Introduction of new technology to form Schottky junction at heterojunction interface of electrocatalyst
[인더스트리뉴스 이건오 기자] A domestic research team has succeeded in developing a highly efficient water electrolysis catalyst that generates green hydrogen and oxygen using seawater as a raw material.
At the Gwangju Institute of Science and Technology (GIST), Professor Seo Jun-hyuk’s research team in the Department of Chemistry, together with Professor Han Jeong-woo’s team at Pohang University of Science and Technology, developed a technology to improve electron movement using ‘Schottky Junction’ and innovatively improved the catalytic reaction efficiency by using this technology. He said that he used it to do so.
(Left) Scanning electron microscope photo, (Right) transmission electron microscope photo of ‘nickel-tungsten nitride’/’nickel-iron oxide hydroxide’ heterojunction material, which is a catalyst for electrochemical oxygen generation reaction. [자료=GIST]
Unlike existing water electrolysis systems that use water without salt (fresh water), the research team confirmed the possibility of producing green hydrogen without carbon emissions by using seawater, which is the most abundant on Earth.
According to the research team, a heterojunction of metal and semiconductor materials was formed using an electrochemical reorganization reaction method, and the Schottky junction formed during heterojunction has 2.8 times higher electron transfer than ‘nickel-tungsten nitride’, known as a highly efficient water decomposition reaction catalyst. It showed efficiency. This study confirmed that it can be used as a seawater decomposition cell using highly efficient cathode and oxidation electrodes.
A research team official said, “The technology development strategy is to create Schottky bonding between ‘nickel-iron oxide hydroxide’ and ‘nickel-tungsten nitride’ materials through a reorganization reaction of ‘nickel-iron oxide hydroxide’, which is known to be a material with high efficiency in water oxidation reaction. “Through the reorganization reaction, we were able to form a ‘nickel-iron oxide hydroxide’ layer of a certain thickness on the surface of ‘nickel-tungsten nitride’,” he explained.
“At this time, a Schottky junction is formed between ‘nickel-tungsten nitride’ with a high work function and ‘nickel-iron oxide hydroxide’ with a low work function, and electrons are moved very efficiently, increasing the efficiency of oxygen generation on the electrode surface. “I did it,” he added.
Description of electron flow through Schottky junction formed at the ‘nickel-tungsten nitride’/’nickel-iron oxide hydroxide’ interface. (Left) Before creating a heterojunction, (Right) After creating a heterojunction [자료=GIST]
The research team experimentally demonstrated the effect of the effective electron transfer process through Schottky junction on the water electrolysis reaction efficiency. As a result of the seawater decomposition stability test conducted along with the dramatically improved efficiency and catalyst durability, the developed ‘heterojunction catalyst’ requires only 0.2 V overvoltage at 0.1 A and has better oxygen generation reactivity than expensive ruthenium oxide catalysts. It seemed.
In addition, ‘nickel-iron oxide hydroxide’ required an overvoltage of 0.01 V at 0.01 A and showed hydrogen generation reactivity that surpassed that of a platinum catalyst. The research team obtained experimental results that reached a high efficiency of 0.1 A with only an overvoltage of 0.2 V in an actual seawater decomposition reaction conducted for 10 days, confirming the possibility of commercialization of a highly efficient, high stability catalyst.
In this study, a) comparison of hydrogen production reaction efficiency of ‘nickel-tungsten nitride’ and platinum catalyst, b) oxygen generation reaction efficiency of ‘nickel-tungsten nitride’/’nickel-iron oxide hydroxide’ heterojunction material and ruthenium oxide catalyst. Comparison graph, c) Water electrolysis reaction test results using seawater [자료=GIST]
Professor Seo Jun-hyuk of the research team said, “This research outcome is significant in that it innovatively improved the catalytic reaction efficiency by introducing a new technology to form a Schottky junction at the heterojunction interface of the electrode catalyst in the field of water electrolysis catalyst technology development research.” “We can look forward to the possibility of commercialization in the future by producing green hydrogen using a water electrolysis catalyst or manufacturing equipment to supply oxygen,” he said.
Professor Seo Jun-hyuk, Department of Chemistry, Gwangju Institute of Science and Technology (GIST)
This research, led by Professor Seo Jun-hyuk of the Department of Chemistry and conducted by postdoctoral researcher Selvaraj Sinivasan and doctoral student Taewan Lim, was supported by the National Research Foundation of Korea’s basic research project and the Korea Institute for the Promotion of Oceans and Fisheries Science and Technology’s marine and fisheries new industry technology commercialization support project, and was a top-tier environmental research project. The paper, ‘Applied Catalysis B: Environmental’, was published online on August 30, 2023.
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2023-10-02 23:30:00
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