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Phase-Transition of MoC Induced by Tungsten Doping as Heterointerface-Rich Electrocatalyst for Optimizing Hydrogen Evolution Activity. | LitMetric

AI Article Synopsis

  • Electrochemical hydrogen evolution reaction (HER) from water splitting is a promising way to produce hydrogen using renewable energy, with molybdenum carbide (MoC) as an effective catalyst alternative to noble metals.
  • The study introduces a phase-transition strategy, showing that tungsten (W) doping helps convert hexagonal β-MoC to cubic δ-MoC, creating heterointerface-rich MoC composites that enhance electron accumulation and improve HER kinetics.
  • Key findings suggest that the interface between β-MoC and MoO optimizes the electronic structure and hydrogen adsorption properties, leading to outstanding catalytic performance, characterized by low overpotential, small Tafel slope, and high stability.

Article Abstract

Electrochemical hydrogen evolution reaction (HER) from water splitting driven by renewable energy is considered a promising method for large-scale hydrogen production, and as an alternative to noble-metal electrocatalysts, molybdenum carbide (MoC) has exhibited effective HER performance. However, the strong bonding strength of intermediate adsorbed H (H) with Mo active site slows down the HER kinetics of MoC. Herein, using phase-transition strategy, hexagonal β-MoC could be easily transferred to cubic δ-MoC through electron injection triggered by tungsten (W) doping, and heterointerface-rich MoC-based composites, including β-MoC, δ-MoC, and MoO, are presented. Experimental results and density functional theory calculations reveal that W doping mainly contributes to the phase-transition process, and the generated heterointerfaces are the dominant factor in inducing remarkable electron accumulation around Mo active sites, thus weakening the Mo─H coupling. Wherein, the β-MoC/MoO interface plays an important role in optimizing the electronic structure of Mo 3d orbital and hydrogen adsorption Gibbs free energy (ΔG), enabling these MoC-based composites to have excellent intrinsic catalytic activity like low overpotential (η = 99.8 mV), small Tafel slope (60.16 dec), and good stability in 1 m KOH. This work sheds light on phase-transition engineering and offers a convenient route to construct heterointerfaces for large-scale HER production.

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http://dx.doi.org/10.1002/smll.202311026DOI Listing

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