本文選題：光催化 + 可見光�。� 參考：《江蘇大學》2017年博士論文

【摘要】：半導體光催化技術對解決能源和環(huán)境危機具有重要的意義。光催化技術通過半導體光催化劑吸收清潔、可再生的太陽能,在溫和的條件下實現(xiàn)光催化氧化還原反應。制備高活性、高選擇性、高穩(wěn)定性、廉價的光催化劑是光催化技術實現(xiàn)大規(guī)模應用的關鍵。以二氧化鈦(Ti02)為代表的傳統(tǒng)光催化劑的帶隙寬,只能被紫外光激發(fā),這極大地阻礙了 Ti02作為光催化劑的發(fā)展。因此,廉價、高效、高穩(wěn)定的可見光催化劑的開發(fā)備受關注。本文將材料的可控合成、先進的表征和機理研究“三位一體”相結(jié)合,用于廉價、高效、高穩(wěn)定性的具有可見光響應能力的石墨相氮化碳(g-C3N4)材料的設計和制備,以提高單體g-C3N4在可見光照射下催化降解環(huán)境有機污染物的性能。同時,根據(jù)所制備的g-C3N4材料的性能、結(jié)構(gòu)、組成等之間的構(gòu)效關系深入研究光催化性能增強機制。在本論文中,我們通過調(diào)控g-C3N4的組成來提高其對可見光的吸收和光生電子-空穴對的分離效率;通過調(diào)節(jié)g-C3N4的維度來提高光生電荷的分離和傳輸能力,以改善其光催化降解污染物的活性;并通過調(diào)控g-C3N4的光生電荷的遷移來實現(xiàn)光生載流子的生成,以提高其光催化降解污染物的性能。本文的主要研究成果如下:1.以納米立方體的Ce02負載g-C3N4為體系,通過調(diào)控復合物的組成來研究Ce02/g-C3N4光催化降解環(huán)境有機污染物的性能。研究結(jié)果表明,Ce02的引入抑制了 g-C3N4的光生載流子的復合。負載在單體g-C3N4表面的Ce02具有規(guī)則的立方體形貌,且尺寸在3-10 nm,小尺寸的CeO2具有量子限制效應。光生載流子的有效分離和量子限制效應共同作用于光催化反應,提升了 Ce02/g-C3N4復合物的光催化活性。2.采用機溶劑液相剝落法合成了二維類石墨烯氮化碳,通過優(yōu)化不同的有機溶劑,調(diào)控類石墨烯氮化碳的層厚,并研究了類石墨烯氮化碳的光催化降解環(huán)境有機污染物的性能。研究發(fā)現(xiàn),由于類石墨烯氮化碳在Z-軸方向上只有幾個原子層厚度,極大地縮短了光生載流子從其體相遷移到表面的距離。因此,類石墨烯氮化碳的光生載流子得到有效的分離。同時,由于類石墨烯氮化碳具有較大的比表面積,其能提供更多的吸附位點和活性位點,從而有效地提升其光催化降解環(huán)境有機污染物性能。3.采用熱氧化法控制合成了單原子層氧摻雜g-C3N4 (O-g-C3N4)納米片光催化材料,通過調(diào)控鍛燒時間和次數(shù),宏量制備了具有原子層結(jié)構(gòu)的氧摻雜g-C3N4納米片,并將其應用于光催化降解環(huán)境有機污染物。研究發(fā)現(xiàn),在空氣氣氛下,多層氮化碳被逐步裁剪成二維結(jié)構(gòu),并最終形成單原子層結(jié)構(gòu)。少量的O有效地摻雜于g-C3N4納米片結(jié)構(gòu)中。單原子層的O-g-C3N4納米片在Z-軸方向只有一層,其光生載流子遷移到催化劑表面的距離大大縮短,有利于提升光生載流子的遷移速率;且二維單原子結(jié)構(gòu)和O的引入還抑制了單原子層的O-g-C3N4的光生載流子復合率,提升了其光催化降解環(huán)境有機污染物的性能。此外,單原子層的O-g-C3N4納米片能光催化降解多種有機污染物。與P25相比,單原子層的O-g-C3N4紫外光催化降解4-CP的性能也得到了明顯的提升。4.采用非模板法制備二維超薄多孔氧摻雜g-C3N4納米片(PUOCNs),并研究了二維多孔結(jié)構(gòu)和O摻雜對g-C3N4光催化降解環(huán)境污染物性能的影響。通過鍛燒使g-C3N4膨脹;隨后在常溫下,通過混合酸氧化法制備了 PUOCNs。研究發(fā)現(xiàn),二維超薄多孔結(jié)構(gòu)和O的引入提升了 g-C3N4光催化降解環(huán)境有機污染物的性能。其中,PUOCNs的二維超薄多孔結(jié)構(gòu)不僅大大縮短了光生載流子的遷移距離,而且提供了更多的吸附位點和活性位點。此外,O的引入使材料的電荷分布發(fā)生了改變,光生載流子的壽命得到了延長,提高了其參與光催化反應的概率,從而提升了 PUOCNs的光催化性能。PUOCNs的光催化降解有機污染物MO的活性比單體g-C3N4提升了 71倍。5.構(gòu)建了具有電子定向遷移能力的Ag/2D-C3N4/CNTs光催化復合材料,協(xié)同地利用Ag的等離子效應和CNTs的導電性來提升2D-C3N4光催化材料的光生載流子的生成、遷移和分離,從而提升了其光催化降解環(huán)境有機污染物的性能。在可見光照射下,Ag/2D-C3N4/CNTs復合物中Ag納米立方體的表面等離子共振效應被激發(fā)產(chǎn)生熱電子并注入2D-C3N4的導帶中與2D-C3N4的光生電子匯集。隨后,在2D-C3N4導帶上的高密度的電子通過具有優(yōu)良導電性的CNTs遷移到催化劑的表面參與光催化反應。Ag納米立方體和CNTs兩者協(xié)同作用于2D-C3N4,從而提高了 Ag/2D-C3N4/CNTs復合物可見光催化降解環(huán)境有機污染物的性能。6.以二維層狀結(jié)構(gòu)的α-Fe203/2D g-C3N4為體系,通過水熱法先合成了α-Fe203,隨后通過與三聚氰胺分步多次煅燒形成二維結(jié)構(gòu)的Z-型機制復合光催化劑:α-Fe2O3/2D g-C3N4。在可見光照射下,α-Fe2O3導帶上的光生電子與2D g-C3N4價帶上的光生空穴通過α-Fe2O3和2D g-C3N4形成的致密界面進行復合,而留在α-Fe203價帶上的光生空穴和留在2D g-C3N4導帶上的光生電子能有效地參與光催化氧化還原反應。這不僅提高了單一組分光催化劑的氧化還原能力,還抑制了其光生電子-空穴對的復合。通過同步輻射表征發(fā)現(xiàn)α-Fe203是與2D g-C3N4中的碳原子發(fā)生相互作用,從而提高了 Z-型機制光催化劑α-Fe203/2D g-C3N4光催化降解環(huán)境有機污染物的性能。
[Abstract]:Semiconductor photocatalytic technology is of great significance for solving the crisis of energy and environment. Photocatalytic technology absorbs clean, renewable solar energy through semiconductor photocatalyst, and realizes photocatalytic redox reaction under mild conditions. The preparation of high activity, high selectivity, high stability and cheap photocatalyst is realized by photocatalysis technology. The key of scale application. The band gap of the traditional photocatalyst represented by titanium dioxide (Ti02) is wide and can only be excited by ultraviolet light, which greatly hinders the development of Ti02 as a photocatalyst. Therefore, the development of cheap, high efficient and highly stable visible light catalyst has attracted much attention. This paper has studied the controllable synthesis of materials, advanced characterization and mechanism research. The combination of "Trinity" is used for the design and preparation of graphite phase carbon nitride (g-C3N4) materials with visible light response capacity for low cost, high efficiency and high stability, in order to improve the performance of the organic pollutants in the photocatalytic degradation of the environmental pollutants by the visible light irradiation of the monomer g-C3N4. At the same time, the properties, structure, composition and so on of the g-C3N4 materials are prepared. In this paper, we improve the absorption of visible light and the separation efficiency of the photoelectron hole pair by regulating the composition of g-C3N4 in this paper. By adjusting the dimension of g-C3N4, we can improve the separation and transmission of light generated charge, so as to improve the photocatalytic activity of photocatalytic degradation of pollutants. In order to improve the performance of photocatalytic degradation of pollutants by regulating the migration of photogenerated charge of g-C3N4, the main research results of this paper are as follows: 1. the Ce02/g-C3N4 photocatalytic degradation of environmental organic pollutants by Ce02/g-C3N4 photocatalyst was studied by using g-C3N4 as the system of nano cubes. The results show that the introduction of Ce02 inhibits the recombination of the photogenerated carriers of g-C3N4. The Ce02 loaded on the surface of the monomer g-C3N4 has a regular cube shape, and the size is 3-10 nm, and the small size CeO2 has the quantum confinement effect. The effective separation of the light carrier and the quantum confinement effect co act on the photocatalytic reaction and the enhancement. The photocatalytic activity of the Ce02/g-C3N4 complex was used to synthesize the two dimensional graphene like carbon nitride by means of liquid phase stripping in the machine solvent. By optimizing the different organic solvents, the thickness of the carbon nitride of graphene like carbon was regulated. The performance of the photocatalytic degradation of the environmental organic contaminants was studied. There are only a few atomic layers in the direction of the Z- axis, which greatly shortens the distance of the photogenerated carrier from its body to the surface. Therefore, the photogenerated carrier of carbon like carbon nitride can be effectively separated. At the same time, it can provide more adsorption sites and active sites because of the larger specific surface product of carbon like carbon nitride. In order to effectively improve the photocatalytic degradation of environmental organic pollutant performance.3., a single atomic layer oxygen doped g-C3N4 (O-g-C3N4) nanoscale photocatalyst was synthesized by thermal oxidation, and the oxygen doped g-C3N4 nanoscale with atomic layer structure was prepared by controlling the time and times of the calcination, and applied to the photocatalytic degradation. The study found that in the air atmosphere, the multilayer nitriding carbon was gradually cut into two dimensional structure and finally formed a single atomic layer structure. A small amount of O was effectively doped in the structure of g-C3N4 nanoscale. The O-g-C3N4 nanoscale of the single atomic layer was only one layer in the direction of the Z- axis, and the distance of the photogenerated carrier to the surface of the catalyst. It can greatly shorten the migration rate of the photogenerated carrier, and the introduction of two dimensional monatomic structure and O also inhibits the photogenerated carrier recombination rate of O-g-C3N4 in the single atomic layer, and improves the photocatalytic degradation of the environmental organic pollutants. In addition, the O-g-C3N4 nanoscale of the single atomic layer can photocatalytic degradation of various organic pollutants. Compared with P25, the performance of O-g-C3N4 UV photocatalytic degradation of 4-CP in single atomic layer also improved the performance of 4-CP, and.4. was prepared by non template method to prepare two-dimensional ultrathin porous oxygen doped g-C3N4 nanoscale (PUOCNs) by non template method. The effect of two-dimensional porous structure and O doping on the performance of g-C3N4 photocatalytic degradation of environmental contaminants was studied. At the normal temperature, PUOCNs. studies have been prepared by the mixed acid oxidation method. It is found that the two-dimensional ultrathin porous structure and the introduction of O enhance the performance of g-C3N4 photocatalytic degradation of environmental organic pollutants. Among them, the two-dimensional ultrathin porous structure of PUOCNs not only greatly shortens the migration distance of the photogenerated carrier, but also provides more adsorption sites. In addition, the introduction of O makes the charge distribution of the material changes, the lifetime of the photogenerated carrier is prolonged, the probability of its participation in the photocatalytic reaction is increased, and the photocatalytic activity of the PUOCNs is enhanced by the photocatalytic degradation of the organic pollutant MO, which is 71 times higher than that of the monomer g-C3N4, and the electricity is constructed with electricity. Ag/2D-C3N4/CNTs photocatalytic composites with the ability of subdirectional migration are used to enhance the photocatalytic degradation of environmental organic pollutants by using the plasma effect of Ag and the conductivity of CNTs to enhance the performance of photocatalytic degradation of organic pollutants in the 2D-C3N4 photocatalyst. Ag/2D-C3N4/CNTs composite under visible light irradiation. The surface plasmon resonance effect of the Ag nanometers in the substance is excited to produce hot electrons and into the photoelectron collection of 2D-C3N4 in the guide band of 2D-C3N4. Then, the high density electrons in the 2D-C3N4 conduction band migrate to the surface of the catalyst through the CNTs with excellent conductivity, and participate in the photocatalytic reaction between the.Ag nanometers and the CNTs. The synergistic effect on 2D-C3N4, thus improving the performance of the Ag/2D-C3N4/CNTs complex in the visible photocatalytic degradation of environmental organic pollutants,.6. with two-dimensional layered structure of alpha -Fe203/2D g-C3N4, first synthesized alpha -Fe203 by hydrothermal method, and then by calcining with melamine multiple steps to form a two-dimensional structure of Z- type mechanism composite photocatalysis. Agent: alpha -Fe2O3/2D g-C3N4. is irradiated by visible light, the photogenerated holes on the valence band of the alpha -Fe2O3 conduction band and the 2D g-C3N4 valence band are compounded by the dense interface formed by the alpha -Fe2O3 and 2D g-C3N4, while the photogenerated holes on the alpha -Fe203 valence band and the photoelectrons left on the 2D g-C3N4 Guide band are effectively involved in the photocatalytic redox reaction. It not only improves the redox ability of the single component light catalyst, but also inhibits the recombination of the photogenerated electron hole pair. Through the synchrotron radiation characterization, it is found that the alpha -Fe203 is interacting with the carbon atoms in the 2D g-C3N4, thus improving the Z- type photocatalyst alpha -Fe203/2D g-C3N4 for the photocatalytic degradation of the environmental organic pollutants. Performance.
【學位授予單位】：江蘇大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：O643.36;O644.1;X505

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本文編號：1969254