Ta3N5 nanotubes and -rods: doping, band-gap engineering and stabilization (co-catalysis)

目前的研究项目是基于太阳能的水电解，使用一维（1D）形式的潜在高活性半导体作为光吸收剂和能量转换器，直接从水中产生氢和氧。由一维纳米结构X:Ta3N5光阳极（X：改性）组成的光阳极将作为一种新型的光催化剂进行研究。由于相对合适的小带隙（~2.1 eV）和带边位置，Ta3N5将作为进一步修改的平台。这项工作的关键创新将是开发理想结构和掺杂的Ta3N5纳米管/纳米棒，通过体掺杂和表面催化剂进行修饰，以大幅提高其效率。这里使用的纳米结构是基于低成本的阳极自组织工艺或水热方法，这种纳米管/纳米棒具有高表面积、定向电荷传输、按载流子扩散长度顺序排列的尺寸以及原位嵌入掺杂物质的能力（带隙工程）。此外，为了缓解光腐蚀问题，X:Ta3N5结构将采用新开发的电荷转移催化剂，如NiFe层状双氢氧化物层来装饰。最近，我们的团队开发了一种方法，用合适的催化剂修饰纳米级Ta3N5结构，获得了10倍的水分解效率，以及W掺杂Ta3N5的第一个结果（将带隙降低到1.75 eV）。这些初步的发现，将在拟议的项目中，通过研究材料的性能作为生长形态的功能，掺杂，优化自排列的纳米管/纳米棒Ta3N5及其新型共催化剂的稳定性，系统地跟进。

The present research project tackles solar-based photoelectrolysis of water, using potentially highly active semiconductors in one dimensional (1D) form as the light absorber and energy converter to directly produce hydrogen and oxygen from water. Photoanodes consisting of a 1D nanostructured X:Ta3N5 photoanode (X: modified) will be investigated as a new category of photocatalysts. Due to the relatively suitable small band gap (~2.1 eV) and band edge positions, Ta3N5 will serve as a platform for further modification. Key innovation in this work will be the development of ideally structured and doped Ta3N5 nanotubes/nanorods, modified by bulk doping and surface catalysts to drastically increase their efficiency. The nanostructures used here are based on low cost anodic self-organization processes or on a hydrothermal method, such nanotubes/nanorods have the intrinsic key advantages of a high surface area, directional charge transport, dimensions in the order of charge carrier diffusion length, and the ability to in-situ embed doping species (band-gap engineering). Additionally, in order to alleviate the photocorrosion problem, X:Ta3N5 structures will be decorated with newly developed charge transfer catalysts, such as NiFe layered double hydroxide layers. Recently, our group developed an approach to grow a nanoscale Ta3N5 architecture decorated with suitable catalysts to obtain a 10-fold increase in water splitting efficiency as well as first results on W doped Ta3N5 (shifting the band gap down to 1.75 eV). These preliminary findings will, within the proposed project, be systematically followed up - by studying the properties of the material as a function of growth-morphology, doping, and optimization of self-arranged nanotubular/nanorod Ta3N5 and its stabilization by novel co-catalysts.