Structure Sensitivity of an Atomic Co-Promoted In₂O₃ Catalyst toward CO₂ Hydrogenation to Methanol

Deciphering the relationship between the active site structure and the CO2 hydrogenation to methanol mechanism over In2O3-supported high-dispersed metal catalysts faces great challenges. Herein, by using atomically dispersed Co@In2O3 with the main exposed facet as a model catalyst, Co@In2O3 (111) and Co@In2O3 (012) are prepared to investigate the structure sensitivity toward CO2 hydrogenation. Co@In2O3 (012) exhibits higher methanol selectivity (78.0%) with a prominent durability within a 100 h time-on-stream test at 280 °C and 9000 mL g–1 h–1, while Co@In2O3 (111) exhibits a mediocre selectivity of methanol (64.7%) but relatively higher CO2 conversion. Experiments and theoretical simulations substantiate that the hydrogenation of CO2 to methanol follows the formate pathway over both catalysts. The oxygen vacancy sites on the Co@In2O3 (012) surface can more effectively stabilize the intermediates of the CO2 hydrogenation reaction and exhibit a lower reaction energy barrier of the rate-determining step about the conversion of HCOO* to H2COO*, achieving a higher methanol selectivity. This study might be of great aid in providing comprehensive insight into the structure–activity relationship of Co@In2O3 catalysts and the design of robust catalysts for highly selective hydrogenation of CO2 to methanol.