多孔硅纳米线的形貌控制以及在传感器中的应用

Single crystalline porous silicon nanowires have been reported with both electrical and optical activities. The visible photoluminescence properties of porous silicon nanowires are attributed to the deep quantum confinement effect and/or complex surface states.Combining other fantastic properties of porous silicon nanowire, including large surface area, rich surface chemistry, high chemical reactivity, biodegradability and biocompatibility, it has been considered as an interesting material for potential applications in a wide range of fields, such as optics, electronics, optoelectronics, chemical sensors, energy production and biology. Although significant advancements have been made in both synthesis and applications of porous silicon nanowires, there are still several fundamental challenges for future applications. （a）the mechanism of pore formation is still not fully understood. Further investigation of the growth mechanism will help improve the geometric structures of porous silicon nanowires with specific chemical and physical properties. The current synthesis approaches generally result in porous nanowires with a wide pore size distribution ranging from 2 nm to 20 nm. The narrow pore size distribution, controllable pore depth, pore density and order pore structures are important attributes for many applications such as catalysis and drug delivery. （b）the surface chemistry of porous silicon nanowires remains largely unexplored. Rich surface chemistry can be explored on both silicon and silicon oxide, which can lead to important new functions on the silicon surface for potential applications in the areas of sensors and biological systems. （c） future applications require a thorough understanding of the chemical and physical properties of porous silicon nanowires synthesized from both n- and p-type Si wafers with different dopants, doping levels and crystallographic orientations. Optical and electric properties of porous silicon nanowires have only been studied on several types of silicon wafers. A thorough investigation will be desirable for future applications. In this proposal, we focus on: (1) Systematic study on pore formation mechanism of porous silicon nanowires from different silicon wafers with various doping concentrations, orientations and dopants. The goal is to control pore size, pore depth, pore density and order pore structure, which are expected for many applications. (2) Systematic investigations of physical and chemical properties of porous silicon nanowires, including the effects of surface modification by molecules and nanostructures. (3) Application of porous silicon nanowires for bio-sensor, gas sensor and metal ion detections.

多孔硅纳米线是一种新型多孔材料。其不仅保持原硅衬底的电学性能，而且有宏观硅所不具有的荧光效应。结合其大比表面积、丰富的化学反应活性、生物兼容性和可降解性，其将在光学、电子器件、光电器件、传感器、能源转换和生物领域中获得广泛的应用。但是目前多孔硅纳米钱的进展存在如下局限性：（a）孔的形成机制并没有完全被理解。可控的孔径，孔分布密度和有序度对很多应用都非常重要。（b）多孔硅纳米线的表面化学还没有被广泛研究。（c）从不同衬底所生长的多孔硅纳米线的物理和化学性能缺乏系统研究。本项目将注重于：对不同硅衬底上多孔硅纳米线机制进行系统研究并注重于孔径尺寸、孔深、孔密度和有序度的控制；系统研究多孔硅纳米线的物理化学性能，并研究表面修饰对其性能带来的变化；多孔硅纳米线作为生物传感器，气体传感器和重金属离子检测的应用性研究。

过渡态金属氧化物由于其独特的可变化合价在催化反应中起到催化活性中心、辅助催化剂以及催化剂载体的多重功能。合理调控金属氧化物表面的物理化学性能，不仅仅对催化反应有着显著的提高作用，而且有利于理解催化反应的机制。从而，可以开发出低廉高效的催化剂并且降低催化反应条件和开发绿色催化新工艺。在项目支持之下，研究主要集中在两个方面。之一是发展第一行过渡态金属氧化物在产氢和产氧催化方面的研究。发展一种低成本能批量制备第一行过渡态金属氧化物超薄纳米片的方法，并成功发展为高效和稳定的产氧催化剂。并在此基础上金属氧化物转化为硫化物和磷化物作为双功能的产氢和产氧催化剂。其催化全水分解反应具有高效稳定的性能。研究方向之二在于通过压力调控或者化学刻蚀法达到对二氧化铈纳米材料的表面性质的连续可控调控。在此基础上制备出一种新颖而二氧化铈材料：多孔二氧化铈纳米棒(PN-CeO2)。其具有最大的储氧量(900 μmol-O2/g)。该结构具有优良的低温催化燃烧CO和碳颗粒的性能。其低廉的制备成本有望在柴油机和汽车尾气处理方面有着应用前景。并在基础上发展两种绿色催化新工艺。(1)通过化学制备法形成Pd/Au/PN-CeO2多功能催化实现常温活化氯苯进行碳碳偶联反应。(2)高分散贵重金属分散在PN-CeO2上的催化剂首次实现在最高反应活性下将硝基苯以及其衍生物高度选择性还原成苯胺以及其衍生物。此外，PN-CeO2在模拟生物催化上面具有高效peroxidase性能。并且实现对检测不收温度影响的优越性能。结合其高度灵敏性有望用于疾病诊断。