Producing hydrogen from solar energy
New catalyst for future energy storage
In order to allow solar and wind energy to make a greater contribution to our future energy supply, it must be possible to store this energy efficiently, for instance in the form of hydrogen. This is done by means of the electrical cleavage of water in an electrolyser. Thanks to a new catalyst material developed by researchers at the Paul Scherrer Institute (PSI) and Empa, the Swiss Federal Laboratories for Materials Science and Technology, this process may become cheaper and more efficient in the future. The team has also been able to demonstrate how the new catalyst can be produced in large quantities, as reported in the latest issue of “Nature Materials”.
As solar and wind energy are not always available, they can only make a significant contribution to achieving a sustainable energy supply if they can be stored efficiently. A promising approach to this is energy storage in the form of hydrogen. For this, water is split into hydrogen and oxygen in an electrolyser, using electricity from solar or wind energy. The hydrogen can then be used as an energy carrier – it can be stored in tanks and later converted into electrical energy using fuel cells, for example in residential buildings or in fuel cell vehicles, which allow mobility without any CO2 emissions.
Cheap – and now also efficient
Researchers at the Paul Scherrer Institute (PSI) have now developed a new material that acts as a catalyst and accelerates the cleavage of water molecules, which is the first step in hydrogen production. "There are currently two types of electrolysers on the market: some are efficient but expensive, because their catalysts include precious metals such as iridium. The others are cheaper, but less efficient," explains PSI researcher Emiliana Fabbri. "We wanted to develop an efficient catalyst that is also cheap because it does not require the use of precious metals."
For this, the researchers used an already known material: a complex combination of the elements barium, strontium, cobalt, iron and oxygen – a so-called perovskite. However, they were the first researchers to develop a process for producing it in the form of tiny nanoparticles. This is the only way to make it work efficiently, as a catalyst requires the largest possible surface area, on which the electrochemical reactions can take place.
A so-called flame-spray device was used at Empa to produce the nanopowder; this device is used by Empa researchers to produce various materials in powder form. In this process, all components of the material are passed through a flame at the same time, which mixes them together, and then rapidly solidify to form small particles as soon as they leave the flame. The challenge was to use the device in such a way that the atoms of the different elements would combine to create the right structure. By varying the oxygen content in a targeted way, the researchers were able to produce different variants of the perovskite material.
Proven in practice
The researchers also demonstrated that their developments not only work in lab tests, but also in practice. The production process described above can thus yield large amounts of the catalyst powder and it should be easy to scale it up to an industrial volume. "It was also important for us to subject the catalyst to a real-world test," says Fabbri. The researchers, therefore, tested the catalyst in cooperation with a US producer of electrolysers and were able to demonstrate that the device worked more reliably with the new perovskite than with a conventional iridium oxide catalyst.