Bi/B-TiO_(2)/Bi_(2)WO_(6)催化剂的制备及Bi纳米粒子影响光催化氧化甲苯的性能研究

Preparation of Bi/B-TiO_(2)/Bi_(2)WO_(6) catalyst and effects of Bi nanoparticles on photocatalytic oxidation of toluene

挥发性有机化合物(VOCs)作为具有较强毒性的污染物,对生物和环境都产生了巨大的威胁.本文通过改变N,N-二甲基甲酰胺(DMF)的添加量,制得不同比例的Bi/Bi_(2)WO_(6)(简称BBWO),通过调控Bi单质的含量制得一系列Bi/B-TiO_(2)/Bi_(2)WO_(6)(简称BBTB)催化剂,并测试其光催化降解甲苯的活性.结果表明:利用5 mL DMF制备的Bi/B-TiO_(2)/Bi_(2)WO_(6)(简称5-BBTB)表现出最高的甲苯降解活性,1 h内甲苯降解效率可达85%.通过XRD、FTIR、Raman、XPS、SEM、TEM等表征技术对BBTB催化剂进行化学组成及氧空位等结构的分析,证明了Bi单质的成功析出.DRS、PL及电化学性能测试证明了Bi单质的引入可以有效地提高催化剂对于可见光的响应能力及电子-空穴的分离效率.同时,利用EPR表征分析了光催化降解甲苯的过程中产生的主要活性氧物种.Bi_(2)WO_(6)与B-TiO_(2)(N2氛围下,500℃,3 h煅烧后的黑色TiO_(2))的异质结及Bi单质的存在提高了BBTB催化剂光催化转化甲苯的效率,但较多的Bi单质的存在会成为电子和空穴重组中心,从而造成催化活性的下降.

Volatile organic compounds(VOCs),as highly toxic pollutants,pose a great threat to both organisms and the environment.In this paper,different proportions of Bi/Bi_(2)WO_(6)(BBWO)were prepared by changing the addition amount of N,N-Dimethylformamide(DMF),and a series of Bi/BTiO_(2)/Bi_(2)WO_(6)(BBTB)catalysts were prepared by actively adjusting the content of Bi monomers,and their photocatalytic degradation activity of toluene was tested.The results showed that Bi/B-TiO_(2)/Bi_(2)WO_(6) prepared using 5 mL of DMF(referred to as 5-BBTB)exhibited the highest toluene degradation activity,and the toluene degradation efficiency could reach 85%within 1 h.The chemical composition and oxygen vacancies of the BBTB catalysts were analyzed by XRD,FTIR,Raman,XPS,SEM,TEM and other characterization techniques,and the successful precipitation of Bi monomers was demonstrated;then DRS,PL and electrochemical experiments were used to demonstrate that the introduction of Bi monomers could effectively improve the response of the catalysts to visible light and the electron-hole separation.Finally,the main reactive oxygen species generated in the photocatalytic degradation of toluene were investigated by EPR technique.It was found that the efficient removal of toluene by BBTB catalyst was attributed to the presence of heterojunction and Bi monomer between Bi_(2)WO_(6) and B-TiO_(2)(black TiO_(2) after calcination at 500℃for 3 h in N2 atmosphere),but the presence of more Bi monomers would become the electron and hole recombination center,resulting in reduced catalytic activity.