【作者】 罗洁；

【导师】 刘孝恒；

【作者基本信息】 南京理工大学 ， 材料科学与工程， 2018， 博士

【摘要】 随着经济的发展,能源短缺和环境污染越来越成为人们所关注的全球性的问题。为了人类社会的可持续发展,无二次污染的环境治理技术和清洁能源的开发迫在眉睫。在目前所开展的相关开发研究中,半导体光催化技术被普遍认为是一种重要的有用的方法,其可直接利用自然界中的太阳光实现污染物降解和完成氢能的转化。最传统的半导体光催化剂是二氧化钛(Ti02),但是因为它只对紫外光产生响应,制约了其实际应用。因此,研究和开发具有可见光响应能力的光催化材料具有重要意义。基于此,本论文选择了磷酸银、氯氧铋和氧化亚铜这三种光催化剂进行改性研究,采用控制晶体尺寸和形貌、离子掺杂以及复合的方法,开发了具有较高催化活性的可见光响应的光催化剂。全文主要研究内容如下:1.磷酸银的制备条件探索研究磷酸银(Ag3PO4)制备过程中制备体系的条件变化会影响其结构、尺寸和形貌等,我们考察了反应溶液的pH值、不同银源、不同磷源、不同助剂和溶剂组成的变化对Ag3PO4晶体的影响,结果表明:Ag3PCO4的形貌受磷源的影响较大,其中采用焦磷酸钠制备的四面体型Ag3PO4表现出较好的催化性能;Ag3PCO4晶体的尺寸可通过加入表面活性剂或者采用水-乙二醇复合溶剂来调节,减小Ag3PO4的尺寸可提高其光催化性能。2.碳酸根离子掺杂的磷酸银的制备以碳酸银(Ag2CO3)为前驱体,室温下采用离子交换的方法制得了甜甜圈状碳酸根离子掺杂的Ag3PO4。研究发现柯肯达尔效应对于甜甜圈形貌的形成起主导作用,碳酸根离子的掺杂不但减小了Ag3PO4的禁带宽度,还有效提高了光生电子-空穴对的分离效率,使得掺杂后的Ag3PO4显示出较好的可见光催化活性。3.基于凹凸棒石作用的尺寸可控的磷酸银复合光催化剂的制备采用不同浓度的凹凸棒石(PAL)分散液参与Ag3PO4的合成反应,制得PAL/Ag3PO4复合光催化剂。在PAL/Ag3PO4复合体系中,Ag3PO4颗粒的尺寸可通过加入的凹凸棒石的含量不同进行控制,其中当凹凸棒石所占的质量比为20%时,Ag3PO4尺寸可减小至10 nm,结合凹凸棒石的结构特点,分析认为凹凸棒石的胶状流变性能和其表面带有负电荷的特性是影响复合物中Ag3PO4尺寸的重要因素。与Ag3PO4相比,所得的PAL/Ag3PO4纳米复合物具有较好的可见光催化性能和稳定性。4.基于凹凸棒石作用的3D氯氧铋复合微球光催化剂的制备在凹凸棒石分散液中采用简单温和的室温反应制备了三维立体的PAL/氯氧铋(BiOCl)复合微球,通过观察微球的形貌发现其中凹凸棒石纳米棒与BiOCl结合紧密且分布均匀,微球的自组装形成与凹凸棒石的加入量息息相关。复合微球的特殊结构使得PAL/BiOCl复合物具有较好的可见光催化性能。5.基于凹凸棒石作用的氧化亚铜复合光催化剂的制备采用溶液法在凹凸棒石分散液中制得了PAL/氧化亚铜(Cu2O)复合物,与纯Cu20相比,PAL/Cu2O复合物表现出较好的可见光催化性能和稳定性,主要是因为其中光生电子和空穴可以有效分离,依据Cu20和凹凸棒石的带隙结构对复合物中光生电子和空穴转移的可能路径进行了探讨,并分析了其可见光催化降解染料的过程。更多还原

【Abstract】 Along with the rapid economic development,steadily worsening environmental pollution and energy shortages have raised awareness of a potential global crisis.For the sustainable development of human society,the development of both pollution-free technologies for environmental remediation and alternative clean energy supplies is an urgent task.Among the wide variety of green earth and renewable energy projects underway,semiconductor photocatalysis has emerged as one of the most promising technologies,which can degrade the contaminats and produce hydrogen using solar energy directly.Due to the large band gap,the traditional photocatalytic semiconductor titanium dioxide(TiO2)is only active in the UV region,which greatly limits its applications.Therefore,the development of visible-light photocatalyses is important and received widespread attentions.In this dissertation,we have studied the modification of three photocatalysts including silver phosphate(Ag3PO4),bismoclite(BiOCl)and cuprous oxide(Cu2O),with the methods of controlling particle sizes and morphologies,ion doping and composing with other semiconductors.The visible-light-driven photocatalysts with higher activities have been developed.The main contributions invoved in this dissertation are as follows:1.Exploration for the preparation conditions of Ag3PO4In the Ag3PO4 preparation process,the reaction conditions can significantly affect the structures,sizes and morphologies of Ag3PO4 particles.The impacts of pH values,silver sources,phosphorus sources,addition agents and solvents were investigated.Results showed that the phosphorus sources took effects on the morphologies of Ag3PO4,and tetrahedral Ag3PO4 synthesized with sodium pyrophosphate showed better properties in visible-light photocatalytic reaction.With the surfactants or the mixed solvent of water and ethylene glycol,the size of Ag3PO4 was reduced,which can bring about the more effective activity of Ag3PO4.2.Synthesis of carbonate ion-doped Ag3PO4 and its photocatalytic activityCarbonate ion-doped Ag3PO4 photocatalyst with doughnut-like morphology was synthesized by an ion exchange method at room temperature with silver carbonate(Ag2CO3)as the precursor.It was found that the doughnut-like Ag3PO4 was formed mainly due to the Kirkendall effect.Because of CO32-doping,the carbonate ion-doped Ag3PO4 photocatalyst showed a higher photocatalytic activity than polyhedral Ag3PO4,which were attributed to the narrower band gap and effective separation of photoinduced charges.3.Size-controlled synthesis of PAL-based Ag3PO4 composite photocatalystsPAL/Ag3PO4 composite photocatalysts were sythesized with the employment of PAL dispersion at different concentrations.It can be found that the particle size of Ag3PO4 could be well controlled by adjusting the concentration of PAL in the composites.The smaller size Ag3PO4 particles with average diameter size of 10 nm were obtained when 20%PAL dispersion was employed.Based on the structure characteristics of PAL,it was inferred that the typical negative surface charges and specific colloidal-rheological properties of PAL played an important role on the size-controlled synthesis of Ag3PO4.It was shown that the visible-light photocatalytic activity and stability of PAL/Ag3PO4 nanocomposites were greatly enhanced.4.Synthesis of PAL-based 3D bismoclite(BiOCL)composite microspheres3D PAL/BiOCl composite microspheres were easily synthesized with a facile room temperature reaction in the PAL dispersion.It was significant that the morphologies of composites displayed remarkable changes with adding different amounts of PAL.In the composite microspheres,PAL nanorods dispersed on the BiOCl nanosheets uniformly and coupled with BiOCl.The special structure of composite microspheres efficiently enhanced the visible-light photocatalytic activity of BiOCl.5.Synthesis of PAL-based cuprous oxide(Cu2O)composite photocatalystsPAL/Cu2O composites were prepared through solution method in the PAL dispersion.Compared with the pristine Cu2O,the PAL/Cu2O composites showed good visible-light photocatalytic properties and stability,which could be attributed to the constructed coupling between PAL and Cu2O,leading to the effective charge separation.By analyzing the band gaps and band potentials,we investigated the possible migration direction of photo-generated charge carrier pairs and the process of photo-degradation reaction.更多还原