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Fuelling a revolution: Hydro-genius engineers slash green hydrogen costs

05 June 2023

Could this be the game-changer on the road to a hydrogen economy? Innovative technology is now propelling a significant reduction in the use of costly rare metals in green hydrogen production, all while ensuring optimal performance is maintained.

(Image: Shutterstock)
(Image: Shutterstock)

The challenge
Green hydrogen, a clean and carbon-neutral fuel, has become increasingly important in our pursuit of a decarbonised economy. However, the high production costs associated with its production have hindered its widespread adoption.

Water electrolysis devices are crucial in the production of high-purity hydrogen without the use of fossil fuels or carbon dioxide emissions. In these devices, platinum and iridium are traditionally used as protective layers in the electrode structure, ensuring performance and durability.

However, their scarcity and high costs have been major obstacles to the economic viability of green hydrogen production.

In a promising breakthrough, however, researchers at the Korea Institute of Science and Technology (KIST) have developed a technology that dramatically reduces the amount of platinum and iridium used in water electrolysis devices.
This advancement holds the potential to lower production costs significantly, making green hydrogen more economically feasible.

The solution: A deep dive
Previous studies focused solely on reducing the amount of iridium catalyst, while maintaining the structure that uses a significant amount of platinum and gold as the protection layer.

By contrast, Dr Hyun S. Park and Sung Jong Yoo, who led the research team at KIST's Hydrogen and Fuel Cell Research Center, replaced the precious metals in the electrode protection layer with inexpensive iron nitride. By uniformly coating a small amount of iridium catalyst on top of the iron nitride, they were able to increase greatly the economic efficiency of the electrolysis device.

The impact on hydrogen economy
The polymer electrolyte membrane water electrolysis device produces high-purity hydrogen and oxygen by decomposing water using electricity supplied by renewable energy, such as solar power. It plays a critical role in supplying hydrogen to industries such as steelmaking and chemicals.

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 realisation of the green hydrogen economy.

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/cm2 as a protective layer to ensure durability and production efficiency, and 1-2 mg/cm2 of iridium catalyst is coated on top.

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 order to replace the rare metals with inexpensive iron nitride, 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. 

The team also developed a process that coats an iridium catalyst about 25nm thick on top of the iron nitride protective layer, reducing the amount of iridium catalyst to less than 0.1mg/cm2. This resulted in an electrode with high hydrogen production efficiency and durability.

The developed electrode maintains a similar performance to existing commercial electrolysis units, whilst reducing the amount of iridium catalyst by 90 percent. In addition, the electrolysis unit with the new components was operated for more than 100 hours to verify its initial stability.

"Reducing the amount of iridium catalyst and developing alternative materials for the platinum protective layer are 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 of great significance," said Dr Hyun S. Park of KIST. 

"After further observing the performance and durability of the electrode, we will apply it to commercial devices in the near future."

This research offers a glimmer of hope for the economic feasibility of green hydrogen production. By significantly reducing the reliance on scarce and expensive metals like platinum and iridium, the technology presents a promising path to lower the production costs of water electrolysis devices.

As efforts continue to transition towards a decarbonised economy, advancements like these play a vital role in accelerating the adoption of green hydrogen and achieving a sustainable future.


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