掺硼金刚石薄膜的制备、修饰及应用性能研究

发布时间：2018-03-07 13:33

本文选题：掺硼金刚石薄膜　切入点：二氧化钛　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：作为优异的电极材料,掺硼金刚石(Boron-Doped Diamond,BDD)薄膜电极被应用于电化学氧化处理废水领域。与传统电化学氧化电极材料相比,BDD薄膜电极具有宽的电化学势窗、高的析氧过电位、低背景电流和良好的可逆性等优异的电化学性能。在对废水处理过程中具有目标降解物范围广、电流效率高、耐酸碱腐蚀、低吸附性及催化活性好等优点,同时BDD薄膜也是性能优异的电极衬底材料,可实现光催化性能优异TiO2的固定化,从而解决悬浮于溶液中的TiO2在光催化过程中存在易团聚、与废水分离困难、容易失去活性且回收处理不方便等问题。本文以制备出面积大、品级高、电化学性能优异及对模拟染料废水降解性能好的BDD薄膜电极和具备p-n异质结结构且界面结合好的纳米棒状TiO2修饰BDD复合电极材料为目标,采用微波等离子体化学气相沉积(Microwave Plasma Chemical Vapor Deposition,MPCVD)的方法合成BDD薄膜,通过水热法在BDD薄膜衬底上修饰TiO2纳米棒层,封装成电极材料后,研究其对模拟染料废水的降解。主要的研究结果如下:(1)以甲烷、氢气和乙硼烷为气源,在预处理过的(100)单晶硅衬底上采用MPCVD法制备BDD薄膜。通过表征,合成的BDD薄膜材料具有较低的电阻率,其值为2.84×10-3?·cm,作为p型半导体,其空穴浓度为1.03×1019 cm-3,迁移率达到214 cm2/v·s。显微结构观察发现该BDD薄膜呈多晶态,晶粒尺寸分布在10μm以下,薄膜厚度约为12μm,金刚石相含量高。通过循环伏安测试可以看出,BDD薄膜电极的电化学势窗较宽,酸性、中性和碱性条件下分别达到3.5 V、4.5 V和3 V,另外酸性和中性条件下析氧过电位达到2.3~2.5 V。(2)以钛酸丁酯为原料,超纯水为溶剂,浓盐酸为催化剂,采用水热法制备TiO2纳米棒修饰BDD复合薄膜材料。首先研究不同钛酸丁酯添加量条件下制备TiO2修饰金刚石单晶材料的最佳工艺,然后确定出钛酸丁酯添加量为1 mL时能够生长出均匀、致密,并与金刚石结合紧密的TiO2纳米棒层,最后按该工艺制备出具有p-n异质结结构的TiO2/BDD复合材料,其中TiO2形貌成纳米棒团聚而成的纳米束状,排列均匀、致密,晶型为金红石相,并且与BDD薄膜结合紧密。(3)研究了不同条件下多晶BDD电极对亚甲基蓝模拟染料废水的降解,Na2SO4作为支撑电解质,浓度值为2 g/L,电流密度设定为70 mA/cm2,在碱性环境中降解效果最优。在此基础上,研究了材料结构优化后的TiO2/BDD复合电极对活性艳红X-3B的降解。研究表明,BDD薄膜由于TiO2的引入,形成了具有p-n异质结结构的电极材料,由于二者光电协同效应,与BDD电极单独电化学氧化比较,对活性艳红的降解效率得到进一步提升。
[Abstract]:As an excellent electrode material, boron-doped diamond boron-Doped Diamondd (BDD) thin film electrode is used in the field of electrochemical oxidation treatment of wastewater. Compared with traditional electrochemical oxidation electrode material, BDD thin film electrode has wide electrochemical potential window and high oxygen evolution overpotential. Excellent electrochemical properties such as low background current and good reversibility. It has many advantages such as wide range of target degradation, high current efficiency, resistance to acid and alkali corrosion, low adsorption and good catalytic activity. At the same time, BDD film is also an excellent electrode substrate material, which can immobilize TiO2 with excellent photocatalytic performance, thus solve the problem that TiO2 suspended in solution is easy to agglomerate in the photocatalytic process, and it is difficult to separate it from wastewater. It is easy to lose activity and it is not convenient to recycle. In this paper, large area, high grade, BDD thin film electrode with excellent electrochemical performance and good degradation performance for simulated dye wastewater and nanorod TiO2 modified BDD composite electrode with p-n heterojunction structure and good interface are the targets. The BDD thin films were synthesized by microwave plasma chemical vapor deposition (microwave plasma chemical vapor deposition). The BDD films were modified on the BDD substrate by hydrothermal method and encapsulated into electrode materials. The main results of this study are as follows: (1) using methane, hydrogen and ethylborane as gas sources, BDD thin films were prepared on pretreated Si substrates by MPCVD method. The synthesized BDD thin films have low resistivity with a value of 2.84 脳 10 ~ (-3)? 路cm. as a p-type semiconductor, the hole concentration is 1.03 脳 1019 cm-3 and the mobility is 214 cm2/v 路s. It is found that the BDD thin film is polycrystalline and its grain size distribution is below 10 渭 m. The thickness of the film is about 12 渭 m and the content of diamond phase is high. The electrochemical potential window of BDD thin film electrode is wide and acidic by cyclic voltammetry. In neutral and alkaline conditions, 3.5 V and 3 V, respectively, and in acidic and neutral conditions, the oxygen evolution overpotential reached 2.3U 2.5 V / v 路m ~ (2)) using butyl titanate as raw material, ultrapure water as solvent, and concentrated hydrochloric acid as catalyst. TiO2 nanorods modified BDD composite films were prepared by hydrothermal method. Firstly, the optimum process of preparing TiO2 modified diamond single crystal materials with different amounts of butyl titanate was studied. Then, the TiO2 nanorods layer with uniform, dense and compact diamond binding was obtained when the addition of butyl titanate was 1 mL. Finally, the TiO2/BDD composite with p-n heterojunction structure was prepared by this process. The morphology of TiO2 is nanorod agglomerated nanorods with uniform arrangement, dense and rutile phase. The degradation of methylene blue simulated dye wastewater by polycrystalline BDD electrode under different conditions was studied. The concentration is 2 g / L and the current density is 70 Ma / cm 2, which is the best degradation effect in alkaline environment. On the basis of this, the degradation of reactive brilliant red X-3B by TiO2/BDD composite electrode with optimized material structure has been studied. The electrode materials with p-n heterojunction structure were formed and the degradation efficiency of reactive brilliant red was further improved compared with that of BDD electrode due to the photoelectricity synergistic effect of the two materials.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.2;O646

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