KAIST

< (From left) Ph.D candidate Jaeho Byeon, Ph.D candidate Minkyeong Ban, Professor Jinwoo Lee, Dr. Sungjun Kim, Professor Jang Yong Lee>

As the global transition toward carbon neutrality accelerates, "water electrolysis"—a technology that splits water electrically to produce clean hydrogen—is drawing significant attention. However, a major limitation has been the decline in efficiency caused by bubbles formed during the electrolysis process that block the pathways. A domestic research team has resolved this challenge by developing an innovative technology that rapidly discharges bubbles and boosts hydrogen production efficiency, much like clearing an expressway through a heavily congested road.

KAIST announced on May 28th that a research team led by Professor Jinwoo Lee from the Department of Chemical and Biomolecular Engineering, in collaboration with a research team led by Dr. Sungjun Kim from KRICT (President Suk-min Shin) and a research team led by Professor Jang Yong Lee from Konkuk University (President Jong-phil Won), has departed from the conventional method of simply increasing catalytic activity itself. Instead, they have successfully secured both water electrolysis performance and stability simultaneously by newly designing a "pathway" inside the catalyst layer through which water and gas pass.

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Using paper-thin 2D mesoporous carbon (a thin carbon structure with numerous nanoscale pores) nanosheets, the research team created a low-tortuosity structure where materials can move without obstruction. Simply put, they implemented a "highway-like pathway" inside the catalyst layer through which water and gas can pass rapidly, instead of a narrow and complex alleyway.

Furthermore, ruthenium (Ru) nanoclusters (ultrafine metal particles several nanometers in size) were stably anchored onto the defect-introduced carbon surface to accelerate the hydrogen evolution reaction rate. Simultaneously, the interface structure was controlled to prevent catalyst degradation even during long-term operation.

Through this technology, it was confirmed that bubbles generated during the water electrolysis process were rapidly discharged without accumulating inside the catalyst layer, and a stable reaction was maintained even under extreme environments with high current density.

As a result, the technology recorded a world-class performance of 17.1 A cm⁻² at 80°C, vastly exceeding the 2026 target set by the U.S. Department of Energy (DOE). This figure represents the amount of current flowing per unit area; a higher value signifies that more hydrogen can be produced faster.

In addition, it demonstrated practical industrial applicability by operating stably for over 1,000 hours even under a low noble metal loading condition (0.09 mgRu cm⁻²). This means that the amount of ruthenium, a precious metal used in the catalyst, has been significantly reduced, which can also enhance the economic viability of water electrolysis systems.

The core of this research lies not simply in making a "good catalyst," but in newly designing the pathway itself through which hydrogen is formed. In conventional water electrolysis devices, bubbles generated during the reaction process accumulate inside, blocking the flow of water and electricity, which leads to a degradation in performance. The research team solved this problem by changing the structure of the catalyst layer so that bubbles can exit rapidly.

This technology holds great significance as it opens the way to produce eco-friendly hydrogen more affordably and efficiently in the future. Hydrogen is currently attracting attention as a core clean energy source for the carbon-neutral era, but it has faced limitations due to high production costs and low system efficiency. In particular, conventional high-performance water electrolysis devices required large amounts of expensive noble metals, making large-scale commercialization difficult.

The research team explained that this technology demonstrates the potential to achieve high performance and stability with only a small amount of noble metals. It is expected to expand into various fields in the future, including large-scale green hydrogen production, eco-friendly power generation systems, hydrogen vehicles/eco-friendly mobility, and carbon-neutral industrial processes.

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Professor Jinwoo Lee stated, "This research is a technology that improves water electrolysis efficiency by designing not only the catalyst itself but also the path through which energy flows. Since high-efficiency green hydrogen production is possible with only a small amount of noble metals, we expect to accelerate the commercialization of eco-friendly hydrogen production in the future."

In this study, PhD students Jaeho Byeon and Minkyeong Ban from the KAIST Department of Chemical and Biomolecular Engineering participated as co-first authors. The research findings were published online on May 22, 2026, in Joule, the world's leading academic journal in the energy field, and will be featured in the formal issue of Joule on September 16.

※ Paper Title: Outperforming water electrolysis through catalyst layer structuring with defective 2D mesoporous carbon, DOI: 10.1016/j.joule.2026.102478

※ Author Information: A total of 18 authors including Jaeho Byeon (KAIST, co-first author), Minkyeong Ban (KAIST, co-first author), Liangliang Xu (co-first author), Seunggeon Lee, Seongbeen Kim, Seonggyu Lee, Seongmin Shin, Donghyeok Son, Wonchul Park, Jinkyu Park, Hoyoung Kim, Dongyoon Woo, Seongseop Kim, Dong Young Chung, Jaewook Nam, Jang Yong Lee (Konkuk University, corresponding author), Sungjun Kim (KRICT, corresponding author), and Jinwoo Lee (KAIST, corresponding author).

This research was conducted with support from the National Research Foundation of Korea’s "AEM Water Electrolysis Technology Development" (RS-2024-00467234), the "Nano-Future Materials Source Technology Development" (RS-2023-00235596), the Ministry of Education’s "Ph.D. Student Research Support Project" (RS-2025-25424765), the Korea Research Institute of Chemical Technology (KS2522-10), and the Lotte Chemical Carbon Neutral Center.