Hydrogen evolution reaction on Co-Ni core-shell nanoclusters in different sizes: A DFT investigation from geometric structures to electronic structures

Nanoclusters have broad prospects in the application of hydrogen evolution reaction (HER) electrocatalysis. Its high specific surface area, surface geometry effect, electronic properties, and quantum size effect often make the nanoclusters have higher activity than ordinary electrocatalytic materials. However, it is still challenging to design and regulate nanoclusters and make them have better HER performance. In this work, through first-principles calculation from geometric structures to electronic structures, we try to understand the basic physical and chemical properties and HER performance of nanoclusters composed of transition metals Co and Ni. We optimize the electronic structure and promote effective charge transfer by adjusting the size of nanoclusters and constructing core-shell alloying. First-principles studies reveal that the geometric size and electronic structures of Co-Ni nanoclusters can significantly affect the performance of the hydrogen evolution reaction. We found that Co@Ni12 (|ΔGH*|=0.01eV) shows the best HER performance. The Gibbs free energy of hydrogen adsorption of Co-Ni nanoclusters is positively related to the size of the clusters, and the ΔGH* can be adjusted within a certain range by changing the electronic structures of the clusters. Our research helps to understand and design high-efficiency nanocluster electrocatalysts, paving the way for the rational design and synthesis of advanced electrocatalysts for HER.