Enhancing hydrogen evolution by heterointerface engineering of Ni/MoN catalysts

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Molybdenum nitrides are promising for hydrogen evolution reaction (HER) due to stability and metallic properties.
• Poor hydrogen adsorption limits molybdenum nitride performance in HER.
• Understanding active sites and mechanisms at catalyst heterointerfaces is crucial for enhancing HER.

Purpose of the Study:

• To fabricate a Ni/MoN heterostructure electrocatalyst to improve hydrogen adsorption and HER performance.
• To elucidate the role of electronic interactions and active sites at the Ni/MoN heterointerface.
• To investigate the fundamental mechanisms of water splitting via density-functional theory (DFT) calculations.

Main Methods:

• Fabrication of a composite electrocatalyst with Ni and MoN phases forming a heterointerface (Ni/MoN).
• Electrochemical characterization of the Ni/MoN electrocatalyst for HER performance in alkaline media.
• Density-functional theory (DFT) calculations to determine active sites and reaction mechanisms.

Main Results:

• The Ni/MoN heterointerface facilitates electron transfer and creates a built-in electric field, optimizing charge transfer.
• DFT calculations reveal H2O dissociation at Ni sites and H2 desorption at Mo sites.
• The Ni/MoN/CC catalyst achieved an overpotential of 95 mV for 10 mA cm-2 and a Tafel slope of 104 mV dec-1, with excellent stability.

Conclusions:

• Modulating the electronic structure of transition metal-based heterostructures is an effective strategy for high-performance electrocatalysts.
• The Ni/MoN heterostructure demonstrates significant potential for efficient and stable hydrogen evolution reaction.
• This approach offers a commercially viable pathway for designing advanced electrocatalysts for water splitting.