Mesoporous Molybdenum Sulfide-Oxide Composite Thin-Film Electrodes Prepared by a Soft Templating Method for the Hydrogen Evolution Reaction

Electrode designs involving binder-free nanoparticles integrated within interconnected pore networks are critical in scaling up electrolyzers. MoS₂is the most promising electrocatalyst candidate that can show hydrogen evolution reaction (HER) activity comparable to platinum (Pt). Herein, a facile one-step soft templating method was developed to synthesize mesoporous molybdenum sulfide-oxide composite thin-film electrocatalysts directly on any substrate without using a binder or a template. Fabricated electrocatalysts contain amorphous MoS₃and small crystallite-sized MoS₂embedded into amorphous MoO₃with a large surface area (around 182 m²/g). The electrocatalyst layer undergoes in situ electrochemical activation in which amorphous MoS₃is reduced to MoS₂during the HER in acidic media. The electrocatalyst layer on the carbon fiber exhibits a low overpotential (∼189 mV at 10 mA/cm²) and Tafel slope (53 mV/dec) toward the HER after electrochemical activation.