Tungsten-Assisted\nPhase Tuning of Molybdenum Carbide for Efficient Electrocatalytic\nHydrogen Evolution

Abstract

Phase\ntuning during crystal phase transformation is an important but challenging\nstep toward the development of effective hydrogen evolution reaction\n(HER) catalysts. Herein, we report on a feasible approach to achieve\neffective polycrystalline molybdenum carbides during transformation\nfrom α-phase to β-phase through the regulation of additive\n(tungsten) amount. Benefiting from the optimal Mo–C bond lengths\nand abundant active sites, molybdenum carbide prepared with a moderate\naddition of tungsten enhanced electrocatalytic activity and stability\ncompared with pure α-phase and β-phase Mo₂C\nin the HER, and only required an overpotential of 148 and 93 mV to\ndrive 20 mA cm^–2 of current density in 0.5 M H₂SO₄ and 1.0 M KOH, respectively.