Structural properties and surface chemistry of nano structured electroactive materials

纳米结构过渡金属氧化物体系，如金属尖晶石氧化物，因其在广泛的电化学反应中的应用和作为电池电极材料和燃料电池氧还原催化剂的应用，以及作为有趣的磁性材料、传感器和电容器而重新引起人们的关注。在这项研究计划中，我们将利用我们在电化学、表面科学和材料表征方面的专业知识来识别、量化和了解过渡金属氧化物(如axb3-xO4、axByzzOq)表面的活性中心的作用，并研究这些金属阳离子的氧化还原特性在电化学反应中的作用，以建立可用于预测其性能的趋势和指导方针。我们计划的短期目标是识别、量化和了解过渡金属(M)-氧化钴尖晶石(MxCo3-xO4)薄膜中活性中心的作用，以及制备方法、热处理和电极历史对材料结构、表面化学和相关性能的影响。这些材料将用于我们的第一次原位X射线吸收光谱(XAS)研究，更具体地说，是原位X射线吸收近边结构(XANES)。使用这些材料，我们将确定它们的主体结构，包括阳离子的类型和它们的化学环境，以及可能在材料表面的相分离，确定它们如何形成和影响电化学反应。一旦获得了明确的认识，将使用我们的方法来研究额外掺杂剂在这些材料中的作用，以系统地形成(M)(M‘)CoO4尖晶石，例如，M，M’=铜，镍，锰，铁。基于它们的组成和结构，这些氧化物材料在多相催化、电极、气体和葡萄糖传感器、燃料电池和与生产氢燃料相关的光驱动电解水等领域得到了应用。

Nanostructured transition metal oxide systems such as metal spinel oxides have received renewed attention due to their demonstrated usefulness for a wide range of electrochemical reactions and recent applications as electrode materials in batteries and as oxygen reduction catalysts in fuel cells, but also as interesting magnetic materials, sensors, and capacitors. In this research program, we will use our expertise in electrochemistry, surface science and materials characterization to identify, quantify and understand the role of active sites at the surface of transition metal oxides (such as AxB3-xO4, AxByCzOq) and study the role that the redox properties of these metal cations have in electrochemical reactions to establish trends and guidelines that can be employed to predict their performance. The short terms objectives of our program are to identify, quantify and understand the role of active sites in transition metal (M)-cobalt oxide spinel (MxCo3-xO4) thin films with M = Cu, Ni and Fe and x values ranging from 0 to 1, as well as the effects of the preparation method, annealing and electrode history on the material's structure, surface chemistry and relevant properties. These materials will be used to perform our first in situ X-ray absorption spectroscopy (XAS) studies, more specifically in situ X-ray absorption near-edge structure (XANES). Using these materials, we will identify their bulk structures including types of cations and their chemical environments, as well as possible phase segregation at the surface of the materials, identifying how they form and affect electrochemical reactions. Once, a clear understanding is obtained the role of additional dopants in these materials will be investigated using our methodology to form (M)(M')CoO4 spinels with, for example, M, M' = Cu, Ni, Mn, Fe, in a systematic way. Based on their composition and structure, these oxide materials find applications in areas such as heterogeneous catalysis, electrode, gas and glucose sensors, fuel cells and photo driven electrolysis of water relevant to the production of H2 fuel.**