Converting the greenhouse gas CO₂ into useful chemical compounds could help to alleviate climate change and reduce the dependence on fossil resources. The transformation of CO₂ to value-added products such as methane or methanol is one option for this. However, existing catalysts for, e.g., the hydrogenation of CO₂ to CH₄ often require high pressures and/or temperatures. Photocatalytic processes could be an alternative.

Xu Liu, Jing Ma, Nanjing University, China, Zhong Jin, Nanjing University and Shenzhen Research Institute of Nanjing University, China, and colleagues have found that Ag₂₅-based clusters can catalyze a light-driven CO₂ reduction reaction to CH₄ with high selectivity at relatively low temperatures. The atomically precise silver clusters were prepared from AgNO₃ and 2,4-dimethylbenzenethiol by adding tetraphenylphosphonium bromide and NaBH₄. The clusters have an Ag₁₃ core, surrounded by a shell containing six Ag₂S₃ units.

The team performed a light-driven catalytic CO₂ reduction with H₂ on the Ag₂₅ clusters (supported on a glass microfiber membrane) under a Xe lamp at 100 °C. They observed high catalytic activity and almost complete selectivity for the formation of methane.

• Photodriven Catalytic Hydrogenation of CO₂ to CH₄ with Nearly 100% Selectivity over Ag₂₅ Clusters,
  Yan Xiong, Hongwei Chen, Yi Hu, Songyuan Yang, Xiaolan Xue, Lingfeng He, Xu Liu, Jing Ma, Zhong Jin,
  Nano Lett. 2021.
  https://doi.org/10.1021/acs.nanolett.1c02784