Photocatalytic CO2 reduction to formate using triarylphosphine as reductant

The increasing concentration of CO₂ in the Earth's atmosphere represents a pressing global challenge for humanity. The reduction of CO₂ to formate offers a promising strategy for carbon capture and utilization, thereby contributing to the realization of sustainable development. In this study, the photocatalytic reduction of CO₂ using triarylphosphine as a reductant was investigated. However, due to the higher oxidation potential of triarylphosphine compared to the employed photosensitizer (PS), efficient regeneration of the PS poses a significant challenge. This issue was successfully addressed by introducing aryl thiol as a crucial co-catalyst in the reaction. Mechanistic studies revealed that the formation and cleavage of phosphorus–sulfur bonds drive the otherwise unfavored electron transfer process. These findings provide valuable insights toward the development of catalytic systems capable of utilizing reductants with even higher oxidation potentials.