Liquid Phase Synthesis And Photocatalytic Properties Of Bismuth Semiconductor Composites

Semiconductor photocatalysis technology is an ideal pollution control technology,which shows great potential in the degradation of organic pollutants.Among the traditional photocatalysts,Ti O₂,as an effective photocatalyst,is widely used for water decomposition and organic pollutant degradation under ultraviolet（UV）light.However,due to its high band gap energy（3.0～3.2 e V）,photons can only be induced in the ultraviolet region which accounts for about 7%of the solar energy.Therefore,in order to make full use of solar energy,it is of great significance to develop photocatalysts with response in the visible light region.Bismuth based photocatalyst semiconductors and their composites have attracted many researchers’attention because of their unique electronic structure,high stability and good visible photocatalytic activity.In this paper,a series of bismuth semiconductor composites were prepared by using a mild low temperature liquid phase synthesis technique and optimized synthesis method by controlling reaction conditions,including Bi/Bi O_2-xcomposite micro-nano hollow cake,Bi/Bi₂O₂CO₃/Bi₁₂O₁₇Cl₂ composite nano tablet and Bi/Bi₁₂Si O₂₀ nanowire materials.This paper mainly studied the preparation of Bi and bismuth composite materials,and discussed the influence of photocatalysts with different components on photocatalytic activity,and revealed the important significance of composite composition control in the preparation of photocatalysts.First,with glucose as the reducing agent,through the low temperature liquid phase reduction method in aqueous solution was synthesized Bi/Bi O_2-x composite hollow micro-nano bread in the standard experiment,on the basis of further study on the reaction time of Na OH addition,amount of PVP K30 concentration and reaction temperature on the influence of reaction parameters on the morphology and structure,this paper discusses the typical morphology of samples.The samples with reduction time of 40 minutes has the best degradation effect of LEV,and the degradation rate reaches 96.1%when it is irradiated by visible light for 60 minutes.The acti ve species produced in the photocatalytic process are studied through the capture experiment,and the photodegradation mechanism of the material is inferred.Second,in alkaline system,liquid-phase synthesis was prepared successfully using simple Bi/Bi₂O₂CO₃/Bi₁₂O₁₇Cl₂ composite nanometer piece of photocatalytic materials first in Na OH,Bi Cl₃ and PVP K30 co-exist under the conditions of preparation of yellow precursor Bi₂O₂CO₃/Bi₁₂O₁₇Cl₂ composite material,and then add in glucose reductant restore the elemental bismuth reduced by changing the system.By changing the amount of alkali,reduction time and reaction temperature,the morphology,structure and material composition of the nanocomposites were controlled to reveal the formation and growth mechanism of the composites.The composite material was applied to the visible light catalytic degradation of levofloxacin.The degradation efficiency of 60 mg samples was up to 93.9%after 120 min of visible light irradiation,and the degradation rate constant was 21.02·10^–3 min^–1.Combined with the results of the capture experiment,the degradation mechanism was deduced reasonably.Third,sodium phosphite as a condition for reducing agent,PVP K30 as surface active agent,through the low temperature liquid phase red uction method successfully synthesized Bi/Bi₁₂Si O₂₀ a wiener rice noodle photocatalytic materials in the first place in the acid reaction system restore the highly active,60～300 nm size in a wiener rice noodle structure between elemental bismuth,then r eaction system adjustment is weakly alkaline,After adding TEOS solution,Bi ₁₂Si O₂₀ was grown in situ,ultimately successful preparation of Bi/Bi₁₂Si O₂₀ composites was studied different acidity reduction time.Effects of alkalinity and temperature on the m orphology,composition and structure of composites;The photocatalytic degradation of levofloxacin by different volumes of TEOS was studied.The photocatalytic degradation efficiency of40 mg samples under visible light was 95%,and the degradation rate co nstant was0.0198 min^–1.The photocatalytic stability of the composite was proved by cyclic experiments.The mechanism of photocatalytic degradation was explained by capture experiment.The simulated water experiment further proves that the composite mater ial has good practical performance.