The team’s innovation is seen as tackling big challenges for green hydrogen production.
“One of the main challenges of electrolysis is the high cost of electrode materials used, such as platinum or iridium,” said Associate Professor Amgad Rezk from RMIT University. “With sound waves making it much easier to extract hydrogen from water, it eliminates the need to use corrosive electrolytes and expensive electrodes such as platinum or iridium.
“As water is not a corrosive electrolyte, we can use much cheaper electrode materials such as silver.”
According to Prof. Rezk, the ability to use low-cost electrode materials and avoiding the use of highly corrosive electrolytes were game changers for lowering the costs of producing green hydrogen.
The sound waves also prevented the build-up of hydrogen and oxygen bubbles on the electrodes, which greatly improved its conductivity and stability.
“Electrode materials used in electrolysis suffer from hydrogen and oxygen gas build-up, forming a gas layer that minimises the electrodes’ activity and significantly reduces its performance,” said Yemima Ehrnst (pictured), a PhD researcher at RMIT’s School of Engineering and the first author of the research article.
As part of their experiments the team measured the amount of hydrogen produced through electrolysis with and without sound waves from the electrical output.
“The electrical output of the electrolysis with sound waves was about 14 times greater than electrolysis without them, for a given input voltage. This was equivalent to the amount of hydrogen produced,” said Ehrnst.
Distinguished Professor Leslie Yeo, one of the lead senior researchers, said the team’s breakthrough opened the door to using this new acoustic platform for other applications, especially where bubble build-up on the electrodes was a challenge.
“Our ability to suppress bubble build-up on the electrodes and rapidly remove them through high-frequency vibrations represents a major advance for electrode conductivity and stability,” said Prof. Yeo.
“With our method, we can potentially improve the conversion efficiency leading to a net-positive energy saving of 27%.”
While the innovation is promising, the team needs to overcome challenges with integrating the sound-wave innovation with existing electrolysers to scale up the work.
“We are keen to collaborate with industry partners to boost and complement their existing electrolyser technology and integrate into existing processes and systems,” said Prof. Yeo.