Synthesis, characterisation and photocatalytic activity of porous silicon-based materials

Li, Ting (2017) Synthesis, characterisation and photocatalytic activity of porous silicon-based materials. Doctoral thesis, University of East Anglia.

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    Abstract

    As a free and abundant alternative energy source, the use of sunlight to store and transfer energy is of great importance to a clean and sustainable future. Aiming for an environmentally and economically friendly approach to utilizing solar energy, metal-free, earth-abundant mesoporous silicon with hydrogen termination were developed via inexpensive electrochemical etching. By means of a range of characterisation tools, a detailed structural analysis was established, showing a large surface area, open porous system and abundant quantum confined Si nanocrystallites of which the morphological properties can be controllably tuned through adjusting etching parameters and wafer resistivity. As a result, an excellent efficiency in degrading methyl orange under visible light irradiation was achieved in the following photocatalytic study, which also revealed the influence of different structural factors on the photocatalytic performance by affecting mass transport, light absorption and photoexcited charge recombination. The photocatalytic mechanism of mesoporous silicon in methyl orange degradation was also investigated in this research, with insights gained into the electronic band properties, photocatalytic oxidation facilitated by the generation of reactive oxygen species and the roles of surface hydrides on the degradation pathways of methyl orange. By coupling with graphitic carbon nitride (g-C3N4) nanosheets, the formed heterostructure showed an enhanced degradation activity towards methyl orange under visible light illumination. An exciton-related pathway was proposed to explain the promoted reducing power of the surface hydrides upon irradiation with or without the participation of g-C3N4. In general, this work highlighted the potentiality of H-terminated mesoporous silicon in photocatalytic applications and deepened the understanding of its photocatalytic mechanism and degradation behaviour for future exploration of porous silicon-based photocatalysts.

    Item Type: Thesis (Doctoral)
    Faculty \ School: Faculty of Science > School of Chemistry
    Depositing User: Gillian Aldus
    Date Deposited: 22 Mar 2018 13:47
    Last Modified: 22 Mar 2018 13:47
    URI: https://ueaeprints.uea.ac.uk/id/eprint/66556
    DOI:

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