Friction Induced Structural Transformation of Bulk Nanostructured MoS2 for Hydrogen Evolution Reaction

MoS2 is a good candidate for Hydrogen Evolution Reaction (HER) catalyst because it has low overpotential at 10 mA/cm2 and low Tafel slope close to platinum, is inexpensive, and is abundant. High surface area and mass loading of the Friction Induced Structural Transformation of crumpled MoS2 (FIST c-MoS2) could lower the overpotential at 10 mA/cm2 and Tafel slope compared to c-MoS2 and chemically exfoliated MoS2 (ce-MoS2). In this work, MoS2 catalysts are synthesized at room temperature to preserve active basal plane for hydrogen adsorption. The overpotential at 10 mA/cm2 of the catalyst after cyclic voltammetry is -196 mV vs. Reversible Hydrogen Electrode (RHE); the Tafel slope is 91.9 mV/dec, and the exchange current density is 75.9 µA/cm2 in 0.5 M H2SO4 electrolyte. After cyclic voltammetry from +0.2 V to -0.3 V vs. RHE for 1,000 cycles, FIST c-MoS2 on ce-MoS2, c-MoS2 on ce-MoS2, and ce-MoS2, all on carbon cloth, show similar overpotential at 10 mA/cm2, and similar Tafel slope. MoS2 catalysts from this work exhibit among the lowest overpotentials at 10 mA/cm2 of MoS2 based catalysts. Capacitance data derived from EIS plots reveal that cyclic voltammetry leads to an increased surface area of all the MoS2 catalysts. The increased surface area promotes low overpotential at 10 mA/cm2, and high exchange current density.