【作者】 贾永芳；

【导师】 赵勇； 杨峰；

【作者基本信息】 西南交通大学 ， 凝聚态物理， 2013， 硕士

【摘要】 Ti02作为一种重要的无机半导体功能材料,具有无毒、化学稳定性良好、成本低、光催化活性高等优势,在光催化分解水制氢方面有着相当大的应用潜力。纳米管阵列结构相对于其他形态的TiO2纳米材料,有着高度有序的阵列结构、更大的比表面积、高效的电子传输等优势,引起了人们广泛的重视。Nb205也是一种重要的半导体功能材料,与Ti02相比有着更负的导带边,有望获得更高的开路电压和光电转化效率。但是ZiO2／Nb205均属于宽禁带半导体,仅能吸收太阳能光中的紫外光部分,而紫外光仅占太阳光的5%,如何能拓宽两者对太阳光的吸收范围,进一步提高其的光催化能力。依据与窄禁带半导体复合可以有效的拓宽宽禁带半导体的光响应范围,我们选择SnS作为窄禁带半导体复合材料与Ti02纳米管和Nb205纳米棒进行复合。SnS作为一种重要的p型半导体材料,禁带宽度为1.32eV,对可见光有较强的吸收能力,是一种很重要的光吸收材料。在本文中,采用连续离子层吸附反应法制备出SnS/TiO2纳米管复合材料,并对复合结构进行了表面光电压谱、I-V曲线等测试,并且发现复合结构较单纯的Ti02纳米管阵列光吸收范围得到了提高,光电转化效率达到了0.75%,并且还进一步分析了SnS/TiO2异质结结构中的电荷转移机制。通过对循环次数的控制,得到不同循环次数下SnS与TiO2(?)内米管阵列的复合结构,并讨论了循环次数对SnS/TiO2异质结复合结构形貌和光电性能的影响,结果显示循环次数为10次时,光电转化效率为最高的。在制备SnS/Nb2O5纳米棒复合材料之前,首先将不同形貌Nb2O5纳米粉体材料在正、负电场作用下的光伏响应情况进行了分析,发现类片状Nb2O5纳米粉体材料有着较高的表面光电压响应强度,究其原因应该得益于其有利的电子传输。除了对其粉体材料的研究外,利用操作简便地水热法成功地制备出Nb2O5纳米棒状结构,同样是由于其较宽的禁带宽度(Eg=3.4eV),我们采取了连续离子层吸附反应法制备得到了SnS/Nb2O5纳米棒复合阵列材料,以拓宽其的光响应范围,并对SnS/Nb2O5纳米棒复合阵列材料的形貌和光电化学性能进行了分析,结果发现复合结构较纯的Nb205纳米棒结构有着更高的短路电流和光电转化效率。更多还原

【Abstract】 Titanium dioxide(TiO2) is an inorganic functional semiconductor materials,widely used as photocatalyst because of its non-toxicity,high chemical stability, high photocatalytic activity and low cost.Among all of the TiO2nanomaterials, TiO2nanotube arrays prepared by electrochemical anodization of titanium has attracted great attention due to their advantages of highly ordered array structure, the larger specific surface area and efficient electron transport. Niobium oxide (Nb2O5), an important functiona semiconductor materials, has a higher conduction band edge than TiO2, and therefore, it is possible to attain higher open circuit voltage and photo-conversion efficiency (η). Both TiO2and Nb2O5are wide gap semiconductors and efficiently absorb only a very small UV part (approximately5%) of solar light. Coupling TiO2nanotube and Nb2O5nanorod with low-band-gap is an efficient way to extend the range of light response. Tin suifide (SnS) was choosed as the narrow-band-gap semiconductor.It is a candidate for the absorber materials because there are many advantages of SnS such as proper bangdgap (1.32eV),high absorption coefficient in the visible solar spectrum.In this article, SnS/TiO2nannotube arrays composite materials were prepared through a successive ionic layer adsorption and reaction process.The photoelectrochemical property and surface photovoltaic response of the SnS/TiO2nanotube arrays composites have been improved due to the enhanced electron-hole separation that because heterojunctions between SnS and TiO2could provide the driving force. SnS/TiO2heteroj unction nanotube arrays with different deposition cycles were elevated in terms of morphology and photoelectrochemical property of the composites. Ultimately the optimum number of cycles was obtained.Before the preparation of surface SnS/Nb2O5nanorodcompositis,filed-induced photovoltage response of the different morphology of Nb2O5nano-powder under the positive and negative external electric field was analyzed. These flake-like structures Nb2O5nano-powder demonstrated higher surface photovoltage response due to its advantages of electronic transmission. In addition,Nb2O5nanorods were also prepared by using the niobium foil as a precursor via hydrothermal method. In view of its wide band gap (Eg=3.4eV), SnS nanoparticles was used to sensitize Nb2O5nanorods to improve the optical absorption property.The SnS/Nb2O5nanorod composites with the successive ionic layer adsorption and reaction process were obtained. Then the morphology and photoelectrochemical properties of the composites were analyzed and discussed, and found that the composite structure has a higher short-circuit current and photoelectric conversion efficiency than pure Nb2O5nanorod structure.更多还原