氧化石墨烯调控纳米结构ZnO和TiO 2 及光催化性能改善

发布时间：2022-01-22 17:48

　　半导体的光催化特性作为一种重要的材料性能,在有机物污染降解、细菌灭活、水分解和二氧化碳还原等方面具有重要的应用价值。利用半导体光催化可以环保地将光能转化为化学能,为解决能源短缺问题提供了一种可行的解决方案,因此这方面的研究发展非常迅速。金属氧化物、氮基或硫基半导体、硅、III-V族半导体、导电聚合物、石墨烯基材料、新兴层状化合物等都可用于光催化。本论文工作基于半导体催化基本原理以及金属氧化物和异质结构中载流子特性,研究纳米结构ZnO和TiO₂的基本缺陷,并通过将这些纳米材料与微波合成的石墨烯氧化物进行杂化来调控这些缺陷,最终改善纳米材料在污染物分解、氧化降解以及CO₂转化催化性能。首先,制备了ZnO纳米颗粒,并采用微波合成将ZnO纳米颗粒与氧化石墨烯（GO）复合得到石墨烯含量分别为10%、20%和30%的纳米ZnO-GO复合材料（GZCs）。获得的复合材料中纳米氧化锌很好地分散在石墨烯层之间或者之上。退火温度和GO含量对复合材料的紫外吸收光谱、光致发光、氧化锌缺陷态、电子顺磁共振谱、光电响应和电荷转移特性有重要的影响。GZC的高分辨透射电镜图... 

【文章来源】：华南理工大学广东省 211工程院校 985工程院校 教育部直属院校

【文章页数】：148 页

【学位级别】：博士

【文章目录】：
摘要
Abstract
Chapter 1 Introduction and Literature review
    1.1 Background
    1.2 Introduction to materials and defect states
    1.3 Wide bandgap semiconductors
    1.4 ZnO and TiO_2
    1.5 Graphene and Graphene oxide
    1.6 Reduced graphene oxide and semiconductor composites
        1.6.1 Reduced graphene oxide-ZnO
        1.6.2 Reduced graphene oxide-TiO_2
    1.7 Defects in semiconductors
    1.8 ZnO defect states
    1.9 TiO_2 defect states
    1.10 Effect of defect states on photocatalysis
    1.11 Recovery of photocatalyst
    1.12 Chemical synthesis of catalyst magnetic nanocomposites
        1.12.1 Co-precipitation Method
        1.12.2 Microwave Synthesis
    1.13 The objective of this work
Chapter 2 Experimental and Instrumentation
    2.1 Introduction
    2.2 Experimental section
        2.2.1 Reagents and Chemicals
        2.2.2 Sample preparations
    2.3 Instrumentation
        2.3.1 X-ray diffraction (XRD)
        2.3.2 RAMAN spectroscopy
        2.3.3 Transmission electron microscopy (TEM)
        2.3.4 Scanning electron microscopy (SEM)
        2.3.5 UV-VIS spectroscopy
        2.3.6 X-ray photoelectron spectroscopy (XPS)
        2.3.7 PL spectroscopy
        2.3.8 Photocurrent and EIS
    2.4 Summary
Chapter 3 Lattice defects of ZnO and hybrids with GO: Characterization, EPR and Optoelectronic properties
    3.1 Introduction
    3.2 Preparation of samples
        3.2.1 Preparation of ZnO nanoparticles
        3.2.2 Preparation of GZ composites
    3.3 Microstructures, morphology and phase composition characterization
    3.4 Photoluminescence properties
    3.5 Bonding and defect characterization by XPS
    3.6 Absorbance properties
    3.7 Electrochemical properties
    3.8 Electron paramagnetic resonance properties
    3.9 Summary
Chapter 4 Defect engineering of ZnO nanoparticles by graphene oxide leading to enhanced visible light photocatalysis
    4.1 Introduction
    4.2 Preparation of samples
        4.2.1 Preparation of zinc oxide nanoparticles
        4.2.2 Preparation of Fe_3O_4@Si O2 magnetic nanoparticles
        4.2.3 Preparation of GZF composites
    4.3 Microstructures, morphology and phase composition characterization
    4.4 Magnetic measurements
    4.5 Photoluminescence properties
    4.6 Bonding and defects characterizations by XPS
    4.7 Absorbance properties
    4.8 Photocurrent response
    4.9 Photocatalytic activity
        4.9.1 Photocatalytic degradation of methylene blue and BPA
        4.9.2 Apparent rate constants
        4.9.3 Methylene blue and BPA photodegradation
    4.10 Summary
Chapter 5 ZnO flowers and graphene oxide hybridization for efficient photocatalytic degradation of o-xylene in water
    5.1 Introduction
    5.2 Sample preparation
        5.2.1 Preparation of zinc oxide flowers
        5.2.2 Preparation of GZ-hybrids
    5.3 Growth of ZnO from particles to flowers
    5.4 Microstructures, morphology and phase composition characterization
    5.5 Absorbance properties
    5.6 Photoluminescence properties
    5.7 ZnO-graphene oxide bonding and defect characterization by XPS
    5.8 Photocurrent response
    5.9 Electrochemical Properties
    5.10 Photocatalytic activity
        5.10.1 Photo-catalytic degradation of o-xylene
        5.10.2 Effect of Ethanol on the degradation percentage of o-xylene
        5.10.3 Effect of potassium iodide (KI) on the degradation percentage of o-xylene ..
        5.10.4 Effect of N2 gas purging on photo-catalytic degradation of o-xylene
        5.10.5 Recyclability
    5.11 Summary
Chapter 6 TiO_2 hollow nanobox-graphene composites for excellent photo-catalytic conversion of CO_2 to CH_4
    6.1 Introduction
    6.2 Preparation of samples
        6.2.1 Preparation of hollow TiO_2 nanoboxes
        6.2.2 Preparation of Fe_3O_4@SiO_2 magnetic nanoparticles
        6.2.3 Preparation of TFSG composites
    6.3 Microstructures, morphology and phase composition characterization
    6.4 Bonding and defect characteristics by XPS
    6.5 Electron paramagnetic resonance measurements
    6.6 Absorbance and magnetic properties
    6.7 Photo current and electrochemical measurements
    6.8 Photocatalytic activity
        6.8.1 Photocatalytic CO_2 conversion to CH_4 and H_2 production
        6.8.2 Photocatalytic CO_2 conversion to CH_4
        6.8.3 Photocatalytic H_2 evaluation
    6.9 Summary
Chapter 7 Conclusion and Future work
    7.1 Conclusions
    7.2 Future work
References
List of Publications
Acknowledgements



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