Boosting CO ₂ Hydrogenation to Ethanol Over CoCeO _x : Synergy of Cobalt Species and Oxygen Vacancies

Abstract CO 2 hydrogenation to ethanol is an attractive strategy for mitigating CO 2 emissions. In this work, CoCeO x complex oxide catalysts with different Co/Ce ratios were used for CO 2 hydrogenation to ethanol. It was found that a decrease in Co/Ce ratio contributed to oxygen vacancy formation, which facilitated the adsorption and activation of CO 2 . However, the decrease in Co/Ce ratio hampered H 2 adsorption and activation due to the decreased Co sites. Therefore, moderate Co/Ce ratio maintained a balance between H 2 and CO 2 activation, resulting in the best catalytic activity and STY. CoCeO x catalyst with Co/Ce ratio of 1 exhibited the highest space‐time yield of 1.40 mmol EtOH ·g cat −1 ·h −1 with ethanol selectivity of 12.3% and CO 2 conversion of 51.4% under 235 °C and 2 MPa. In situ DRIFTS analysis further proved the synergistic effect between oxygen vacancies and cobalt species. On one hand, oxygen vacancies provide cobalt species with more HCOO * species, promoting the formation of ethanol. One the other hand, cobalt species make the oxygen vacancies from nonrenewable to recyclable by dissociating hydrogen. Our work provides valuable guidance for the design of catalysts and insights into the synergistic effect between oxygen vacancies and cobalt species in CO 2 hydrogenation.