TiO2-Coated ZnO Nanowire Arrays: A Photocatalyst with Enhanced Chemical Corrosion Resistance (original) (raw)
Related papers
The study concerns vertically well-aligned ZnO nanowires and TiO 2 -ZnO films on Si substrates. They were prepared by a two-step chemical bath deposition (CBD) method, witch includes seed deposition and growth of ZnO nanowires. SEM and X-ray diffraction are used for the ZnO and TiO 2 /ZnO thin films characterization. The film thickness is of 3-3.5 μm and the average diameter of ZnO nanowires is 100-150 nm, as determinated by SEM. Thus prepared films (pure ZnO nanowires and mixed with TiO 2 nanoparticles) are tested in comparison to TiO 2 and ZnO powder catalysts. TiO 2 doped ZnO nanowire films show a significant rise in the photocatalytic efficiency. The photocatalytic tests are performed in cylindrical glass reactors under UV and visible light irradiation. The effect is due to the successful separation of photogenerated charge carriers in the prepared TiO 2 /ZnO photocatalytic film. The pollutants concentrations are 20 ppm Orange II for slurry and 10 ppm for film photocatalysis. The photodegradation of organic dye Orange II is observed spectrophotometrically.
ZnO Nanostructure Based Photocatalysis for Water Purification
NanoWorld Journal, 2020
In recent years, semiconductor based photocatalysis has shown great potential for an application as a low-cost, environmentally friendly and sustainable water treatment technology. Its efficiency has been widely demonstrated on the removal of persistent organic compounds in water. This paper studies the photocatalytic activity of ZnO nanowires (NWs) grown on a substrate, a configuration which can be considered advantageous over freely suspended nanoparticles (NPs) commonly used in many research works, due to its easy removal from purified water and reutilization. The characterization of the ZnO NWs morphology and structure was performed by scanning electron microscope (SEM) and X-ray diffraction (XRD) measurements. The photocatalytic efficiency study has been carried out by using three organic dyes (MB, MO and AR14), as commonly used pollutants in various industrial activities. For a better understanding of the photocatalytic efficiency versus the liquid regime, the photocatalysis has been carried out under classic mode and microfluidic mode. All tests shown the notable photocatalytic efficiency of ZnO NWs. Moreover, remarkable results were achieved with our ZnO-NWs-integrated microfluidic reactor, which exhibited an important enhancement of photocatalytic activity by reducing the photodegradation time from hours to minutes.
Materials, 2021
The main goal of the study was the hydrothermal-assisted synthesis of TiO2-ZnO systems and their subsequent use in photoactive processes. Additionally, an important objective was to propose a method for synthesizing TiO2-ZnO systems enabling the control of crystallinity and morphology through epitaxial growth of ZnO nanowires. Based on the results of X-ray diffraction analysis, in the case of materials containing a small addition of ZnO (≥5 wt.%), no crystalline phase of wurtzite was observed, proving that a high amount of modified titanium dioxide can inhibit the crystallization of ZnO. The transmission electron microscopy (TEM) results confirmed the formation of ZnO nanowires for systems containing ≥ 5% ZnO. Moreover, for the synthesized systems, there were no significant changes in the band gap energy. One of the primary purposes of this study was to test the TiO2-ZnO system in the photodegradation process of 4-chlorophenol using low-power UV-LED lamps. The results of photo-oxida...
Vertically aligned zinc oxide nanosheet for high-performance photocatalysis of water pollutants
Ceramics International, 2019
The present work is focused on the synthesis of morphology-controlled vertically aligned Zinc oxide (ZnO) nanosheets (NSs) using a high power low-temperature sonochemical process. The synthesis process is a facile and low-temperature process, which can be able to produce largearea, homogeneously-grown, vertically-aligned ZnO NSs with high surface to volume ratio. Also, using the same process, we have developed a low-temperature in-situ method of the magnesium (Mg), doped ZnO NSs with identical structure and morphology. The process is versatile, scalable and can be adopted for synthesizing various other doped morphology controlled nanosheets synthesis. The morphology and structure were confirmed using X-ray diffraction technique, FESEM, TEM/HRTEM while surface composition, bonding and doping were confirmed using XPS and UV-VISIBLE spectroscopy. We obtained that the 2D few layered thick ZnO nanosheets of flake size 2-5 µm with bandgap ~3.38 eV, which was increased to ~3.7 eV due to the Mg doping. Furthermore, we demonstrated the comparative photocatalytic activity of the as-synthesized pristine and doped ZnO nanosheets and found that Mg-doping promotes the faster catalytically active redox reaction, hence; the dye degradation time was 15 minute faster compared to the pristine ZnO NSs under identical conditions. We believe that the rate-enhancement in photocatalytic dye degradation of Mg-doped ZnO NSs are obtained due to the faster hole transport properties and low recombination rate.
The Journal of …, 2001
The multiwall carbon nanotubes (MWCNTs)/titanium dioxide (P25) composite in different ratios was prepared using simple evaporation and drying process. The composite was characterized by Raman spectroscopy, X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy, and scanning electron microscopy (SEM). The photocatalytic activity of this composite was investigated using degradation of the Bismarck brown R dye (BBR). An optimal MWCNTs/TiO 2 ratio of 0.5% (w/w) was found to achieve the maximum rate of BBR degradation. It was observed that the composite exhibits enhanced photocatalytic activity compared with TiO 2 . The enhancement in photocatalytic activity performance of the MWCNTs/P25 composite is explained in terms of recombination of photogenerated electron-hole pairs. In addition, MWCNTs act as a dispersing support to control the morphology of TiO 2 particles in the MWCNTs/TiO 2 composite.
Effect of aspect ratio and surface defects on the photocatalytic activity of ZnO nanorods
Scientific reports, 2014
ZnO, aside from TiO2, has been considered as a promising material for purification and disinfection of water and air, and remediation of hazardous waste, owing to its high activity, environment-friendly feature and lower cost. However, their poor visible light utilization greatly limited their practical applications. Herein, we demonstrate the fabrication of different aspect ratios of the ZnO nanorods with surface defects by mechanical-assisted thermal decomposition method. The experiments revealed that ZnO nanorods with higher aspect ratio and surface defects show significantly higher photocatalytic performances.
Materials Science in Semiconductor Processing, 2015
In this research, ZnO nanostructured layers with various morphology, i.e. nanoneedles, nanorods, pyramid shaped ZnO crystals, and hierarchical structures of ZnO deposited on nanorods and pyramid shaped crystals, were synthesised by pneumatic spray pyrolysis method. Hierarchical structures, a dense network of well-ordered platelets covering the side facets of the rod-like and pyramid shaped ZnO crystals, were obtained by spraying Zn (Ac) 2 solution over the surface of pre-grown ZnO crystals at deposition temperature of 330 1C within 5 min. All ZnO layers have been characterised by scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), absorbance of ultraviolet and visible light (UV-vis), surface wettability measurements and photoluminescence (PL). Photocatalytic activity of the layers was evaluated by means of photocatalytic oxidation activity (PCO) of several organic pollutants, namely, methyl-tert-butyl ether (MTBE), humic acid (HA), N,N-dimethyl p-nitrosoaniline (RNO), and prednisolone (PNL); the results were compared to the performance of well-established commercial photocatalyst, P25 titanium dioxide (Evonik). MTBE was the most efficiently degradable compound by all objects, while RNO was effectively degraded by plain structures only. In HA photocatalysis, needle-like ZnO as the most efficient material; PNL was the least degradable by ZnO layers. In the degradation of MTBE, RNO and HA, ZnO objects have shown activity comparable to or highly exceeding that of P25 TiO 2. The explanation of the differences in ZnO objects' photoactivity is proposed to be the different character of oxidising species produced by the ZnO objects, and different interactions of these with the degradation substrates, based on the relative amount of surface defects, surface morphology and hydroxylation of the ZnO structures' surface.