The future of hydrogen catalysts: Researchers have developed a highly durable platinum–nickel (PtNi) catalyst for anion exchange membrane water electrolysis (AEMWE)
By controlling the catalyst’s atomic structure, the team from Korea Institute of Materials Science (KIMS), in collaboration with Pukyong National University and POSTECH, successfully suppressed nickel dissolution, enabling continuous hydrogen production for 3,000 hours with minimal performance degradation.
Suppressing nickel leaching through atomic ordering
Anion exchange membrane water electrolysis generates green hydrogen by splitting water under alkaline conditions. While AEMWE is considered a promising, cost-effective alternative to precious-metal-heavy technologies, the hydrogen evolution reaction proceeds slowly in alkaline environments.
Conventional platinum–nickel catalysts initially offer high activity, but extended operation causes nickel to dissolve into the electrolyte as ions or hydroxides. This leaching alters the catalyst’s chemical composition and electronic structure, leading to rapid performance loss.
To resolve this issue, the research team engineered an atomically ordered PtNi catalyst. Unlike conventional disordered catalysts where platinum and nickel atoms are randomly mixed, the new material arranges both elements into precise lattice positions.
Using computational materials science, the researchers determined that this ordered intermetallic structure binds nickel atoms more tightly, significantly increasing their resistance to chemical dissolution during electrolysis.
Synthesis process and performance testing
The synthesis involved reducing platinum and nickel precursors at low temperatures using sodium borohydride (NaBH4), followed by heat treatment under a nitrogen atmosphere. The thermal processing reorganised the randomly mixed atoms into a stable, ordered configuration that traps nickel securely within the lattice.
The team evaluated the catalyst across multiple scales, progressing from half-cell laboratory setups to single cells and ultimately a large-area, three-cell stack with an active area of 64cm2:
- Nickel retention:
- In comparative durability tests, conventional disordered catalysts lost approximately 54 per cent of their initial nickel content, whereas the ordered PtNi catalyst lost only 9 per cent.
- Long-term operational stability:
- Applied to the cathode of a 64cm2 three-cell electrolyser stack, the catalyst ran continuously for 3,000 hours (roughly four months). Over this period, total performance degradation remained below 2 per cent.
Commercial implications for green hydrogen catalysts
Extending catalyst lifetime is a critical requirement for commercialising green hydrogen infrastructure, as frequent catalyst degradation drives up replacement and maintenance costs.
By reducing platinum requirements while maintaining structural integrity over thousands of hours, the ordered PtNi catalyst offers a viable path for large-scale electrolysers, distributed water systems, and renewable energy storage facilities.
