6 days ago
Korean scientists unveil most efficient platinum-free system for hydrogen electrolysis yet
As the world races to adopt clean energy solutions, hydrogen has emerged as a leading candidate for decarbonizing everything from heavy industry to long-haul transport.
Among the various production methods, proton exchange membrane water electrolysis (PEMWE) stands out for generating high-purity hydrogen using only water and electricity.
Yet despite its promise, PEMWE faces a costly bottleneck due to its dependence on rare, expensive metals like platinum and iridium.
Korean researchers may have just found a way around that. A team led by Professor Hee-Tak Kim of KAIST, working with Dr. Gisu Doo from the Korea Institute of Energy Research (KIER), has developed a new method that delivers high PEMWE performance without platinum coating.
Their results could significantly lower production costs and accelerate hydrogen adoption worldwide.
PEMWE cells use iridium oxide (IrOx) as a catalyst to drive the oxygen evolution reaction. While IrOx is highly active, it doesn't perform at its full potential without platinum, which is a costly addition. The team uncovered that the poor electron transport is caused by structural issues within the electrode interface.
They pinpointed a key problem known as the "pinch-off" effect. It occurs where the IrOx catalyst, ionomer (a solid electrolyte), and titanium substrate meet.
The ionomer, though essential for conducting ions, acts as an electrical insulator around small catalyst particles. And when the ionomer touches the titanium substrate, a barrier forms on the oxide layer, worsening the conductivity.
To overcome this, the researchers changed one variable: particle size. They fabricated IrOx catalysts of varying diameters and evaluated them using real PEMWE single cells and computational simulations. The results were striking.
Particles larger than 20 nanometers created fewer pinch-off zones. This allowed electrons to travel more freely between the catalyst and the substrate, restoring performance without any platinum.
For the first time globally, the team proved that particle size alone can dramatically improve conductivity in PEMWE systems.
The team didn't just stop there. They also optimized the structure of the catalyst layer. Their design reduced the ionomer's interference while maintaining strong catalytic activity. This broke the long-standing trade-off between activity and conductivity, two factors previously thought to be mutually exclusive.
By engineering the interface at the microscopic level, they delivered both high reactivity and low resistance, even without platinum.
'This research presents a new interface design strategy that can resolve the interfacial conductivity problem, which was a bottleneck in high-performance water electrolysis technology,' said Professor Kim.
'By securing high performance even without expensive materials like platinum, it will be a stepping stone closer to realizing a hydrogen economy.'
The study not only opens the door to cheaper electrolysis systems but also strengthens South Korea's position in the global push for sustainable energy.
The study is published in Energy & Environmental Science.
