Methanol is a strategic energy vector for the storage and delivery of energy and is a widely used precursor for the synthesis of many high-value chemicals. The hydrogenation of carbon dioxide (CO2) into methanol is a key process in industrial operations. In this study, we show that an oxide-oxide interface generated by a low loading (0.15 ML) of In2O3-x on a TiO2(110) substrate has a high activity and selectivity as a catalyst for the CO2 + 3H2 → CH3OH + H2O process. The properties of the In2O3-x-TiO2 interface under reaction conditions were investigated using a combination of synchrotron-based ambient pressure X-ray photoelectron spectroscopy (AP-XPS), temperature-programmed desorption (TPD), and catalytic testing. The In2O3-x overlayer spread out on top of the titania and was rich in defects and O vacancies that activated CO2 and H2 as reactants, without destroying CH3O and CH3OH as reaction products. The In2O3-x/TiO2(110) catalyst is at least 1 order of magnitude more active than bulk indium oxide while maintaining a very high selectivity (∼80%) toward methanol production. Under the rich hydrogen environment of methanol synthesis, the oxide-oxide interactions allowed only a partial reduction of the In cations, preventing the formation of metal alloys as seen in the case of catalysts with metal-indium oxide interfaces. Thus, the dispersion of low loadings of In2O3-x on a stable oxide substrate is a valid and low-cost approach for generating efficient catalysts for CO2 valorization.
Reddy et al. (Mon,) studied this question.