Metal oxide photocatalytic nanostructures fabricated by dynamic shadowing growth
MetadataShow full item record
Metal oxides (MOs) nanostructures, as visible light active photocatalysts, are widely used in applications such as solar energy conversion, biocidal coating, and environmental remediation. This dissertation investigates the morphological, structural, optical, and photocatalytic properties of some visible light active MO photocatalysts, WO3, CuxO (x = 1, 2), and α-Fe2O3 nanostructures fabricated by the dynamic shadowing growth for above mentioned applications. Dye adsorption and photodegradation property of WO3 nanorods (NRs) has first been studied. The porous and amorphous WO3 NRs are observed to exhibit superior methylene blue (MB) adsorption capability in aqueous solution due to its large specific surface area and active surface functionality. The adsorption of MB on the surface of WO3 NRs are well described by Langmuir isotherm behavior. Photocatalytic MB degradation with WO3 NRs under UV irradiation is observed to be relatively higher than that under visible light. The solar water splitting reaction in a photoelectrochemical (PEC) cell and photocatalytic dye degradation behavior of CuxO (x=1,2) NR arrays have been studied under visible light irradiation. Both single phase Cu2O and CuO, and mixed phase Cu2O/CuO polycrystalline NRs are observed to exhibit excellent visible light induced photocatalytic activity for both cationic (MB) and anionic (methyl orange) dye degradation. When used as a photocathode, they also show good PEC performance, especially for the mixed phase Cu2O/CuO NRs. The maximum stable photocurrent density is observed to be -0.24 mA/cm2 under a simulated solar light (AM 1.5G) at an applied bias potential of -0.5 V (versus Ag/AgCl reference electrode). About 20% and 44% incident photon-to-current conversion efficiency are obtained at incident light wavelengths λ = 500 nm and 400 nm respectively. Finally, both MB degradation and bactericidal activities are studied for the α-Fe2O3 NR arrays and films under the ambient light conditions. The α-Fe2O3 NR arrays annealed at 350 °C exhibit an enhanced bactericidal performance in inactivating E. coli O157:H7, when compared to α-Fe2O3 film. Mathematical models are used to correlate the observed photocatalytic activities.