Mechanism of methanol synthesis from CO2 on Cu/CeO2 and Cu/W-CeO2: a DFT investigation into the nature of W-doping

Cu/CeO2 catalysts have garnered great interest for efficient methanol synthesis from CO2, and a recent report found that doping W into CeO2 to construct Cu/W-CeO2 significantly improves methanol productivity and selectivity. The report indicated that W-doping increases and stabilizes the Ce3+ concentration on Cu/CeW0.25Ox for inhibiting the loss of lattice oxygen and creating redox-active oxygen vacancies on the CeO2 surface. However, the mechanistic function of the modified Cu/CeO2 has not been fully understood. In this work, starting from the determination of calculated models Cu-8/CeO2-O-v and Cu-8/W-CeO2-O-v, we theoretically investigated two possible reaction pathways, the formate pathway and the reverse water gas shift (RWGS) + CO hydrogenation pathway, aiming to have an insight into the nature of W-doping on methanol productivity and selectivity. The calculated results indicate that for Cu-8/CeO2-O-v, the energy barrier for the rate-determining step (H2COOH* + H* -> H2CO* + H2O*) in the formate pathway is higher than that of the rate-determining step () in the RWGS + CO hydrogenation pathway, both of which involve the cleavage of the C-O bond of . However W-doping into Cu-8/CeO2-O-v weakens the interaction of the Cu cluster with the O-up atom in but enhances the C-O-down bonds, favoring the reaction towards the formate pathway and inhibiting the RWGS + CO hydrogenation pathway.