Preparation And Photocatalytic Performance Of Ag₁₀Si₄O₁₃/TiO₂ Heterojunction Photocatalyst

The rapid industrial development has caused energy shortages and environmental pollution,which have already had a significant impact on s ocial progress and human development.Photocatalytic technology is a new technology with great potential for environmental protection and energy saving,with low cost,low toxicity,mild reaction conditions and high reaction rate,it might be a scientific coping strategy.However,it is difficult for most photocatalysts to possess a wide light response range and low carrier recombination rate at the same time.In view of the above problems,combining wide-band gap semiconductors and narrow-band gap semiconductors to construct a heterojunction is considered to be an effective solution.Wide-band gap semiconductor TiO₂ has been extensively studied due to various advantages such as stability and high efficiency,but it has the disadvantages of low utilization o f sunlight and short carrier lifetime,which leads to its l ow photocatalytic activity.In order to solve these problems,this paper uses the sol-gel method combined with heat treatment to composite Ag₁₀Si₄O₁₃ and TiO₂ to construct a heterojunction photocat alyst,in order to improve its light absorption capacity an d solve the problem of carrier recombination,thereby increasing the photocatalytic degradation efficiency.Analyze d crystals structure,microscopic morphology,optical properties and electrochemic al properties by X-ray diffraction（XRD）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）,ultraviolet-visible diffuse reflectance（UV-Vis DRS）,fluorescence spectroscopy（PL）,and electrochemical testing.Under simulated sunlight and visible light conditions,studied the effect of ASO/TO composite materials with different compound ratios ASO/TO(Ag₁₀Si₄O₁₃/TiO₂)on the adsorption performance,photocatalytic performance and reaction rate with methylene blue（MB）as the target degradation product,and then explored its degradation mechanism.Finally,cycling stability and photo-corrosion of Ag₁₀Si₄O₁₃and ASO/TO（2:1）composites were evaluated.Concluded as follows:1.The ASO/TO composite was prepared by sol-gel method,mixing TiO₂,silicic acid sol and AgNO₃ uniformly in sequence.When the ASO/TO compound ratio is 2:1,the carrier separation efficiency of the composite is improved,and the absorption band edge is red-shifted,and the light response range becomes wider,compared with a single Ag₁₀Si₄O₁₃ and TiO₂ photocatalyst.2.ASO/TO（2:1）composite material has the best degradation effect on MB under simulated sunlight and visible light conditions.The degradation rate of ASO/TO（2:1）under visible light is 96 times and 1.46 times that of TiO₂and Ag₁₀Si₄O₁₃;the degradation rate under sunlight is 33 times and 1.36 times that of Ti O ₂ and Ag₁₀Si₄O₁₃.Compared with a single photocatalyst,the degradation rate of composites has been improved;in addition,the degradation rate of ASO/TO（2:1）composite material under visible light is faster than that under sunlight.This is due to the stronger photo-corrosion of composite material under sunlight,which makes the material structure is destroyed and the photocatalytic rate slows down.3.Active radical capture experiments show that h⁺is the main active species to degrade MB in the process of photocatalytic degradation.According to the photocatalytic mechanism test,ASO/TO is a type II heterojunction photocatalyst.4.The photocatalytic efficiency stability test showed that the degradation efficiency of Ag₁₀Si₄O₁₃ and ASO/TO（2:1）composites after five photocatalytic cycle tests was 86.85%and 89.92%of the first time,respectively,indicating that the photocatalysis has a good cyclic stability.In addition,the composition stability of photocatalytic materials shows that,although the Ag content in ASO/TO（2:1）composites is higher than Ag₁₀Si₄O₁₃ during the five cycles,it tends to be stable.In combination with the stability of photocatalytic efficiency,the ASO/TO heterojunction has good stability and has potential practical application value.