Domestic Research Team Develops Large Photoelectrode Module... Accelerating Commercialization of Solar Hydrogen

UNIST Joint Research Team Completes 'Perovskite Module' Enlarged 10,000 Times

Achieves World's Highest Solar-to-Hydrogen Conversion Efficiency, Published in Nature Energy

A large-area photoelectrode module that can be used for green hydrogen production has been developed. Achieving the world's highest efficiency based on the module, the commercialization of solar hydrogen production is expected to be accelerated.

UNIST (President Yong-Hoon Lee) announced on the 6th that a joint research team consisting of Professors Jaesung Lee, Jiuk Jang, Sangil Seok from the Department of Energy and Chemical Engineering, and Professor Hangwon Lim from the Carbon Neutrality Graduate School developed a green hydrogen production technology that uses solar energy with high efficiency, durability, and large-scale production capability.

The research team addressed the drawbacks of perovskite solar cells and increased the size of the photoelectrode by 10,000 times to enhance its practical applicability.

Conceptual diagram of large-area fabrication through modularization.

Solar hydrogen technology is an ideal green hydrogen production technology that obtains hydrogen by splitting water using solar energy, the most abundant renewable energy on Earth.

Professor Jaesung Lee explained, “Recently, technologies that have somewhat solved efficiency issues have been developed, but these results were obtained from small laboratory devices, so scale-up is necessary to increase the size for practical use.”

The research team selected perovskite as the photoelectrode material due to its high efficiency and relatively low cost. Perovskite solar cells are a research and development field led by UNIST professors including Professor Sangil Seok, who participated in this study.

However, perovskite solar cells have low stability against ultraviolet rays contained in sunlight and moisture in the air. Especially, to produce hydrogen by splitting water, the photoelectrode must be immersed in water, and the research team improved both of these issues.

Solar hydrogen generator installed outdoors.

The research team manufactured the most UV-stable perovskite by using formamidinium instead of methylammonium as the cation of perovskite. They completely sealed the water contact surface with nickel foil to maintain stability even underwater.

Typically, research and development photoelectrodes are small, less than 1 cm², and must be scaled up about 10,000 times to reach the practical scale of 1 m². Since hydrogen production efficiency decreases during the scale-up process, technology to minimize this loss is also necessary.

To scale up this photoelectrode, the research team utilized a “module-based design” that connects small photoelectrodes arranged in a fixed size. Small photoelectrodes are repeatedly connected horizontally and vertically like stacking blocks to manufacture large-area photoelectrodes.

The scaled-up module achieved a solar-to-hydrogen conversion efficiency of over 10%, which is the minimum condition for commercialization. This is known to be the world’s highest efficiency for large-area photoelectrodes.

Research team. (Top row from left: First author Researcher Yujin Wook, Professor Im Hangwon; Bottom row from left: Seok Sangil, Professor Jang Jiuk, First author Researcher Dharmesh Hansora, Professor Lee Jaesung, First author Rashmi Mehrotra)

First author Dr. Sora Han said, “The developed photoelectrode maintained high efficiency even at a large area,” and added, “If field demonstrations for the practical use of green hydrogen production are focused on, solar-based green hydrogen technology is expected to be commercialized before 2030.”

The research results were published online on January 23 in Nature Energy, the top academic journal in the energy field. The research was supported by the Climate Change Response Project and Brain Link Project promoted by the Ministry of Science and ICT.

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