Abstract
A research team affiliated with UNIST has made a breakthrough discovery by developing a new technology that produces hydrogen at high efficiency from hematite (α-Fe2O3), a form of iron oxide (Fe2O3), which has been exposed to oxygen and water. This innovation has resulted in a 3.2-fold increase in efficiency compared to previous methods of producing hydrogen from water using sunlight. This breakthrough is expected to enable the use of more affordable and environmentally friendly energy in everyday life.
Led by Ji-Hyun Jang from the School of Energy and Chemical Engineering at UNIST, the team developed an environmentally friendly hydrogen production system using hematite-based photoelectrodes with excellent electrical properties. Hydrogen production currently relies heavily on fossil fuels, which poses significant environmental concerns. However, with the advent of environmentally friendly hydrogen production technology, commercialization is expected to accelerate.
The poor electrical performance of hematite has been a major obstacle to its commercialization, mainly due to its narrow reaction zone and long electron transport distance. To address these limitations, the research team optimized its structural characteristics.
By incorporating germanium (Ge), titanium (Ti), and tin (Sn) into the hematite matrix, the team improved its electrical properties and designed a porous structure with an average diameter of less than 10 nm through heat treatment. This innovative approach significantly enlarged the reaction zone and shortened the electron transport distance, thereby overcoming the defects of hematite and enabling a substantial improvement in the efficiency of water decomposition.
By fabricating branched hematite precursors, the team produced a highly nanoporous structure with an average support diameter of less than 10 nm between pores. Their results showed that the hydrogen conversion efficiency using sunlight was increased by 3.2 times, as well as excellent long-term stability over 100 hours without any noticeable degradation.
Hydrogen production currently relies heavily on fossil fuels, which poses environmental problems. However, with the development of environmentally friendly hydrogen production technology, commercialization is expected to accelerate. Professor Jang emphasized that their research is an important step toward the commercialization of green hydrogen production and its application to various semiconductor systems.
“Our results demonstrate the potential of our strategy to develop highly nanoporous structures and suggest its applicability to a wide range of materials for various applications relying on surface reactions, including solar conversion, energy storage and sensors,” the research team noted.
The results of this study were published in the June 2024 issue of the journal ACS Energy Letters. Juhyung Park, a postdoctoral researcher, participated in the study as the first author. The research was supported by the National Research Foundation of Korea (NRF), the Ministry of Science and ICT (MSIT), and the Engineering Research Center for Microplastics through the Bio/Chemical Engineering Convergence Process.
Journal reference
Juhyung Park, Ki-Yong Yoon, Balaji G. Ghule, et al., “Morphology-Modified Hematite Photoanode for Photoelectrochemical Water Splitting,” ACS Energy Letters, (2024).
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