There is an illustration of switchable wettability. Credit: V. Tileli.
Engineers need to find a way to store renewable energy on a large scale if it is to replace fossil fuels. Many researchers are studying a method of storing energy in gaseous form.
Water is split into hydrogen and oxygen bylytic cells when they use electricity. The hydrogen and oxygen can be recovered by reversing the reaction.
Understanding how catalysts work.
Catalysts are used to speed up reactions. Some metal oxides work better than others, although the exact reason remains unknown. "We've been able to see that some oxides are particularly effective, robust, and stable, and that's what we've been able to see during water electrolysis," says Vasiliki Tileli, an assistant professor and head of EPFL's Laboratory for in situ Nanomaterials We don't know what happens to the catalyst during the reaction, so we can't explain why these oxides function better.
A new catalyst.
Tileli and Tzu-Hsien Shen, a student at her lab, observed water electrolysis reactions under an electron microscope, looking at how the catalyst behaves during the entire process. The catalyst they used was a type of oxide. Tileli says it is an intriguing catalyst with exceptional water-splitting properties. Most of the catalysts currently in use, like those made from iridium and ruthenium, are very expensive and their supply is limited. Eventually, alternatives will have to be found.
The images were captured by Tileli and Shen. They saw that the process was irreversible and that it was happening again. They saw that the BSCF is strong.
Surfaces that are hydrophilic.
The research team found that the surface of the particles changed during the reaction. The particles interact with their surroundings differently at different points in the cycle. During some steps the surface is water-repellent, while during others it's attracted water. Tileli says that these observations are unique. We suspected that the particle surface might be changing, but we had never seen it in real time. The ability of a material to switch back and forth between the two states is very valuable to engineers and can be used in a variety of applications. Nature Catalysis contains the scientists' findings.
More information about the switchable wetting of oxygen-evolving oxide catalysts. The DOI is 10.1038/s41929-021-00723-w.
Nature catalysis is in a journal.
The path to renewable-energy storage has a hurdle that needs to be overcome.
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