【作者】 王江；

【导师】 张密林；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2008， 博士

【摘要】 有序纳米介孔材料具有规则连续可调的纳米级孔道结构,具有量子限制效应,小尺寸效应,表面效应,宏观量子隧道效应,以及介电限域效应,在石油化工、生物催化、光催化、环境保护、医药分离、微型电磁装置、光致发光材料、电极材料、信息储存等领域存在诱人的应用前景,引起国际物理学、化学及材料学界的高度关注,成为跨学科的研究热点之一。对于介孔材料,目前的发展主要集中在介孔材料的制备、功能化及其应用方面。其中有序的TiO₂介孔材料为在其孔道内负荷半导体,功能染料、贵金属、碳纳米管等异质组分以提高介孔TiO₂在光催化、亲水性等领域的效率提供了理想的宿主材料。本文采用溶剂蒸发诱导自组装法,在不同条件下分别制备了蠕虫状介孔TiO₂和粒子规整排列的纳米TiO₂薄膜和粉体材料。利用TG-DSC、XRD、FT-IR、Raman、AFM、SEM、TEM等测试技术对所制备的样品进行了表征,发现蠕虫状介孔TiO₂经350℃焙烧后,模板被完全去除,而且为有序的蠕虫状介孔结构,晶相为锐钛矿;而粒子规整排列的纳米TiO₂经400℃焙烧后为粒子均匀排列的球状结构,晶相为锐钛矿。对不同焙烧温度的样品进行光催化降解罗丹明B的性能研究,发现400℃焙烧的蠕虫状介孔TiO₂和500℃焙烧的粒子规整排列的纳米TiO₂具有最高的光催化活性。通过测量不同焙烧温度下TiO₂薄膜的接触角,发现蠕虫状介孔TiO₂薄膜的亲水性优于粒子规整排列的纳米TiO₂薄膜,这与介孔TiO₂的多孔结构有关。经高压汞灯照射后二者亲水性均有显著提高,蠕虫状介孔TiO₂具有多孔结构和大的比表面积,经紫外光照射后产生了光诱导超亲水性。在蠕虫状介孔TiO₂薄膜电极上利用电沉积法沉积了CdS,通过测定ITO/TiO₂/CdS复合薄膜的光电流响应谱,判定CdS被沉积在了介孔TiO₂孔道及其表面上,而且其光电响应范围被拓宽至可见光区,光电流显著增强。通过测定薄膜的吸收光谱,发现ITO/TiO₂/CdS复合薄膜的吸收强度大大增加,且吸收显著红移,由此判定形成了TiO₂-CdS异质结,从而使可激发光波长拓展到可见光部分,提高了对太阳光的利用率。更多还原

【Abstract】 In reeent years, Periodic mesoporous materials with uniform pore diameters and high specific surface area have been widely used as catalysts, catalyst supports, chemical sensors, electrical and optical devices, and shape/size selective adsorbents for environmentally hazardous chemicals. Although the synthesis and application of ordered microporous solids have been well established , uumerous attempts to obtain geometrically regular mesoporous materials were unsuccessful until in the early 1990s. For mesoporous materials, the investigation focus on the preparing, function, and application. Among these, the large pore meso-nc-TiO2 materials present good host porous structure to form novel heterojunction through growing a variety of wide hand-gap semiconductors and assembling functional polymers, noble metals, carbon nanotubes, and other components in the large mesopore channels, which could be useful for the development of improved efficiency in photocatalysis, photoelectric conversion, and hydrophilic coating materials applications.Wormhole-like mesoporous titania and uniformed nanocrystalline titania have been successfully synthesized through evaporate-induced self-assembly （EISA） method. The obtained samples were characterized in detail by TG-DSC, XRD, Raman, AFM, SEM and TEM. As for wormhole-like mesoporous TiO₂, the template can be removed completely and ordered wormhole-like mesoporous titania structure was formed after being calcinated at 350℃. As for uniformed nanocrystalline titania thin film, uniformed and spheric titania structure was formed after being calcinated at 400℃. The photocatalytic activity experiments of TiO₂ powders with different calcination temperatures were also presented in this thesis. The highest photoactivity of wormhole-like mesoporous titania and uniformed nanocrystalline titania were presented at 400℃and 500℃, respectively. The hydrophilicity of wormhole-like mesoporous titania thin film was higher than that of uniformed nanocrystalline titania thin film, which can be ascribed to the structure of its porous nature. Both obtained samples presented higher hydrophilicity after being irradiated by high press Hg lamp. Furthermore, the wormhole-like mesoporous titania thin film produced photo-induced super hydrophilicity because of its porous structure and large surface area. CdS was deposited on the wormhole-like mesoporous titania thin film electrode through electrodeposition method. The photocurrent action spectra of ITO/TiO₂/CdS composites thin film demonstrated that CdS was successfully deposited on the surface and in the hole of mesoporous titania thin film. Furthermore, the range of photoelectricity response extended to visible light region and photocurrent increased obviously. The absorption intensity of ITO/TiO₂/CdS composites thin film increased and the absorption edge showed red shift obviously, the results demonstrated the formation of TiO₂-CdS heterojunction. In conclusion, the exciting wavelength was extended to visible light region and the utilization efficiency of sun light was enhanced.更多还原