Dual Reaction Pathways on Ga2O3-ZnO/Cu for Efficient CO2-to-Methanol Conversion

Abstract

The design of metal–support interfaces is critical for overcoming the persistent trade-off between CO2 conversion and methanol selectivity in CO2 hydrogenation. Though an inverse catalyst with an oxide-on-metal configuration provides a platform for tuning interfacial properties, the distinct roles of multi-interfaces with different electronic properties and how they collectively govern reaction pathways remain largely unexplored. Herein, we constructed an inverse Ga2O3-ZnO/Cu catalyst to engineer dual pathways for efficient CO2-to-methanol conversion. Comprehensive characterization reveals that Ga2O3 induces charge redistribution in the catalyst for more oxygen vacancies, which enhance CO2 adsorption. The Cu-ZnO interface facilitates the formation of key intermediates along the formate pathway. Meanwhile, Ga also introduces a RWGS + CO* hydrogenation pathway to preferentially convert CO2 to methanol. In addition, Ga2O3 loading-enabled smaller Cu nanoparticles further enhanced H2 dissociation and spillover on the surface. Consequently, the optimized Ga2O3-ZnO/Cu catalyst achieves a high space time yield of methanol (728.73 gCH3OH kgcat–1 h–1) with a high methanol selectivity of 82.37% at 220 °C and 3 MPa. This work provides insights into engineering reaction pathways for methanol synthesis via the rational design of synergistic active sites.