CO2 and CH3O intermediate adsorption on subnanometer Pdx clusters supported on the ZnO(1010) surface

We study CO2 and CH3O intermediate adsorption on subnanometer Pdx clusters (e.g., Pd7, Pd9, and Pd13) supported on the ZnO(1010) surface. Our results indicate that the activity of unsupported Pdx clusters in the CO2 hydrogenation largely remains unchanged after these clusters are supported. This behavior is attributed to a bidentate CO2 adsorption configuration that forms not only on top of the clusters but also at the Pdx-ZnO interface, providing an additional active site. The CO2 adsorption energies range from -0.32 to -0.55 eV (top) and from -0.56 to -0.91 eV (interface), while the CH3O intermediate exhibits adsorption energies of -2.73 to -2.96 eV (top) and -2.56 to -3.17 eV (interface). Based on these adsorption patterns, larger supported Pdx clusters favor methanol formation on top of the cluster, whereas smaller clusters expected to show better activity at the interface. The results contribute to addressing the key challenges in sustainable energy production and climate change mitigation.