Ni5 Nanoclusters on a Cu(111) Surface: A DFT Study of Selective CO2 Electroreduction

The electrochemical reduction of carbon dioxide (CO2) to value-added chemicals offers a promising approach for mitigating climate change and achieving carbon neutrality; however, the advancement of highly active and selective catalysts is still a vital challenge. Herein, we present a density functional theory (DFT) study, within the generalized gradient approximation (GGA), of Ni5 nanoclusters deposited on a Cu(111) surface for CO2 electroreduction, aiming to identify the structural and electronic characteristics that govern the stability of the reaction intermediates. The electronic structure is further analyzed with the HSE06 hybrid functional. Our results show that the Ni5 clusters reveal weak adsorption of CO2, while its intermediates show strong adsorption to the Ni5 clusters, with the free-energy analysis revealing a thermodynamic preference for CO over HCOOH. Ni5 deposition stabilizes the *COOH intermediate by approximately 0.4 eV and reduces the thermodynamic preference for the competing hydrogen evolution reaction (HER), although HER remains a competing pathway. Furthermore, Ni–Cu interfacial hybridization modulates the electronic structure of the Ni5 cluster and favors the *COOH-mediated pathway to CO. The mechanistic insights presented in this study highlight the potential of supported Ni clusters for tailoring the intermediates of CO2 reduction.