Oxygen vacancy induced metal-support interaction in the Au-Cu promoted In2O3 catalyst for enhanced CO2 hydrogenation to methanol

The preparation and application of supported gold and copper catalysts are fundamentally and practically very important. Herein, we confirm that the Au-Cu promoted In2O3 catalyst demonstrates a significant electronic metal-support interaction (EMSI), which plays a critical role in CO2 hydrogenation to methanol and leads to significantly improved activity, compared to the mono-metallic Au and Cu promoted In2O3 catalysts. This interaction arises from electron transfer between the oxygen deficient In2O3 support and the bimetallic clusters, rendering both Au and Cu clusters positively charged. The presence of Cuδ+ stabilizes and optimizes the content of oxygen vacancies, leading to a more pronounced positive charge on Au clusters (Auδ+). The ability to activate H2 is thus enhanced. CO adsorption on Au-Cu/In2O3 is also stronger than Au/In2O3. This results in higher methanol selectivity of Au-Cu/In2O3, with which CO hydrogenation pathway is taken for CO2 hydrogenation to methanol. The enhanced H2 activation and stronger CO adsorption over Au-Cu/In2O3 are key factors in boosting the activity for methanol formation from CO2 hydrogenation.