Development of Iridium Catalyst Synthesis Method to Reduce Green Hydrogen Production Costs

Published 25 Mar.2021 10:17(KST)

Professor Chanho Park's Team at Gwanggu Institute of Science and Technology Reduces Iridium Input by Half While Increasing Efficiency

Schematic diagram of the synthesis of new iridium/iridium oxide catalysts and TEM images. Image courtesy of Gwangju Institute of Science and Technology

[Asia Economy Reporter Kim Bong-su] One of the challenges in producing hydrogen by electrolyzing water is the high cost of iridium, a rare metal used as a catalyst, which reduces economic feasibility. Iridium is usually included with platinum, but due to its extreme scarcity, it costs about 170,000 KRW per gram, nearly three times more expensive than gold. In response, a domestic research team has attracted attention by developing a technology that significantly reduces the amount of iridium used in the hydrogen production process while increasing efficiency.

Gwangju Institute of Science and Technology (GIST) announced on the 25th that Professor Park Chan-ho's research team at the Graduate School of Energy Convergence, Institute for Convergence Technology, developed a liquid-phase catalyst synthesis method to create a high-efficiency iridium oxide catalyst applicable to renewable energy-linked water electrolysis.

The research team controlled the oxidation state of iridium to greatly enhance the catalytic activity and stability for the oxygen evolution reaction occurring at the anode during water electrolysis. The catalyst showed 1.1 times better activity compared to commercial catalysts and maintained 5.3 times superior activity even after stability evaluation.

Water electrolysis technology produces hydrogen by electrolyzing water, emitting no carbon dioxide, enabling environmentally friendly green hydrogen production. However, iridium, used as a catalyst, is a scarce metal resource and expensive, which is a drawback. Currently, its efficiency is also low, posing an obstacle to the activation of green hydrogen production.

The research team developed a new liquid-phase reduction method to change and optimize the oxidation states of iridium on the catalyst surface and core. When applying the iridium oxide catalyst developed by the team to a water electrolysis unit cell, they confirmed significantly improved performance compared to existing commercial catalysts, even when using less than 50% of the catalyst amount.

Professor Park Chan-ho said, “By using the new liquid-phase reduction method, we created a gradient distribution of iridium oxidation states within the iridium oxide catalyst, improving both activity and durability simultaneously.” He added, “As demonstrated in the unit cell, it is expected that applying this to actual systems will not only increase water electrolysis efficiency but also reduce the amount of iridium used at the anode in the future.”