Scientists have taken a major step towards solving one of the biggest challenges facing green hydrogen: the scarcity of iridium, a rare and expensive metal crucial to current production methods.
"Right now, the most advanced technology for sustainable hydrogen production uses iridium-based catalysts in proton-exchange membrane water electrolysers," said lead study author Associate Professor Alexandr N. Simonov from the Monash University School of Chemistry.
"But there simply isn't enough iridium mined to build the scale of electrolysers needed for green hydrogen to truly decarbonise our energy and chemical industries."
The global push for green hydrogen as a clean fuel has highlighted an uncomfortable truth: while iridium works extremely well, its availability is an order of magnitude too low for the multi-gigawatt installations required worldwide.
To tackle this problem, researchers have been looking for effective anode catalysts made from cheaper and more abundant materials. Cobalt-based catalysts have shown promise, including previous breakthroughs by the Monash team, but until now, their limited stability has been a roadblock to real-world use.
"Cobalt is much cheaper than iridium, but the challenge has always been making cobalt-based catalysts stable enough to survive the harsh conditions inside these electrolysers," said study contributor Monash PhD alumnus Dr Darcy Simondson.
A new paper published today in Nature Energy, and led by the Monash University School of Chemistry with collaborators from the Max Planck Institute for Chemical Energy Conversion, Swinburne University of Technology, Los Alamos National Laboratory, Helmholtz-Zentrum Berlin for Materials and Energy, Cambridge University, and synchrotron facilities in Australia and Germany explores exactly why cobalt catalysts degrade and how to fix it.
"This was more than three years of research using some of the world's most advanced spectroscopic, electrochemical, and computational techniques," said Dr Marc Tesch, from the Max Planck Institute for Chemical Energy Conversion. "We discovered that the major catalytic function of these cobalt-based anodes, and their degradation, actually occur independently of each other. That wasn't what was expected from the previous research."
This new understanding could revolutionise how catalysts are designed. By showing that degradation and catalytic activity are decoupled, scientists can now focus on engineering cobalt materials to maximise their performance while separately tackling stability issues.
"Essentially, we've uncovered that these processes run in parallel rather than being directly linked. That gives us a clear pathway to making cobalt-based anodes robust and economically viable for green hydrogen production. There is also a potential to apply the same synchrotron methods to other catalysts providing critical insights across a range of systems," said study contributor Associate Professor Rosalie Hocking from the Swinburne University of Technology.
The team's findings bring the vision of cheaper, large-scale green hydrogen a step closer. If cobalt-based catalysts can be stabilised for long-term use, it could remove a major barrier in the multi-GW application of this technology worldwide.
"This research is critical for the development of new anodes that don't rely on scarce materials," said Associate Professor Simonov. "Green hydrogen can be a major tool in decarbonising our economy but only if we can make its production truly sustainable and scalable."
The work was supported by Monash University, the Australian Research Council, Office of Naval Research Global, Australian Renewable Energy Agency, Deutscher Akademischer Austauschdienst (DAAD), German Federal Ministry of Education and Research (BMBF), and international partners.
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