A car drives near the open-cast mine, with piles of mine waste.

Making hydrogen with mining waste

A group of Queensland researchers have used mining waste to make a catalyst that could render hydrogen fuel production cheaper and more efficient.

Hydrogen gas, which can be made by electrolysing water, should be a critical clean fuel by mid-century. The electrolysis process needs metals to catalyse it – and generally, expensive precious metals do a better job as catalysts.

Feldspar. Credit: Dr Hong Peng.

A paper published in Advanced Energy & Sustainability Research describes a cheaper type of hydrogen catalyst. These catalysts are made mostly from feldspars: aluminosilicate rocks which make up a large proportion of the Earth’s crust, and thus often turn up in mining waste. The feldspars are coated with a few nanometres of nickel, cobalt or iron.

“Water splitting involves two chemical reactions – one with the hydrogen atom and one with the oxygen atom – to cause them to separate,” explains Professor Ziqi Sun, a researcher at Queensland University of Technology and co-author on the paper.

“This new nano-coated material triggered the oxygen evolution reaction, which controls the overall efficiency of the whole water-splitting process.”

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The cobalt-covered feldspar was the most effective of the catalysts, rivalling much pricier commercial ruthenium catalysts in efficiency.

Sun says the catalysts could also be used in lithium-ion batteries and other electrochemical processes, giving it further renewable energy applications.

The catalyst is ready for pilot testing, and the researchers say it would be a simple thing to scale up.

Professor Ziqi Sun is a researcher with the QUT Centre for Materials Science. Credit: QUT

“Aluminosilicate is commonly found in various mining tailings and is so cheap that mining companies would normally pay to dispose of it,” says Dr Hong Peng, a researcher at the University of Queensland and co-author on the paper.

“Australia’s abundance of aluminosilicate and the simplicity of this modification process should make industrial scale production of this new catalyst easy to achieve,” says Sun.