Alternative chemical methods for the catalytic processes within hydrogen fuelled proton exchange membrane fuel cells

摘要

This thesis explores three routes to alleviating the economic barriers to proton exchange membrane fuel cells through reducing, recycling and removing platinum group metals (PGMs).ududThe reduction of PGM content is explored using electrochemistry to assess the novel materials produced when combining fullerene based compounds with electron beam lithography. This technique yields the potential to precisely control the distance between platinum (or other metal) atoms embedded within carbon materials. It is shown that the material alters the onset potential of proton reduction compared to glassy carbon and the methodology for study is developed.ududThe recycling of PGMs is demonstrated by testing the electrochemical behaviour and particle structure of deposited palladium within biomass produced through biohydrometallurgy. Electron microscopy and electrochemistry is used to investigate the biohydrometallurgy process and how the substrate, leachate and reducing agent effect both the particles produced and the electrochemistry observed. Concluding that the un-processed materials may function as future electrocatalysts without further processing steps.udThe removal of PGM content is investigated, through the electrochemical characterisation of the adsorbed layers and solutions of phosphomolybdic acid, singularly substituted vanadophosphomolybdic acid and doubly substituted vanadophosphomolybdic acid. Describing the complicated multi-electron, multi-step redox chemistry of the potential mediator species, with specific focus on electrode material and the effect of pH.