卤氧化铋基光催化剂的制备及性能研究

发布时间：2018-06-30 04:21

本文选题：BiOX + 光催化　；参考：《聊城大学》2017年硕士论文

【摘要】：目前,随着环境污染和能源短缺的日益严重,环境污染治理和新能源技术已经成为国内外科研工作者高度关注的研究方向。半导体光催化技术在太阳能转换、污水和空气污染治理领域表现出巨大应用潜力,而受到广泛关注。传统的半导体光催化剂,例如TiO2和ZnO等,具有原料来源丰富,合成成本较低,无毒和化学稳定性强等优点,在过去的四十多年得到了广泛关注和深入研究。但是,研究发现这些传统的半导体材料由于禁带宽度大的原因,只能响应占太阳光能量比例较少的紫外光,导致光催化材料对太阳光的利用率低;同时,由于光生电子和空穴不能得到有效分离,光催化材料对光子的转换效率低,也严重限制了其光催化活性的提高。为了解决上述问题国内外学者一直在努力开发和探索具有可见光活性的新型光催化材料。卤氧化铋是典型的P型半导体,具有独特的电子结构,使得其具有良好的光学和电学性能;另外,卤氧化铋具有特殊的层状结构,层与层之间形成的内电场有助于电子的转移。因此,该材料在光催化方面具有很大应用潜力。目前卤氧化铋材料的制备方法主要有水解法、溶剂热法和水热法等,但是制备过程复杂,条件要求苛刻。另外,卤氧化铋光催化材料的量子效率低也严重影响了其光催化活性,还具有较低的太阳光利用率等缺点。为克服上述缺陷并进一步提高其光催化性能,本学位论文分别采用燃烧法和酸腐蚀法制备了一系列高活性的BiOX/半导体复合光催化材料。具体研究工作如下:(1)采用燃烧法制备了可磁性分离的NiFe_2O_4/BiOBr复合光催化材料。NiFe_2O_4/BiOBr异质结构可以导致光生电子和空穴在空间上的有效分离,大幅提高了材料的光催化活性;另外,借助于NiFe_2O_4的顺磁性,该复合材料可以在外磁场作用下,实现方便快捷的磁性回收。(2)采用一步燃烧法制备了BiVO_4/BiOCl复合光催化材料。借助于BiVO_4材料的敏化作用,BiVO_4/BiOCl复合材料比单体BiOCl对可见光的吸收能力更大,可以更加高效的利用太阳光;另外,通过构建BiVO_4和BiOCl异质结构,促进了光生电子和空穴的有效分离,提高了对RhB的降解活性。(3)采用酸腐蚀法成功制备了BiOBr/Bi_2Sn_2O_7异质结光催化材料。在酸腐蚀过程中成功构建BiOBr/Bi_2Sn_2O_7异质结;通过调整HBr的浓度,可有效调控微球状Bi_2Sn_2O_7在片状BiOBr的分布量。该复合材料中,两相界面连接紧密,有利于电荷的快速传输,效抑制了光致电荷的复合,最终大幅提高了材料的光催化性能。(4)采用酸腐蚀法制备了BiOCl/Bi_2Sn_2O_7异质结光催化材料。通过HCl处理Bi_2Sn_2O_7,成功制备了BiOCl/Bi_2Sn_2O_7异质结复合材料。Bi_2Sn_2O_7的敏化作用与特殊的形貌结构协同作用,有效提高了太阳光利用率和光催化活性。
[Abstract]:At present, with the increasingly serious environmental pollution and energy shortage, environmental pollution control and new energy technology have become the research direction that researchers at home and abroad pay close attention to. Semiconductor photocatalytic technology has shown great application potential in solar energy conversion, sewage and air pollution treatment, and has attracted wide attention. Traditional semiconductor photocatalysts, such as TIO _ 2 and ZnO, have many advantages, such as abundant raw materials, low synthesis cost, non-toxic and strong chemical stability, and have been widely concerned and deeply studied in the past 40 years. However, the study found that these traditional semiconductor materials can only respond to ultraviolet light, which accounts for a small proportion of solar energy, because of the large band gap, which leads to the low utilization ratio of photocatalytic materials to solar light; at the same time, The photocatalytic efficiency of photocatalytic materials is low, which limits the improvement of photocatalytic activity because of the lack of effective separation of photogenerated electrons and holes. In order to solve these problems, scholars at home and abroad have been developing and exploring new photocatalytic materials with visible light activity. Bismuth halide is a typical P-type semiconductor with unique electronic structure, which makes it have good optical and electrical properties. In addition, bismuth halide has a special layered structure, and the internal electric field formed between layers is conducive to the transfer of electrons. Therefore, this material has great application potential in photocatalysis. At present, the preparation methods of bismuth halide mainly include hydrolysis method, solvothermal method and hydrothermal method, but the preparation process is complicated and the conditions are demanding. In addition, the low quantum efficiency of bismuth halide photocatalytic material also seriously affects its photocatalytic activity, and has some disadvantages such as low solar light utilization rate and so on. In order to overcome the above defects and further improve its photocatalytic performance, a series of highly active BiOX / semiconductor composite photocatalytic materials were prepared by combustion method and acid corrosion method respectively. The specific research works are as follows: (1) the magnetically separated NiFe2O4 / BiOBr composite photocatalytic material. NiFe2O4 / BiOBr heterostructure can lead to the effective separation of photogenerated electrons and holes in space, and greatly improve the photocatalytic activity of the materials. With the help of the paramagnetism of NiFe _ 2O _ 4, the composite can realize the quick and convenient magnetic recovery under the action of external magnetic field. (2) Bivos _ 4 / BiOCl composite photocatalytic material was prepared by one-step combustion method. With the help of the sensitization of BiVO4 materials, BiVO4 / BiOCl composite has greater absorbability to visible light than the monomer BiOCl, and can utilize solar light more efficiently. In addition, by constructing BiVO4 and BiOCl heterostructures, the effective separation of photogenerated electrons and holes is promoted. The degradation activity of RhB was improved. (3) BiOBr-Bi2Sn2O7 heterojunction photocatalytic materials were successfully prepared by acid etching. BiOBr-Bi2Sn2O7 heterojunction was successfully constructed during acid corrosion, and the distribution of Bi2Sn2O7 in flake BiOBr could be effectively regulated by adjusting the concentration of HBR. In this composite, the two-phase interface is closely connected, which is favorable to the fast charge transfer, and the photocatalytic properties of the composite are greatly improved. (4) BiOCl-Bi2Sn2O7 heterojunction photocatalytic materials are prepared by acid etching method. By treating Bi2Sn2O7 with HCl, BiOCl / Bi2Sn2O7 heterojunction composite, Bi2Sn2O7, has been successfully prepared. The sensitizing effect of BiOCl / Bi2Sn2O7 and the synergistic effect of special morphology and structure have effectively improved the solar light utilization rate and photocatalytic activity.
【学位授予单位】：聊城大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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