CO2 Hydrogenation on Gas-Phase Palladium-Zinc Bimetallic Clusters.

Hydrogenation of CO2 to valuable products is an attractive method to mitigate the greenhouse effect. Palladium-zinc-based nanomaterials are stable and selective catalysts in the methanol formation process. For a better understanding of the catalytic reaction mechanisms, here, we investigate hydrogen activation and carbon dioxide hydrogenation on Pd x Zn x (x = 2-4) and Pd6 clusters using systematic density functional theory analysis, selected on the basis of high-level benchmarks. We show that alloying palladium with zinc makes the H2 adsorption and dissociation less favored and increases the energies of the highest lying transition states, while zinc strongly stabilizes the formate intermediate, by binding one of its oxygen atoms through a (partial) ionic bond.