Professor Lee Chan-woo of Kookmin University (President Jung Seung-ryul) has developed an electrochemical catalyst that will lead the next generation of eco-friendly hydrogen production, together with Professor Kim Jin-young of Seoul National University and Dr. Yoo Sung-jong of the Korea Institute of Science and Technology. The ruthenium-based nanocluster catalyst with a core-shell structure designed by the research team has secured world-class performance and stability with only a small amount of precious metal, and has demonstrated excellent efficiency in commercial water electrolysis stacks.

Anion exchange membrane water electrolysis (AEMWE) is a next-generation technology that produces high-purity hydrogen through electrolysis, and a catalyst electrode with high efficiency and stability is essential. Currently, platinum (Pt) is used as a representative catalyst, but its high cost and rapid degradation are hindering its commercialization. To solve this problem, non-precious metal-based catalysts are being researched, but low efficiency and instability are issues.

In response, the research team developed a “core-shell nanocluster catalyst” based on ruthenium (Ru), which is more than twice as cheap as platinum. Despite reducing the size of the catalyst to less than 2 nm and significantly reducing the amount of precious metal used to one-third of that of commercial platinum electrodes, the team succeeded in achieving performance that surpasses that of platinum catalysts.

The research team formed a thin titanium oxide layer by treating a titanium foam substrate with hydrogen peroxide, then doped it with the transition metal molybdenum (Mo) and uniformly deposited ruthenium oxide nanoparticles of 1-2 nm in size on it. Afterwards, a unique core-shell structure was formed by inducing thermal diffusion at the atomic level through sophisticated low-temperature heat treatment. Finally, the core-shell structure was reduced through an electrochemical reduction reaction that occurs during the hydrogen evolution reaction. As a result, the developed catalyst has a unique core-shell structure with a porous single layer of reduced titania on a ruthenium metal core and metallic molybdenum atoms at its interface.

This innovative core-shell catalyst has shown 4.4 times higher performance than conventional platinum-based catalysts at the same precious metal content, and boasts the world's best performance among hydrogen-generating catalysts reported so far. In addition, by applying a foam electrode structure to optimize the supply rate of reactants, it showed excellent stability at high current densities. Furthermore, it demonstrated significantly lower power consumption than commercial platinum electrodes in actual AEMWE industrial environments, establishing itself as a strong candidate for next-generation water electrolysis catalysts.

The research team emphasized that “the development of a core-shell cluster catalyst with a size of less than 2 nm and its excellent performance and stability will dramatically improve the efficiency of hydrogen production and make a significant contribution to the technology for producing nanocore-cell devices and hydrogen production technology for a carbon-neutral era.”

Meanwhile, this research was conducted with the support of the Ministry of Science and ICT's Excellent Emerging and Basic Research Lab Project and the Ministry of Education's 4th-stage BK21 Project. The research results were also published in the latest issue of Energy & Environmental Science (IF 32.4, top 0.5% in the JCR field), a renowned academic journal in the field of catalysis. In particular, this research was selected as the cover article of the journal, and its innovation and academic value were recognized.

Dr. Hyunwoo Lim, the first author of the paper, is continuing his research as a postdoctoral researcher in the laboratory of Professor Jin-Young Kim of the Department of Materials Science and Engineering at Seoul National University, with the support of the Sejong Fellowship program of the government, starting this year, based on his excellent research results. In particular, he plans to focus on follow-up research to commercialize the core-shell structure of the catalyst developed this time.