Iridium might solve the problems with water supply for making hydrogen fuel

A team of researchers has figured out how to dramatically improve the performance of one of the most precious metals used in hydrogen electrolysis: iridium.

Electrolysers which split water into oxygen and hydrogen are crucial for making green hydrogen.

But they’re still relatively inefficient at an industrial scale, needing expensive catalysts that can withstand high amounts of water and corrosive hydrogen. Chemists are hunting for materials that can make hydrogen electrolysis work better.

The research, done at the University of Adelaide, revolves around a particularly promising type of electrolysis called proton exchange membrane water electrolysis, or PEMWE.

This technique could make pure hydrogen efficiently, but it needs iridium oxide as a catalyst.

“Water splitting using PEMWE is a promising method for generating green hydrogen. However, only iridium-based electrocatalysts can withstand the harsh acidic conditions that occur during the reaction,” says Associate Professor Yao Zheng, from the University’s School of Chemical Engineering.

The researchers have published their findings in Science Advances.

“Our work prepared a new iridium-based catalyst that is active and stable for PEMWE,” says co-author and colleague Dr Huanyu Jin.

“We have found that a lattice-water-assisted mechanism – a way of arranging water molecules in a specific pattern – boosts the efficiency of an iridium oxide catalyst by 5-12% resulting in higher energy output while consuming less energy,” says Zheng.

While iridium itself, being one of the rarest elements in the Earth’s crust, is still a costly material, it doesn’t take much work to turn it into the efficient catalyst.

“The iridium oxide catalyst was developed by a molten salt method that was followed by our previous work,” says Jin.

“The synthesis could be finished only in five minutes, which provides a rapid and low-cost way to produce.”

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Now they have an efficient catalyst, the researchers are looking to see where they could best use the electrolysers.

“We would like to develop novel PEMWE electrocatalysts that can be operated in natural seawater,” says Jin.

“Compared to pure water electrolysis, seawater electrolysis is more suitable for Australia. In Australia, we have plenty of renewable energy, such as solar and wind power—however, scarce fresh water. For example, recent cancellations of large-scale electrolysis projects, such as the one in South Australia due to water supply concerns, highlight the need for more sustainable and flexible solutions.

“PEMWE using seawater as the feedstock will solve this problem well.”

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