Fundamental Research of Electrocatalysts for Application within Proton Exchange Membrane Water Electrolysers

Abstract

Proton Exchange Membrane (PEM) electrolysis as a method of generating green hydrogen is due to be adopted globally at scale in the coming years as governments release legislation aimed at reducing carbon emissions produced by fossil fuels. It is vital that technological advancements and cost targets are first achieved in the technology in order to meet the substantial supply and demand that adding hydrogen to the global energy supply chain will cause. When producing electrolyser systems in high volumes the catalyst is the largest contributor to the capital cost breakdown. There are multiple methods used by researchers and industry worldwide to reduce the cost or mass loading of a catalyst whilst maintaining or improving performance of the catalyst within a PEM electrolyser cell. This is nominally achieved by the targeted deposition of precious metal nanoparticles, using optimised mass manufacturing coating methods, developing non-precious metal catalysts or developing novel catalyst support materials. This thesis showcases research that utilises all of the above approaches in order to reduce the capital expenditure associated with the catalyst layers within PEM electrolyser cells. Non precious metals such as transition metal dichalcogenides and phosphides are utilised as catalysts for the hydrogen and oxygen evolution reactions. The faradaic efficiency of iron phosphide (Fe3P) is shown to be enhanced by the presence of a weak external magnetic field. The scalable electrode fabrication technique of screen-printing is used throughout the thesis, except for in the final publication where additive manufacturing is used to fabricate the anode and cathode. Nanoscale catalyst deposition techniques such as magnetron sputtering are used to deposit Platinum (Pt) nanoparticles on single layer graphene sheets, which show industry standard performance.