Develop technologies to reduce the cost of producing green hydrogen

Green hydrogen, which generates hydrogen without the use of fossil fuels or carbon dioxide emissions, has become increasingly important in recent years as part of efforts to achieve a zero-carbon economy. However, due to the high cost of producing green hydrogen-generating water electrolysis devices, the economic feasibility of green hydrogen is not very high. However, the development of technologies that drastically reduce the amount of rare metals such as iridium and platinum used in polymer electrolyte membrane water electrolysis devices paved the way for lowering production costs.

A research team led by Dr. Hyun S. 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 protective coatings on device electrodes. polymer electrolyte membrane water electrolysis, and the safe performance and durability are on par with existing devices. Specifically, unlike previous studies that focused on reducing the amount of iridium catalyst while maintaining structures that use large amounts of platinum and gold as electrode shielding coatings, the researchers replaced the precious metal in the electrode shielding coating with inexpensive iron nitride. large surface area and evenly coating a small amount of iridium catalyst on it, greatly increasing the economic efficiency of the electrolysis device.

The polymer electrolyte membrane water electrolysis device is a device that generates high purity hydrogen and oxygen by decomposing water using electricity supplied by renewable energy such as solar power, and plays a role in supplying hydrogen to various industries such as steelmaking and chemicals. In addition, converting energy to store renewable energy as hydrogen energy is advantageous, so increasing the economic efficiency of these devices is critical to realizing a green hydrogen economy.

In a typical electrolytic device, there are two electrodes producing 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/cm2 as a shielding. layer to ensure durability and production efficiency, and 1-2 mg/cm2 of iridium catalyst is coated on it. The precious metals used in these electrolysis devices have very low reserves and production, which are the main factors hindering the widespread adoption of green hydrogen production devices.

To improve the economics of water electrolysis, the team replaced the rare metals gold and platinum used as protective coatings for oxygen electrodes in polymer electrolyte membrane hydrogen production devices with inexpensive iron nitride (Fe2N). To do so, the team developed a composite process that first coats the electrode with iron oxide, which has a low electrical conductivity, and then converts the iron oxide to iron nitride to increase its conductivity. The team also developed a process that uniformly coats an iridium catalyst about 25 nanometers (nm) thick over a protective layer of iron nitride, reducing the amount of iridium catalyst to less than 0.1 mg/cm2, resulting in an electrode with high hydrogen production. efficiency and durability.

The developed electrode replaces the gold or platinum used as a protective layer for oxygen generating electrodes with non-noble metal nitrides while maintaining performance similar to existing commercial electrolysis units, and reducing the amount of iridium catalyst to 10% of existing levels. Additionally, the electrolysis unit with new components was operated for over 100 hours to verify its initial stability.

“Reducing the amount of iridium catalyst and developing alternative materials for platinum protective coatings is essential for the economical and widespread use of polymer electrolyte membrane green hydrogen production devices, and the use of inexpensive iron nitride instead of platinum is essential,” said Dr. Hyun S. Park of KIST . “After taking a closer look at the performance and durability of the electrodes, we will be implementing it in commercial devices in the near future.”

This research was supported by the Ministry of Commerce, Industry and Energy (Minister Lee, Chang-Yang) and KIST Main Project, and the results are published online in the latest issue of the international scientific journal Applied Catalysis B:Environmental (IF: 24.319 , top 0.926% in JCR) .

###

KIST was founded in 1966 as the first government-funded research institute in Korea. KIST now seeks to solve national and social challenges and secure engines of growth through leading and innovative research. For more information, please visit the KIST website at https://eng.kist.re.kr/

This research was carried out through the KIST Main Project supported by the Ministry of Science and ICT (Minister Lee Jong-ho), and the results are published online in the latest issue of the international scientific journal Applied Catalysis B:Environmental (IF: 24.319, over 0.926% in JCR).