Understanding the synergistic role of Ni/Pt doping and γ-Al2O3 support in tuning CO2 adsorption and activation on Cu13 nanoclusters.

Metal nanoclusters supported on metal oxides are known to exhibit high catalytic performance in a range of reactions, with their shape and oxidation state, key factors influencing catalytic behavior, often governed by the support material. Herein, density functional theory (DFT) is employed to investigate the adsorption and activation of carbon dioxide (CO2) on an icosahedral Cu13 cluster supported on the (110) surface of γ-alumina (γ-Al2O3), with a focus on the effects of nickel and platinum (NiCu12 and PtCu12) doping. CO2 adsorption was first examined on isolated clusters. Enhanced binding observed for PtCu12 was attributed to increased charge transfer and higher orbital overlap between the cluster and CO2. Subsequent structural optimizations of the cluster/γ-Al2O3 interfaces revealed that all supported clusters carry a net positive charge, resulting from electron transfer from interfacial Cu atoms into the underlying Al2O3 layers. As a result, the upper regions of the clusters become relatively electron-deficient. Furthermore, the most reactive sites are anchored to the oxide surface, limiting their accessibility for adsorbates, while the remaining exposed Cu sites exhibit enhanced CO2 activation. The support thus plays a dual role: (i) it strengthens CO2 adsorption on Cu13, NiCu12, and PtCu12 clusters, and (ii) it promotes both thermodynamic and kinetic favorability for CO2 dissociation on PtCu12/γ-Al2O3, thereby enabling more efficient subsequent conversion. These findings reveal the synergistic interplay between structural and electronic effects facilitated by the γ-Al2O3 support, providing a rational basis for designing Cu-based catalysts tailored for enhanced CO2 utilization.