Preparation, characterisation and application of single and multilayer mixed-matrix membranes

Ibrahim, Ahmed (2025). Preparation, characterisation and application of single and multilayer mixed-matrix membranes. University of Birmingham. Ph.D.

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Abstract

Single layer and multilayer Nafion membranes incorporated with graphene oxide (GO) were investigated for application in polymer electrolyte fuel cells operating at intermediate temperatures (IT-PEFCs). The intermediate temperature regime has been utilised as a method to improve the power density output of fuel cells used in transport applications and graphene oxide was identified as the filler of choice due to its oxygen containing functional groups.

An experimental approach was taken, with membranes prepared with a variety of parameters such as graphene oxide weight loading, number of membrane layers, and membrane thickness. A variety of characterisation techniques were utilised to confirm successful incorporation of graphene oxide within the membrane, and subsequent samples were tested in a fuel cell at elevated temperatures.

Introducing graphene oxide suppressed the hydrogen crossover current density experienced during fuel cell operation in comparison to the reference Nafion sample. The multilayer membranes had even more pronounced hydrogen crossover barrier properties because of their three individual layers. Additionally, decreasing the membrane thickness led to improved fuel cell performance. The use of a Nafion/cerium oxide composite layer was found to maintain hydrogen crossover levels under 10 mA cm-2 for over a week at 100°C during accelerated stress tests (AST).

However, some challenges in producing multilayer membranes pertained due to frequent interruption of the interfaces of the separate layers, which was further emphasised when fabricating thinner membranes. The development of thinner membranes, the improvement of interlayer contact, and the optimisation of cerium oxide fillers are topics that should be further explored in future work.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):