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

Deciphering the relationship between the active site structure and the CO 2 hydrogenation to methanol mechanism over In 2 O 3 -supported high-dispersed metal catalysts faces great challenges. Herein, by using atomically dispersed Co@In 2 O 3 with the main exposed facet as a model catalyst, Co@In 2 O 3 (111) and Co@In 2 O 3 (012) are prepared to investigate the structure sensitivity toward CO 2 hydrogenation. Co@In 2 O 3 (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@In 2 O 3 (111) exhibits a mediocre selectivity of methanol (64.7%) but relatively higher CO 2 conversion. Experiments and theoretical simulations substantiate that the hydrogenation of CO 2 to methanol follows the formate pathway over both catalysts. The oxygen vacancy sites on the Co@In 2 O 3 (012) surface can more effectively stabilize the intermediates of the CO 2 hydrogenation reaction and exhibit a lower reaction energy barrier of the rate-determining step about the conversion of HCOO* to H 2 COO*, achieving a higher methanol selectivity. This study might be of great aid in providing comprehensive insight into the structure–activity relationship of Co@In 2 O 3 catalysts and the design of robust catalysts for highly selective hydrogenation of CO 2 to methanol.