A team led by Ji Ho-il at the Korea Institute of Science and Technology (KIST) devised a new analytical protocol that pinpointed for the first time how oxygen reduction reactions unfold inside the cathodes of protonic ceramic fuel cells (PCFCs), the institute said on Wednesday.
PCFCs operate at temperatures below 500 degrees Celsius, well under the threshold required by conventional solid oxide fuel cells, which translates into lower manufacturing costs and significantly longer lifespans.
The technology has drawn growing attention as a pillar of the global shift toward hydrogen-based energy, yet progress has been hampered by the sheer complexity of the electrochemical reactions occurring at the cathode, where oxygen, electrons and protons collide simultaneously.
Previous studies relied on researchers selecting one assumed reaction pathway from hundreds of possibilities — a method prone to decisive bias. Ji's team upended that convention by developing a protocol that identifies the rate-determining step through precision experiments first, then traces the reaction pathway backward without any prior assumptions.
When the protocol was applied to two widely studied cathode materials — PBSCF and BCFZY — the team confirmed for the first time that the two materials follow entirely distinct reaction pathways. One material showed a sharp drop in resistance as water vapor increased, while the other remained virtually unchanged, offering direct experimental proof of the divergence.
"This study fundamentally reveals why hydrogen fuel cells suffer from low efficiency," Ji said. "We expect it to serve as an important foundation for developing the high-performance fuel cells essential to realizing a clean hydrogen economy."
Beyond fuel cells, the researchers said the analytical framework could be applied broadly to other electrochemical devices, including systems that produce green hydrogen by running the cells in reverse to harness solar, wind and nuclear energy.
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