Designing a Dry Cathode via Hydrogen-Bond Network Regulation at Phosphide Heterostructure/Electrolyte Interfaces for...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing platinum group metal (PGM)-free catalysts is essential for cost-effective hydrogen production via anion-exchange membrane water electrolyzers (AEMWEs).
• Existing PGM-free catalysts struggle with water and proton supply limitations in the dry-cathode environments typical of AEMWEs, hindering performance.

Purpose of the Study:

• To engineer a novel PGM-free catalyst overcoming mass-transport and interfacial limitations in AEMWEs.
• To enhance the hydrogen evolution reaction (HER) kinetics and stability under realistic AEMWE operating conditions.

Main Methods:

• Synthesis and characterization of a Re2P/MoP heterostructure catalyst.
• Electrochemical measurements (HER performance, overpotentials) and theoretical calculations (electronic structure, kinetics).
• Assembly and testing of a membrane electrode assembly (MEA) using the Re2P/MoP catalyst in an AEMWE.

Main Results:

• The Re2P/MoP heterostructure catalyst demonstrated significantly lower HER overpotentials compared to individual components.
• Coupling of Re2P and MoP optimized electronic structure, enhancing hydrogen adsorption and water dissociation.
• The catalyst facilitated interfacial water molecule population and proton/hydroxide transfer, enabling high-current-density operation.
• The PGM-free MEA achieved industrial-level current densities (1.0 and 3.0 A cm⁻²) and maintained stable operation (>1000 h at 2.0 A cm⁻²).

Conclusions:

• The Re2P/MoP heterostructure represents a high-performance PGM-free cathode for AEMWEs.
• Interface engineering is critical for addressing mass-transport limitations and achieving efficient HER in AEMWEs.
• This catalyst offers a viable pathway towards low-cost, sustainable hydrogen production.