本文選題：磷酸銀基半導(dǎo)體　切入點：Z型異質(zhì)結(jié)　出處：《江蘇大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：半導(dǎo)體光催化技術(shù)作為一種“綠色”技術(shù),在環(huán)境凈化和能源轉(zhuǎn)換等方面有著巨大的潛力。傳統(tǒng)的光催化劑如TiO2雖然無毒且具有較好的光催化活性和穩(wěn)定性,但由于其能帶間距較寬而不能得到廣泛應(yīng)用。近年來,銀基半導(dǎo)體光催化劑,如AgX、Ag_2O、Ag_2CO3和Ag_3PO_4等已被廣泛應(yīng)用于光催化降解廢水中的有機物和光解水等領(lǐng)域。其中,Ag_3PO_4因其強的光氧化和高效光催化降解有機污染物的能力成為能源轉(zhuǎn)換和清除環(huán)境污染物方面最有潛力的光催化劑之一。然而,Ag_3PO_4微溶于水,且光照下容易發(fā)生光腐蝕現(xiàn)象導(dǎo)致其很少應(yīng)用于實際領(lǐng)域�；诎雽�(dǎo)體納米顆粒的人工光合作用,即Z-scheme體系通過光還原催化劑的空穴與光氧化催化劑的電子在電子傳輸介質(zhì)處的結(jié)合,使得體系具有更正的氧化電勢和更負(fù)的還原電勢,不僅可以實現(xiàn)太陽能的高效利用,提高氧化還原能力,還能改善單一半導(dǎo)體材料的不穩(wěn)定性。本論文從能帶結(jié)構(gòu)匹配的角度考慮,利用Z-scheme原理,首次構(gòu)筑了Ag_2MoO_4/Ag_3PO_4、g-C_3N_4/Ag_2MoO_4/Ag_3PO_4和GO/Ag_2MoO_4/Ag_3PO_4復(fù)合光催化體系,旨在通過Ag_3PO_4與其它半導(dǎo)體材料的復(fù)合,在保持Ag_3PO_4高催化活性的同時提高材料的光催化穩(wěn)定性。研究了復(fù)合材料的結(jié)構(gòu)、形貌、光吸收能力以及光生載流子的分離效率,探討了復(fù)合光催化劑的光催化機理。主要的研究內(nèi)容如下:(1)利用半導(dǎo)體耦合技術(shù),以硝酸銀(AgNO3)和三氧化鉬(MoO3)為原料,采用簡單的沉淀法制備了可見光響應(yīng)的Z型Ag_2MoO_4/Ag_3PO_4半導(dǎo)體復(fù)合光催化劑。通過調(diào)控前驅(qū)體的摩爾比例,考察了復(fù)合材料在可見光下對有機污染物的光降解效率和光解水產(chǎn)氧效率。通過SEM、TEM、XRD、FTIR、BET等表征方法對Ag_2MoO_4/Ag_3PO_4樣品微觀形貌和結(jié)構(gòu)特征進行分析。利用光電流和阻抗實驗分析了光催化過程光生載流子的分離和傳輸效率。結(jié)果表明,在光催化反應(yīng)的早期階段,Ag_2MoO_4/Ag_3PO_4表面產(chǎn)生的Ag單質(zhì)作為光生電子空穴轉(zhuǎn)移的橋梁,提高了光生載流子的分離效率,進而提高了復(fù)合材料的光催化活性和穩(wěn)定性。(2)利用能帶匹配原理,以g-C_3N_4為前驅(qū)體,采用固相法+沉淀法制備了一系列雙Z構(gòu)型的g-C_3N_4/Ag_2MoO_4/Ag_3PO_4復(fù)合光催化材料。綜合運用各種測試手段對復(fù)合材料的形貌特征、微觀結(jié)構(gòu)、化合價態(tài)進行分析,研究了g-C_3N_4添加量對光解水產(chǎn)氧效率的影響。通過光電流、阻抗、熒光和電子自旋共振等分析測試揭示了三相復(fù)合材料的光生電子空穴的產(chǎn)生、分離與轉(zhuǎn)移狀況。結(jié)果表明,雙Z構(gòu)型中Z型體系g-C_3N_4/Ag/Ag_3PO_4和Z型體系A(chǔ)g_2MoO_4/Ag/Ag_3PO_4的協(xié)同作用可以有效地阻止光生電子和空穴再結(jié)合,提高電子和空穴的分離效率。(3)以氧化石墨烯(GO)為前驅(qū)體,通過簡單的沉淀法制備GO/Ag_2Mo O_4/Ag_3PO_4三元復(fù)合半導(dǎo)體光催化劑,利用SEM、TEM、XRD、XPS、DRS等手段對復(fù)合材料的形貌、結(jié)構(gòu)、光吸收狀態(tài)進行分析,探討了其光催化分解水產(chǎn)氧性能,對比了GO不同添加量對產(chǎn)氧效率的影響。通過光電流、阻抗和熒光分析了GO/Ag_2MoO_4/Ag_3PO_4的光生電子空穴分離和傳輸效率。電子自旋共振(ESR)圖譜分析了復(fù)合材料在光催化過程中的活性基團產(chǎn)生狀況。實驗結(jié)果表明,光催化過程中,石墨烯特殊的電子結(jié)構(gòu)使得Ag_3PO_4光催化劑中光致電子迅速傳輸、轉(zhuǎn)移,使得光致電子和空穴達到有效分離,提高了光催化劑的量子產(chǎn)率。
[Abstract]:The semiconductor photocatalytic technology as a kind of "green" technology, has great potential in environmental purification and energy conversion. Although traditional photocatalysts such as TiO2 is non-toxic and has better photocatalytic activity and stability, but because of its wide band spacing and can not be widely used. In recent years, silver based semiconductor the photocatalyst, such as AgX, Ag_2O, Ag_2CO3 and Ag_3PO_4 have been widely used in photocatalytic degradation of organic matter in wastewater and water splitting fields. Among them, Ag_3PO_4 for light oxidation and high photocatalytic degradation of organic pollutants has become its strong light catalyst for removing environmental pollutants and one of the most potential energy conversion however, Ag_3PO_4 is slightly soluble in water, and the illumination light is susceptible to corrosion phenomenon which is rarely applied in practical fields. Semiconductor nanoparticles artificial photosynthesis based on Z-scheme system Through a combination of electron hole and light light oxidation catalyst reduction catalyst in the electronic transmission medium, the system has the correct oxidation potential and more negative reduction potential, not only can realize the efficient use of solar energy, improve the redox ability, but also improve the stability of single semiconductor materials. In this thesis, energy band structure point of view, using the principle of Z-scheme, the first to build Ag_2MoO_4/Ag_3PO_4, g-C_3N_4/Ag_2MoO_4/Ag_3PO_4 and GO/Ag_2MoO_4/Ag_3PO_4 Composite Photocatalytic System, to compound with other semiconductor materials by Ag_3PO_4, improve the Ag_3PO_4 maintain high catalytic activity and stability of photocatalytic materials. The morphology of the composite structure, the light absorption ability and photoinduced charge separation to explore the mechanism of photocatalytic efficiency of composite photocatalysts. The main contents are as follows: (1) The use of semiconductor coupling technology, using silver nitrate (AgNO3) and molybdenum trioxide (MoO3) as raw materials, Z type Ag_2MoO_4/Ag_3PO_4 semiconductor photocatalyst with visible light response were synthesized by precipitation method. The molar ratio of simple manipulation of precursor, composites were investigated under visible light photocatalytic degradation of organic pollutants and photocatalytic efficiency oxygen efficiency. Through SEM, TEM, XRD, FTIR, BET and other characterization methods to analyze the morphology and microstructure of Ag_2MoO_4/Ag_3PO_4 samples. The use of optical current and impedance of the experimental analysis of the separation and the transmission efficiency of the photocatalytic process of photogenerated carrier. The results showed that in the early stages of photocatalytic reaction, the surface of Ag_2MoO_4/Ag_3PO_4 Ag as the photogenerated electron hole bridge mass transfer, improve the separation efficiency of photogenerated carriers, and thus improve the composite photocatalytic activity and stability. (2). With the energy band matching principle, using g-C_3N_4 as the precursor, prepared g-C_3N_4/Ag_2MoO_4/Ag_3PO_4 composite photocatalyst a series of double Z configuration by solid phase +. Morphology, comprehensive use of various test methods of composite microstructure, valence state analysis of the effects of g-C_3N_4 addition on the photocatalytic efficiency of oxygen through the light current, impedance, fluorescence and electron spin resonance analysis reveals a three-phase composite photo electron hole generation, separation and metastasis. The results showed that the synergistic effect of double Z configuration in Z system g-C_3N_4/Ag/Ag_3PO_4 and Z type Ag_2MoO_4/Ag/Ag_3PO_4 system can effectively prevent the photogenerated electrons and holes with and improve the separation efficiency of electron and hole. (3) to graphene oxide (GO) as the precursor, through a simple precipitation method to prepare GO/Ag_2Mo O_4/ Ag_3PO_4 three complex Semiconductor photocatalyst, using SEM, TEM, XRD, XPS, morphology of composite DRS structure, analysis of light absorption, discusses the photocatalytic decomposition of water to oxygen properties, effects of GO on different oxygen production efficiency. Compared with light current, impedance and fluorescence analysis GO/Ag_2MoO_4/Ag_3PO_4 the photogenerated electron hole separation and transmission efficiency. Electron spin resonance (ESR) spectra of the active groups of composite materials in the photocatalytic process produced. Experimental results show that the photocatalytic process, electronic structure of graphene special structure makes the electronic rapid transmission, light induced Ag_3PO_4 photocatalyst in the light induced transfer the electrons and holes to achieve effective separation, improve the quantum yield of photocatalyst.

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

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