Hollow Core–Shell Structured Ni–Sn@C Nanoparticles: A Novel Electrocatalyst for the Hydrogen Evolution Reaction

Pt-free electrocatalysts with high activity and low cost are highly pursued for hydrogen production by electrochemically splitting water. Ni-based alloy catalysts are potential candidates for the hydrogen evolution reaction (HER) and have been studied extensively. Here, we synthesized novel hollow core–shell structure Ni–Sn@C nanoparticles (NPs) by sol–gel, chemical vapor deposition, and etching processes. The prepared electrocatalysts with porous hollow carbon layers have a high conductivity and large active area, which exhibit good electrocatalytic activity toward HER. The Tafel slope of ∼35 millivolts per decade measured in acidic solution for Ni–Sn@C NPs is the smallest one to date for the Ni–Sn alloy catalysts, and exceeds those of the most non-noble metal catalysts, indicating a possible Volmer–Heyrovsky reaction mechanism. The synthetic method can be extended to prepare other hollow core–shell structure electrocatalysts for low-temperature fuel cells.