pH Modulated Atomic Distribution in NiMo Alloys for Ultrastable Water Electrolysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Surface engineering is key for alkaline hydrogen evolution reaction (HER) catalysts, but subsurface architecture is overlooked due to synthesis difficulties.
• Understanding subsurface effects is crucial for advancing HER catalyst design.

Purpose of the Study:

• To develop a novel "precursor hereditary" strategy to control subsurface architecture in HER catalysts.
• To optimize catalyst electronic structure and hydrogen adsorption/desorption energetics.

Main Methods:

• Modulating pH-dependent molybdate cluster speciation to control metal atom migration during thermal reduction.
• Creating a compositional gradient with an optimized depth profile.

Main Results:

• Achieved an ultralow overpotential of 61 mV at 200 mA cm⁻² with outstanding kinetics.
• Demonstrated industrial-level performance in an anion exchange membrane water electrolyzer (AEMWE) at 1.5 A cm⁻² and 1.88 V.
• Exhibited stable operation for 2,500 hours with minimal degradation (28 µV h⁻¹).

Conclusions:

• Established a universal strategy for manipulating atomic-scale depth profiles in catalysts.
• Bridged the gap between fundamental surface science and practical electrolyzer applications.
• Enabled efficient and stable hydrogen production through advanced catalyst design.