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

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Affordable and durable electrocatalysts are essential for sustainable hydrogen production via the hydrogen evolution reaction (HER).
• Transition metal dichalcogenides (TMDs) are promising HER catalysts, but their performance is often limited by phase and substrate interactions.

Purpose of the Study:

• To investigate the potential of electrochemically exfoliated multilayer tantalum disulfide (TaS₂) flakes in the metallic 6R phase, anchored on a conductive molybdenum (Mo) foil, as a high-performance HER catalyst.
• To explore the role of substrate engineering in enhancing the catalytic activity of 2D materials.

Main Methods:

• Electrochemical exfoliation of multilayer TaS₂ flakes.
• Anchoring TaS₂ flakes onto conductive Mo foil.
• Electrochemical characterization of the hybrid catalyst for HER activity, including overpotential, current density, Tafel slope, and long-term stability.
• Comparison with TaS₂ drop-cast on glassy carbon.

Main Results:

• The optimized hybrid catalyst (0.8 mg TaS₂/Mo foil) exhibits excellent HER activity, initiating HER at -0.06 V vs RHE and achieving -10 mA cm^-2 at -150 mV vs RHE.
• The catalyst demonstrates fast kinetics (Tafel slope of 68 mV dec^-1), low charge-transfer resistance, and a high electrochemically active surface area (∼5.5 cm²).
• The Mo substrate significantly enhances HER performance compared to glassy carbon by facilitating electron transport and proton adsorption, with the catalyst maintaining ∼58% of its initial current after ∼56 h of operation.

Conclusions:

• Substrate engineering combined with metallic 6R-phase TaS₂ offers a scalable route to high-performance, earth-abundant HER catalysts.
• The 6R polymorph of TaS₂ possesses intrinsic metallicity and distinct stacking, presenting new opportunities for interface engineering in 2D electrocatalysts for hydrogen production.
• This work highlights the potential of Mo-supported metallic TMDs as efficient and durable alternatives to precious metal catalysts for sustainable energy applications.