本文選題：氮摻雜石墨烯量子點(diǎn)　切入點(diǎn)：上轉(zhuǎn)換發(fā)光性能　出處：《江蘇大學(xué)》2017年碩士論文

【摘要】：石墨烯量子點(diǎn)作為一種新型的發(fā)光碳納米材料,是目前研究的重點(diǎn)和熱點(diǎn)之一。與傳統(tǒng)的半導(dǎo)體量子點(diǎn)相比,石墨烯量子點(diǎn)既有其良好的熒光性能,又具有碳材料天然的無(wú)毒性。此外,其表面因含官能團(tuán)而易于溶劑分散和改性應(yīng)用。基于石墨烯量子點(diǎn)優(yōu)異的性能,其在各個(gè)領(lǐng)域尤其是光催化方面體現(xiàn)出了重要的價(jià)值。石墨烯量子點(diǎn)合成方便,無(wú)毒性及穩(wěn)定的熒光特性尤其是上轉(zhuǎn)換發(fā)光特性,并且還能改善催化劑的光催化活性。因此,石墨烯量子點(diǎn)在光催化領(lǐng)域的實(shí)際應(yīng)用有著十分明顯的優(yōu)勢(shì)�；谝陨戏治�,我們制備了氮摻雜石墨烯量子點(diǎn)(NGQDs),以及開展了氮摻雜石墨烯量子點(diǎn)/釩酸鉍復(fù)合物、氮摻雜石墨烯量子點(diǎn)/納米Ag/釩酸鉍三元復(fù)合物的制備工藝及光催化性能方面的研究和探索。具體工作如下:(1)以一水合檸檬酸和尿素分別作為碳源和氮源,在水熱環(huán)境下通過熱解法成功制備了熒光量子產(chǎn)率達(dá)到18.9%的氮摻雜石墨烯量子點(diǎn)(NGQDs)。該方法簡(jiǎn)單方便,且條件可控,制備出來(lái)的NGQDs發(fā)藍(lán)色熒光。我們通過延長(zhǎng)反應(yīng)時(shí)間來(lái)調(diào)控NGQDs的尺寸,從而實(shí)現(xiàn)對(duì)其光學(xué)性質(zhì)的調(diào)控研究。然后,借助于一系列的形貌、結(jié)構(gòu)和光學(xué)表征手段,系統(tǒng)分析了NGQDs的尺寸與熒光性能之間的聯(lián)系。并且我們探究pH值的大小對(duì)NGQDs熒光強(qiáng)度的影響,得知在中性條件下NGQDs的熒光最強(qiáng)。也研究了不同離子濃度和不同溶劑對(duì)NGQDs熒光強(qiáng)度的影響,實(shí)驗(yàn)結(jié)果表明不同離子濃度對(duì)其熒光強(qiáng)度無(wú)甚大影響,而不同溶劑則表現(xiàn)出了一定程度的熒光淬滅現(xiàn)象。并通過Zet a電位測(cè)定NGQDs具有良好的物理穩(wěn)定性。(2)通過直接和簡(jiǎn)單的“自下而上”的方法,在水熱條件下合成了具有優(yōu)異發(fā)光性能的NGQDs。所制備的NGQDs表現(xiàn)出不依賴激發(fā)的上轉(zhuǎn)換熒光特征。然后,又通過水熱反應(yīng)及沉積技術(shù)制備了NGQDs/BiVO_4復(fù)合光催化劑,并通過一系列表征手段證明NGQDs成功地負(fù)載在BiVO_4表面。通過光催化降解亞甲基藍(lán)(MB)實(shí)驗(yàn)可得,復(fù)合光催化劑表現(xiàn)出增強(qiáng)的可見光光催化活性。NGQDs/BiVO_4復(fù)合物的光催化增強(qiáng)性能可以歸因于NGQDs的上轉(zhuǎn)換發(fā)光性能以及降低電子-空穴對(duì)的復(fù)合率。此外,該NGQDs/Bi VO4復(fù)合光催化劑顯示出良好的穩(wěn)定性。通過固體紫外、熒光及電化學(xué)檢測(cè)等表征分析和自由基捕獲實(shí)驗(yàn)研究了復(fù)合光催化劑的催化機(jī)理,揭示了材料界面的電子轉(zhuǎn)移情況以及超氧自由基作為主要活性物質(zhì)進(jìn)行了光催化降解MB。(3)采用水熱還原法和沉積法制備了NGQDs/Ag/BiVO_4三元復(fù)合納米材料,基于納米Ag的LSPR效應(yīng),構(gòu)建了NGQDs/Ag/Bi VO4三元等離子體型復(fù)合物降解鹽酸四環(huán)素(TC·HCl)的催化體系。由于納米Ag的LSPR效應(yīng),光生電子和空穴得到了有效分離,其中,納米Ag的電子存儲(chǔ)作用、LSPR效應(yīng)引起的直接電子遷移作用(DET)和能量遷移(PIR ET)三者的共同作用促使了電子-空穴對(duì)的分離。通過XRD、XPS、SEM和TEM對(duì)三元復(fù)合物進(jìn)行了結(jié)構(gòu)和形貌表征,利用電化學(xué)檢測(cè)對(duì)所制備樣品的電化學(xué)穩(wěn)定性和載流子遷移情況進(jìn)行了研究。同時(shí)自由基捕獲實(shí)驗(yàn)和順磁共振技術(shù)測(cè)試(ESR)檢測(cè)證實(shí)了·O2-和·OH自由基是在光催化降解體系中的最主要的活性物質(zhì)。也利用質(zhì)譜對(duì)TC·HCl的反應(yīng)中間產(chǎn)物進(jìn)行了研究。基于以上的分析,我們對(duì)NGQDs/Ag/BiVO_4三元復(fù)合物在光催化降解TC·HCl過程中可能的電荷轉(zhuǎn)移機(jī)理進(jìn)行了系統(tǒng)分析和深入研究。
[Abstract]:A new type of luminescent carbon nano materials as graphene quantum dots, is one of the key and hot research. Compared with traditional semiconductor quantum dots, graphene quantum dots have good fluorescence properties, and is non-toxic natural carbon materials. In addition, the surface for easily dispersed and solvent containing functional groups the application of modification of properties. Graphene quantum dot based on its excellent, especially in the fields of photocatalytic show the important value. Graphene quantum dots synthesized convenient, non-toxic and stable fluorescence characteristics especially the luminescence properties of upconversion, and can improve the photocatalytic activity of the catalyst. Therefore, the actual application of graphite graphene quantum dots in the field of photocatalysis has very obvious advantages. Based on the above analysis, we prepared nitrogen doped graphene quantum dots (NGQDs) were prepared, and the nitrogen doped graphene quantum dots / vanadate Bi compound, to study and explore the preparation and photocatalytic performance of nitrogen doped graphene quantum dots / nano Ag/ three element bismuth vanadate complexes. The specific work is as follows: (1) with citric acid monohydrate and urea were used as carbon source and nitrogen source, the nitrogen doped graphene quantum dots pyrolysis was successfully prepared fluorescence quantum yield reached 18.9% in the hydrothermal environment (NGQDs). This method is simple and convenient, and controllable conditions, the synthesized NGQDs blue fluorescence. We by prolonging the reaction time to control the size of the NGQDs, so as to realize the control of the optical properties. Then, with the help of morphology a series of methods, structural and optical characterization, system analysis between the size and fluorescence properties of NGQDs contact. And we explore the impact of pH value on the fluorescence intensity of NGQDs, that NGQDs had the strongest fluorescence under neutral conditions. Also studied Influence of concentration and different solvents on the fluorescence intensity of NGQDs, the experimental results show that the different ion concentration without great influence on its fluorescence intensity, and different solvents showed fluorescence quenching degree of arc phenomenon. And through the Zet a potential determination of NGQDs with physical stability is good. (2) through a direct and simple method the "bottom-up", was synthesized under hydrothermal conditions with excellent luminescent properties of NGQDs. prepared by NGQDs showed no dependence on the excitation of the luminescence characteristics. Then, through the NGQDs/ BiVO_4 composite photocatalyst prepared by hydrothermal reaction and deposition process, and through a series of characterization means that NGQDs successfully the load on the surface of BiVO_4. The photocatalytic degradation of methylene blue (MB) experiment, the composite photocatalyst exhibited photocatalytic photocatalytic activity of.NGQDs/BiVO_4 composite material enhanced performance can be enhanced To attribute to NGQDs upconversion luminescence properties and reduce the recombination rate of electron hole pairs. In addition, the NGQDs/Bi VO4 composite photocatalyst exhibited good stability. By UV, fluorescence and electrochemical detection and characterization analysis of free radical trapping experiment on the catalytic mechanism of composite photocatalyst was revealed and superoxide free radical electron transfer material interface as the main active substance of the photocatalytic degradation of MB. (3) NGQDs/Ag/BiVO_4 three composite nano materials were prepared by reduction method and hydrothermal deposition method, the LSPR effect of nano Ag on the construction of degradation of complex NGQDs/Ag/Bi VO4 three plasma type (TC - HCl) tetracycline catalysis system. Due to the LSPR effect of Ag nanoparticles, the photogenerated electrons and holes were effectively separated from the electronic storage effect of nano Ag, direct electron transfer effect caused by LSPR The role of (DET) and energy transfer (PIR ET) three together promote the separation of electron hole pairs. By XRD, XPS, the structure and morphology of the composites were three yuan SEM and TEM on the electrochemical stability and mobility of sample preparation were studied by electrochemical detection. At the same time, free radical trapping experiment and magnetic resonance imaging (ESR) detection test confirmed that O2- and OH free radical is the main active substance in the photocatalysis system. Also the use of mass spectrometry in TC HCl reaction was investigated. Based on the above analysis, we have to charge three yuan compound NGQDs/Ag/BiVO_4 in the photocatalytic degradation of TC and HCl in the process of transfer mechanism was analyzed and studied.

【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36;TB383.1

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