磷酸铋基光催化材料的制备与性能研究
发布时间：2018-08-15 18:14
【摘要】：磷酸铋是一种n型宽^/隙半导体材料,电子结构独特,^/隙宽在3.85 eV左右,对太阳光的响应在紫外线范围内,其催化反应性能稳定。对磷酸铋的研究虽然已取得了一些成果,但还有很多不完善的地方。基于此,本文对磷酸铋及其异质结构的制备和性能进行了深入探讨,并进行了计算机模拟研究。(1)采用直接沉淀法、水热法和二元溶剂热法合成了不同形貌的磷酸铋,通过沉淀转化法制备了纳米氧化铜,通过葡萄糖还原法制备了微米级氧化亚铜。采用室温固相反应和水热法合成了BiPO4/CuO和BiPO4/Cu2O异质结构材料,通过对比各样品降解甲基橙的速率分析了各样品催化活性的高低。(2)通过X射线衍射(XRD)确定了样品的晶体结构,对样品粒径和结晶度进行了粗略估计,通过晶面指数、衍射角和相关计算公式判断材料的吸收波长。在透射电镜下观察样品形貌,通过样品分散性、形貌、颗粒尺寸的比较及电子能谱EDS分析其催化性能变化的原因,得出六方相磷酸铋的催化活性低于单斜相磷酸铋,甘油含量的增加会对颗粒表面有包覆作用,阻止晶粒的结晶成长,有利于减小颗粒尺寸;纳米粒子的小尺寸效应和表面效应会增大材料的禁带宽度,但同时增大了表面反应活性中心的范围,提高了催化过程的稳定性。BiPO4/CuO异质结的形成有利于催化性能的提高,但一价铜离子掺杂替换磷酸铋晶格中的原子会使催化活性降低。(3)采用MS中CASTEP软件包对材料的能带以及电子态密度进行计算。利用第一性原理对磷酸铋晶体模型进行了计算,坐标参数来源于Findit软件,计算得到的磷酸铋禁带宽度为3.814 eV,与文献结果一致;对氧化铜和氧化亚铜标准晶体结构进行了计算,模型取自于Materials Studio的标准库。采用广义梯度近似对晶体结构进行几何优化后,采用局域密度近似对优化后的结构进行能带结构、态密度等能量计算,都分别得到了与文献中一致的结果。在MS中模拟金属铜离子掺杂磷酸铋,对异质结中发生掺杂的情况进行能量计算,结果表明铜离子进入磷酸铋晶体结构中后,会降低磷酸铋的禁带宽度。
[Abstract]:Bismuth phosphate is a kind of n-type wide ^ / gap semiconductor material with unique electronic structure, ^ / gap width of about 3.85 EV. The response of bismuth phosphate to solar light is in the range of ultraviolet light, and its catalytic reaction performance is stable. Although some achievements have been made on bismuth phosphate, there are still many imperfections. In this paper, the preparation and properties of bismuth phosphate and its heterostructure are discussed, and the computer simulation is carried out. (1) bismuth phosphate with different morphologies has been synthesized by direct precipitation, hydrothermal and binary solvothermal methods. Nanocrystalline copper oxide was prepared by precipitation conversion method and micron copper oxide was prepared by glucose reduction method. BiPO4/CuO and BiPO4/Cu2O heterostructure materials were synthesized by solid state reaction at room temperature and hydrothermal method. The catalytic activity of each sample was analyzed by comparing the degradation rate of methyl orange. (2) the crystal structure of the samples was determined by X-ray diffraction (XRD). The particle size and crystallinity of the sample were roughly estimated, and the absorption wavelength of the material was determined by the crystal plane index, diffraction angle and correlation formula. The morphology of the samples was observed under transmission electron microscope. The results showed that the catalytic activity of hexagonal bismuth phosphate was lower than that of monoclinic bismuth phosphate. The increase of glycerol content will cover the grain surface, prevent the crystal growth, and decrease the particle size, and the small size effect and surface effect of nano-particles will increase the band gap of the material. But at the same time, the range of the active center of the surface reaction was increased, and the stability of the catalytic process was improved. The formation of BiPO _ 4 / CuO heterojunction was beneficial to the improvement of the catalytic performance. However, substitution of atoms in bismuth phosphate lattice by doping of monovalent copper ions will decrease the catalytic activity. (3) the energy bands and the electronic density of states of the materials are calculated by CASTEP software package in MS. The crystal model of bismuth phosphate is calculated by first principle. The coordinate parameters are derived from Findit software. The calculated bandgap of bismuth phosphate is 3.814 EV, which is in agreement with the results in literature, and the crystal structures of copper oxide and copper oxide are calculated. The model is taken from the standard library of Materials Studio. After geometric optimization of crystal structure by generalized gradient approximation, the energy of the optimized structure is calculated by using local density approximation. The results are in agreement with those obtained in the literature. The energy calculation of the doping of bismuth phosphate in heterojunction by simulated metal copper ion doping in MS shows that the band gap of bismuth phosphate decreases when copper ions enter the crystal structure of bismuth phosphate.
【学位授予单位】：石家庄铁道大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ135.32;O643.36
[Abstract]:Bismuth phosphate is a kind of n-type wide ^ / gap semiconductor material with unique electronic structure, ^ / gap width of about 3.85 EV. The response of bismuth phosphate to solar light is in the range of ultraviolet light, and its catalytic reaction performance is stable. Although some achievements have been made on bismuth phosphate, there are still many imperfections. In this paper, the preparation and properties of bismuth phosphate and its heterostructure are discussed, and the computer simulation is carried out. (1) bismuth phosphate with different morphologies has been synthesized by direct precipitation, hydrothermal and binary solvothermal methods. Nanocrystalline copper oxide was prepared by precipitation conversion method and micron copper oxide was prepared by glucose reduction method. BiPO4/CuO and BiPO4/Cu2O heterostructure materials were synthesized by solid state reaction at room temperature and hydrothermal method. The catalytic activity of each sample was analyzed by comparing the degradation rate of methyl orange. (2) the crystal structure of the samples was determined by X-ray diffraction (XRD). The particle size and crystallinity of the sample were roughly estimated, and the absorption wavelength of the material was determined by the crystal plane index, diffraction angle and correlation formula. The morphology of the samples was observed under transmission electron microscope. The results showed that the catalytic activity of hexagonal bismuth phosphate was lower than that of monoclinic bismuth phosphate. The increase of glycerol content will cover the grain surface, prevent the crystal growth, and decrease the particle size, and the small size effect and surface effect of nano-particles will increase the band gap of the material. But at the same time, the range of the active center of the surface reaction was increased, and the stability of the catalytic process was improved. The formation of BiPO _ 4 / CuO heterojunction was beneficial to the improvement of the catalytic performance. However, substitution of atoms in bismuth phosphate lattice by doping of monovalent copper ions will decrease the catalytic activity. (3) the energy bands and the electronic density of states of the materials are calculated by CASTEP software package in MS. The crystal model of bismuth phosphate is calculated by first principle. The coordinate parameters are derived from Findit software. The calculated bandgap of bismuth phosphate is 3.814 EV, which is in agreement with the results in literature, and the crystal structures of copper oxide and copper oxide are calculated. The model is taken from the standard library of Materials Studio. After geometric optimization of crystal structure by generalized gradient approximation, the energy of the optimized structure is calculated by using local density approximation. The results are in agreement with those obtained in the literature. The energy calculation of the doping of bismuth phosphate in heterojunction by simulated metal copper ion doping in MS shows that the band gap of bismuth phosphate decreases when copper ions enter the crystal structure of bismuth phosphate.
【学位授予单位】：石家庄铁道大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ135.32;O643.36
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