Graphene-derived materials as oxygen reduction catalysts in alkaline conditions for energy applications

Molina García, Miguel Ángel (2018). Graphene-derived materials as oxygen reduction catalysts in alkaline conditions for energy applications. University of Birmingham. Ph.D.

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Abstract

Graphene is a relatively new carbon material increasingly finding technological applications due to its unique physical and engineering properties. Here, its application as catalyst for the oxygen reduction reaction (ORR) in alkaline media is investigated.
First, the role of graphene-related materials (including multi-walled carbon nanotubes) as catalyst supports is compared to the widely used carbon black, finding that the ORR follows a mixed behaviour between the direct 4-electron pathway and the indirect 2-step mechanism on graphene-supported platinum catalysts.
Further, different combinations of boron, nitrogen, phosphorus and sulphur metal-free doped-graphene catalysts have been systematically synthesised and evaluated, finding that dual-doped graphene catalysts yield the best ORR performance. Specifically, phosphorus and nitrogen dual-doped graphene (PN-Gr) demonstrates the highest catalytic activity, with 3.5 electrons transferred during the ORR.
Doped-graphene/perovskite oxide hybrid catalysts have been also tested, yielding PN-Gr/La0.8Sr0.2MnO3 the best ORR activity in terms of measured current density, achieving a value that is 85% of that reported for a commercial Pt/C catalyst. Moreover, SN-Gr/La0.8Sr0.2MnO3 produces the lowest amount of peroxide formation with only 10%.
These results confirm the graphene-derived catalysts as promising alternatives to the current platinum-based catalysts, and could enable the important issues related to its practical application to be overcome.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):