Metal Foam Electrodes Split Water With Unprecedented Efficiency

By coating nickel foam with a nickel-iron nanosheets, scientists have made an efficient catalyst that could be used to produce hydrogen at the industrial scale.

AsianScientist (Mar. 27, 2015) – Scientists have developed a highly efficient oxygen-producing electrode for splitting water that has the potential to be scaled up for industrial production of hydrogen. Their technology, published in Nature Communications, 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, from the University of New South Wales (UNSW) School of Chemistry.

“It is inexpensive, sturdy and simple to make, and can potentially be scaled up for industrial application of water splitting.”

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. This ultra-thin layer of a nickel–iron composite also has tiny pores in it, about 50 nanometres across.

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.

Nickel foam. Credit: UNSW.
Nickel foam. Credit: UNSW.

“The three-dimensional architecture of the electrode means it has an enormous surface area on which the oxygen evolution reaction can occur,” says Zhao.

“The larger bubbles of oxygen can escape easily through the big holes in the foam. In addition, 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.”

Hydrogen is a great fuel for powering mobile devices or vehicles, and storing electricity generated from renewable energy, such as solar. Hydrogen production is a rapidly growing industry, but the majority of hydrogen is still produced using fossils fuels such as natural gas, oil and coal, because this approach is still cheaper than electrolysis of water.

“I think this electrode has great potential for the industrial-scale production of hydrogen. Our next goal is to understand the science behind it and to further improve its performance. Cleaner sources of fuel like hydrogen will be particularly important for reducing carbon dioxide emissions and solving the air pollution problems from the burning of fossil fuels such as coal,” says Zhao.

The article can be found at: Lu and Zhao (2015) Electrodeposition of Hierarchically Structured Three-Dimensional ​Nickel–Iron Electrodes for Efficient ​Oxygen Evolution at High Current Densities.

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Source: University of New South Wales.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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