【作者】 周强；

【导师】 肇启东；

【作者基本信息】 大连理工大学 ， 环境科学与工程， 2018， 硕士

【摘要】 挥发性有机化合物（Volatile Organic Compounds,VOCs）可严重影响室内空气质量和人体健康,实现对VOCs的有效治理已显得尤为迫切。光催化氧化技术因其具有反应条件易满足（常温、常压）、耗能少、氧化能力强和无二次污染等优点,在VOCs的净化处理方面具有较大发展前景。对光催化技术而言,影响光催化剂催化活性的两大关键因素分别是光响应范围和量子效率。尖晶石型钴酸锌作为光催化剂材料具备可见光响应特性,且其结构牢固、化学性质稳定、廉价易得且无毒,在有机污染物的净化处理领域已获得较多应用。本论文以钴酸锌材料为基础,通过自牺牲模板法和共沉淀热解法制备了不同形貌的钴酸锌催化剂及其复合物,利用多种表征技术分析对比了材料间物理化学性质的差异。以气相甲苯的光催化剂降解实验评估了不同催化剂的催化活性,并推测了光催化过程的降解机理。论文获得以下研究结果:（1）采用自牺牲模板法和共沉淀热解法分别制备出了中空多孔Zn_xCo_3-xO₄纳米立方体和ZnCo₂O₄纳米颗粒催化剂。通过对两种催化剂的晶体结构、尺寸形貌、元素组成和光学特性等的表征,发现Zn_xCo_3-xO₄纳米立方体相对具有更大的比表面积、更高的可见光吸收能力和光生载流子的分离效率。在可见光的照射下反应6 h,中空多孔Zn_xCo_3-xO₄对甲苯的降解转化率可达78%,高出ZnCo₂O₄纳米颗粒在相同反应条件下降解率的13%。借助in-situ FTIR光谱和EPR技术对气相甲苯的光催化降解实验进行分析,发现甲苯降解反应过程中会产生苯甲醛和苯甲酸等中间产物以及CO₂和H₂O等最终产物,而光催化体系中可直接生成的反应活性物种为光生空穴（h⁺）和超氧自由基（·O₂^─）。（2）采用自牺牲模板法原位制得了Zn_xCo_3-xO₄和rGO/Zn_xCo_3-xO₄催化材料体系。通过XRD、SEM、TEM、拉曼、XPS和EDX表征发现rGO的引入没有影响Zn_xCo_3-xO₄晶体结构的生成。与纯的Zn_xCo_3-xO₄材料相比,rGO/Zn_xCo_3-xO₄的表面更加粗糙,在Zn_xCo_3-xO₄的外壁上可明显观察到一层薄的褶皱状rGO。DRS的表征结果显示rGO/Zn_xCo_3-xO₄具有相对更强的光能吸收。通过气相甲苯的光催化降解实验,对比发现在同等实验条件下rGO/Zn_xCo_3-xO₄反应6 h后的降解效率可达82%,高出纯的Zn_xCo_3-xO₄降解转化率大约9%。更多还原

【Abstract】 Volatile organic compounds（VOCs）can seriously affect indoor air quality and human health,and the implementation of effective treatment of emergent VOCs has become particularly urgent.Photocatalytic oxidation technology has great prospect in the purification treatment of VOCs due to its moderate reaction conditions（normal temperature and pressure）,low energy consumption,strong oxidizing ability and environmental friendliness.Regarding photocatalytic technology,the two key factors affecting the photocatalytic activity of the photocatalyst are the spectral response range and quantum efficiency.As a photocatalyst material,spinel zinc cobaltate possesses characteristics of visible-light response,stable structure and chemical stability,low cost,availability and non-toxicity.It has been widely used in the field of organic pollutants purification.In this dissertation,the zinc cobaltate catalyst and its composites with different morphologies were prepared by self-sacrificial template method and co-precipitation pyrolysis method.The differences in physical and chemical properties of the as-prepared materials were analyzed and compared by implementing various characterization techniques.The catalytic activity of different catalysts was evaluated by photocatalytic degradation of gaseous toluene and the degradation mechanism of the photocatalytic process were inferred.The obtained results of the thesis work are introduced as follows:（1）Hollow porous Zn_xCo_3-xO₄ nanocubes and ZnCo₂O₄ nano particulate catalysts were prepared by self-sacrificial template method and co-precipitation pyrolysis method,respectively.Through the characterization of the crystal structure,size morphology,elemental composition and optical properties of the two catalysts,it was found that Zn_xCo_3-xO₄nanocubes have relatively larger specific surface area,higher visible light absorption capacity and improved separation efficiency of photogenerated carriers.Under the irradiation of visible light for 6 h,the degradation rate of toluene over hollow porous Zn_xCo_3-xO₄ was about 78%,which was 13%higher than that of the ZnCo₂O₄ nanoparticles under the same reaction conditions.The in-situ FTIR spectra and EPR techniques were used to analyze the photocatalytic degradation of gaseous toluene.It was found that during the degradation reaction,intermediate products such as benzaldehyde and benzoic acid,and final products such as CO₂ and H₂O were produced,and the reactive species directly generated in the photocatalytic system involved h⁺and·O₂^─.（2）The Zn_xCo_3-xO₄ and rGO/Zn_xCo_3-xO₄ catalytic materials systems were prepared in situ using a sacrificial template method.By XRD,SEM,TEM,Raman,XPS and EDX characterizations,it was found that the introduction of rGO did not affect the formation of Zn_xCo_3-xO₄ crystal structure.Compared with pure Zn_xCo_3-xO₄ material,the surface of rGO/Zn_xCo_3-xO₄ was rougher,and a thin wrinkled rGO layer could be observed on the outer wall of Zn_xCo_3-xO₄.The characterization results of DRS showed that rGO/Zn_xCo_3-xO₄ showed relatively higher light energy absorption.Through the photocatalytic degradation of gaseous toluene,it was observed that the degradation efficiency of rGO/Zn_xCo_3-xO₄ after 6 h exposure to visible light was about 82%,which is 9%higher than that of pure Zn_xCo_3-xO₄ under the same experimental conditions.更多还原