Preparation Of Ag-enhanced WO₃/TiO₂ Heterojunction Photocatalyst And Its Photocatalytic Performance

Utilizing solar energy to drive the semiconductor photocatalysis for degradation of water pollutant is an ideal strategy to solve the increasingly serious world energy crisis and environment pollution.Titanium dioxide?TiO₂?has excellent photochemical properties and stability,which has been extensively researched in the fields of photocatalysis,commercial lithium batteries,fuel photovoltaic cells,gas sensors and bionic functional materials.Tungsten trioxide?WO₃?has been applied in clean energy utilization,photocatalytic degradation,gas sensor and other fields due to its unique physical and chemical properties.However,TiO₂can only use ultraviolet band in photocatalytic reaction,and WO₃can only use a small part of the band of visible light.Due to the combined effect of photoelectron-hole pairs occurring in semiconductor materials,a single semiconductor photocatalyst has low solar energy utilization efficiency and low quantum efficiency.In this paper,TiO₂and WO₃semiconductor materials are used as the research subjects to improve the activity of photocatalytic materials by constructing heterojunction and precious metal deposition.The research's contents are as follows:1. WO₃ of monocline phase was prepared by hydrothermal method,and anatase type TiO₂was prepared by sol-gel method.The bandgap of WO₃ and TiO₂were 2.52 ev and 3.12 ev respectively,which was consistent with the theoretical calculation.The results of photocatalysis experiments under the same conditions indicated that the degradation rates of methylene blue solution with 300 mg/L concentration by WO₃and TiO₂in 120 minutes were 51.13%and 24.46%,respectively.The EIS test results showed that the arc radius of WO₃was smaller than TiO₂,indicating that the electron transfer efficiency of WO₃was higher than TiO₂,which was consistent with the photocatalytic performance test results.2. TiO₂-WO₃ composite catalysts were prepared by sol-gel method,degradation of methylene blue solution showed that when the molar ratio of TiO₂and WO₃was3:1,the photocatalytic activity of the heterojunction composite catalyst was the highest,with a degradation rate of 84.2%in 20 min and a degradation rate of nearly98%in 60 min.The results of EIS showed that the semi-arc diameter of EIS curve was the smallest when T:W=3:1,and the semi-arc diameter of EIS curve was the largest when T:W=1:1.The composite catalyst effectively broadened the spectral response range,inhibited the photogenic carrier recombination,and improved the photocatalytic activity.3. The catalytic activity of Ag-TiO₂-WO₃,which was added with Ag,was higher than that of T:W=3:1,the degradation rate of MB solution was close to 96% at 20 min,and the degradation rate of MB solution was more than 99%within 40min.EIS?electrochemical impedance?curve showed that the diameter of EIS curve decreased when the composite catalyst T:W=3:1 was doped with silver,indicating that the resistance of electron migration encountered in the catalytic reaction process decreased after the sample was doped with silver.