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  本文選題：碳點　切入點：有機染料　出處：《江蘇大學》2017年碩士論文　論文類型：學位論文

【摘要】：抗生素和有機染料的大規(guī)模使用,給人類的生產(chǎn)和生活帶來極大便利的同時,對生態(tài)環(huán)境和人類健康也構成了嚴重威脅。傳統(tǒng)的污水處理技術無法實現(xiàn)有機分子的高效去除,相比之下,光催化氧化技術在有機染料、醫(yī)療廢水凈化中具有潛在的應用前景。但光催化材料普遍存在光響應范圍窄、光生電子-空穴對易復合導致的光催化效率低等諸多問題,這嚴重制約了光催化技術的推廣應用。目前研究較為廣泛的光催化劑大多僅能響應紫外光或可見光。為了拓寬光吸收范圍,近幾年碳點復合光催化劑逐漸發(fā)展起來。碳點具有獨特的光學性質優(yōu)勢,尺寸僅為幾納米,量子限域效應使得其尺寸與光學性質相關聯(lián)且可調(diào)。本文針對碳點復合光催化劑,圍繞光生電子的矢量轉移設計、界面修飾和實現(xiàn)紅外光的催化應用等問題開發(fā)了一系列碳量子點復合光催化劑,并從組分調(diào)控、表面包覆、助催化劑負載和異質結構筑等方面探究了該體系的光催化降解速率和機理,優(yōu)化了碳點復合材料性能和反應條件,為實現(xiàn)工業(yè)化應用奠定了基礎。本文的主要研究內(nèi)容如下:(1)通過濕化學法合成CQDs/Ag_2O復合材料,隨后通過NaBH4還原法在CQDs層表面沉積Ag納米粒子合成了CQDs/Ag/Ag_2O表面等離子體復合催化劑。CQDs在催化劑中作為介質存在,與Ag_2O和Ag納米顆粒均存在強烈的化學鍵,這有利于光生載流子的有效轉移和分離。與光致還原法相比,NaBH4原位還原Ag納米粒子的合成方法簡單、快速,并且不需要任何額外的光致還原設備,有利于大批量合成其它負載Ag納米單質的銀鹽基復合材料。CQDs/Ag/Ag_2O復合催化劑具有全光譜催化活性,首先Ag粒子的Plasmon效應有利于可見光的吸收,同時,碳點的上轉換熒光效應能將紅外光轉換為高能量光子,從而實現(xiàn)紅外光催化。實驗結果表明,所制備的復合光催化劑的催化活性和穩(wěn)定性能均顯著增強是由CQDs包覆以及Ag顆粒的成功負載等協(xié)同效應所導致。(2)用氫氣退火對TiO_2進行改性,制備了氫化TiO_2納米帶(H-TiO_2),并研究了可見光催化性能。通過水熱合成法構建了CDs/MoS_2@H-TiO_2核(H-TiO_2)殼(CDs/MoS_2)結構復合材料。H-TiO_2納米帶的氧缺陷有利于促進可見光的吸收,MoS_2和H-TiO_2之間異質結的形成有利于光生電子的傳遞。同時,MoS_2表面負載的碳點具有熒光和光致電子轉移性質,不僅使CDs/MoS_2@H-TiO_2復合物能夠吸收近紅外進行光催化,而且能促進躍遷到MoS_2導帶上的電子的進一步躍遷,極大地抑制了光生電子空穴對的復合。(3)利用水熱合成法制備碳點,以三聚氰胺為原料在550℃下熱解制備氮化碳(g-C_3N_4),隨后進一步通過水熱合成法制得CDs/g-C_3N_4復合催化劑。將其分散在不同有機污染物中,在光照下評估其光催化降解速率。通過SEM、XRD、UV-Vis和EIS等基礎表征手段研究復合催化劑的基本性質。研究表明,在g-C_3N_4的基礎上負載CDs可能引入了自帶帶隙(sub-band gap),增強對光譜的吸收范圍,最大吸收波長可以達到620 nm,這意味著可以更加有效地利用低能光子。實驗結果顯示,在0.50 wt%CDs/g-C_3N_4的光催化作用下,有機分子(RhB、MB、MO、TC、CIP)均可以得到有效的去除。
[Abstract]:The large-scale use of antibiotics and organic dyes, brings great convenience to people's production and life at the same time, the ecological environment and human health also pose a serious threat. The traditional wastewater treatment process to achieve efficient removal of organic molecules, in contrast, the photocatalytic oxidation technology in organic dye wastewater purification, medical application potential. But photocatalytic materials generally narrow light response range, the photogenerated electron hole pairs to many problems caused by the low efficiency of photocatalytic composite, which seriously restricted the application of photocatalytic technology. The photocatalyst is widely studied mostly only in response to ultraviolet or visible light. In order to broaden the range of light absorption in recent years, carbon composite photocatalyst carbon has developed gradually. The optical properties of the unique advantages, the size of only a few nanometers, quantum confinement effect due to its size and The optical properties associated with adjustable. The carbon composite photocatalyst, photoinduced electron transfer around the vector design, interface modification and implementation of a series of catalytic applications of infrared carbon quantum dots composite photocatalyst was developed, and the control group, the surface coating, catalyst loading and heterogeneous structure etc. on the rate of photocatalytic degradation and the mechanism of the system, carbon composites properties and reaction conditions were optimized, which laid the foundation for the realization of industrial application. The main contents of this paper are as follows: (1) a CQDs/Ag_2O composite material by wet chemical method, then deposited on the surface of the CQDs layer of Ag nanoparticles were synthesized by surface plasmon CQDs/Ag/Ag_2O the.CQDs complex catalyst in the catalyst as a medium by NaBH4 reduction method, there were strong chemical bonds with Ag_2O and Ag nano particles, which is conducive to the photocarrier The effective transfer and separation. Compared with light induced reduction method, the synthesis method of NaBH4 in situ reduction of Ag nanoparticles is simple, fast, and does not require any additional light induced reduction equipment, suitable for large scale synthesis of silver base composite material.CQDs/Ag/Ag_2O composite catalyst Ag loaded with other nano elemental full spectrum catalytic activity, Plasmon first Ag effect the particle is conducive to the absorption of visible light, at the same time, the carbon upconversion effect can be converted to a high energy photon infrared light, infrared light to achieve catalysis. The experimental results show that the catalytic activity of the composite photocatalyst and preparation stability was significantly enhanced by CQDs coated Ag particles and successfully loaded together the effect of the cause. (2) TiO_2 was modified by hydrogen annealing, preparation of hydrogenated TiO_2 nanoribbons (H-TiO_2), and to study the photocatalytic properties through hydrothermal synthesis. The construction of CDs/MoS_2@H-TiO_2 core (H-TiO_2) shell (CDs/MoS_2) oxygen defect structure of composite material of.H-TiO_2 nanobelts is conducive to the absorption of visible light, between MoS_2 and H-TiO_2 heterojunction is conducive to the formation of photoinduced electron transfer. At the same time, the surface of MoS_2 loaded carbon with fluorescence and photoinduced electron transfer properties, not only the CDs/MoS_2@H-TiO_2 complexes can absorb near-infrared light catalysis, but also can accelerate the transition to further transition electron conduction band of MoS_2 on, greatly inhibited the photogenerated electron hole pair recombination. (3) were synthesized by using hydrothermal carbon materials, under the temperature of 550 DEG C prepared by pyrolysis of carbon nitride (using melamine as g-C_3N_4), then through the hydrothermal synthesis of CDs/g-C_3N_4 composite catalyst. The dispersed in different organic pollutants, evaluate the photocatalytic degradation rate under light. Through SEM, XRD, UV-Vis and EI The basic properties of S based composite catalyst characterization. The results show that, on the basis of the g-C_3N_4 load CDs likely introduced with the band gap (sub-band gap), enhanced absorption range of the spectrum, the maximum absorption wavelength can reach 620 nm, which means that we can more effectively use low energy photons. Experimental results show that the photocatalytic effect of 0.50 wt%CDs/g-C_3N_4, organic molecules (RhB, MB, MO, TC, CIP) can be effectively removed.

【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36

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相關期刊論文 前1條

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本文編號：1566132