Mechanism of transition metal cluster catalysts for hydrogen evolution reaction

Studying the hydrogen evolution reaction (HER) catalyst is important for the global energy crisis. Clusters have many special characteristics due to quantum size effect and super high specific surface area, including optical performance, catalytic performance, etc. In this work, the structures of transition metal cluster TMn (TM = Co, Ni, Cu, Pd, Pt, n = 4–10) were searched and optimized by quantum chemistry methods. To search for non-precious metal catalysts, we calculated the Gibbs free energies for HER process on different clusters. Furthermore, the electronic structures of clusters before and after the reaction with H were analyzed, including the molecular surface electron distribution, the frontier molecular orbital, and the charge transfer properties, which dominated the HER processes. The results show that the Cu clusters have excellent HER catalytic properties due to its suitable surface electron distribution and HOMO/LUMO levels, especially Cu4, Cu7 and Cu9, which even comparable to Pt catalysts. These results can help us better understand the mechanism of clusters catalyze HER process.