Copper Deposited on Reduced Titania as Catalyst for the Production of CH₄ from Sunlight and Air

Atmospheric CO₂ and H₂O adsorbed on the photocatalyst surface undergo sunlight-assisted conversion to solar products that bridge the gaps between artificial and natural photosynthesis. Herein, we report a Lewis acid-base interaction derived photocatalyst, Cu deposited on reduced titania, that harvests CO₂ and H₂O from the air and transforms them to CH₄. Photocatalyst surface studies confirm that coordinately unsaturated Cu atoms and oxygen vacancies are formed that facilitate CO₂ and H₂O adsorption. The mechanistic studies, combined with tandem secondary ion mass spectroscopy and isotopic labelling, confirm the CH₄ origin from atmosphere-adsorbed CO₂ and H₂O. The contributing factors to photocatalyst instability are explored. We expect that this study will have an impact on the widespread application and economic viability of photocatalytic CO₂ reduction.