Photocatalytic reduction of CO₂ into renewable hydrocarbon solar fuels is considered as a promising strategy to simultaneously address global energy and environmental issues.

Jingdong Lin, Xiamen University, China, and colleagues have developed an easy and highly efficient strategy for alkane production by using CO₂ and solar energy. They directly coupled photocatalytic water splitting and thermocatalytic hydrogenation of CO₂ on a bifunctional Au-Ru/TiO₂ catalyst with active sites for both photocatalytic water splitting and thermocatalytic hydrogenation of CO₂ to convert CO₂–H₂O into fuels.

The direct coupling of thermo- and photocatalysis over Au−Ru/TiO₂ leads to 15 times higher activity (T = 358 K; ca. 99 % CH₄ selectivity) in the conversion of CO₂–H₂O into fuels than purely photocatalytic water splitting. This is attributed to the promoting effect of thermocatalytic hydrogenation of CO₂ with highly active hydrogen atoms generated in situ by photocatalytic water splitting, which can greatly reduce the recombination rate of photogenerated electrons and holes.

According to the researchers, the direct coupling of photocatalysis with thermocatalysis may be further extended to other hydrogenation reactions, such as ammonia synthesis or CO_x to methanol, with hydrogen derived in situ by solar energy.

• Direct Coupling of Thermo- and Photocatalysis for Conversion of CO₂–H₂O into Fuels,
  Li Zhang, Guoguo Kong, Yaping Meng, Jinshu Tian, Lijie Zhang, Prof. Shaolong Wan, Prof. Jingdong Lin and Prof. Yong Wang,
  ChemSusChem 2017.
  https://doi.org/10.1002/cssc.201701472