Study On Synthesis And Photocatalytic Properties Of Loaded-ZnO Nanorod Arrays

Zinc oxide (ZnO) is recognized as one of the most important photonic materials forapplications in the blue-ultraviolet region owing to its direct wide bandgap (~3.37eV) andlarge excitation binding energy (60meV at room temperature). Since the first report onultraviolet lasing from ZnO nanorods(NRs), remarkable effort has been dedicated to thedevelopment of novel synthesis routes for1D ZnO nanostructures. Ordered arrays of1D ZnONRs have a promising future as applications in photocatalyst for its high efficiency, non-toxicnature and low-cost, has been paid much attention in the degradation environment pollutants.Loaded-ZnO nanorod arrays (loaded-ZnO NRs) that combine properties of3D and1Dmaterials may emerge as a more interesting alternative than simple arrays of NRs due to thehigher specific surface and porosity, especially for application in photocatalytic degradationof organic pollutants and dye/semiconductor-sensitized solar cells. Until now, a suitabletechnique is still missing for the fabrication of loaded-ZnO NRs with tunable sizes.In the present work, loaded-ZnO NRs were prepared on different substrate andcharacterized. Meanwhile, the optical properties and photocatalytic degradation activitieswere investigated. In this dissertation, our investigations are carried out as follows:Polystyrene spheres of different sizes were successfully synthesized by emulsionpolymerization, and loaded-ZnO NRs were prepared on different substrate(ceramic spheres,polyethylene spheres and polystyrene spheres) by the catalyst-free, low temperature (350℃~450℃) wet chemical method and sol-gel method. The as-prepared sample werecharacterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmissionelectron microscopy (TEM) and selected area electron diffraction (SAED), energy dispersivespectroscopy(EDS) and ultraviolet-visible (UV-vis) spectrophotometer. We found that theseZnO single-crystalline nanorods with the wurtzite structure grow along the [0001] direction,and loaded-ZnO NRs grown relatively uniform, covering the entire area of the substrate.ZnO nanorod arrays grew well on polystyrene spheres with size of300~600nm, with thelength more than1μm.We discussed the Photocatalytic properties of its photocatalytic degradation of methylorange with the as-prepared loaded-ZnO nanorod arrays as photocatalysts. The results showthat the Photocatalytic with optimal conditions as follows: catalyst0.5g/l; illumination time120min; light source with UV; methyl orange20mg/l; with the O2in the reaction. At thesame time, we conducted a study with the photocatalysts degradation of industrial wastewater,and measured the CODCrcontent of wastewater before and after the degradation. The testresults as follows: after photocatalytic degradation with Load-ZnO nanorod arrays, theCODCrcontent in the industrial wastewater is from2934mg/L to600mg/L.Using the self-assembled experimental apparatus, we researched photocatalyticdegradation of formaldehyde with loaded (ceramic spheres)-ZnO nanorod arrays as photocatalysts. The effects of the amount of the photocatalyst, initial concentration offormaldehyde and different light catalytic reactor on photocatalytic activity were investigated.The Fe3+-modified-loaded-ZnO nanorod arrays were characterized by scanning electronmicroscopy (SEM), X-ray diffraction (XRD) and ultraviolet-visible (UV-vis)spectrophotometer. The influence of Fe3+doping quantity and doping process were researchedon the photocatalytic degradation of formaldehyde and photocatalyst reusability were alsoinvestigated, especially providing an effective way to design and fabrication of equipmentsfor indoor pollutants-formaldehyde photocatalyst degradation.