Model of the 'Alkaline Anion Exchange Membrane Water Electrolyzer' used in the catalytic demonstration experiment
[Asia Economy Reporter Junho Hwang] Domestic researchers have developed a catalyst necessary for the commercialization of 'white hydrogen.' This catalyst enhances the efficiency of water electrolysis, a process that obtains hydrogen by splitting water. It is expected that this catalyst will replace 'gray hydrogen' derived from fossil fuels and contribute to realizing an eco-friendly hydrogen economy.
The research team led by Professor Kwangsoo Kim of the Department of Chemistry, School of Natural Sciences at Ulsan National Institute of Science and Technology announced on the 4th that they developed a 'metal-organic complex' catalyst to improve the efficiency of water electrolysis through theoretical calculations, and the related results were introduced in the energy field journal, Energy & Environmental Science.
Increasing Oxygen Reaction Rate with Metal-Organic Framework
The research team developed a catalyst that promotes water electrolysis by constructing a metal-organic framework containing nickel and iron through simulations. Water electrolysis is a method of producing hydrogen and oxygen by splitting water using electricity. However, in this process, the oxygen evolution reaction rate is slow, which lowers the hydrogen production rate and leads to reduced hydrogen productivity, making commercialization difficult.
The team increased the oxygen reaction rate by constructing a metal-organic framework where metals and organic materials form a skeleton like rebar in a building.
Doctoral researcher Tang Gabel explained, "Metal-organic frameworks have the disadvantages of low electrical conductivity and instability, so we integrated highly conductive and stable graphene," adding, "Through this, we were able to develop an oxygen evolution reaction catalyst with high efficiency."
Efficiency at Commercialization Level for Water Electrolysis
The newly developed catalyst can produce a large amount of hydrogen (current density) with much less energy (overpotential) than the existing iridium oxide catalysts. When evaluating the catalyst's performance by creating an 'alkaline anion exchange membrane water electrolysis device,' a current density of 0.5 A (amperes) per unit area (cm2) was achieved at 300 mV (millivolts) voltage. This value is sufficient for commercial use of the catalyst. Notably, the catalyst demonstrated excellent durability even after operating for more than 1,000 hours. Additionally, the metal-organic framework constituting the catalyst is more cost-competitive than iridium, which is currently used as a catalyst.
Professor Kwangsoo Kim said, "Through this research, we not only improved the slow oxygen evolution reaction rate problem but also simultaneously solved the price and stability issues of existing commercial catalysts," adding, "The developed catalyst can be used in various energy conversion devices."
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