Molten salt-assisted synthesis of S anion doped rhenium diboride nanosheets for efficient hydrogen evolution in wide pH range

Water splitting requires the development of efficient and economical materials that catalyze hydrogen evolution reaction (HER) in diverse and complex environments. At present, HER in multi-environment mainly relies on noble metal catalysts, because the tolerance of non-noble metals is greatly limited under acidic conditions. In this study, we report the synthesis of sulfur (S)-anion-doped rhenium diboride (ReB 2 ) nanosheets using a molten salt-assisted method. This novel approach facilitates the uniform incorporation of S anions into the ReB 2 lattice. This leads to enhanced electrocatalytic activity. The resulting S-doped ReB 2 nanosheets exhibit superior performance with remarkable activity and stability across a wide pH range in HER. Specifically, overpotential of 144 mV, 158 mV, and 139 mV (1.0 M KOH) are required in 1.0 M PBS, 0.5 M H 2 SO 4 , and 1.0 M KOH, respectively, to achieve a current density of 10 mA/cm 2 . with long-term durability over 50 h in all three media. Due to their unique porous structure, the nanosheets exhibit a large electrochemical active area, exposing more active sites, promoting the diffusion of electrolyte and the generation and release of gas bubbles on the catalyst surface, and they can be used as efficient bifunctional electrocatalysts for overall water splitting. In addition, the introduction of anion S effectively regulates the electronic structure of Re, thereby enhancing the catalytic reaction kinetics and intrinsic catalytic performance.