Gallium–Nickel Subnano Clusters for Electrochemical Carbon Dioxide Reduction

The hydrogenation of CO2 into valuable products offers a promising approach for carbon neutral technologies, with gallium–nickel alloys emerging as effective catalysts. Structuring the catalyst on the nano or subnano scale can be used effectively for tuning the catalytic activity and selectivity. In this study, we investigated the geometry, stability, electronic structure, and reactivity of small gallium–nickel subnano clusters for electrochemical carbon dioxide hydrogenation. The stabilities were investigated by the generalization of the second differential energy to bimetallic clusters, that combined with cluster composition appears as a promising descriptor for reactivity with carbon monoxide. The electronic structures were extensively characterized using electronic structure analysis, including molecular orbitals, density of states, d-band center theory, as well as by Energy Decomposition Analysis. We systematically explored cluster reactivity with carbon monoxide, hydrogen, and carbon dioxide, identifying key trends and their potential impact on catalytic activity. Finally, we investigated the possible reaction pathways on Ni4, Ga2Ni3, and Ga4Ni2 clusters toward C1 products using Computational Hydrogen Electrode model-based computations. The results indicate that Ga2Ni3 exhibits enhanced product desorption and reduced catalyst poisoning, making it a promising candidate for further investigation. Our observations provide valuable insights into the catalytic activity of Ga–Ni alloy clusters, demonstrating that subnano structuring represents a promising approach for catalytic tuning.