Abstract
dc:description.abstractThis thesis explores several titania-based composites for photocatalytic water treatment and hydrogen evolution. For water treatment, TiO2-C core-shell composites were prepared through controlled hydrolysis of titanium alkoxides followed by calcination in a non-oxygenating atmosphere. A total of nine TiO2-C samples were synthesized by combining different alkoxides and solvents. The sub-micron sized composites displayed eight times faster photocatalytic activity for degradation of aqueous methylene blue under simulated sunlight compared to pristine TiO2. Particle size of the best performing TiO2-C catalyst was further reduced through hydrolysis with aqueous KCl. The resulting nanoparticles (~10 nm) displayed a comparable rate of photodegradation for methylene blue with only 1/5th catalyst loading by weight. This nano-sized powder composite (nanocomposite) photocatalyst was also tested for photodegradation of other dyes, pharmaceuticals and Escherichia coli bacteria. The photo-activity was found to be at par or better than several state-of-art TiO2-C materials reported in the literature and approximately twice as better as standard commercially available TiO2 (P25). Second part of the thesis explores three different nickel-based cocatalysts for TiO2 for visible-light driven hydrogen evolution. Composites containing Ni(OH)2, NiO, and Ni2P were prepared and the effects of loading concentration and synthesis method on the rate of hydrogen evolution were studied. It was observed that hydrogen evolution could be achieved in the presence of a sacrificial electron donor (ethylenediaminetetraacetic acid disodium). Catalysts with Ni(OH)2 and Ni2P displayed significant photoactivity, in which highest rate of hydrogen production was achieved with TiO2-Ni2P nanoparticles. The prepared catalyst also displayed excellent long-term stability under continuous illumination tested for seven days. The final section of this thesis reports on the synthesis and visible-light activity of a hybrid Bi0.5Na0.5TiO3-BiOCl (BNT-BiOCl) ferroelectric photocatalyst. The parent ferroelectric BNT microparticles were prepared by solid-oxide reaction route and BiOCl growth on surface was achieved by treatment with dilute HCl. Despite a large bandgap and large particle size (>1 µm), the composite photocatalyst displayed a high rate of rhodamine B degradation under visible light. The high photoactivity was attributed to the heterojunction formed between the two phases, which improved charge separation.
Degree
thesis:*- Name dc:type.qualificationname
- Doctor of Philosophy (PhD)
- Level dc:type.qualificationlevel
- Doctoral
- Grantor dc:publisher.institution
- University of Cambridge
- Year dc:date.issued
- 2019
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Chauhan, Aditya
- Advisor dc:contributor.advisor
-
- Kumar, Ramachandran Vasant
Subjects
dc:subject × 3Rights
dc:rightsIdentifiers
dc:identifier.*- Author Identifier
-
0000-0002-7287-3922
0000-0001-9223-2332 - OAI identifier oai:identifier
- oai:www.repository.cam.ac.uk:1810/297681