3R TaS₂ Surpasses the Corresponding 1T and 2H Phases for the Hydrogen Evolution Reaction

We prepared new two-dimensional 3R TaS₂ nanomaterials and investigated their application in hydrogen evolution reaction (HER) under acidic condition for the first time. The partial orientation aligned 3R TaS₂ nanosheets show excellent electrocatalytic performance toward HER and outperform the corresponding 1T and 2H TaS₂. Benefiting from the broken inversion symmetry and large exposed edge sites, the obtained 3R TaS₂ nanomaterial exhibits optimized electrocatalytic activity for HER with onset overpotential as low as 106 mV, low Tafel slope of 85 mV decade^-1 and high current density of 10 mA cm^-2 at η = 196 mV. First-principles calculations suggest that the 3R TaS₂ has more adsorption energies than 1T and 2H TaS₂, confirming that the polymorph structures of TaS₂ do influence their HER electrocatalytic performance. We expect that the control of polymorph structures can be an effective way to enhance the catalytic performance of transition-metal dichalcogenides (TMDs) in hydrogen evolution reaction and 3R TaS₂ nanosheet is one of the most promising electrocatalysts for hydrogen production.