Preparation Of Visible Light-driven WO₃-based Photocatalyst And Study On Its Photodegradation Performance

Since the twenty-first century,technology has developed by leaps and bounds,and while people’s lives have become more and more convenient,environmental problems that cannot be ignored have also emerged.A large number of pollutants entering water bodies have caused serious water pollution,especially the proliferation of various drugs leading to a sharp increase in the concentration of antibiotics in water bodies,seriously endangering the survival of human security.Antibiotic wastewater is a kind of high concentration organic wastewater with high color and difficult to degrade,which is difficult to be degraded by traditional water treatment methods.At this time,photocatalytic technology has been widely studied because it can efficiently remove such organic pollutants and convert them into environmentally friendly products such as carbon dioxide and water.The development of stable and efficient photocatalysts is the core of photocatalysis,and WO₃ is an n-type semiconductor that responds to visible light,is stable and easy to prepare,and can be used as both a primary catalyst and a co-catalyst,making it one of the best candidates for photocatalytic materials.However,the band gap of WO₃ is large,the utilization of visible light is very limited,and the high photogenerated carrier complexation rate affects its photocatalytic performance.Therefore,the study was conducted with WO₃ as the substrate and tetracycline hydrochloride as the target pollutant,and it was expected to improve its photocatalytic degradation performance under visible light by compounding with semiconductor materials.The main studies are as follows:（1）The WO₃/Ag₃PO₄ composite photocatalytic materials were successfully prepared by calcination and in situ precipitation methods,and the prepared materials were characterized by XRD,SEM,FTIR,XPS and UV-Vis DRS,and the photocatalytic activities of the composites were investigated under different ratios.The results showed that the photocatalytic performance of the composites all had different degrees of improvement over the single photocatalyst,among which the WO₃/Ag₃PO₄ composite had the optimal photocatalytic performance at 25%WO₃ mass ratio,which was 3.9times higher than that of WO₃ alone,and still had good photocatalytic activity after 5cycle tests,indicating the good stability and reproducibility of the material.And based on the energy band analysis and radical capture test,it was reasoned that the WO₃/Ag₃PO₄ composite photocatalyst was compounded to form a p-n type heterostructure,which enhanced the effective separation and transfer rate of photogenerated charge carriers,thus enhancing the photocatalytic performance.（2）The WO₃/BiOCl_0.7I_0.3 composite photocatalytic materials were successfully prepared by calcination method combined with water bath heating and in situ precipitation method.The elemental composition,apparent morphology and chemical structure of this series of photocatalysts were characterized and analyzed,and the photocatalytic degradation test of tetracycline hydrochloride（20 mg/L）was carried out.The results showed that the composite material has better photocatalytic performance than WO₃ and BiOCl_0.7I_0.3 monomeric materials.The degradation effect of the prepared composite was optimal when the molar ratio of WO₃ and BiOCl_0.7I_0.3 was（1:15）,and the degradation rate reached 93.84%after 1 h of light exposure.By analyzing the results of free radical capture test and ESR patterns,the main active substances in the photodegradation process were clarified,and the Z-type photocatalytic reaction mechanism of WO₃/BiOCl_0.7I_0.3 composites was proposed in combination with the energy band structure reasoning.