Acid Resilient Electrocatalyst Materials for Water Splitting

Professor Richard Walton, Department of Chemistry

Drs James Stevens and Jonathan Sharman, Johnson Matthey Technology Centre

The splitting of water to form hydrogen as a fuel requires effective electrocatalysts to allow for viable electrolysers. The bottleneck in developing this technology further is the poor kinetics of the anodic oxygen evolution reaction. This requires highly active and stable materials that can operate under the highly acidic and oxidising condition of a proton exchange membrane (PEM) electrolyser anode. Oxides of iridium offer a promising solution to this challenge but structure property relationships are not well understood. The most active materials usually are the least stable and one key challenge is developing materials that have enhanced activity and at the same time long-term stability.

The aim of this project is to target the synthesis of a set of iridium oxide materials with elemental substitution that may lead to stability, and at the same time lower the use of the expensive precious metal. By partnering active iridium with base metals, or transition metals with limited redox chemistry, the activity/stability relationship could be optimised. This work will be underpinned by an extensive use of analytical techniques to build up a complete view of structure, from the atomic-scale crystal structure to crystal morphology, making use of Warwick’s facilities for characterisation. This will include X-ray powder diffraction, X-ray spectroscopy (XPS and XAS), small-angle X-ray scattering for nanostructure, electron microscopy and vibrational spectroscopy. Using central facilities we will complement the laboratory work, with the ISIS neutron facility for inelastic scattering to probe interactions with acidic solutions, and Diamond Light Source for XAS to examine redox chemistry in situ.

Collaboration with Johnson Matthey will allow materials to be fabricated into catalyst layers to be tested in real devices, and at the same time will provide access to further analysis capabilities. The student will be expected to spend time at the Technology Centre in Sonning Common to transfer their materials towards practical application.