UNSW Australia scientists have developed a highly efficient oxygen-producing electrode for splitting water that has the potential to be scaled up for industrial production of the clean energy fuel, hydrogen. The new technology is based on an inexpensive, specially coated foam material that lets the bubbles of oxygen escape quickly.
"Our electrode is the most efficient oxygen-producing electrode in alkaline electrolytes reported to date, to the best of our knowledge," says Associate Professor Chuan Zhao, of the UNSW School of Chemistry.
"It is inexpensive, sturdy and simple to make, and can potentially be scaled up for industrial application of water splitting."
The research, by Associate Professor Zhao and Dr Xunyu Lu, is published in Nature Communications.
Inefficient and costly oxygen-producing electrodes are one of the major barriers to the widespread commercial production of hydrogen by electrolysis, where the water is split into hydrogen and oxygen using an electrical current.
Unlike other water electrolysers that use precious metals as catalysts, the new UNSW electrode is made entirely from two non-precious and abundant metals - nickel and iron.
Commercially available nickel foam, which has holes in it about 200 micrometres across, or twice the diameter of a human hair, is electroplated with a highly active nickel-iron catalyst, which reduces the amount of costly electricity needed for the water-splitting to occur.
This ultra-thin layer of a nickel-iron composite also has tiny pores in it, about 50 nanometres across.
"The three-dimensional architecture of the electrode means it has an enormous surface area on which the oxygen evolution reaction can occur," says Associate Professor Zhao.
"The larger bubbles of oxygen can escape easily through the big holes in the foam. As well, the smaller holes make the electrode surface 'wetter', so the bubbles do not stick to it, which is a common problem that makes electrodes less efficient."