Up-Scaling Support Materials for PEM Electrolysis

Due to the increasing concerns in the environmental issues, the need to establish a sustainable and circular economy has become significant. Hydrogen has high potential as a future energy carrier. The readers of this project work can gain an understanding of the importance of hydrogen and its production by high purity water electrolysis in proton exchange membrane water electrolyzers (PEMWE). In this project, we focus on bringing sustainable and cost-effective changes to the PEMWE which uses expensive noble metal catalysts. Currently used iridium catalyst has proven to be the potential bottleneck of PEM expansion in terms of both cost and availability when analysed, thus various support materials for the Oxygen Evolution Reaction (OER) catalysts are explored in order to bring down the iridium loading. Potentially effective supports are brought forward for the readers to obtain a good idea of current research activities to limit iridium at the anode. Since antimony doped tin oxide (ATO) has proven to have the best properties in terms of an OER catalyst support, this project focuses on upscaling the product in order to pave way for scale-up of hydrogen production. It presents the optimum way of production of ATO by sol-gel process which has been developed on a small-scale at Fraunhofer ICT. The effects of the heat treatment temperature and other process parameters on the properties of ATO like morphology, surface area and conductivity are stated. Main aim of this project work is the scale-up and optimization of ATO to obtain a product of
around 100 g. Larger reactor setup has been established to get an optimum yield and the best product properties. This report gives a detailed view on the production and characterization of the ATO product where the microstructure was analysed by methods like scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD) and laser diffraction particle size analysis; and the electrical resistance, conductivity and the electrochemical properties using rotating disk electrode (RDE). Multiple batches of the large-scale are compared along with the small-scale batches to improve efficiency in scaling up. The possible improvements to this scale-up process are brought forward so that the readers
can obtain a good idea of current progress and realize the importance of eliminating bottlenecks in the scale-up of hydrogen production.