Influence of Co Doping on Copper Nanoclusters for CO₂ Electroreduction

Copper stands out as one of the few metals capable of reducing carbon dioxide (CO₂) beyond carbon monoxide (CO) and formic acid (HCOOH). Furthermore, substitutional doping in nanoclusters (NCs) has been expected to enhance their catalytic performance, even though our atomistic understanding of the influence of dopants is far from complete. Here, we investigate the effects induced by cobalt (Co) substitution doping in the Cu₅₅ NC on the electroreduction of CO₂ using density functional theory calculations combined with the computational hydrogen electrode model. We found that the replacement of a single copper atom in Cu₅₅ by Co is energetically favorable, and it induces a drastic change in the density of states, for example, the appearance of a sharp peak near the Fermi level. The presence of a dopant atom on the surface increases the adsorption strength for all reaction intermediates, while also changing the preference of the adsorption site for selected species. The presence of the dopant atom on the surface of the particle hinders the production of CO in favor of more reduced products such as methane and methanol. From our analysis, it was observed that the catalyst will not suffer from poisoning by the OH species. However, our calculations predict that the catalysts will also enhance the formation of hydrogen in a competing reaction.