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Title: Synthesis, characterisation and photocatalytic application of rhodium-doped oxides upon irradiation with visible light
Author: Kiss, B.
ISNI:       0000 0004 6059 2482
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2016
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As stated earlier in the title, the overall aim of the project has been to investigate “Synthesis, Characterisation and Photocatalytic Application of Rhodium-doped Oxides upon Irradiation with Visible Light”. The key considerations in photocatalyst design, assessment and challenges and energy requirements in application is reviewed in the Introduction chapter. In the Discussion chapters, first, a simple one-step strategy was employed to produce a high surface area, phase pure metal oxide that is active in UV light. Various structures have been produced as parent phases such as SrTiO3, BaTiO3 and Y2Ti2O7, and once the presence of phase pure material was confirmed, rhodium substitution was initiated by B site doping of structures by adding soluble Rh salts during phase formation. The idea of using rhodium was to provide active, new rhodium states within the band gap therefore induce e- and h+ transfer that will presumably facilitate photochemical reduction/oxidation reactions with a longer excited wavelength than 400 nm, visible light photons. The series of nanoparticulate SrTi1-xRhxO3 and BaTi1-xRhxO3 materials with x = 0; 0.01; 0.025; 0.050; 0.075 and 0.1 rhodium content have been fully characterised. The functionality of well-known SrTi1-xRhxO3 H2 generating p-type oxide was extended to be successfully applied in water remediation and disinfection with excellent performance in model Methyl Orange molecule degradation and reasonable efficiency in E. coli Gram-negative bacteria inactivation when exposed to visible light (λ > 420 mm). So far, of semiconductor oxides, nitrogen-doped titania in particular have demonstrated activity under visible light in all three functionalities mentioned above, making this new finding very encouraging in the application of SrTi0.95Rh0.05O3 compound. As the investigation of novel advanced materials is crucial in the field, following up on this, a novel stable visible-light-driven photocatalyst (λ ≥ 450 nm) for water oxidation is reported. Rhodium substitution into the pyrochlore Y2Ti2O7 is demonstrated by monitoring the Vegard’s law evolution of the unit-cell parameters with changing rhodium content, to a maximum content of 3% dopant. Substitution renders the solid solutions visible-light active. The overall rate of oxygen evolution is comparable to WO3 but with superior light-harvesting and surface-area-normalized turnover rates, making Y2Ti1.94Rh0.06O7 an excellent candidate for use in a Z-scheme water splitting system and photoanode.
Supervisor: Rosseinsky, M. ; Claridge, J. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral