By reducing the amount of platinum and iridium used in water electrolysis devices, scientists believe they could bridge one of the largest barriers to green hydrogen production.
Hydrogen is a versatile, storable, potentially zero-carbon fuel source, that has been hailed as one of the solutions that will enable countries to reach their net-zero targets. It produces just heat and water as by-products when burned or used in fuel cells, making it a highly attractive alternative to fossil fuels in industry, power, shipping and transport.
However, due to the high production cost of water electrolysis devices required to produce it, green hydrogen has been considered too expensive to be worthwhile investing in.
A research team at the Korea Institute of Science and Technology (KIST) could have found the solution to this issue.
The researchers announced that they have developed a technology that can significantly reduce the amount of platinum and iridium, precious metals used in the electrode protection layer of polymer electrolyte membrane water electrolysis devices, and secure performance and durability on par with existing devices.
Unlike previous studies that focused on reducing the amount of iridium catalyst while maintaining a structure reliant on precious metals as the electrode protection layer, the researchers replaced these metals with inexpensive iron nitride.
"Reducing the amount of iridium catalyst and developing alternative materials for the platinum protective layer are essential for the economical and widespread use of polymer electrolyte membrane green hydrogen production devices and the use of inexpensive iron nitride instead of platinum is of great significance," said Dr. Hyun S. Park of KIST.
The polymer electrolyte membrane water electrolysis device is a device that produces high-purity hydrogen and oxygen by decomposing water using electricity supplied by renewable energy.
In a typical electrolysis device, there are two electrodes that produce hydrogen and oxygen. The latter is often coated with gold or platinum, with a second layer of iridium catalyst to prevent corrosion. The need to use these precious metals is a major deterrent to expanding hydrogen production.
To improve the economics of water electrolysis, the team replaced rare metals with inexpensive iron nitride (Fe2N). They first coated the electrode with iron oxide and then converted the iron oxide to iron nitride to increase its conductivity.
The experiment resulted in an electrode with high hydrogen production efficiency and durability.
"After further observing the performance and durability of the electrode, we will apply it to commercial devices in the near future," Park said.
The researchers' findings were published in the journal Applied Catalysis.
In the UK, the government is consulting on new plans to mandate that all new boilers can generate heat from hydrogen instead of gas from 2026, as part of a set of initiatives aimed at helping households save on energy bills.
The decision goes against a recent review of more than two dozen independent studies, which concluded that hydrogen will not have a major role in the future of heating homes across Britain.
