Oxygen vacancy-engineered In2O3@carbon catalysts from steam-pyrolyzed MOFs for photothermal CO2 hydrogenation†

Abstract

Photothermal CO₂ hydrogenation has attracted considerable attention as a promising approach to utilize carbon dioxide through the efficient conversion of solar energy into chemicals and fuels. In this study, we report a novel approach to improve the catalytic performance of indium oxide-based catalysts for the photothermal reverse water-gas shift (RWGS) reaction. Catalysts derived from the steam pyrolysis of the metal–organic framework MIL(In)-68 display a high density of oxygen vacancies and defect sites on the In₂O₃ surface. These features significantly enhance CO₂ adsorption and H₂ dissociation ability while maintaining the porosity of the material and enhancing its photothermal properties. Among the catalysts investigated, the Rb-promoted catalyst exhibited superior activity, achieving CO production rates of 53 mmol g_In2O3⁻¹ h⁻¹ with 100% selectivity without any external heating. Comprehensive characterization, including XPS and Raman spectroscopy, confirmed that steam-pyrolysis leads to extensive defective site formation, resulting in improved catalytic performance. These results highlight the potential of steam-pyrolyzed MOF materials as efficient and selective catalysts for photothermal CO₂ hydrogenation, offering a sustainable route to valuable chemical production.