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New conductive support materials for fuel cell catalyst layers
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McLeod, Lucy Katherine (2019) New conductive support materials for fuel cell catalyst layers. PhD thesis, University of Warwick.
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WRAP_Theses_McCleod_2019.pdf - Submitted Version - Requires a PDF viewer. Download (41Mb) | Preview |
Official URL: http://webcat.warwick.ac.uk/record=b3490591~S15
Abstract
New mixed-metal manganese ruthenium oxides have been synthesised hydrothermally in aqueous acid at 200 oC. The resulting materials Mn1-xRuxO2 (x<0.6) show a rutile type structure with the P42/mnm space group in which the manganese is reduced below the +4 oxidation state and the ruthenium is oxidised above +4. These materials were characterised by a range of diffraction, spectroscopic and other analytical techniques to confirm their structures, metal oxidation states, surface areas and powder conductivities. The materials have been shown to have some stability in aqueous sulfuric acid but are degraded under more harsh conditions.
Niobium, titanium and niobium titanium carbonitrides, Nb1-qTiqC1-pNp (0≤q≤1, p<1), were made via a new low temperature synthesis using nitrogen gas flow from a guanidine carbonate precursor. The resulting materials offer higher surface areas than conventional synthesis techniques. These materials have been characterised using a range of diffraction, spectroscopic and other analytical techniques. Neutron diffraction allows the C:N ratio to be determined and analysis of total scattering shows that at higher temperatures of synthesis the amount of amorphous carbon contaminant is minimised. The materials have been shown to have good conductivity and surface areas making them good candidates as catalyst supports in proton exchange membrane fuel cells. The niobium and niobium titanium carbonitrides show good stability in sulfuric acid and have shown stability whilst under electrochemical potential in acid. Preliminary tests of iridium loaded niobium carbonitrides suggest that the materials provide useful electrochemical activities for practical applications.
The synthesis of various other materials has been explored for use as catalyst supports, including titanium niobium oxides, tantalum carbonitrides, tantalum titanium carbonitride, tantalum niobium carbonitride, iron carbide, vanadium carbonitrides, molybdenum carbonitrides and tungsten carbonitrides. These materials have all be synthesised via a new low temperature synthesis under nitrogen gas flow. They have been analysed by a range of techniques including X-ray diffraction and spectroscopy. Electrochemical testing of the conducting titanium niobium oxide (Ti0.89Nb0.11O2) showed good stability under electrochemical potential whilst in acid.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QD Chemistry | ||||
Library of Congress Subject Headings (LCSH): | Fuel cells, Catalysts -- Materials, Materials at low temperatures, Catalyst supports | ||||
Official Date: | June 2019 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Chemistry | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Walton, Richard I. | ||||
Format of File: | |||||
Extent: | xxiv, 318 leaves : illustrations, charts | ||||
Language: | eng |
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