作为一类新型的功能复合材料，核壳结构纳米材料成功实现了内核材料和壳材料的结合与互补，所以其设计概念逐渐开始被引入到隔热、催化和能量存储等领域。但作为一种未来新能源和环境领域的重要候选材料，目前核壳结构纳米材料还局限于实验室小规模、不计成本制备的阶段，并且调控程度有限，合成壳厚均一、单分散的颗粒具有一定挑战性。因此，本论文以核壳型纳米复合材料为研究对象，材料体系选择了过渡金属氧化物、Al金属和La2Zr2O7，结合模板法、原位化学合成法和粒子表面化学处理等技术，合成了可规模化生产的三类核壳结构，包括核壳紧贴型、半空型（蛋黄-蛋壳结构）和全空型（空心结构）纳米材料，并分别对其微观形貌、结构调控及功能化特性进行了详细的研究。在探索核壳紧贴型结构纳米材料的可控合成和性能优化方面，利用KMnO4与还原性碳球模板的原位氧化还原反应制备了C@MnO2核壳紧贴型结构。尽管获得了改善的电容性质，但距MnO2比容量的理论值仍有较大差距。因此在对MnO2充放电机理理解的基础上，本研究又设计并合成了尺寸小于10nm的MnO2@C核壳紧贴型结构。在扫描速率为1mV/s时，该材料的比容量达到1103F/g，5000次循环后容量保持率仍超过96%。另外，为发展核壳结构纳米材料在锂离子电池负极中的应用，本研究以Al为核心，在其表面合成能够同时传导Li+和电子的TiO2壳层，并在核-壳之间引入适当的空隙，制备出Al@TiO2蛋黄-蛋壳结构。电化学测试结果表明，其首次循环的可逆容量为1237 mAh/g，并且在1C倍率下的容量可稳定在1170 mAh/g，平均库伦效率约为99.2%，平均每次循环容量衰减小于0.01%；在10C倍率下的可逆容量达到690 mAh/g。为进一步得到全空型核壳结构纳米材料，本研究以有机碳球为模板，制备了具有多级孔结构和高比表面积的Co3O4空心球，并通过对碳球模板酸处理或碱处理，实现了空心球球壳厚度和孔结构的调节，获得了优异的催化CH4燃烧的活性和催化稳定性。为证明这种制备陶瓷空心球方法的普适性，本研究还利用同样的方法制备出TiO2-Ag空心结构，并表征了其光催化性能。最后，在核壳结构纳米粉体合成的基础上，发展一种两步烧结工艺，成功地制备超低热导率（0.016Wm-1K-1）、超高强度（251.3MPa）和良好的热稳定性（1400oC）的空心晶粒La2Zr2O7高强度超级隔热材料和优异催化性能的多级孔结构的Co3O4蜂窝结构块体。
As one of the new functional composites, core-shell nano-structures, which could successfully integrate the properties of core and shell materials, have gradually found wide applications in thermal insulation, catalysis, lithium ion battery and supercapacitors and so on. Therefore, in this study we will focus on the core-shell nanostructures and prepare hollow, yolk-shell as well as traditional core-shell structures using the hydrothermal method, template method and surface modification. The micro-morphology, structure tuning and applications were systemically studied and the main work includes the following four parts:C@MnO2 and MnO2@C core-shell structuresC@MnO2 core-shell structure was prepared through an in-situ redox reaction between KMnO4 and reducing carbon templates. Although improved super capacitor performance was found in the resultant products, there was still some distance away from the theoretical specific capacity of MnO2. Therefore, we design and synthesize a sub-10 nm MnO2@C core-shell nano-composites based on the understanding of charging-discharging mechanism of MnO2. The specific capacity of such sub-10 nm MnO2@C core-shell nano-composites reaches 1103 F/g at a scan rate of 1mV/s and the capacity retention remains 96% even after 5000 cycles.TiO2@Al yolk-shell structureThe core materials were successfully extended to metal nanoparticles and TiO2@Al yolk-shell structure was prepared in this study. When it was utilized as the anode material of lithium-ion batteries, its initial reversible capacity reached 1237 mAh/g and stabilized then on 1170 mAh/g at 1 C. The average Coulombic efficiency was about 99.2% and capacity degradation was less then 0.01% per cycle. It's worth mentioning its high-rate performance, which has a reversible capacity of 690 mAh/g at 10 C.Ceramic hollow spheresCo3O4 hollow spheres were prepared using organic carbon spheres as templates, which were obtained through a hydrothermal process of glucose. It was found that the shell thickness of Co3O4 hollow spheres could be easily tuned by a simple treatment of carbon templates with acid and alkaline. Besides, the N2 adsorption-desorption results revealed that the Co3O4 hollow spheres possessed meso pores and macro pores at the same time, as well as high surface area, thus excellent catalysis performance of CH4 combustion was observed. In order to justify the universality of our method, we synthesized TiO2 hollow sphere using a similar approach and its photocatalysis performance was also characterized.Bulk preparation based on the core-shell structureBased on the synthesis of core-shell nano particles, we developed a two-step sintering process to prepare La2Zr2O7 hollow-grain ceramics, which have an ultra-low thermal conductivities (0.016 Wm-1K-1), super-high strength (251.3 MPa) and excellent thermal stability (up to 1400 oC), and hierarchically porous Co3O4 honeycombed monolith with a scale of centimeters.
