Photocatalytic reforming for hydrogen production using metal/TiO2

Kennedy, Julia ORCID: https://orcid.org/0000-0003-4482-6392 2016. Photocatalytic reforming for hydrogen production using metal/TiO2. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The aim of this study was to develop photocatalysts which are active for the production of hydrogen from water and to further understanding of the factors involved in promoting the reaction. Different metals were loaded onto titania and used as photocatalysts for photocatalytic methanol reforming for hydrogen production. The catalysts were characterised using XPS and TPR to understand what produced highly active catalyst. The main factors influencing the catalysts were found to be the ease of reducibility and the work function of the metal used. Pt/TiO2 was the most active of the catalysts tested for photocatalytic methanol reforming. This was attributed to the fact that platinum oxide is easily reduced to platinum metal. Platinum also has a high work function and it was concluded that this property allows better charge transfer and longer charge separation due to a Schottky barrier. Different sacrificial agents with varying numbers of hydroxyl species were tested for photocatalytic hydrogen production. Alcohols, polyols, cyclo-alcohols and carboxylic acids were investigated. A relationship between the number of hydroxyl groups and hydrogen yield was established. The formula suggested for this was 2n+1 = number of moles of hydrogen, where n = number of C-OH groups. The best sacrificial agent was found to be xylitol as it has five C-OH groups and it fully decomposes to carbon dioxide and hydrogen. TiO2 was synthesised using a sol-gel preparation method in an attempt to produce active photocatalysts for photocatalytic methanol reforming for hydrogen production. The phases of TiO2 produced via this method were found to be anatase and brookite. The catalysts with more brookite were found to be more active. The study also highlighted the importance of crystallinity and surface area. The Turkevich method of producing gold nanoparticles was used to produce Au/TiO2. This method produced a more active catalyst than the incipient wetness Au/TiO2 and also emphasized the importance of removal of stabilising agents.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
Date of First Compliant Deposit:	16 February 2017
Last Modified:	24 May 2023 15:24
URI:	https://orca.cardiff.ac.uk/id/eprint/98350

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