Heterostructure Engineering of a Reverse Water Gas Shift Photocatalyst

To achieve substantial reductions in CO₂ emissions, catalysts for the photoreduction of CO₂ into value-added chemicals and fuels will most likely be at the heart of key renewable-energy technologies. Despite tremendous efforts, developing highly active and selective CO₂ reduction photocatalysts remains a great challenge. Herein, a metal oxide heterostructure engineering strategy that enables the gas-phase, photocatalytic, heterogeneous hydrogenation of CO₂ to CO with high performance metrics (i.e., the conversion rate of CO₂ to CO reached as high as 1400 µmol g cat⁻¹ h⁻¹) is reported. The catalyst is comprised of indium oxide nanocrystals, In₂O_{3− x}(OH)_y, nucleated and grown on the surface of niobium pentoxide (Nb₂O₅) nanorods. The heterostructure between In₂O_{3− x}(OH)_y nanocrystals and the Nb₂O₅ nanorod support increases the concentration of oxygen vacancies and prolongs excited state (electron and hole) lifetimes. Together, these effects result in a dramatically improved photocatalytic performance compared to the isolated In₂O_{3− x}(OH)_y material. The defect optimized heterostructure exhibits a 44-fold higher conversion rate than pristine In₂O_{3− x}(OH)_y. It also exhibits selective conversion of CO₂ to CO as well as long-term operational stability.