CO2 and H2 Activation on Zinc-Doped Copper Clusters

Abstract

Here we systematically investigate the CO₂ and H₂ activation and dissociation on small Cu_n Zn^0/+ (n=3-6) clusters using Density Functional Theory. We show that Cu₆ Zn is a superatom, displaying an increased HOMO-LUMO gap and is inert towards CO₂ or H₂ activation or dissociation. While other neutral clusters weakly activate CO₂ , the cationic clusters preferentially bind the CO₂ in monodentate nonactivated way. Notably, Cu₄ Zn allows for the dissociation of activated CO₂ , whereas larger clusters destabilize all activated CO₂ binding modes. Conversely, H₂ dissociation is favored on all clusters examined, except for Cu₆ Zn. Cu₃ Zn⁺ and Cu₄ Zn, favor the formation of formate through the H₂ dissociation pathway rather than CO₂ dissociation. These findings suggest the potential of these clusters as synthetic targets and underscore their significance in the realm of CO₂ hydrogenation.

Keywords: CO2 activation; CO2 hydrogenation; H2 activation; copper-zinc catalyst; metal clusters.