Abstract
Hydrogen provides a means of storing renewable energy, which is highly important for the green energy transition. One of the most promising technologies for splitting water and producing hydrogen is PEM water electrolysis. This electrolysis process takes place via two half-cell reactions, of which the oxygen evolution reaction (OER) is the slowest. It is reliant on iridium as anodic electrocatalyst, one of the rarest and most expensive metals on Earth. Therefore, this thesis explores ruthenate pyrochlores as a sustainable alternative. The studied pyrochlores are made from more abundant elements and can be tailored to perform better than iridium-based catalysts. Through investigating synthesis methods, dopant strategies and by studying the materials with advanced in-situ techniques, the thesis thoroughly analyses the suitability of yttrium ruthenate pyrochlores as OER electrocatalysts in acidic media.
We found that using a glycine combustion synthesis method not only saves time and energy, but also creates more porous structures that are better at catalysing reactions. By adding small amounts of other elements like calcium, zinc and strontium, the amount of ruthenium needed was reduced without sacrificing performance. It was also found that excess yttrium is crucial for enhanced performance. This research shows that with smart design and careful testing, we can move away from rare metals and still achieve high performance. However, the stability of these electrocatalysts needs further assessment.