磷酸铋基复合材料的制备及性能研究
发布时间：2018-10-30 11:01
【摘要】：近几年来,生态环境污染越来越严重,而传统的治理方法因其处理成本较高、周期长、效率低等缺点不能满足要求。半导体光催化剂因其在环境治理方面的优势引发了越来越多的关注。作为一种含氧酸盐催化剂,BiPO4展现出良好的光催化性能,然而其光响应范围位于紫外光区,光生电子-空穴对分离效率较低,故需要对BiPO4进行改性来提高它的催化性能,扩展光响应范围。本文中采用一步水热法合成的BiPO4纳米棒为基体,通过非金属元素掺杂、贵金属修饰、半导体复合等方法对BiPO4进行改性,结合一些测试手段,对材料的晶型、微观形貌、吸光性能进行表征,对材料的光电转化性能和体系中的光生电子-空穴对的分离效率和载流子的迁移速率进行测试分析,以甲基橙(MO)为模拟污染物,对材料的光催化性能进行测试。(1)以NaN3为N源,通过一步水热法合成了不同掺杂比的N掺杂BiPO4 (N-BiPO4)。利用第一性原理,对于样品的价带和导带的能带位置和电子态密度进行模拟计算。实验结果发现,BiPO4和N-BiPO4的晶型结构相同,N3-取代了BiPO4中的02-之后,材料的光吸收边际发生了微弱的红移,样品的形貌也发生了变化。在紫外光的照射下,与纯的BiPO4相比,N/Bi摩尔比为0.2的样品的催化效率提升了50%,原因归结为N3-的引入限制了光生电子和光生空穴的再复合,然而,过量的掺杂反而会降低样品的光催化活性。(2)在有机溶液C2H5OH中通过原位生长的方法合成了核壳结构Ag3PO4/N-BiPO4光催化剂,通过在模拟太阳光照射下降解MO的效率来评价样品的光催化效率,Ag3PO4/N-BiPO4在光照40min后降解了95%的污染物。体系中光催化活性的提高归因于N掺杂之后,引入的N-O杂质能级促进了电子-空穴对的分离效率。同时,Ag3PO4和N-BiPO4间经过原位反应之后生成的化学键,加速了电子-空穴对的分离速率。(3)以硫脲为前驱体制备出了g-C3N4,在不同的反应温度下通过三步反应法制备出了Z型g-C3N4/Au/BiPO4分层体系。通过降解MO,评价材料的光电性能和光催化性能。与g-C3N4、BiPO4和g-C3N4/BiPO4相比,样品g-C3N4/Au/BiPO4表现出了良好的光电化学性能和光催化性能。交流阻抗谱和光电流测试结果都证明了,g-C3N4/Au/BiPO4中的光电子分离速率和迁移速率较高。样品g-C3N4/Au/BiPO4性能的提升归因于体系中构造的Z型结构,在Z型体系中,经光照之后所产生的载流子的分离速率加快,阻止了光照后产生的电子和空穴的又一次结合。值得指出的是,Au颗粒不仅作为一种固态电介质,而且在光照下吸收光子发生等离子共振效应。(4)以Bi(NO3)3·5H2O为原料,采用水热法制备出P-N型Bi2O3/BiPO4异质结,再将g-C3N4包覆在其表面,形成g-C3N4/Bi203/BiP04材料体系,研究了样品BiPO4、g-C3N4/BiPO4、Bi2O3/BiPO4和g-C3N4/Bi2O3/BiPO4的光学性能、形貌和光电化学性能。在模拟太阳光照射160min后样品g-C3N4/Bi2O3/BiPO4的降解效率达到90%,远高于其他样品。交流阻抗谱和光电流测试结果都证明了,g-C3N4/Bi2O3/BiPO4中的光电子分离速率和迁移速率较高。总的来说,g-C3N4的加入,引领P型Bi2O3上剩余的电子与g-C3N4价带位置的光生空穴进行复合,留下氧化和还原能力更强的光生载流子促进活性基团的产生。
[Abstract]:In recent years, the ecological environment pollution is becoming more and more serious, and the traditional treatment method can not meet the requirements because of its high processing cost, long cycle and low efficiency. Semiconductor photocatalyst has attracted more and more attention because of its advantages in environmental governance. As a salt catalyst, BiPO4 exhibits good photocatalytic performance. However, the light response range is located in the ultraviolet region, and the light-generating electron-hole has lower separation efficiency. Therefore, BiPO4 needs to be modified to improve its catalytic performance and extend the light response range. BiPO4 nano-rod synthesized by one-step hydrothermal method is used as the substrate, and BiPO4 is modified by non-metal element doping, noble metal modification, semiconductor recombination and the like, and the crystal type, the micro-morphology and the light absorption performance of the material are characterized by combining with some testing methods. The photoelectric conversion performance of materials and the separation efficiency of the photogenic electron-hole pairs in the system and the migration rate of carriers were tested and analyzed, and the photocatalytic properties of the materials were tested with methyl orange (MO) as the simulated pollutant. (1) N-doped BiPO4 (N-BiPO4) with different doping ratios was synthesized by one-step hydrothermal method with NaN3 as N source. With the first principle, the energy band position and electron density of the valence band and conduction band of the sample are simulated. The experimental results show that the crystal structure of BiPO4 and N-BiPO4 is the same, N3-substituted for 02-in BiPO4, the light absorption margin of the material has changed slightly, and the morphology of the sample also changes. Under the irradiation of ultraviolet light, the catalytic efficiency of N/ Bi molar ratio of 0. 2 was increased by 50% as compared with pure BiPO4, because the introduction of N3-was restricted to recombination of light-generating electrons and light-generating holes, however, excessive doping would decrease the photocatalytic activity of samples. (2) The Ag3PO4/ N-BiPO4 photocatalyst of nuclear shell structure was synthesized by in situ growth method in the organic solution C2H5OH, and the photocatalytic efficiency of the sample was evaluated by simulating the efficiency of the degradation solution MO. Ag3PO4/ N-BiPO4 degraded 95% of the pollutants after illumination for 40min. The enhancement of photocatalytic activity in the system is due to N doping, and the introduced N-O impurity level promotes the separation efficiency of electron-hole pairs. Meanwhile, the chemical bonds generated after the in situ reaction between Ag3PO4 and N-BiPO4 accelerated the separation rate of electron-hole pairs. (3) The g-C3N4/ Au/ BiPO4 layered system was prepared by three-step reaction at different reaction temperatures. The photoelectric properties and photocatalytic properties of the materials were evaluated by degradation of MO. Compared with the g-C3N4, BiPO4 and g-C3N4/ BiPO4, the sample g-C3N4/ Au/ BiPO4 exhibited good photoelectrochemical performance and photocatalytic performance. The results of AC impedance spectroscopy and photocurrent measurements show that the photoelectron separation rate and migration rate in g-C3N4/ Au/ BiPO4 are high. The performance of the sample g-C3N4/ Au/ BiPO4 is attributed to the Z-type structure constructed in the system. In the Z-type system, the separation rate of carriers generated after illumination is accelerated, and the electrons and holes generated after illumination are prevented from being combined again. It is worth noting that Au particles not only act as a solid dielectric but also absorb photons under illumination to generate a plasma plume effect. (4) Bi (NO3) 3 路 5H2O was used as raw material, P-N Bi2O3/ BiPO4 heterojunction was prepared by hydrothermal method, and g-C3N4 was coated on its surface to form g-C3N4/ Bi203/ BiP04 material system. The optical properties, morphology and photoelectrochemical properties of BiPO4, g-C3N4/ BiPO4, Bi2O3/ BiPO4 and g-C3N4/ Bi2O3/ BiPO4 were studied. The degradation efficiency of g-C3N4/ Bi2O3/ BiPO4 was up to 90% after irradiation with simulated sunlight for 160min, much higher than that of other samples. The results of AC impedance spectroscopy and photocurrent tests show that the photoelectron separation rate and migration rate in g-C3N4/ Bi2O3/ BiPO4 are high. In general, the addition of the g-C3N4 leads to recombination of the remaining electrons on the P-type Bi2O3 with the light-generating holes in the valence band position of the g-C3N4, leaving more light-generating carriers with higher oxidation and reduction ability to promote the generation of the active groups.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O643.36;O644.1
本文编号：2299820
[Abstract]:In recent years, the ecological environment pollution is becoming more and more serious, and the traditional treatment method can not meet the requirements because of its high processing cost, long cycle and low efficiency. Semiconductor photocatalyst has attracted more and more attention because of its advantages in environmental governance. As a salt catalyst, BiPO4 exhibits good photocatalytic performance. However, the light response range is located in the ultraviolet region, and the light-generating electron-hole has lower separation efficiency. Therefore, BiPO4 needs to be modified to improve its catalytic performance and extend the light response range. BiPO4 nano-rod synthesized by one-step hydrothermal method is used as the substrate, and BiPO4 is modified by non-metal element doping, noble metal modification, semiconductor recombination and the like, and the crystal type, the micro-morphology and the light absorption performance of the material are characterized by combining with some testing methods. The photoelectric conversion performance of materials and the separation efficiency of the photogenic electron-hole pairs in the system and the migration rate of carriers were tested and analyzed, and the photocatalytic properties of the materials were tested with methyl orange (MO) as the simulated pollutant. (1) N-doped BiPO4 (N-BiPO4) with different doping ratios was synthesized by one-step hydrothermal method with NaN3 as N source. With the first principle, the energy band position and electron density of the valence band and conduction band of the sample are simulated. The experimental results show that the crystal structure of BiPO4 and N-BiPO4 is the same, N3-substituted for 02-in BiPO4, the light absorption margin of the material has changed slightly, and the morphology of the sample also changes. Under the irradiation of ultraviolet light, the catalytic efficiency of N/ Bi molar ratio of 0. 2 was increased by 50% as compared with pure BiPO4, because the introduction of N3-was restricted to recombination of light-generating electrons and light-generating holes, however, excessive doping would decrease the photocatalytic activity of samples. (2) The Ag3PO4/ N-BiPO4 photocatalyst of nuclear shell structure was synthesized by in situ growth method in the organic solution C2H5OH, and the photocatalytic efficiency of the sample was evaluated by simulating the efficiency of the degradation solution MO. Ag3PO4/ N-BiPO4 degraded 95% of the pollutants after illumination for 40min. The enhancement of photocatalytic activity in the system is due to N doping, and the introduced N-O impurity level promotes the separation efficiency of electron-hole pairs. Meanwhile, the chemical bonds generated after the in situ reaction between Ag3PO4 and N-BiPO4 accelerated the separation rate of electron-hole pairs. (3) The g-C3N4/ Au/ BiPO4 layered system was prepared by three-step reaction at different reaction temperatures. The photoelectric properties and photocatalytic properties of the materials were evaluated by degradation of MO. Compared with the g-C3N4, BiPO4 and g-C3N4/ BiPO4, the sample g-C3N4/ Au/ BiPO4 exhibited good photoelectrochemical performance and photocatalytic performance. The results of AC impedance spectroscopy and photocurrent measurements show that the photoelectron separation rate and migration rate in g-C3N4/ Au/ BiPO4 are high. The performance of the sample g-C3N4/ Au/ BiPO4 is attributed to the Z-type structure constructed in the system. In the Z-type system, the separation rate of carriers generated after illumination is accelerated, and the electrons and holes generated after illumination are prevented from being combined again. It is worth noting that Au particles not only act as a solid dielectric but also absorb photons under illumination to generate a plasma plume effect. (4) Bi (NO3) 3 路 5H2O was used as raw material, P-N Bi2O3/ BiPO4 heterojunction was prepared by hydrothermal method, and g-C3N4 was coated on its surface to form g-C3N4/ Bi203/ BiP04 material system. The optical properties, morphology and photoelectrochemical properties of BiPO4, g-C3N4/ BiPO4, Bi2O3/ BiPO4 and g-C3N4/ Bi2O3/ BiPO4 were studied. The degradation efficiency of g-C3N4/ Bi2O3/ BiPO4 was up to 90% after irradiation with simulated sunlight for 160min, much higher than that of other samples. The results of AC impedance spectroscopy and photocurrent tests show that the photoelectron separation rate and migration rate in g-C3N4/ Bi2O3/ BiPO4 are high. In general, the addition of the g-C3N4 leads to recombination of the remaining electrons on the P-type Bi2O3 with the light-generating holes in the valence band position of the g-C3N4, leaving more light-generating carriers with higher oxidation and reduction ability to promote the generation of the active groups.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O643.36;O644.1
【相似文献】
相关期刊论文 前5条
1 ;过程工程所等金属-半导体复合物核壳纳米结构研究获进展[J];人工晶体学报;2013年11期
2 谢普会,曹怡,张宝文;有机-无机半导体复合体系中光诱导电子转移及光电转换性质的研究[J];感光科学与光化学;2000年03期
3 孙益民;;n型TiO_2-Ni半导体复合光电极的制备与研究[J];河南科学;1985年01期
4 郑禾;钟近艺;韩世同;陈新启;闵崎;;LaVO_4/TiO_2光催化复合材料对芥子气模拟剂2-氯乙基乙基硫醚的降解性能[J];环境化学;2014年06期
5 ;[J];;年期
相关会议论文 前3条
1 余家国;向全军;马婷婷;李覃;;碳/半导体复合光催化材料的制备与光催化性能增强[A];第六届全国环境化学大会暨环境科学仪器与分析仪器展览会摘要集[C];2011年
2 王利利;熊宇杰;;用于光解水的金属-半导体复合结构设计中的晶面效应[A];中国化学会第29届学术年会摘要集——第21分会：光化学[C];2014年
3 刘春艳;;金属与半导体复合纳微米材料结构与性能研究[A];纳米材料和技术应用进展——全国第三届纳米材料和技术应用会议论文集（下卷）[C];2003年
相关重要报纸文章 前1条
1 ;科学家发现半导体复合材料的光伏极性可被改变[N];中国有色金属报;2003年
相关博士学位论文 前1条
1 蔡倩;贵金属/半导体复合物：表面增强光谱基底和原位监测[D];苏州大学;2015年
相关硕士学位论文 前2条
1 单姝;基于功能化纳米半导体复合物的光电化学生物传感研究[D];南京大学;2014年
2 袁欢;磷酸铋基复合材料的制备及性能研究[D];陕西科技大学;2016年
，本文编号：2299820
本文链接：https://www.wllwen.com/kejilunwen/huaxue/2299820.html
教材专著
