New electrolyser uses 200 times less iridium

Electrolysers make it possible to produce hydrogen through a process called electrolysis, offering interesting opportunities. However, the widely used Proton Exchange Membrane (PEM) method requires iridium, which is a scarce material. A new method developed by TNO researchers ensures that 200 times less iridium is needed for the same process, while 25 to 46% of the performance of the current generation of electrolysers can be realised.

Electrolysis is a chemical reaction in which substances are decomposed under the influence of electricity. An important and well-known application of electrolysis is the production of hydrogen. In this case, we separate water into hydrogen and oxygen. This process takes place in an electrolyser.

Electrolysis therefore costs electricity. We currently produce most hydrogen using fossil fuels. Does the process use renewable energy without CO2 emissions, e.g. solar or wind energy? Then we are talking about green hydrogen.

The demand for green hydrogen is rising rapidly. For instance, more and more industrial companies are using hydrogen, including in steel production. The use of green hydrogen could make this process more sustainable and enable the production of 'green' steel.

"The projected growth of green hydrogen from 300 megawatts in 2020 to dozens of gigawatts in 2030, has a downside," says TNO expert Lennart van der Burg. "It means a proportionally growing need for the scarce iridium for the electrolysers to be built. Previous TNO research shows that the scale-up of electrolysis is jeopardised because of the very limited availability of scarce materials, especially Iridium and Platinum. Ten years from now, the demand for iridium would far exceed the available quantity. Moreover, we depend on only a handful of countries for supply, with all the risks involved."

"The fact that we are reducing the iridium required by a factor of 200 and in doing so are already at an average of a third of the performance of current electrolysers is a technological breakthrough," says Van der Burg.

The new method presented by TNO is based on the technology spatial Atomic Layer Deposition (sALD). This is a method for applying extremely thin layers of functional materials to large surfaces. sALD was developed to enable a new generation of displays for TVs, tablets and smartphones. The technology has now also been made applicable to electrolyzers. Researchers from TNO specialising in electrolysis, worked on this with colleagues from Holst Centre in Eindhoven at the Faraday Lab in Petten.

TNO reports having experimented with sALD over the past two years. For instance, the researchers applied a very thin layer of iridium to the porous transport layer of titanium as a catalyst material. The performance and stability of the new process the researchers demonstrated in the lab using various tests; little to no degradation occurred after the stress tests.

An additional advantage, according to the researchers, is that the membrane in the electrolyser remains free of iridium. This means, among other things, that it is more recyclable and reusable.

TNO is working on the project with a group of industrial partners. The parties have united in the partnership Voltachem. The partners want to take the technology - which they call promising - from the lab to practice. To do so, they first want to scale up the method and test its operation in practical conditions in a pilot project.

"So we are not there yet," reports Van der Burg. "Demonstrating in the lab that the technology works is nice but further development is needed to improve its lifespan and efficiency and produce it at scale. Earlier, together with a number of European research institutes, we called for large pilot projects to include requirements on the use of scarce materials. Then in that year, according to current targets, there should be an electrolysis capacity of 40 GW in Europe, hopefully then with much lower use of scarce materials."

Author: Wouter Hoeffnagel
Photo: akitada31 via Pixabay