Quantification and Tuning of Surface Oxygen Vacancies for the Hydrogenation of CO 2 on Indium Oxide Catalysts

Abstract The direct hydrogenation of CO 2 to methanol is an attractive approach to employ the greenhouse gas as a chemical feedstock. However, the commercial copper catalyst, used for methanol synthesis from CO‐rich syngas, suffers from deactivation at elevated CO 2 partial pressure. An emerging alternative is represented by In 2 O 3 as it withstands the hydrothermal conditions induced by the reverse water‐gas shift reaction. The active sites for the adsorption of CO 2 and the subsequent conversion into methanol were shown to be oxygen vacancies on the surface of In 2 O 3 . In this study, N 2 O was utilized as a probe molecule to quantify the number of vacancies on indium oxide catalysts. The number of inserted oxygen atoms could be correlated to the respective CO 2 hydrogenation activity. Furthermore, the atomic efficiency of indium was enhanced by applying atomic layer deposition of indium oxide on ZrO 2 .