钛基石墨烯光催化气态汞的理论研究
发布时间：2019-05-18 14:04
【摘要】：光催化是光和物质相互作用的重要表现形式之一,是指发生在材料和表面吸附物之间的光反应和催化反应的复杂过程。最常用的半导体催化剂是TiO_2,但是TiO_2的禁带宽度较大,使得光催化氧化只能在紫外光环境下进行反应。目前工作的重点是对TiO_2进行改性,使其在可见光下也能有较好的光催化效果。国内外对TiO_2的改性研究已经取得了很大的进展,石墨烯作为辅助光催化材料近年来也得到广泛的关注,但是对其物理机理的研究还不够深入。为此,本文基于密度泛函理论,针对钛基石墨烯材料光催化氧化气态汞的反应机理进行深入研究。首先,建立锐钛矿相TiO_2的晶体模型,基于密度泛函理论,采用从头计算法计算锐钛矿相TiO_2的能带结构和电子态密度。基于上述模型构建锐钛矿相TiO_2热力学最稳定面(101)晶面,研究在该晶面分别掺杂N和Eu元素对能带结构和电子态密度的影响,揭示该掺杂对光催化性能的影响的物理机制。其次,构建石墨烯掺杂锐钛矿相TiO_2模型,在TiO_2(101)面上覆盖单层石墨烯材料,并分别利用第一动力学原理和第一性原理对该模型进行几何优化,计算优化完成模型的能带结构和电子态密度,说明石墨烯掺杂钛基材料光催化性能改善的物理机制;在上述模型的基础之上,构建N、Eu和石墨烯混掺钛基材料,研究N和Eu的掺杂对Gr/TiO_2能带结构的影响。结果表明混掺情况下材料的光催化活性最高。最后,为验证上述计算结果的准确性,利用水热反应法制备锐钛矿相TiO_2,调节制备条件,使材料主要暴露面为(101)晶面。对制备完成的材料进行SEM、XRD、UV-Vis和BET表征。同时,利用曲面积分法探究不同掺杂对光催化脱汞性能的影响,进一步证明上述模型计算结果的正确性,并确定材料的最佳制备条件。通过计算材料的结果和实验结果进行对比,成功验证计算结果的可靠性,为钛基材料改性的理论研究提供了支持。
[Abstract]:Photocatalysis is one of the important forms of interaction between light and matter, which refers to the complex process of photoreaction and catalytic reaction between material and surface adsorbents. The most commonly used semiconductor catalyst is TiO_2, but the band gap of TiO_2 is large, so that photocatalytic oxidation can only react in UV environment. At present, the focus of the work is to modify TiO_2 so that it can also have a good photocatalytic effect under visible light. Great progress has been made in the modification of TiO_2 at home and abroad. Graphene as an auxiliary photocatalysis material has also received extensive attention in recent years, but the physical mechanism of graphene is not deep enough. In this paper, based on density functional theory (DFT), the mechanism of photocatalytic oxidation of gaseous mercury by graphene, the cornerstone of titanium, was studied. Firstly, the crystal model of anatase phase TiO_2 is established. Based on density functional theory, the band structure and electronic state density of anatase phase TiO_2 are calculated by ab initio method. Based on the above model, the thermodynamic most stable surface of anatase phase TiO_2 was constructed, and the effects of N and Eu elements on the energy band structure and electronic state density were studied. The physical mechanism of the effect of the doping on the photocatalytic performance was revealed. Secondly, the graphene-doped anatase phase TiO_2 model is constructed, and the monolayer graphene material is covered on the TiO_2 surface, and the geometric optimization of the model is carried out by using the first kinetic principle and the first principle, respectively. The energy band structure and electronic state density of the model are calculated and optimized, which shows the physical mechanism of improving the photocatalytic performance of graphene-doped titanium-based materials. On the basis of the above model, N, EU and graphene mixed titanium-based materials were constructed, and the effect of N and Eu doping on the energy band structure of Gr/TiO_2 was studied. The results show that the photocatalytic activity of the material is the highest under the condition of mixing. Finally, in order to verify the accuracy of the above calculation results, anatase phase TiO_2, was prepared by hydrothermal reaction method to adjust the preparation conditions, so that the main appearance of the material was (101) crystal plane. The prepared materials were characterized by SEM,XRD,UV-Vis and BET. At the same time, the effect of different doping on photocatalytic mercury removal performance was studied by surface integration method, which further proved the correctness of the calculated results of the above model, and determined the optimum preparation conditions of the material. By comparing the calculated results with the experimental results, the reliability of the calculated results is successfully verified, which provides support for the theoretical study of the modification of titanium-based materials.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.3
本文编号：2480068
[Abstract]:Photocatalysis is one of the important forms of interaction between light and matter, which refers to the complex process of photoreaction and catalytic reaction between material and surface adsorbents. The most commonly used semiconductor catalyst is TiO_2, but the band gap of TiO_2 is large, so that photocatalytic oxidation can only react in UV environment. At present, the focus of the work is to modify TiO_2 so that it can also have a good photocatalytic effect under visible light. Great progress has been made in the modification of TiO_2 at home and abroad. Graphene as an auxiliary photocatalysis material has also received extensive attention in recent years, but the physical mechanism of graphene is not deep enough. In this paper, based on density functional theory (DFT), the mechanism of photocatalytic oxidation of gaseous mercury by graphene, the cornerstone of titanium, was studied. Firstly, the crystal model of anatase phase TiO_2 is established. Based on density functional theory, the band structure and electronic state density of anatase phase TiO_2 are calculated by ab initio method. Based on the above model, the thermodynamic most stable surface of anatase phase TiO_2 was constructed, and the effects of N and Eu elements on the energy band structure and electronic state density were studied. The physical mechanism of the effect of the doping on the photocatalytic performance was revealed. Secondly, the graphene-doped anatase phase TiO_2 model is constructed, and the monolayer graphene material is covered on the TiO_2 surface, and the geometric optimization of the model is carried out by using the first kinetic principle and the first principle, respectively. The energy band structure and electronic state density of the model are calculated and optimized, which shows the physical mechanism of improving the photocatalytic performance of graphene-doped titanium-based materials. On the basis of the above model, N, EU and graphene mixed titanium-based materials were constructed, and the effect of N and Eu doping on the energy band structure of Gr/TiO_2 was studied. The results show that the photocatalytic activity of the material is the highest under the condition of mixing. Finally, in order to verify the accuracy of the above calculation results, anatase phase TiO_2, was prepared by hydrothermal reaction method to adjust the preparation conditions, so that the main appearance of the material was (101) crystal plane. The prepared materials were characterized by SEM,XRD,UV-Vis and BET. At the same time, the effect of different doping on photocatalytic mercury removal performance was studied by surface integration method, which further proved the correctness of the calculated results of the above model, and determined the optimum preparation conditions of the material. By comparing the calculated results with the experimental results, the reliability of the calculated results is successfully verified, which provides support for the theoretical study of the modification of titanium-based materials.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.3
【参考文献】
相关期刊论文 前1条
1 吕维阳;刘盛余;能子礼超;汪雪婷;吴萧;;载硫活性炭脱除天然气中单质汞的研究[J];中国环境科学;2016年02期
相关博士学位论文 前4条
1 侯文慧;模拟煤气条件下金属氧化物吸附脱除单质汞的机理研究[D];浙江大学;2015年
2 谭增强;改性竹炭基吸附剂脱汞的实验及机理研究[D];华中科技大学;2012年
3 丁峰;矿物吸附剂对燃煤烟气中汞的脱除机制的研究[D];华中科技大学;2012年
4 张安超;改性壳聚糖吸附剂脱除烟气中汞的实验与机理研究[D];华中科技大学;2010年
相关硕士学位论文 前8条
1 耿璐;基于密度泛函理论研究Pd和Pd/γ-Al_2O_3上汞的吸附性能[D];太原理工大学;2015年
2 沈彩琴;活性炭纤维表面吸附汞机理的密度泛函理论研究[D];浙江工业大学;2015年
3 车宇;V_2O_5/TiO_2催化剂载体晶面对汞氧化性能的影响机理研究[D];浙江大学;2015年
4 杨振美;非金属改性TiO_2光催化氧化脱除烟气中零价汞的实验研究[D];浙江大学;2014年
5 钟隆春;燃煤电厂飞灰汞吸附性能评价及其机理研究[D];华北电力大学;2014年
6 牛晓琦;煤气和燃煤烟气中铁基氧化物脱汞机理研究[D];太原理工大学;2014年
7 翟影;密度泛函理论研究锐钛矿晶体掺杂以及锐钛矿TiO_2（101）表面对氨基酸吸附[D];中国海洋大学;2013年
8 徐天华;计算机模拟方法在TiO_2掺杂研究中的应用[D];浙江大学;2006年
，本文编号：2480068
本文链接：https://www.wllwen.com/kejilunwen/huaxue/2480068.html
教材专著
