不同形貌铌酸钾功能组装体的制备及其性能研究

发布时间：2018-10-12 21:43

【摘要】：通过半导体光催化还原水制氢,将太阳能转化为清洁、可再生的氢能,已经成为目前光催化领域的研究热点。铌酸钾是一种稳定、廉价,形貌可调、易于被改性的半导体,在光催化还原水制氢和传感等领域有潜在的应用前景。本文首先以还原氧化石墨烯替代贵金属Pt作为助催化剂,与不同形貌的铌酸钾组装制备得到了多种光催化剂,进而研究其在光催化还原水制氢中的活性、稳定性及电子转移机制。其次,组装了层数可控、有序的铌酸钾纳米片/Ag20复合膜,研究其对低浓度结晶紫的拉曼响应及作用机理。主要研究内容如下：通过在铌酸钾纳米片卷曲过程中插入还原氧化石墨烯(RGO),制备得到了一种新型的RGO/铌酸钾复合纳米轴。通过XRD、TEM、固体紫外-可见漫反射光谱表征了铌酸钾/RGO复合纳米轴的结构、形貌与光学特性。对比研究了铌酸钾/RGO复合纳米轴在紫外光照射下的光催化还原水制氢活性。研究结果表明：复合少量的RGO(2%)即能使铌酸钾纳米轴的光催化制氢量提高3.1倍,而且性能稳定。通过荧光光谱和交流阻抗图谱说明RGO的引入能有效提高铌酸钾纳米轴的光生电子和空穴的分离效率,这是RGO/铌酸钾复合纳米轴具有较高光催化制氢活性的主要原因。在室温下混合、搅拌还原氧化石墨烯和铌酸钾微球制备得到了一种核壳结构的还原氧化石墨烯／铌酸钾复合微球光催化剂。通过XRD、SEM、固体紫外-可见漫反射光谱、荧光光谱和交流阻抗图谱等手段研究了所得产物的组成、形貌与电子转移。由于还原氧化石墨烯作为助催化剂,能够及时将光生电子转移,从而避免了与空穴复合,所以,还原氧化石墨烯／铌酸钾复合微球在紫外光照射下表现出比纯铌酸钾微球和P25 TiO2更高的还原水制氢活性。此外,我们研究了氧化石墨烯-铌酸钾复合微球在紫外光照射下的还原水制氢的循环使用稳定性,结果表明,还原氧化石墨烯／铌酸钾复合微球经六次循环使用后其还原水制氢活性基本不变,说明还原氧化石墨烯／铌酸钾复合微球是一种廉价、易得、光催化制氢活性高、稳定的光催化剂。通过层层自组装技术并结合紫外光原位还原法制备了一种形貌规整、有序的铌酸钾纳米片/氧化银复合膜。通过XRD、SEM、XPS等多种手段对复合膜的组成、结晶性和形貌等进行了表征。以铌酸钾纳米片／纳米氧化银复合膜为活性基底,通过表面增强拉曼散射光谱研究了其对低浓度结晶紫的检测。研究结果显示,铌酸钾纳米片／纳米氧化银复合膜能快速、高效地检测低浓度的结晶紫,而复合膜中纳米氧化银与铌酸钾纳米片之间快速的电子转移是其实现低浓度结晶紫检测的关键。
[Abstract]:The conversion of solar energy to clean and renewable hydrogen energy by photocatalytic reduction of water to hydrogen has become a hot spot in the field of photocatalysis. Potassium niobate is a stable, cheap, adjustable and easily modified semiconductor, which has potential applications in photocatalytic reduction of water for hydrogen production and sensing. In this paper, a variety of photocatalysts were prepared by using reductive graphene instead of noble metal Pt as co-catalysts and assembled with potassium niobate with different morphologies, and their activity in photocatalytic reduction of water for hydrogen production was studied. Stability and electron transfer mechanism. Secondly, the layered and ordered potassium niobate / Ag20 composite films were assembled and their Raman response to low concentration crystal violet was studied. The main research contents are as follows: a novel RGO/ potassium niobate composite nano-axis was prepared by inserting reduced graphene oxide (RGO),) in the crimp process of potassium niobate nanoparticles. The structure, morphology and optical properties of potassium niobate / RGO composite nano-axis were characterized by XRD,TEM, solid-state UV-Vis diffuse reflectance spectroscopy. The photocatalytic reduction activity of potassium niobate / RGO nanoaxis for hydrogen production from water under UV irradiation was studied. The results show that the photocatalytic hydrogen production of potassium niobate nanoaxis can be increased by 3.1 times with a small amount of RGO (2%), and the performance is stable. Fluorescence spectra and AC impedance spectra show that the introduction of RGO can effectively improve the separation efficiency of photogenerated electrons and holes in the potassium niobate nanoaxis, which is the main reason for the high photocatalytic activity of RGO/ potassium niobate nanoaxis. A core-shell structure photocatalyst of reduced graphene / potassium niobate composite microspheres was prepared by mixing graphene oxide and potassium niobate microspheres at room temperature. The composition, morphology and electron transfer of the products were studied by means of XRD,SEM, solid-state UV-Vis diffuse reflectance spectroscopy, fluorescence spectra and AC impedance spectroscopy. Because the reduced graphene oxide acts as a co-catalyst, it can transfer photogenerated electrons in time, thus avoiding the recombination with the hole, so, The redox graphene / potassium niobate composite microspheres exhibit higher hydrogen production activity under UV irradiation than pure potassium niobate microspheres and P25 TiO2. In addition, the stability of hydrogen production by reducing water with graphene oxide and potassium niobate composite microspheres under UV irradiation was studied. The redox graphene / potassium niobate composite microspheres had almost no change in hydrogen production activity after six cycles, which indicated that the reduced graphene / potassium niobate composite microspheres were cheap, easy to obtain and high in photocatalytic hydrogen production. A stable photocatalyst. A structured and ordered potassium niobate / silver oxide composite film was prepared by layer-by-layer self-assembly technique and UV in-situ reduction method. The composition, crystallinity and morphology of the composite films were characterized by XRD,SEM,XPS. The determination of low concentration crystal violet was studied by surface-enhanced Raman scattering with potassium niobate / nano-silver oxide composite film as active substrate. The results show that the potassium niobate nanochip / nano-silver oxide composite film can be used to detect crystal violet with low concentration quickly and efficiently. The rapid electron transfer between nano-silver oxide and potassium niobate nanoparticles in the composite film is the key to the detection of low concentration crystal violet.
【学位授予单位】：上海应用技术学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TQ116.2

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