Preparation And Photocatalytic Properties Of Ag₃PO₄ And ZnO Based Compound Photocatalysts

With the increasing pollution of environment, using photocatalytic technology to solve environmental problems has received lots of attentions, and the photocatalyst is the key problem of this. In this paper, we aimed at the solve problems in the field of semiconductor photocatalysts, which photocatalytic efficiency is low and the materials are instability. The photocatalysts based on Ag3PO4 or ZnO have their advantages and disadvantages, respectively, so we modified them to improve the photocatalytic activity and stability. We synthetized a series of compound semiconductor photocatalytic materials based on the Ag3PO4 or ZnO materials. And we used Rhodamine B as the simulation pollutants to be degraded to study the photocatalytic properties of each compound semiconductor photocatalytic materials. And we also studied the influence factors of photocatalytic activity of compound semiconductor materials, like the loading amount of noble metal, or the molar ratio of each semiconductor materials. The mechanism of photocatalytic process has explored in this paper. A series of studies on materials synthesis, modification and applications have been studied. The details are summarized as follows:(1) Ag3PO4/ZnO heterostructure compound semiconductor materials: A facile process for the fabrication of Ag3PO4/ZnO heterostructure compound semiconductor photocatalyst has been presented in this study. The main raw materials are silver nitrate,disodium hydrogen phosphate and commercial zinc oxide. And we have characterized the Ag3PO4/ZnO compound materials by X ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), UV-visible spectroscopy(UV-Vis) and fourier transform infrared spectroscopy(FT-IR) to study the phase composition, microstructure and properties of light absorption properties of the as-prepared photocatalysts. The photocatalytic properties and optical properties of them also have been detected. Then we explore affect of photocatalytic properties with the molar ratio of Ag3PO4 to ZnO changed, as well as a preliminary study of photocatalytic mechanism has been discussed. The results showed that the best photocatalytic performance composite is the sample which molar ratio is 1:1. And its photocatalytic performance is 3.5 times to the pure Ag3PO4 which under the same conditions has prepared, and 19 times that of commercial ZnO. The photocatalytic activityimprovement and photo-corrosion inhibition of Ag3PO4/ZnO composites may be attributed to the establishment of the energy gradation between the Ag3PO4 and ZnO.And then we catalytic degradation colorless and refractory organic pollutants of o-nitrophenol to exclude dye-sensitized, and it further prominent stand out the contribution of the catalyst to environment.(2) Ag3PO4/WO3 heterostructure compound semiconductor materials:A facile process for the fabrication of Ag3PO4/WO3 heterostructure compound semiconductor photocatalyst has been presented in this study. The main raw materials are silver nitrate,disodium hydrogen phosphate and nano tungsten trioxide. And we have characterized the Ag3PO4/WO3 compound materials by XRD, SEM, UV-Vis and other methods to study the phase composition, microstructure and properties of light absorption properties of the as-prepared photocatalysts. The photocatalytic properties and optical properties of them also have been detected. Then we explore affect of photocatalytic properties with the molar ratio of Ag3PO4 to WO3 changed, as well as a preliminary study of photocatalytic mechanism has been discussed. The results showed that the best photocatalytic performance composite is the sample which molar ratio is 1:0.7. And its photocatalytic performance is 6 times to the pure Ag3PO4 which under the same conditions has prepared, and 122 times that of nano WO3. The photocatalytic activity improvement and photo-corrosion inhibition of Ag3PO4/WO3 composites may be attributed to the establishment of the energy gradation between the Ag3PO4 and WO3.(3) Flower-like ZnO/Ag compound semiconductor materials: In this part, the flower-like ZnO which composed of nano-ZnO particles has been prepared by self-assembled method. And the Ag deposited on the flower-like ZnO using optical reduction method. And we have characterized the ZnO/Ag compound materials by XRD,SEM, EDS, UV-Vis to comprehend the phase composition, microstructure shape appearance and absorbance of flower-like ZnO/Ag compound samples before and after loading Ag particles. We investigated the photocatalyst activity of each materials samples under simulated sunlight irradiation with the rhodamine B solution as the simulated pollution to photocatalytic degradation, in order to explore the impact about ZnO/Ag samples photocatalytic properties of Ag deposition time(i.e. the Ag content).The results showed that the best photocatalytic performance composite is the sample which irradiated 6min to loading Ag particles. And its photocatalytic performance is 5.8times to the pure ZnO which under the same conditions prepared. This is attribute to theloading of Ag, the photogenerated electrons can be captured by Ag particles, it was conducive to the separation of the electron-hole pairs, as well as surface plasmon resonance effect occurs which could enhanced absorption of visible light.