Synthesis And Photocatalytic Performance Of Ion Doped Bi₂WO₆ Powers And Films

Photocatalytic technology has potential application value in solar energy utilization and environment control.Exploring new efficient photocatalytic materials is an important direction of material research at present.Bi₂WO₆ is one of the simplest perovskite-like Aurivillius oxide with high chemical stability.It has a high chemical stability,a suitable bandgap?2.7 eV?,green and rich in compositional abundant.It has great potential in assembling thin film solar cells and degrading organic contaminants.In this paper,Bi₂WO₆was used as the research object.The structure,morphology,element composition and optical properties of the composites were characterized by XRD,SEM,XPS,DRS and so on.The photocatalytic performance of Bi₂WO₆ was evaluated by photocatalytic decomposition of rhodamine-B under visible light.The specific contents of the study are as follows:?1?Bi₂WO₆ powders were prepared by solvothermal method and hydrothermal method.XRD results showed that Bi₂WO₆ samples prepared by the two methods belong to orthorhombic structure,but hydrothermal preparation of the catalyst has a higher crystallinity.Therefore,the Bi₂WO₆ catalyst is prepared by hydrothermal method.The effects of hydrothermal temperature,reaction time and pH value of the precursor on the characterization were systematically investigated.It is found that the morphology,grain size,and specific surface area of the catalysts were significantly affected by the pH value.The results showed that the catalyst of the 3D nested layered structure prepared under the condition of pH=1 has good photocatalytic activity.?2?A series of Bi-doped Bi_2+xWO₆?x=-0.2,-0.1,0,0.1,0.2?photocatalysts were synthesized by adjusting the amount of Bi?NO₃?₃.The results of DRS show that the self-doping of Bi enhances the visible absorption range of Bi₂WO₆ and causes the change of band gap.The photocatalytic degradation of rhodamine-B solution by visible light showed that the photocatalytic activity of Bi_2.1WO₆ was the highest when x=0.1,and the degradation rate of rhodamine-B was 92.1%in 120 min.?3?In order to investigate the effect of ion-doping on the catalytic performance of Bi₂WO₆,Zn/Bi₂WO₆ and Mg/Bi₂WO₆ photocatalysts were synthesized by Zn?NO₃?₂·6H₂O and Mg?NO₃?₂·8H₂O,respectively.With Mg²⁺is added,the photocatalytic activity of Bi₂WO₆is obviously enhanced.When the Mg²⁺content is 1%,the photocatalytic activity of catalysts is the highest.The degradation rate of rhodamine-B reached 94.3%after visible light irradiation for 45 min,24.3%higher than that of undoped Bi₂WO₆.?4?Bi₂WO₆ thin films were successfully prepared by spin coating method using bismuth nitrate?Bi?NO₃?₃·5H₂O?and sodium tungstate?Na₂WO₄·2H₂O?as starting materials.The effects of different Bi³⁺content and different metal ion doping on the surface morphology,chemical composition and humidity sensitivity of Bi₂WO₆ thin films were investigated.The experimental results show that the absence of Bi³⁺has a great influence on the surface morphology of the film,but the sensitivity of the sensor is not significant.Metal ion doping does not affect the phase of the film,and effectively reduces the resistance of the film.The effect of different ion pairs on the sensitivity of the film is different.