Phase-Transition of Mo₂C Induced by Tungsten Doping as Heterointerface-Rich Electrocatalyst for Optimizing Hydrogen...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical hydrogen evolution reaction (HER) is key for sustainable hydrogen production using renewable energy.
• Molybdenum carbide (Mo₂C) shows promise as an alternative electrocatalyst to noble metals for HER.
• A challenge for Mo₂C is the strong binding of hydrogen intermediates, hindering reaction kinetics.

Purpose of the Study:

• To engineer Mo₂C-based electrocatalysts with improved HER performance.
• To utilize a phase-transition strategy to modify Mo₂C structure and enhance catalytic activity.
• To investigate the role of heterointerfaces in optimizing HER kinetics.

Main Methods:

• Phase-transition engineering of hexagonal β-Mo₂C to cubic δ-Mo₂C via tungsten (W) doping.
• Synthesis of Mo₂C-based composites including β-Mo₂C, δ-Mo₂C, and MoO₂.
• Experimental characterization and density functional theory (DFT) calculations to analyze electronic structure and hydrogen adsorption.

Main Results:

• Tungsten doping successfully induced phase transition and created heterointerfaces (β-Mo₂C, δ-Mo₂C, MoO₂).
• Heterointerfaces, particularly β-Mo₂C/MoO₂, were found to be crucial for electron accumulation and weakening Mo-H coupling.
• The engineered composites exhibited excellent HER activity with low overpotential (99.8 mV at 10 mA/cm²) and Tafel slope (60.16 mV/dec) in 1 M KOH.

Conclusions:

• Phase-transition engineering provides an effective route to construct heterointerfaces for advanced electrocatalysts.
• The generated heterointerfaces significantly enhance the intrinsic catalytic activity of Mo₂C for HER.
• This approach offers a viable strategy for developing efficient and stable electrocatalysts for large-scale hydrogen production.