Novel defective oxides: synthesis, properties and applications

我的研究计划的总体长期目标是在分子水平上理解复杂的、通常是有缺陷的无机材料的性质和化学转化。我们努力建立结构-反应性关系，指导材料设计，以提高性能，降低运营成本，提高可靠性。该研究项目隶属于能源和环境研究，旨在从分子水平上了解（电）催化剂的运行过程，并开发其发光和磁性应用的材料特性。所选择的材料是自然界中普遍存在的缺陷氧化物。这些材料价格便宜，易于获得或合成，并且具有可调节的性能，具有解决许多工业和技术问题的潜力。*在氧化物材料的许多晶体家族中，钙钛矿提供了一个独特的机会，通过微调氧化物的化学成分来创造所需的物理性质的材料。由此产生的氧化物性质可以发生巨大变化，例如钙钛矿可以显示离子导电性，电子导电性或仅仅是绝缘体。氧化物结构的复杂组成和典型缺陷性质为材料本身（氧化态、表面物质、偏析和相形成、纳米畴性质等）以及所涉及的反应和机制提供了丰富的化学知识。*钙钛矿催化剂已被提议作为传统贵金属催化剂在环境、工业和“绿色”能源领域的替代品。本研究计划的短期目标是了解化学结构如何影响催化剂的化学性质的基本原理，并应用这些知识来提高这些催化剂在“现实环境”中的效率、电阻率和可操作性。为此，钙钛矿结构将通过溶胶-凝胶或活性混合方法合成，充分表征其晶体结构，电导率和稳定性，并在自制体系中评估其催化剂性能。在本提案中，我们将基于最近在合成掺杂铁氧体方面的经验来开发新的钙钛矿家族，并特别关注三个应用：*1)混合离子-电子导电钙钛矿将被用作固体氧化物燃料电池阳极和气体传感器。高效的LT-SOFCs阳极将大大降低工厂平衡的工程成本，从而彻底改变行业。*2)氧化还原不稳定钙钛矿将成为催化应用的目标。将研究两种类型的反应，挥发性有机物的氧化和水的光催化分裂。这两种催化应用在世界范围内都具有极其重要的环境和经济价值。*3)高自旋原子掺杂的钙钛矿将用于光致发光和磁性应用。例如，掺杂Dy+3有望增强这两种性质。通过适当控制浓度、畴大小和微观结构，可以合成强光致发光和阴极致发光材料，直接影响平板显示和记忆存储的应用。

The general long term objective of my research program is to understand, at the molecular level, the properties and chemical transformations of complex, usually defective, inorganic materials. We strive to establish structure-reactivity relationships that guide material design for increased performance, reduced operating cost, and improved reliability. The research program, under the umbrella of energy and environmental research, aims to obtain a molecular-level understanding of (electro)catalysts during operation and to exploit the material properties for luminescence and magnetic applications. The chosen materials are defective oxides ubiquitous in nature. Being cheap, readily available or synthesizable, and with tunable properties, these material have the potential to solve many industrial and technological problems.*Among the many crystal families of oxide materials, perovskites offer a unique opportunity to create materials of the desired physical properties by fine-tuning the chemical composition of the oxide. The resulting oxide properties can change dramatically, for example perovskite can show ionic conductivity, electronic conductivity or simply be insulators. The complex compositions and typically defective nature of the oxide structure offers a rich chemistry both in terms of the material itself (oxidation states, surface species, segregation and phase formation, nano-domain properties, etc) and the reactions and mechanisms involved.*Pervoskite-based catalysts have been proposed as alternatives to traditional noble metal-based catalysts in the fields of environmental, industrial and "greener" energy. The short term goals of this research program are to understand the fundamentals of how the chemical structure impacts the chemical properties of the catalysts and applying this knowledge to increase the efficiency, resistivity, and operability of these catalysts in "real-world setting". To this end, the perovskite structures will be synthesized by sol-gel or active mixing methods, fully characterized as to their crystal structure, conductivity and stability, and their catalyst performance will be evaluated in home built systems. In this proposal we will build upon recent experience in the synthesis of doped ferrites to develop new families of perovskites with specific focus on three applications:*1) Mixed ion-electron conducting perovskites will be sought after for use as solid oxide fuel cell anodes and gas sensors. An efficient anode for LT-SOFCs will revolutionize the industry by lowering the engineering costs of balance of plant dramatically. *2) Redox labile perovskites will be targeted for catalytic applications. Two types of reaction will be studied, the oxidation of volatile organic compounds and the photocatalytic splitting of water. Both of these catalytic applications have an extremely important environmental and economic value worldwide. *3) Perovskites doped with high spin atoms will be developed for photoluminescence and magnetic applications. Doping with Dy+3 for example is expected to enhance both of these properties. With appropriate control of concentration, domain size and microstructure, strong photoluminescent and cathodeluminescent materials can be synthesized to directly impact applications of flat panel displays and memory storage.