Biogenic precious metal-based magnetic nanocatalyst for enhanced oxygen reduction

Williams, Anna Rose (2016). Biogenic precious metal-based magnetic nanocatalyst for enhanced oxygen reduction. University of Birmingham. Ph.D.

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Abstract

This work contributes to the development of electrocatalysts for use in polymer electrolyte fuel cells, specifically for the cathodic oxygen reduction reaction (ORR). To achieve this, electrochemical analysis was conducted using biofabricated platinum (bio-Pt) catalyst. Bio-Pt per se was found to be a poor catalyst for the ORR, attributed to the platinum being inaccessible to the reactants. Various ‘cleaning’ techniques were tested to partially remove biomass, providing improved catalytic activity.

Bio-Pt was found to possess ferromagnetism under bulk magnetic analysis. Local magnetic analysis of this phenomenon focussed predominantly upon biofabricated palladium (bio-Pd) rather than bio-Pt as the origin of the magnetism appears to be the same in both cases and the effect was stronger in bio-Pd samples. This showed that bio-Pd possessed multiple magnetic types, which were suggested to arise from different types of Pd structure by comparison with electron microscopy studies.

Oxygen is paramagnetic, thus it can be expected to experience a force towards an increasingly strong non-uniform magnetic field. Bio-Pt was exposed to a magnetic field prior to electrochemical testing to magnetise the nanoparticles. Magnetised bio-Pt produced superior diffusion limited current, suggesting that magnetic bio-Pt catalyst enables the enrichment of oxygen from air at the catalyst site.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):