局域表面等离激元共振材料钨青铜的研究

Based on the advantages of tungsten resources in China and the low cost as well as miniaturization needs of biosensors, combined with the accumulation of research by us, this project will focus on different structures, morphologies and doped point-defects of tungsten bronze MxWO3 and localized surface plasmon resonances (LSPRs). The item of ‘tungsten bronze’ is derived from its specific composition whose color and luster are very similar with bronze. At present, the study of LSPRs for MxWO3 is at the very beginning. In generally, MxWO3 is considered a non-stoichiometric trioxide with perovskite structure. On a different perspective, MxWO3 can also be a dioxide of WO3 doped by M ion. — This is just the starting point of this project. It is our target to design molecular formula, crystal structure, and select the dopants, functional molecules together with the reaction systems to investigate structure, defects, And the relationship between the light response of tungsten bronze under one framework for crystal structure of both WO3 and tungsten bronze. By designing route of a colloid-solvothermal synthesis, it is expected to expand the family of plasmonic materials and, like nanorods of gold to tunning morphology and LSPRs. It is significant to study the relationship between structure and properties of compound semiconductors, especially after doping, to understand the theory of plasmonics. It is very important to develop plasmonic materials used in many applications related with LSPRs in the future, e.g., biosensor.

基于我国钨资源优势及生物传感器低成本、小型化的需求，结合申请人的研究积累，本项目拟开展有望替代纳米金的钨青铜MxWO3及其局域等离激元共振（LSPRs）研究。钨青铜名称来源于其特定组成的色泽，因与青铜相似而得名。目前对其LSPRs特性的研究刚起步。一般认为MxWO3为钙钛矿三元非化学计量氧化物；但换个角度，也可理解为M掺杂二元氧化物WO3—这正是本申请构思的出发点，将WO3与钨青铜融入同一结构框架体系，设计分子式、晶体结构，选择掺杂剂、功能分子和反应体系，研究钨青铜结构、缺陷、形貌、尺寸及载流子浓度特性，并探索光响应与这些原子水平的微细结构的关联性。通过设计胶体-溶剂热合成路径，有望扩大等离激元材料家族并如同金纳米棒一样，基本实现形貌及LSPRs可控。深入研究化合物半导体、特别是掺杂后结构与性能关系，掌握等离激元半导体最前沿理论，对未来材料开发及LSPRs生物传感器研发等应用具有重要意义。

本课题主要开展了两方面工作：掺杂和维度控制。.通过水热-氢热还原法成功合成了一系列六方结构Mo掺杂NaxWO3和KxWO3。当Mo/W (mol.) 为0.01时，Mo掺杂KxWO3的形貌为均一的纤维状纳米颗粒，其直径约为20 nm，并具有最佳的红外光响应性能。.从合成不同维钨青铜角度出发，首次突破了化学反应体系以及原材料的惯性思维和关键要素，采用水热/溶剂热法成功合成出了2D、1D及0D纳米Cs0.3WO3粉体。.以(NH4)10[H2W12O42]·xH2O为W源，CsCl为Cs源，合成2D和1D Cs0.3WO3的反应体系，硫脲、油酸和油胺均起到还原剂和形貌控制剂的双重作用，还原性顺序为硫脲 ≈ 油胺 > 油酸。在2D反应体系中油胺为主要还原剂，而1D反应体系中的主要还原剂则为硫脲。以WCl6为W源，CsOH为Cs源，合成0D Cs0.3WO3时，乙醇不仅起还原剂的作用，还和油酸发生酯化反应生成H2O，进而使WCl6水解形成WO3。并通过“水控释热机制”得到纳米短棒状Cs0.3WO3。.从化学机理来看，以(NH4)10[H2W12O42]·xH2O及WCl6为W源来合成不同维度的纳米Cs0.3WO3时，其中间产物均为WO3。.从形貌机理来看， l合成2D及1D Cs0.3WO3时，在引入Cs+前，前者得到的产物主要为矩形片状的h-(NH4)0.33WO3，后者为多肉状的o-WO3·0.33H2O。前者发生的一种“赋形”竞争机制，而后者发生的是一种“破裂自组装”机制。然而在合成0D纳米Cs0.3WO3时，产物形貌及尺寸随时间的演变过程是一种奥斯瓦尔德熟化过程。.最后，系统研究了三种维度的Cs0.3WO3物理化学性能，随着维度的增加，Cs0.3WO3的近红外吸收光谱逐渐蓝移，且其在近红外区光吸收性能的顺序为2D > 1D > 0D。