![]() ![]() Credit: Korea Institute of Science and Technology (A) Durability test of water electrolysis device using the developed electrode(B) Water electrolysis performance before and after the durability test of the water electrolysis device using the developed electrode (C) Durability test of water electrolysis device with electrodes manufactured by conventional technology(D) Water electrolysis performance before and after durability test of water electrolyzer with conventional electrodes. In addition, the electrolysis unit with the new components was operated for more than 100 hours to verify its initial stability. The developed electrode replaces the gold or platinum used as a protective layer for the oxygen generating electrode with non-precious metal nitrides while maintaining similar performance to existing commercial electrolysis units, and reduces the amount of iridium catalyst to 10% of the existing level. The team also developed a process that uniformly coats an iridium catalyst about 25 nanometers (nm) thick on top of the iron nitride protective layer, reducing the amount of iridium catalyst to less than 0.1 mg/cm 2, resulting in an electrode with high hydrogen production efficiency and durability. To do so, the team developed a composite process that first uniformly coats the electrode with iron oxide, which has low electrical conductivity, and then converts the iron oxide to iron nitride to increase its conductivity. To improve the economics of water electrolysis, the team replaced the rare metals gold and platinum used as a protective layer for the oxygen electrode in polymer electrolyte membrane hydrogen production devices with inexpensive iron nitride (Fe 2N). ![]() The precious metals used in these electrolysis devices have very low reserves and production, which is a major factor hindering the widespread adoption of green hydrogen production devices. In a typical electrolysis device, there are two electrodes that produce hydrogen and oxygen, and for the oxygen generating electrode, which operates in a highly corrosive environment, gold or platinum is coated on the surface of the electrode at 1 mg/cm 2 as a protective layer to ensure durability and production efficiency, and 1-2 mg/cm 2 of iridium catalyst is coated on top. ![]() (B) Catalyst shape made with the new technology (red-iridium catalyst/green-iron nitride). (A) Catalyst shapes made with conventional technology (red-iridium catalyst/green-platinum). In addition, it is advantageous for energy conversion to store renewable energy as hydrogen energy, so increasing the economic efficiency of this device is very important for the realization of the green hydrogen economy. The polymer electrolyte membrane water electrolysis device is a device that produces high-purity hydrogen and oxygen by decomposing water using electricity supplied by renewable energy such as solar power, and it plays a role in supplying hydrogen to various industries such as steel making and chemicals. In particular, unlike previous studies that focused on reducing the amount of iridium catalyst while maintaining the structure that uses a large amount of platinum and gold as the electrode protection layer, the researchers replaced the precious metal in the electrode protection layer with inexpensive iron nitride having large surface area and uniformly coated a small amount of iridium catalyst on top of it, greatly increasing the economic efficiency of the electrolysis device. Park and Sung Jong Yoo of the Hydrogen and Fuel Cell Research Center at the Korea Institute of Science and Technology (KIST) announced that they have developed a technology that can significantly reduce the amount of platinum and iridium, precious metals used in the electrode protection layer of polymer electrolyte membrane water electrolysis devices, and secure performance and durability on par with existing devices. ![]()
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