若干新型石墨烯量子点的制备及其在金属离子检测和光催化中的应用研究

发布时间：2018-01-26 15:08

本文关键词： 硫掺杂石墨烯量子点 Pb~(2+) Ag~+ 钛酸盐纳米片可见光催化　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：石墨烯量子点(graphene quantum dots,GQDs)是一种新型的荧光碳纳米材料。它是尺寸小于100 nm且厚度小于10层的石墨烯薄层,也称为零维石墨烯。与传统荧光材料相比,GQDs集量子限域效应、尺寸效应及边缘效应于一体,还兼具良好的生物相容性、优异的发光性能和带隙可调等优势。对石墨烯量子点进行异原子掺杂或表面官能团功能化,可调整GQDs的禁带宽度和电荷密度,进而提高荧光量子产率、增加活性位点和显示化学选择性。近年来,GQDs作为荧光探针和光催化剂或光敏化剂在金属离子检测和光催化中的应用研究备受关注。本论文以1,3,6-三硝基芘为碳源,采用不同掺杂剂,合成了两种硫掺杂石墨烯量子点(S-GQDs1、S-GQDs2)和新型氧掺杂石墨烯量子点(O-GQDs),并研究了上述的三种石墨烯量子点在金属离子检测和光催化中的应用。具体研究内容如下:(1)建立了硫掺杂石墨烯量子点(S-GQDs1)的制备方法并研究了其在Pb2+选择性检测中的应用。采用一步水热法,以具有石墨烯母核结构的1,3,6-三硝基芘为碳源、Na2S为硫原子掺杂剂、Na OH溶液为反应介质,在水热过程中通过分子融合一步合成了S-GQDs1。采用紫外-可见吸收光谱(UV-vis)和荧光光谱对S-GQDs1的光学性质进行了分析;通过原子力显微镜(AFM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)对S-GQDs1的形貌、尺寸分布、化学组成等进行了表征。结果表明,S-GQDs1在365 nm紫外光照射下发射黄绿色荧光,荧光光谱的最大激发波长为490 nm,最大发射波长为535 nm。荧光发射具有激发波长非依赖性,荧光量子产率为11.6%。S以-C-SOx-C-(x=2,3,4)硫桥形式掺杂入GQDs骨架中,S-GQDs1平均粒径为3.2 nm,结晶性好。考察了S-GQDs1对不同金属离子的选择性,发现Pb2+可选择性猝灭S-GQDs1的荧光。基于Pb2+对S-GQDs1的荧光猝灭,建立了Pb2+的荧光检测方法。检测Pb2+的最优p H条件为7.0,反应孵育5 min,检测线性范围为0.1μM~1.0μM、1.0μM~140.0μM,检测限为0.03μM。(2)建立了硫掺杂石墨烯量子点(S-GQDs2)的制备方法并研究了其在Ag+选择性检测中的应用。采用一步水热法,以1,3,6-三硝基芘为碳源、3-巯基丙酸为反应硫源,在水热过程中通过水相分子融合一步合成了S-GQDs2。采用UV-vis和荧光光谱对S-GQDs2的光学性质进行了分析;通过AFM、TEM、XPS对S-GQDs2的形貌、尺寸分布、化学组成等进行了表征。结果表明,S-GQDs2在365 nm紫外光照射下发射亮蓝色荧光,荧光光谱的最大激发波长为360 nm,最大发射波长为450 nm。荧光发射具有激发波长非依赖性,荧光量子产率为9.2%。S以-C-SO_2~-C-硫桥和-C-S-C-噻吩形式掺杂入GQDs骨架中,S-GQDs2平均粒径为2.5 nm,结晶性好。考察了S-GQDs2对不同金属离子的选择性,发现Ag+可选择性猝灭S-GQDs2的荧光。基于Ag+对S-GQDs2的荧光猝灭,建立了Ag+的荧光检测方法。在p H 7.0、反应孵育10 min时进行检测,检测线性范围为0.1μM~130.0μM,检测限为0.03μM。(3)以合成的S-GQDs1为可见光催化剂,实现了S-GQDs1对碱性品红的光催化降解。考察了溶液p H、染料浓度、S-GQDs1添加量对催化降解率的影响。结果表明,在溶液p H为7.0、染料浓度为5 mg L-1、S-GQDs1添加量为20%(体积分数)时,催化降解率最高。相比于无硫掺杂GQDs(S-free GQDs),S-GQDs1在可见光区有较明显的紫外吸收和更高的光生载流子分离率,S-GQDs1的禁带宽度为2.43 e V。对比了S-GQDs1和S-free GQDs对碱性品红的催化降解活性。结果表明,S-GQDs1的催化活性是S-free GQDs的9倍,是碱性品红自降解的45倍。(4)合成了富含含氧基团的氧掺杂石墨烯量子点(O-GQDs),并将其与以碱剥离的钛酸盐纳米片(TNSs)复合,通过一步静电絮凝法成功制备了O-GQDs修饰的TNSs复合材料(O-GQDs/TNSs),并实现了O-GQDs/TNSs对罗丹明B的可见光催化降解。采用粉末X射线衍射法(XRD)、TEM、X射线能量色散谱(EDS)、循环伏安法(CV)、电化学阻抗谱(EIS)等对O-GQDs/TNSs的形貌、化学组成及光电化学性质进行表征。结果表明,静电絮凝过程中TNSs的二维层状结构并未被破坏,O-GQDs成功修饰于TNSs表面,O-GQDs/TNSs的禁带宽度为3.09 e V。以罗丹明B为模拟污染物,以rs-TNSs、O-GQDs为对照材料,考察了O-GQDs/TNSs的光催化性能和重复利用性。结果表明,该复合材料在可见光照射下对罗丹明B具有良好的降解活性并能重复利用,催化降解性能是单纯O-GQDs的22倍,rs-TNSs的5倍。通过可见光催化降解结晶紫、活性蓝、茜素红等染料和光催化制氢考察该复合材料的通用性和普适性。结果表明,O-GQDs/TNSs具有优良的通用性和普适性,O-GQDs/TNSs的光催化制氢速率是纯rs-TNSs的68倍。初步探讨O-GQDs/TNSs可见光催化下降解罗丹明B的机理。认为光催化过程中空穴(h+)和超氧自由基(?O_2~-)起主导作用。
[Abstract]:Graphene quantum dots (graphene quantum, dots, GQDs) is a new type of fluorescent carbon nano materials. It is a size less than 100 nm and a thickness of less than 10 thin graphene layer, also known as zero dimensional graphene. Compared with the traditional fluorescent material, GQDs quantum confinement effect, size effect and edge effect in one also, with good biocompatibility, excellent luminescence properties and tunable band gap and other advantages. Different atoms or functional groups on the surface functionalization of graphene quantum dots, can adjust the band gap of GQDs and the charge density, and improve the fluorescence quantum yield, increase the active sites and chemical selectivity. In recent years, GQDs as a fluorescent probe and application of photocatalyst or photosensitizer in metal ions detection and photocatalysis has attracted much attention. In this paper, 1,3,6- three nitropyrene as carbon source, using different dopants, two kinds of sulfur doped synthetic stone Graphene quantum dots (S-GQDs1, S-GQDs2) and a new type of oxygen doped graphene quantum dots (O-GQDs), and to study the application of three kinds of graphene quantum dots in the metal ion detection and photocatalysis. The specific contents are as follows: (1) the establishment of the sulfur doped graphene quantum dot (S-GQDs1) system the preparation method and its application in Pb2+ selective detection. By using a one-step hydrothermal method with nuclear structure of graphene parent 1,3,6- three nitropyrene as carbon source, Na2S sulfur atom doping agent, Na OH solution as reaction medium, in the hydrothermal process by molecular fusion was synthesized by one step S-GQDs1. the UV Vis absorption spectra and fluorescence spectra (UV-vis) optical properties of S-GQDs1 are analyzed; by atomic force microscopy (AFM), transmission electron microscopy (TEM), X ray photoelectron spectroscopy (XPS) on S-GQDs1 morphology, size distribution and chemical composition were characterized. The results show that the S-GQDs1 emission of yellow green fluorescence at 365 nm under UV light irradiation, the fluorescence spectra of the maximum excitation wavelength is 490 nm, the maximum emission wavelength with excitation wavelength dependent fluorescence emission of 535 nm., the fluorescence quantum yield of 11.6%.S to -C-SOx-C- (x=2,3,4) doped sulfur bridge form into the framework of the GQDs, S-GQDs1 average particle size 3.2 nm, good crystallinity was studied. The selectivity of S-GQDs1 to different metal ions, the fluorescence quenching of S-GQDs1 Pb2+ was found to be selective. The fluorescence quenching of Pb2+ S-GQDs1 based on the established fluorescence detection method of Pb2+. The detection of Pb2+ optimal P of H was 7, the reaction was incubated for 5 min, the linear range of detection was 0.1 M~1.0 M, 1 M~140.0 M, the detection limit was 0.03 M. (2) established a sulfur doped graphene quantum dot (S-GQDs2) preparation method and study its application in Ag+ selective detection. By using a one-step hydrothermal method with three nitro 1,3,6- Pyrene as the carbon source, 3- mercaptopropionic acid as reaction sulfur source, through water molecule fusion step by S-GQDs2. UV-vis and fluorescence spectra of the optical properties of S-GQDs2 were analyzed in the hydrothermal synthesis process; through AFM, TEM, S-GQDs2 XPS on the morphology, size distribution and chemical composition were characterized. The results showed that S-GQDs2, at 365 nm under the irradiation of ultraviolet light emission light blue fluorescence, the fluorescence spectra of the maximum excitation wavelength is 360 nm, the maximum emission wavelength with excitation wavelength dependent fluorescence emission of 450 nm., the fluorescence quantum yield of 9.2%.S to -C-SO_2~-C- and -C-S-C- thiophene sulfur bridge form doped into the framework of the GQDs S-GQDs2, the average particle size of 2.5 nm and good crystallinity was studied. The selectivity of S-GQDs2 to different metal ions, the fluorescence quenching of S-GQDs2 Ag+ was found to be selective. The fluorescence quenching of Ag+ S-GQDs2 based on the established fluorescence detection Ag+ method in P H 7, The reaction was detected at 10 min of incubation, the linear range of detection was 0.1 M~130.0 M, the detection limit was 0.03 M. (3) synthesized S-GQDs1 as photocatalyst, the photocatalytic degradation of basic fuchsin S-GQDs1. The effect of solution P H, dye concentration, the amount of S-GQDs1 on the catalytic effect the degradation rate. The results showed that in the solution of P H was 7, the dye concentration of 5 mg L-1, S-GQDs1 content is 20% (volume fraction), the photocatalytic degradation rate was the highest. Compared to the non sulfur doped GQDs (S-free GQDs), S-GQDs1 has the obvious purple in the visible region and higher light absorption the carrier rate of separation, the band gap of S-GQDs1 is 2.43 e V. compared the photocatalytic activities of S-GQDs1 and S-free GQDs to basic fuchsin. The results showed that the catalytic activity of S-GQDs1 is 9 times that of S-free GQDs, is 45 times since the degradation of basic fuchsin. (4) the amount of oxygen doped graphene rich oxygen containing groups. Synthesis Quantum dots (O-GQDs), and with titanate nanosheets alkali peeling (TNSs) composite, through a successful step electrostatic flocculation of the TNSs composites modified by O-GQDs (O-GQDs/TNSs), and the photocatalytic degradation of Luo Danming B O-GQDs/TNSs. Using powder X ray diffraction method (XRD, TEM, X) and energy dispersive X-ray spectroscopy (EDS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) on the morphology of O-GQDs/TNSs, and photoelectrochemical properties of chemical composition were characterized. The results show that the layered structure of two-dimensional TNSs electrostatic flocculation process has not been destroyed, O-GQDs successfully modified on the surface of TNSs and the band gap of O-GQDs/TNSs is 3.09 e V. with Luo Danming B as a model pollutant to rs-TNSs, O-GQDs as control material, investigated the photocatalytic properties of O-GQDs/TNSs and reusablity. The results show that the composite material in visible light irradiation of Luo Danming B has good The degradation activity and can be used repeatedly, the photocatalytic degradation is 22 times higher than that of pure O-GQDs, 5 times of rs-TNSs. The photocatalytic degradation of crystal violet, active blue, alizarin red dye and photocatalytic hydrogen production and the general investigation of PU composite materials used. Results show that O-GQDs/TNSs has the versatility and universality excellent, photocatalytic hydrogen production rate of O-GQDs/TNSs is 68 times higher than the pure rs-TNSs. Preliminary study on degradation of rhodamine B under visible light. The catalytic mechanism of O-GQDs/TNSs photocatalytic process that the holes (h+) and superoxide radical (? O_2~-) plays a leading role.

【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TB383.1

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