Fabrication And Modification Photocatalytic Properties Of Bi₂WO₆

This thesis is based on the study on structure and catalytic properties of single crystal bismuth tungstate?Bi₂WO₆?materials.Respectively,different morphologies samples at various PH conditions?PH=1,7,10?were synthesized via a hydrothermal route and study the effects of topographt on photocatalytic.By using a series of modified method like suface disorder engineering,inpurity-droped other materials and compounding with carbon materials to improve photocatalytic performance on degradation of organic dye of Bi₂WO₆.Specific research contents are as follows:?1?Cu?OH?₂ clusters were loaded onto the surface of rose flower-like Bi₂WO₆hierarchical architectures with the aim of enhancing the photocatalytic activity.Moreover,the obtained Cu?OH?₂@Bi₂WO₆ was heat-treated at 200?,during which time Cu?OH?₂ was decomposed into CuO particles onto the Bi₂WO₆ surface.Compared to bare Bi₂WO₆,an enhanced separation efficiency of photogenerated electron-hole pairs was observed for both Cu?OH?₂@Bi₂WO₆ and CuO@Bi₂WO₆.The photocatalytic activity of the composites was investigated by using RhB as the target organic pollutant of degradation under simulated sunlight irradiation.It was found that Cu?OH?₂@Bi₂WO₆ and CuO@Bi₂WO₆ showed a photocatalytic activity about 1.9 and 1.6 times higher than that of bare Bi₂WO₆.?2?NaBH₄ reduction method has been used to engineer the surface structure of flake-like Bi₂WO₆?BWO?crystals with the aim of creating disordered surface structure and enhancing the photocatalytic activity.It is demonstrated that 0.03M-BWO treated at 0.03 M NaBH₄solution exhibits the highest photocatalytic activity,2.4 times higher than pristine BWO under simulated sunlight irradiation.The significant increase in the photocatalytic activity is observed at the UV irradiation,which can be explained by the fact that the disordered surface states?formed in the forbidden gap of BWO?can facilitate the separation of photogenerated electron-hole pairsact as electron acceptors.A slightly enhanced photocatalytic activity is observed under visible light irradiation,which is attributed to the enhanced visible light absorption induced by the disordered surface states.In addition,it is found that the treatment with high NaBH₄ concentrations is detrimental to the photocatalytic activity due to the creation of bulk defects in BWO crystals.?3?we have assembled Bi₂WO₆ nanoparticles on the surface of honeycomb-like porous carbon skeleton?PCS?via a hydrothermal route to achieve a new type of PCS@Bi₂WO₆hybrid composite photocatalysts.The photocatalytic performance of the composites were evaluated by using RhB as the model pollutant and simulated sunlight as the light source.It is revealed that the PCS@Bi₂WO₆ hybrid composites manifest much enhanced photocatalytic performance.With increasing the PCS content,the highest photocatalytic activity is observed for the 5wt%PCS@Bi₂WO₆ composite,which is 2.1 times as large as that of bare Bi₂WO₆nanoparticles.This can be ascribed to two factors:?i?The photogenerated electron/hole pairs in Bi₂WO₆ are efficiently separated due to the electron transfer between Bi₂WO₆ and PCS;and?ii?PCS induces enhanced visible-light absorption and the photoexcited electrons in PCS could also take part in the photocatalytic reactions.