6R-TaS2 Anchored on Mo Foil as a Robust Electrocatalyst for Hydrogen Evolution.

Affordable and durable HER catalysts are critical for sustainable hydrogen production. We report electrochemically exfoliated multilayer TaS2 flakes, predominantly in the metallic 6R phase, anchored on conductive Mo foil. The optimized hybrid (0.8 mg TaS2) initiates HER at -0.06 V vs RHE and reaches -10 mA cm-2 at only -150 mV vs RHE, approaching the performance of 20% Pt/C on Mo. Fast kinetics (Tafel slope of 68 mV dec-1), low charge-transfer resistance, and a high electrochemically active surface area (∼5.5 cm2) contribute to the superior HER activity, while maintaining ∼58% of the initial current after ∼56 h of continuous operation. Compared to TaS2 drop-cast on glassy carbon, the Mo substrate boosts performance by facilitating electron transport and proton adsorption. This work demonstrates substrate engineering combined with metallic transition metal dichalcogenide phases as a scalable route to high-performance, earth-abundant HER catalysts. Beyond performance, this study highlights the largely unexplored potential of the 6R polymorph, whose intrinsic metallicity and distinct stacking offer new opportunities for interface engineering in 2D electrocatalysts.