Producing green hydrogen could require fewer precious metals with a new catalyst developed by researchers in Braga, Portugal. The material outperformed a commercial benchmark despite containing roughly half its precious metal content by weight.
The team at the International Iberian Nanotechnology Laboratory (INL) combined platinum, nickel, and ruthenium into an alloy designed for proton exchange membrane water electrolysis, or PEMWE.
The study reported stable operation for more than 300 hours in a single-cell device at 60 °C (140°F).
The findings address a challenge for electrolyzers: reducing their reliance on expensive materials while maintaining performance during sustained operation.
Smaller particles, fewer precious metals
PEMWE uses electricity to split water into hydrogen and oxygen. When powered by renewable electricity, it offers a route to green hydrogen production.
However, the hydrogen-producing reaction at the cathode depends heavily on scarce platinum-group metals.
Researchers in INL’s Kolen’ko Research Group used a continuous-flow synthesis reactor to produce nanoparticles of a platinum-nickel-ruthenium medium-entropy alloy.
Measuring just 1.5 nanometers across, the particles were uniformly anchored on defect-rich graphene.
The catalyst contained 20.5 percent precious metals by weight, compared with the commercial benchmark’s 40 percent platinum content. Despite its lower precious-metal content, it outperformed the benchmark across multiple measurements.
In a single-cell PEMWE device, the catalyst delivered a current density of 1.0 ampere per square centimeter at 1.6 volts.
Surface changes improve activity
The catalyst’s behavior during operation was central to its performance. Initially, nickel-oxide species covered parts of the particle surfaces. Under cathodic polarization, those oxides were reduced, exposing the metallic alloy beneath.
“The catalyst doesn’t degrade, it activates. This is counterintuitive and exactly what you want for long-term operation,” said Sitaramanjaneya Mouli Thalluri, corresponding author of the study.
Synchrotron X-ray absorption spectroscopy confirmed that the surface restructuring was driven electrochemically.
At 60 °C (140°F), a temperature typical of industrial operation, the cell maintained stable voltage for more than 300 hours. The commercial benchmark, by comparison, showed continuous performance decay during testing.
These results suggest the alloy’s changing surface can support sustained activity, addressing the difficulty of improving catalytic performance without compromising stability.
Continuous flow offers a scaling pathway
Beyond the material itself, the researchers highlighted the production process. Combining metals with substantially different reduction potentials presents a challenge because their formation must be coordinated to produce the intended alloy.
“Continuous-flow synthesis is the game-changer here,” said Srinivas Katam, co-corresponding author.
The team said the reactor synchronized the metals’ nucleation, providing a pathway toward larger-scale production.
“This work demonstrates that medium-entropy alloys, when produced via continuous-flow synthesis, can overcome the traditional activity-stability trade-off,” said Dr. Yury V. Kolen’ko, leader of the Kolen’ko Research Group at INL.
The researchers also see potential applications beyond hydrogen production, including other electrochemical energy conversion technologies.
Funding came from Portugal’s Recovery and Resilience Plan (PRR) under the NextGeneration EU framework through the Moving2Neutrality Innovation Pact.
The single-cell results provide a basis for further development toward larger electrolyzer systems, where reducing precious metal requirements and maintaining durability remain key goals.
The study was published in Chemical Engineering Journal.