Activating Sulfur Sites of CoS2 Electrocatalysts through Tin Doping for Hydrogen Evolution Reaction

Abstract Exploring high efficient transition-metal dichalcogenides catalysts for hydrogen evolution reaction (HER) is important for water-derived hydrogen fuel. Pyrite cobalt disulfide (CoS2) is one of the potential HER catalysts due to its low price and inherent metallicity, but its catalytic activity is still unsatisfactory possibly attributed to the S sites with catalytic inert; hydrogen adsorption on S sites is weak extremely. Metal cation doping has been considered as one of the most available methods to modulate the electronic structure of electrocatalysts. Here, we report non-transition metal tin (Sn) doped CoS2 nanowire arrays grown on carbon cloth (Sn-CoS2/CC) as available catalysts for HER. The Sn-CoS2/CC catalyst with optimal doping concentration not only has an enhanced over potential of 161 mV at 10 mA cm-2, and the Tafel slope is 94 mV dec-1, but also shows good long-term durability in 32 hours of testing. Experimental results and further density functional theory (DFT) calculations show that Sn doping can improve the charge transfer ability, enhance electronic conductivity, and arouse the catalytic insert S sites with optimal hydrogen adsorption free energy (ΔGH*). This work investigates a new method to activate the inert sites in metal-compound catalysts for water splitting and beyond through non-transition metal doping.