Functional gold nanomaterials and graphene platinum catalysts for electrochemical energy conversion

Frederick Stappen Nielsen*

*Corresponding author for this work

Research output: Book/ReportPh.D. thesisResearch

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Abstract

The focus on renewable energy has only increased since the signing of the Paris Agreement in 2016. The use of fossil fuels and oil has increased over the previous 30 years and even thou most energy usage has become more energy efficient, CO2 emissions has increased as well. The challenges of CO2 emission reductions are in the utilization of different kinds of fuel. Using a fuel cell allows one to utilize renewable energy sources, small fuel molecules such as methanol or formic acid. These fuels can be derived from a variety of organic sources, fruits and plants. The work presented here is a thorough investigation into the processes used to synthesize and control gold nanoparticles. Using state-of-the-art nuclear magnetic resonance, UV-visible light spectroscopy and computation chemistry, the reduction of HAuCl4 using 2-(N-morpholino)ethanesulfonic acid were examined and explained. The many biproducts of the reaction were analysed and presented, while the formation of AuNPs was monitored. The resulting reaction mechanism were used to understand and modify the reaction to produce different kinds of materials. One of these materials were a nanoporous gold film produced using the before mentioned reaction. The particles were synthesized with an elevated ionic strength forcing the nanoparticles to the surface where they aggregate and form a film. The nanoporous gold film were analysed and described using atomic force microscopy, electrochemistry and electron microscopy. The films CO oxidation electrocatalytic capabilities of were tested. Another material developed using this synthesis was a structured dendrimer gold network immobilized on reduced graphene oxide. The synthesis was the same but the dendrimer aggregation, graphene oxide reduction and immobilization was induced by illumination. The structured gold network material was characterized with electron microscopy, photoelectron spectroscopy and UV-visible light spectroscopy. A third material was synthesized by adding platinum to the nanoporous gold film. The surface of the film was investigated thoroughly, as well as the effects of electrochemical work on the surface of the film. The film was found to be an excellent methanol oxidizing electrocatalyst. The platinum deposition and location on in the bi-metallic film was examined with photoelectron spectroscopy, electron microscopy, electrochemistry and atomic force microscopy.
Original languageEnglish
Place of PublicationKgs. Lyngby
PublisherTechnical University of Denmark
Number of pages134
Publication statusPublished - 2019

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