Wednesday, October 5, 2022

New hydrogen fuel cell uses iron instead of rare and expensive platinum

Hydrogen fuel cells are an environmentally friendly technology that converts hydrogen into electricity, with heat and water being the only by-products. This makes them an attractive green alternative for portable power. However, the fuel cell technology has been constrained by the high cost of fuel cells because they use scarce and expensive materials like platinum for the catalyst.

Now, researchers at Imperial College London have developed a catalyst using only iron, carbon, and nitrogen – materials that are cheap and readily available – for hydrogen fuel cells. It can replace rare and costly platinum, enabling greater use of the technology. When used wisely, these are just as effective as the precious metal in operating a fuel cell at high power.

“Our cheaper catalyst design should make this a reality and allow deployment of significantly more renewable energy systems that use hydrogen as fuel, ultimately reducing greenhouse gas emissions and putting the world on a path to net-zero emissions,” said the lead researcher Professor Anthony Kucernak, from the Department of Chemistry at Imperial.

To make it work, the Imperial team produced a catalyst where all the iron was dispersed as single atoms within an electrically conducting carbon matrix. The single-atom iron has different properties than bulk iron, where all the atoms are clustered together, making it more reactive. This means the iron boosts the reaction needed in the fuel cell, acting as a good substitute for platinum.

“We have developed a new approach to make a range of ‘single atom’ catalysts that offer an opportunity to allow a range of new chemical and electrochemical processes,” said first author Dr. Asad Mehmood, from the Department of Chemistry at Imperial. “Specifically, we used a unique synthetic method, called transmetallation, to avoid forming iron clusters during synthesis. This process should be beneficial to other scientists looking to prepare a similar type of catalyst.”

In lab tests, researchers showed that a single-atom iron catalyst has performance similar to platinum-based catalysts in a real fuel cell system. The iron-based catalyst allows for building cheaper fuel cells that will significantly lower the cost of fuel-cell applications.

The team is now working to improve the stability of the catalyst so it matches platinum in durability as well as performance and is hoping to scale up for use in commercial fuel cells.

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