钴铝类水滑石复合材料的制备及其光催化性能

发布时间：2017-12-26 16:19

  本文关键词：钴铝类水滑石复合材料的制备及其光催化性能　出处：《华侨大学》2016年硕士论文　论文类型：学位论文

  更多相关文章： 钴铝水滑石 剥离 重组 硫化镉 钛铌酸 三钛酸 可见光催化

【摘要】：随着解决环境污染日益迫切的需求,半导体光催化降解技术受到了人们广泛的关注。然而,低的量子效率和太阳能利用率等因素制约了多数半导体的光催化应用。因此,设计合成新型高效光催化材料仍是当前研究的重点。具有光催化活性的层状化合物可剥离为二维纳米片层,作为构筑基元与各种客体形成复合异质结,能够有效地拓展材料的光谱响应范围,抑制载流子的快速复合,提高材料的光催化效率,因此广泛应用于半导体光催化领域。钴铝水滑石(Co Al-LDH)是一种阴离子型层状化合物,可剥离为带正电荷的纳米片层,能够与其它合适的半导体复合,具有较高的可见光催化活性。本文选用Co Al-LDH为研究对象,采用剥离 重组法,将带正电的LDHs纳米片层分别与带负电的Cd S纳米颗粒、Ti Nb O5-纳米片层和Ti3O72-纳米片层复合,利用静电作用自组装构筑了介孔复合材料。采用XRD,SEM,TEM,PL,UV-vis DRS,XPS,N2等温吸附 脱附曲线及光电化学测试等多种手段对材料进行了表征,通过测定材料在可见光下对目标污染物的降解效率来评价光催化活性,并研究了相应的光催化作用机制。(1)Cd S/Co Al-LDH柱撑复合材料的制备与表征。将剥离的LDHs片层与Cd S颗粒溶胶混合,制备出Cd S柱撑的Cd S/Co Al-LDH复合材料。该材料为介孔结构,比表面积为62 m2·g-1,层间通道高度2.14 nm。在可见光照射下,复合材料对酸性红染料具有较高的催化活性,180 min内降解90%,是Co Al-LDH和Cd S的2倍多。同时,复合材料展现出良好的光催化循环稳定性。(2)Co Al-Ti Nb O5间层复合材料的制备与表征。以窄带隙半导体Co Al-LDH和宽带隙半导体HTi Nb O5剥离的纳米片层作为构筑基元,形成了片层相间堆积的复合材料。该材料为多级介孔结构,比表面积增大为46 m2·g-1,两组分间紧密接触,具有较强的电子耦合效应,拓宽了光响应范围,加速了载流子的传导分离。Co Al-Ti Nb O5复合材料对酸性红染料的催化活性分别是Co Al-LDH和HTi Nb O5的3.2倍和17.8倍,光催化循环稳定性良好。(3)Co Al-Ti3O7间层复合材料的制备与表征。Co Al-LDH和H2Ti3O7纳米片层静电作用自组装得到Co Al-Ti3O7复合材料,两组分紧密结合,无序堆积形成类卡片房式结构,孔径出现多级分布,比表面积增大为67 m2·g-1。在增大的比表面积和两者形成的Z型异质结协同效应下,Co Al-Ti3O7复合材料对罗丹明B的可见光催化降解效率分别是Co Al-LDH和H2Ti3O7的6.6倍和3.8倍,表现出较好的光催化循环稳定性。
[Abstract]:With the increasing demand for environmental pollution, the photocatalytic degradation technology of semiconductor has attracted wide attention. However, the low quantum efficiency and the utilization of solar energy have restricted the photocatalytic application of most semiconductors. Therefore, the design and synthesis of novel high photocatalytic materials are still the focus of current research. Layered compounds with photocatalytic activity can be stripped for two-dimensional nano sheets as building elements and objects to form a composite heterojunction, can effectively expand the material spectral response range, suppression of carrier fast composite, improve the photocatalytic efficiency of materials, so it is widely used in the field of semiconductor photocatalysis. Cobalt aluminum hydrotalcite (Co Al-LDH) is an anionic layered compound, which can be stripped to a positively charged nanoscale layer. It can be combined with other suitable semiconductors and has high visible light photocatalytic activity. In this paper, Co Al-LDH is chosen as the research object. The LDHs Nanoplates with positive electricity are combined with negatively charged Cd S nanoparticles, Ti Nb O5- nanosheets and Ti3O72- nanosheets, respectively. The mesoporous composites are fabricated by electrostatic interaction. Using XRD, SEM, TEM, PL, UV-vis, DRS, XPS, N2 adsorption desorption curves and photoelectric chemical testing and other means of materials were characterized, the photocatalytic activity was evaluated by measuring the material degradation efficiency of target pollutants under visible light, and the photocatalytic mechanism of the corresponding. (1) preparation and characterization of Cd S/Co Al-LDH pillared composites. The Cd S pillared Cd S/Co Al-LDH composite was prepared by mixing the stripped LDHs layer with the Cd S granular sol. The material is mesoporous structure with a specific surface area of 62 m2. G-1, and the height of interlaminar channel is 2.14 nm. Under the light of visible light, the composite has high catalytic activity for acid red dye and 90% in 180 min, which is more than 2 times as much as Co Al-LDH and Cd S. At the same time, the composite exhibits good stability of the photocatalytic cycle. (2) preparation and characterization of Co Al-Ti Nb O5 interlayer composites. Nanoscale lamellae stripped with narrow band gap semiconductor Co Al-LDH and broadband gap semiconductor HTi Nb O5 are used as the construction elements to form a composite material that is stacked interphase. The material is multi-stage mesoporous structure with the specific surface area increased to 46 m2. G-1. The two components are closely contacted, which has strong electronic coupling effect. It broadens the light response range and accelerates the conduction and separation of carriers. The catalytic activity of Co Al-Ti Nb O5 composite for acid red dye is 3.2 times and 17.8 times as much as Co Al-LDH and HTi Nb O5, and the stability of the photocatalytic cycle is good. (3) preparation and characterization of Co Al-Ti3O7 interlayer composites. Co Al-LDH and H2Ti3O7 nanoscale layers were self assembled to achieve Co Al-Ti3O7 composites. The two components were closely combined, forming a card like room structure with disorder stacking. The pore size was distributed at multiple levels, and the specific surface area increased to 67 m2 / g-1. Under the synergistic effect of the increased specific surface area and the Z heterojunction formed by them, the visible light photocatalytic degradation efficiency of Co Al-Ti3O7 composite for rhodamine B is 6.6 times and 3.8 times of that of Co Al-LDH and H2Ti3O7, showing better photocatalytic cycle stability.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O643.36
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本文编号：1337958