidation of methane to generate large amounts of carbon dioxide and other by-products."

The photocatalysts commonly used for the anaerobic coupling of methane are mainly metal oxide semiconductor materials. Yujie Xiong said, "The lattice oxygen atoms in this photocatalyst are extremely prone to over-oxidation of methane, so it still generates some byproducts such as carbon monoxide and carbon dioxide and leads to complete deactivation of the catalyst."

To solve this problem, the team of Yujie Xiong and Ran Long proposed to regulate the valence band electronic structure of the photocatalyst by single-atom coordination loading, forming an extremely stable coordination structure of single atoms and lattice oxygen, avoiding the direct participation of lattice oxygen atoms in the photocatalytic methane anaerobic coupling reaction, thus reducing the degree of methane over-oxidation while improving the photocatalytic methane anaerobic coupling performance.

Based on this strategy, the research team achieved the production of 0.7 g of ethane per gram of catalyst per day with a selectivity of 94.3%, while also producing the same proportion of hydrogen. The researchers further improved the stability of the lattice oxygen in the catalyst by elemental doping, which in turn prolonged the stability of the catalytic performance and provided a new idea for the development of efficient photocatalytic methane anaerobic coupling catalysts.

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