Zn and O/OH synergy in H2 activation and CO2 hydrogenation over Cu nanoparticles catalysts

Abstract

The CO₂ hydrogenation reaction to produce methanol holds great significance as it contributes to achieving a CO₂-neutral economy. In this work, we present a molecular-level understanding of how Zn atom doping and oxygen or hydroxyl groups play a crucial role in facilitating CO₂ hydrogenation on the surface of Cu nanoparticles by density functional theory calculations. Computational evidence proves a higher selectivity of CO₂ hydrogenation to HCOO* species as a crucial intermediate in methanol synthesis via the “formate” pathway than that to COOH* via the “RWGS + CO hydro” pathway, by comparing the catalytic performance of pure Cu nanoparticles. Our work highlights the synergistic effect among the doped Zn atom, oxygen or hydroxyl groups and Cu atoms, all of which serve as key parameters in the H₂ dissociation and CO₂ conversion, which significantly reduces the barriers not only in the CO₂ hydrogenation to HCOO, but also in the whole process of CO₂ hydrogenation to methanol. The electronic characteristics of the catalysts altered by Zn atom doping and oxygen or hydroxyl groups when H₂ or CO₂ is adsorbed further confirm their synergistic effect in favor of CO₂ hydrogenation. By elucidating the specific roles of these components, we contribute to advancing our understanding of the underlying mechanisms and provide valuable insights for optimizing methanol synthesis processes.