【作者】 赵君；

【导师】 李国栋；

【作者基本信息】 吉林大学 ， 无机化学， 2014， 博士

【摘要】 过渡金属氧化物基于自身优异的物理、化学性能以及在生产、生活中不可估量的潜在应用价值，成为无机功能材料研究领域的重要分支之一。以低维纳米结构单元组装形成、具有特殊微纳结构状态的过渡金属氧化物材料受到当前科研者的普遍青睐。调控合成具有特殊微纳结构形态（微粒尺寸、选择性暴露晶面、空心及多孔结构等）的微纳米材料，对阐明材料的微纳结构与性能之间的关系，以及进一步拓展材料的功能研究具有重要的意义。在过渡金属氧化物中，二氧化钛（TiO2）、四氧化三钴（Co3O4）、钴酸镍（NiCo2O4）及氧化锌（ZnO）等代表性氧化物都获得了广泛的研究且在光、电、磁等应用中表现优异。本论文采用一种金属醇盐前驱体导向合成的方法，实现了过渡金属氧化物功能材料的可控制备。无需加入任何模板剂、表面活性剂，开发出一种以甘油、异丙醇为混合溶剂的溶剂热方法，调控合成出多种过渡金属醇盐前驱体（Ti、Co、Ni及Zn），进而获得了具有不同微纳结构形态的过渡金属氧化物，并研究了它们在光化学产氢/产氧、电解水及气体传感方面的性能。本论文主要包括以下内容：一、开发出一种无氟离子参与的{010}活性晶面暴露的TiO2纳米材料的合成方法。在甘油、异丙醇混合溶剂中，以异丙醇钛为钛源，溶剂热法合成出具有多级结构的钛甘油盐前驱体，经过煅烧处理后，获得了具有大比表面积的多级结构锐钛矿相TiO2微球，透射电镜数据证实TiO2微球的基本结构单元是洁净{010}活性晶面暴露的纳米带。这种具有{010}活性晶面的多孔TiO2材料在光催化产氢方面表现优异，产氢速率是商业二氧化钛P25的2倍以上。此方法简便、安全可靠，为探索纳米材料的晶面控制合成提供了新的思路。二、设计了一种新奇的“自模板”路线，并合成出由多孔、超薄类单晶纳米片（<5nm）组成的空心Co3O4纳米材料。所得空心Co3O4纳米材料的比表面积高达180m2/g。我们发现该材料是一种高效的非贵金属水氧化催化剂，可用于电催化产氧以及光催化产氧反应。电催化水氧化性能测试中，空心Co3O4纳米材料在采用电流密度为10mA/cm2的工作电流时，过电势大约为0.40V。而且，在光敏化剂（[Ru(bpy)3]2+(bpy=2,2’-bipyridine)）的辅助下，空心Co3O4纳米材料在可见光（>450nm）辐照下，产氧速率可以达到~12218μmol g-1h-1。上述结果表明，设计合成具有精细微观结构的纳米材料是获得高效水氧化催化剂的可行路线。三、通过上述“自模板”路线，并引入镍源，我们合成出双金属NiCo2O4空心微球水氧化催化剂。研究发现，NiCo2O4空心微球由更薄（<3nm）的多孔纳米片组成，比表面积高达180m2/g。在光敏化剂的辅助下，NiCo2O4空心微球的可见光（>420nm）产氧速率可以达到~843μmol g-1min-1。它的产氧速率是相同方法下得到的单金属Co3O4空心微球水氧化剂的2.5倍，NiO纳米片的7.8倍。NiCo2O4空心微球的光催化活性归因于Co和Ni的双金属协同效应和它自身的结构特点。本工作为制备其它具有新奇结构的先进双金属无机功能材料开辟了一条新路径。四、在甘油、异丙醇混合溶剂中，我们还合成出具有多级结构的锌甘油盐微米球。同只有甘油的实验结果相比，在体系中引入异丙醇不仅降低了锌甘油盐的合成温度，而且有助于锌甘油盐纳米片自组装成多级结构的微米球。将此前驱体进行煅烧即可得到一种由放射状排列的多孔纳米棒构筑的纤锌矿ZnO微球，这种材料能够很好的避免纳米粒子团聚的问题，并对乙醇气体有很好的响应。更多还原

【Abstract】 Research on transition metal oxide has been one of the most important branches ofinorganic functional materials due to their excellent physical and chemical properties andpotential applications in industry and daily life. Transition metal oxide with hierarchicalmicro-/nano-structures, which was built by nanosized building blocks, attractedresearcher’s attention. Controllable synthesis of micro/nanomaterials with novel micro-and nano-structure (e.g., size, crystal planes, exposed facets, hollow, porous structure,etc.) is significant for understanding the relationships between their structures andproperties, and further exploring the application of these materials. Typical transitionmetal oxides, such as TiO2, Co3O4, NiCo2O4and ZnO were widely studied and applied inthe field of optical, electrical and magnetic. In this work, metal alkoxide precursormethod was used to prepare transition metal oxide materials with controlled structures.We developed a solvothermal method without any additions of surfactants or templates inpreparation of various transition metal (Ti, Co, Ni and Zn) alkoxide precursors in amixture of glycerol and isopropanol. Then, transition metal oxides with differenthierarchical structure and morphology were obtained by a simple heat-treatment and usedin water splitting and gas sensor, respectively.The main parts of this thesis including:1. A new approach was developed for the preparation of TiO2nanomaterials with {010}facet without the assistance of F ions. Porous anatase TiO2microspheres composed of{010}-faceted nanobelts were prepared by using a hierarchical flower-like titaniumglycerolate as the starting material. Through a simple thermal treatment, the precursorwas directly converted into the desired TiO2material with a large surface area. Theas-prepared TiO2nanomaterial was shown to serve as an efficient photocatalyst for H2evolution, and its activity was more than twice that of the benchmark P25TiO2. The clean {010} active facet, porosity, and especially the high photocatalytic activity of the TiO2material all highlight the importance of this precursor strategy.2. We report the facile synthesis of hollow Co3O4microspheres composed of porous,ultrathin (<5nm), single-crystal-like nanosheets via a novel “self-template” route. Theas-obtained hollow Co3O4nanomaterial possesses a high BET surface area (~180m2/g),and can serve as an active and stable water oxidation catalyst under both electrochemicaland photochemical reaction conditions, owing to its unique structural features. In theelectrochemical water oxidation, this catalyst affords a current density of10mA/cm2(avalue related to practical relevance) at the overpotential of~0.40V. Moreover, with theassistance of sensitizer [Ru(bpy)3]2+(bpy=2,2’-bipyridine), this nanomaterial cancatalyze water oxidation reaction under visible light irradiation (>450nm) with an O2evolution rate of~12218μmol g-1h-1. Our results suggest that delicate nanostructuringcan offer unique advantage for developing efficient water oxidation catalysts.3. Hollow NiCo2O4microspheres as a noble-metal-free solid-state bimetallic wateroxidation catalysts, were successful prepared by a similar approach as that of preparingCo3O4. The as-obtained hollow NiCo2O4microspheres were composed of porous,ultrathin (<3nm) nanosheets, with a large BET surface area of~180m2/g. With theassistance of sensitizer [Ru(bpy)3]2+, this nanomaterial can also catalyzed water oxidationreaction under visible light irradiation (>420nm) with an O2evolution rate of~843μmolg-1min-1, and its activity was more than twice that of the hollow Co3O4microspheres,seven times than that of the NiO nanosheets. NiCo2O4has better performance, owing tothe bimetallic synergy of Co and Ni and its unique structural features. This work isexpected to open up new synthetic avenues towards the preparation of other advancedbimetallic inorganic nanomaterials with with unique structures and excellent properties.4. Wurtzite ZnO microspheres composed of radially aligned porous nanorods wereprepared through simple thermal treatment of a zinc monoglycerolate precursor.Isopropanol solvent can greatly decrease the formation temperature of zincmonoglycerolate (85oC), and also influence the morphology of zinc monoglycerolate. The as-prepared ZnO material was used as a highly sensitive sensing material for ethanoldetection.更多还原