Unraveling the influence of oxygen vacancies in MoOx catalysts on CO2 hydrogenation

Oxygen vacancies in oxides are core parameters determining the catalytic performance in various reactions. This study investigated the influence of oxygen vacancies of MoO x catalysts on the reverse water gas shift (RWGS) reaction to gain a deep insight into the structure–function relationship. A distinct volcano-shaped trend was observed among MoO x catalysts with different amounts of oxygen vacancies. Through comprehensive characterizations and steady-state kinetic analysis, an optimal concentration of oxygen vacancies was identified to not only facilitate the adsorption and activation of CO 2 but also restrain the formation of by-product CH 4 . In-situ characterizations combined with DFT calculations uncovered a formate-involved reaction pathway over the oxygen vacancies structured MoO x catalyst, with the hydrogenation of formate identified as the rate-determining step. These findings not only showcase the potential of Mo-based oxides in CO 2 hydrogenation reactions but also provide fundamental insights into the role of oxygen vacancies in shaping catalytic behavior.