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

Abstract

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.