Tailored carbon-based nanomaterials for biological energy electrocatalysis

Thesis

Hydrogenases are energy relevant bio-electrocatalysts. Their study and applications require immobilisation on carbon scaffolds and benefit from carbon materials design. The present thesis first compares eleven carbon materials for the adsorption of hydrogenase-1 from E. coli. All of them accommodate the enzyme in an electroactive configuration. A high surface area and/or abundance of 'edge' carbon planes are identified as important features to improve studies and applications of hydrogenases. The nanomaterials screened facilitate the coupling of infrared spectroscopy and electrochemistry for study of adsorbed species. This is demonstrated for the first time with a flavin mononucleotide molecule and the hydrogenase and opens the way to unprecedented investigation of (bio)electrocatalysts.

In situ growth of multi-wall carbon nanotubes (MWCNTs) inside quartz columns by aerosol assisted chemical vapour deposition (AACVD) is investigated. Control over the column filling and the thickness of the MWCNT forest profile along the column is achieved. The flow rate of carrier gas is identified as a key parameter for this control. The final structures obtained are columns with their inner walls covered with a porous, interconnected and conductive carbon network. Through H₂-driven biocatalysis, the conversion of acetophenone to 1-phenylethanol is achieved in a flow reactor configuration. The MWCNT columns are shown to be successful and simple, yet versatile, platforms for flow (bio/electro)catalysis.

Finally, large quantities of hetero-MWCNTs are obtained by an original combination of AACVD and chemical vapour deposition. The MWCNTs are extensively characterised and display continuous junctions between nitrogen-doped and un-doped sections along a single MWCNT. The controlled change of chemical properties but also graphitic structure obtained is exploited for the first time to perform spontaneous and selective (1) oxidation reactions and (2) immobilisation of platinum particles on different parts of a single MWCNT. This new approach could be relevant for localised immobilisation of enzymes along a nanomaterial.

This thesis achieves three different degree of carbon nanomaterials design to develop scaffolds suitable for bio-electrocatalyst immobilisation in targeted applications.

Authors: Quinson, J

• DOI: 10.5287/ora-b7xyeojva
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Hetero carbon nanotubes; Biocatalysis; Electrocatalysis; Carbon nanomaterials; Carbon nanotube columns; Flow catalysis
• Subjects: Nanomaterials; Bio-electrochemistry; Materials Science