Identifying the Active Sites in MoSi₂@MoO₃ Heterojunctions for Enhanced Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Developing 2D Mo-based heterogeneous nanomaterials is crucial for energy conversion, particularly the alkaline hydrogen evolution reaction (HER).
• Identifying active sites at the complex interfaces of these nanomaterials remains a significant challenge.

Purpose of the Study:

• To systematically explore the real active sites during the HER process in various Mo-based 2D materials.
• To construct and investigate MoSi2@MoO3 heterojunctions for enhanced electrocatalytic activity.

Main Methods:

• Theoretical computation and magnetron sputtering approaches were used to identify candidate materials.
• Oxygen doping was employed to create MoSi2@MoO3 heterojunctions.
• Density functional theory (DFT) calculations were performed to analyze hydrogen adsorption free energy (ΔG_H*).

Main Results:

• The MoSi2@MoO3 heterojunctions exhibited an outstanding overpotential of 72 mV at a current density of 10 mA cm⁻².
• DFT calculations revealed varying Gibbs free energy of hydrogen adsorption (ΔG_H*) at different interfacial sites.
• Synergistic effects between MoSi2 and MoO3 significantly enhanced catalytic performance.

Conclusions:

• The study successfully identified active sites and optimized heterojunction design for Mo-based 2D materials.
• The developed MoSi2@MoO3 electrocatalyst demonstrates high efficiency for alkaline HER.
• These findings provide valuable insights for designing advanced heterojunction electrocatalysts.