The Preparation And Photocatalytic Performance Of New-type Photocatalyst Based On BiOCl Composites

With the rapid development of the human society, the pollution of environment is increasing more and more severe. It has caused serious pollution especially for industrial wastewater. The application of photocatalysis technique which is a promising technique, has become the current research focuses in this field. This thesis is aimed at the existence problem in photocatalytic technology, such as low photocatalytic efficiency and low solar utilization rate.The target is to develop novel and environment-friendly photocatalyst with high catalytic efficiency. BiOCl was chosen as the typical photocatalyst to design and optimize the photocatalytical properties. The influence factors of photocatalytic activity of compound semiconductor materials, like different loading amount of other semiconductor materials and the mechanism of photocatalytic process of degrading organic pollutants and the application of the photocatalysts based on BiOCl were explored in detail. The details are summarized briefly as follows:1. BiOCl with different morphology was synthesized through simple hydrothermal method and solvothermal method. The as-prepared BiOCl had been characterized by X ray diffraction（XRD）, scanning electron microscopy（SEM）, UV-visible spectroscopy（UV-Vis） and so on. The photocatalytic performances of BiOCl were evaluated and compared by degrading MO. The results showed that the best photocatalytic performance composite is the sample prepared by diethylene glycol,the degradation efficiency of methyl orange reached 87.7% under visible light irradiation after 50 minutes. The holes and super oxygen anion free radicals played an important role during the process.2. Considering the excellent properties of metal oxide Ag₂O, using a facile chemical precipitation method to synthesize a series of BiOCl/Ag₂O composite photocatalysts with the different loading amount of Ag₂O, we explored the photocatalytic degradation activity in decomposing methyl orange solution. The results showed that BiOCl/Ag₂O（6%） had the highest photocatalytic degradation efficiency, 40 minutes up to 98%. Adopting a series of characterization to analyze the catalyst, we deduced the possible mechanism of the BiOCl/Ag₂O composites during the photocatalytic degradation process.3. Carbon quantum dots were synthesized by the hydrothermal method using sodium citrate as carbon source. Due to the good property of carbon quantum dots, weused a one step solvothermal method to prepare the different contents of CQDs composite photocatalyst（1 wt%, 3wt%, 5wt%） CQDs/BiOCl and investigated the morphology and structure of the composite photocatalysts, light absorption properties and photoelectric properties. Photocatalytic activity was evaluated by photocatalytic degradation of 2-nitrophenol. The results revealed that 3wt% CQDs/BiOCl was best to degrade 2-nitrophenol. This is attributed to the CQDs is a good electron carrier which reduced the recombination of electrons-holes, resulting in improving the photo-catalytic efficiency in decomposing 2-nitrophenol.4. The immobilization of BiOCl was explored and the fly ash cenospheres was chosen as the carrier. The BiOCl/FACS composite photocatalysts were prepared by a simple one step solvothermal method with the addition of different surfactants（PVP,SDS and CTAB）. The performance of the catalysts were evaluated by photocatalytic degradation of methyl orange solution. The results showed that the best performance of adsorption on the MO was SDS/BiOCl/FACS, while PVP/BiOCl/FACS was the second one. As to the degradation efficiency, PVP/BiOCl/FACS had the highest efficiency of 98%. We deposited Ag on PVP/BiOCl/FACS using optical reduction method, because of the existence of Ag which increased the separation efficiency of photoinduced hole-electron, further improving the photocatalytic efficiency.