Nontrivial Topological Surface States in Ru Sn toward Wide pH-Range Hydrogen Evolution Reaction.

Nontrivial topological surface states (TSSs), which possess extraordinary carrier mobility and are protected by the bulk symmetry, have emerged as an innovative platform to search for efficient electrocatalysts toward hydrogen evolution reaction (HER). Here, a Sn-based nontrivial metal Ru Sn is prepared using electrical arc melting method. The results indicate that the (001) crystal family of Ru Sn possesses nontrivial TSSs with linear dispersion relation and large nontrivial energy window. Experimental and theoretical results demonstrate that nontrivial TSSs of Ru Sn can significantly boost charge transfer kinetics and optimize adsorption of hydrogen intermediates due to bulk symmetry-protected band structures. As expected, nontrivial Ru Sn exhibits superior HER activity to Ru, Pt/C, and trivial counterparts (e.g., Ru Sn , IrSn , and Rh Sn ) with higher ratios of noble metals. Furthermore, the wide pH-range activity of topologically nontrivial Ru Sn implies the robustness of its TSSs against pH variation during the HER. These findings provide a promising approach to the rational design of topologically nontrivial metals as highly efficient electrocatalysts.