A Study On Preparation And Photoelectrocatalytic Properties Of WO₃/TiO₂ Composite Thin Film Electrodes

As the global environment worsening,TiO₂ photocatalysis technology used in the amelioration of environmental pollution has attracted more and more people’s attention.However,TiO₂ materials have low sunlight utilization rate and fast electrons and holes recombination rate,as well as powder material is difficult to recover and secondary use.Therefore,how to expand the spectral response range of the TiO₂ catalyst,improve the quantum efficiency of light and speed up the photocatalytic reaction rate have become the major problems of TiO₂ photocatalytic materials.In this paper,taking the main influencing factors of TiO₂photocatalytic materials into consideration,the modification of TiO₂photocatalytic material was studied and its photocatalytic properties were analyzed.The following three aspects of work had been done.Firstly,the combination of WO₃ and TiO₂ can expand the photoreaction range of semiconductor materials and can accumulate photogenerated electrons and holes on different semiconductor materials,which can effectively suppress the recombination of photogenerated carriers.Secondly,the powder material made of thin film electrode,not only to avoid powder material was difficult to recycle and secondary use,but also can be usedin the field of photocatalysis and electrocatalysis.Finally,acetylene black as a good conductor material can promote the transmission of electrons,reduce the recombination rate of electrons with holes when modified film electrode.Based on the above design ideas,a series of composite thin film electrodes were prepared.The morphology,crystal structure,microstructure,spatial distribution of elements,specific surface area and pore size distribution of the composites were characterized by SEM,XRD,TEM,EDS,BET,UV-Vis and photoelectrocatalytic performance test by photoelectric catalytic device.The main conclusions are as follows:（1）Spray drying only undergoes physical changes,so the precursor sample must be calcined before the composite can be converted from amorphous to crystalline.The flow rate has little effect on the morphology of the sample hollow sphere while the calcination temperature has great influence on it.（2）AMT and ammonium sulfate were decomposed into water vapor and ammonia gas etc.What’s more,crystallinity and nanoparticles increased with the calcination temperature,but the specific surface area decreased.（3）The modification of WO₃/TiO₂ composite film electrode by acetylene black did not lead to the change of crystal morphology of theWO₃/TiO₂ composite,but it could significantly improve the photocurrent and the performance of the photocatalytic degradation of methylene blue.In addition,the film is composed of WO₃/TiO₂mesoporous hollow spheres and acetylene black nanoparticles.The thickness of the films is about 20μm,and the size of the acetylene black nanoparticles is about 50 nm.（4）The photochemical and photoelectrochemical properties of the thin films prepared under different conditions were tested.The results show that under the visible light irradiation,when the calcination temperature is 500℃and the molar ratio of WO₃ in the composite is about 5%,the photocurrent of the film electrode is the largest,and the photocatalytic degradation of methylene blue is the best.In summary,this paper has done some research on the problems existing in the photocatalytic degradation of TiO₂ materials.The results show that the modification can significantly improve the photocatalytic properties of the material,and it is a step forward for the industrialization of TiO₂ materials.