Author

Prerna Tiwari

Year

2018

Degree Name

Doctor of Philosophy

Department

Intelligent Polymer Research Institute

Abstract

A growing imperative in the modern world is the development of new or improved technologies that: (i) can store energy efficiently, and (ii) deliver electricity on demand, at peak and off-peak times, whilst, still being (iii) compatible with the goal of sustainable development. One promising approach in this respect is to use hydrogen gas as an energy storage medium. Hydrogen can be manufactured from water, by the application of electrical energy, in an electrolyser. Hydrogen can also be converted back into water, with the production of electrical energy, in a fuel cell. However, present commercial electrolysers and fuel cells are too electrically inefficient and too costly to make such a round-trip storage and release of electrical energy, viable. In this work, a new approach to the problem has been studied using a novel class of gas diffusion electrode based on a Gortex substrate. We report the fabrication, characterization, and operation in fuel cells and electrolysers, of gas diffusion electrodes comprising of finely-pored GE PrevailTM expanded PTFE (ePTFE) (‘Gortex’) membranes over-coated with a wide range of precious metal and transition metal / metal oxide catalysts (PTFE=poly(tetrafluoroethylene). The coatings also incorporated carbon black and PTFE binder, with a fine Ni mesh as a current carrier. The fuel cells and electrolysers generally employed aqueous alkaline 6 M KOH as electrolyte, although selected acid systems were also examined.

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