改性钨酸铋的制备及其光催化性能研究

发布时间：2018-02-03 03:28

  本文关键词： Bi_2WO_6 溶胶-凝胶法 掺杂 复合 光催化　出处：《广西大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来光催化氧化技术作为一种新兴的水污染处理技术已经成为学者们的研究热点。其中,具有类钙钛矿层状结构的Bi2WO6引起了人们的广泛关注。Bi2WO6带隙约为2.7eV左右,能够被可见光激发,能比较好地利用太阳光。同时,Bi2WO6是一种环境友好型的可见光催化材料,不存在光腐蚀的现象,光稳定性良好。研究和开发Bi2WO6系列光催化材料,在净化环境和开发新材料等领域都具有潜在的意义。本文通过溶胶-凝胶法、水热法和溶剂热法,采用金属掺杂、半导体复合等改性手段,分别制备出了Bi2WO6?Eu/Bi2WO6/Bi2O2CO3/Bi3.84W0.16O6.24三种钨酸铋光催化材料。采用XRD、SEM、DRS、EDS、XPS等技术对所制备样品的结构、形貌、光吸收性能进行了表征,并通过在可见光下对罗丹明B(RhB)溶液的降解程度来测定所有样品的光催化活性,获得了光催化性能良好的改性钨酸铋。具体研究内容及结果如下：(1)以柠檬酸(CA)作为络合剂,采用溶胶-凝胶法,在CA与金属离子摩尔比为3：1、分散剂为PEG4000、前驱液的pH值为1时,于450℃煅烧3h,制备出了微纳米结构的Bi2WO6材料。样品为斜方晶系结构,颗粒约为50nm。在可见光照射60min后,样品对RhB溶液的降解率达到了87.9%,表现出良好的光催化性能。(2)采用水热法,在水热温度160℃、水热时间16h、前驱液的pH值为1、Eu掺杂量为5%的优化条件下合成了Eu/Bi2WO6纳米材料。在可见光照1h后,Eu/Bi2WO6对RhB降解率达到了94.2%,优于纯相Bi2WO6的75.4%。Bi2WO6掺杂Eu后,吸收波长边缘发生了红移,促进了样品对可见光的吸收。随着Eu掺杂量的增加,样品发生了形貌演变,由二维片状结构转化为三维花球结构最后变成块状晶粒。结合样品的结构及其光催化性能的分析,可以推断出,光催化效率明显提高是因为三维花球结构中超薄的纳米片之间开放的空间,为RhB提供了运输的通道和强大的储存场所。(3)采用溶剂热法,以乙二醇作溶剂,Bi3+和W6+的摩尔比为2：1,在反应时间为4h、反应温度为160℃、前驱液的pH值为11的条件下,得到了Bi2O2CO3/Bi3.84W0.16O6.24复合催化剂。可见光照15min后,对RhB的降解率已达到92%。样品颗粒尺寸约10nm,明显小于水热法得到的Bi2WO6花球。样品的光吸收波长边缘红移,带隙变窄,对可见光吸收增强。根据Mulliken电负性理论,可以推断Bi3.84W0.16O6.24与Bi2O2CO3复合后,光生电子和空穴分别富集在Bi2O2CO3的导带与Bi3.84W0.i6O6.24的价带上,很大程度上降低了光生载流子的复合率,从而提高样品的光催化效率。
[Abstract]:In recent years, photocatalytic oxidation technology as a new water pollution treatment technology has become a research hotspot of scholars. Bi2WO6 with perovskite-like layered structure has attracted much attention. The band gap of Bi2WO6 is about 2.7 EV, which can be excited by visible light and make good use of solar light. Bi2WO6 is a kind of environment-friendly visible light catalytic material. There is no photocorrosion phenomenon and the light stability is good. The research and development of Bi2WO6 series photocatalytic materials. In this paper, sol-gel method, hydrothermal method and solvothermal method, metal doping, semiconductor composite and other modification methods are used. Bi2WO6? Three kinds of bismuth tungstate photocatalytic materials were used. The structure, morphology and light absorption properties of the prepared samples were characterized by XPS and the photocatalytic activity of all the samples was determined by the degradation degree of Rhodamine XPS solution under visible light. The modified bismuth tungstate with good photocatalytic activity was obtained. The specific research contents and results are as follows: 1) with citric acid as the complexing agent, the sol-gel method is used. When the molar ratio of CA to metal ion is 3: 1, the dispersant is PEG4000, the pH value of the precursor is 1:00 and calcined at 450 鈩，

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