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

Abstract

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/CeW_0.25O_x 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 Cu₈/CeO₂-O_v and Cu₈/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 Cu₈/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 Cu₈/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.