Chemical Sensors Based on Electrodeposited Metal Nanowires

分析和表面化学项目支持加州大学欧文分校的Reginald Penner教授的这一项目，该项目涉及各种金属纳米线的合成及其作为化学传感器的用途评估。 纳米线是通过电化学步骤装饰的程序来制造的，这已经被证明用于钼以制造长度高达150微米、横截面为半圆柱形并且可从其上制备的表面移除的线。 直径在10到500纳米之间的高纵横比纳米线可以在阶梯状石墨表面上进行尺寸选择性制备，转移到聚苯乙烯膜上，然后附着电极。 导电性类似于块状金属。 作为传感器，纳米线通过将金属表面暴露于分析物而起作用，同时测量纳米线的电导率。 例如，钼丝与氧反应，在制成金属氧化物涂层时产生显著但稳定的电导率下降。 未来的研究方向包括贵金属纳米线的制备。 一个有待测试的合成方案是通过汞合金制备金属丝。 然后，传感器将被制造与纳米线，无论是裸金属或金属氧化物覆盖层。 将分析物浓度与金属纳米线电导率的变化联系起来的物理模型尚待确定。 新一代化学传感器将有广泛的应用，从生物医学到污染控制。 随着纳米技术从实验室走向实际应用，器件的合成必须得到改进;更快，更便宜，更好。 存在对纳米线的可靠且有效的合成的巨大需求。 电化学台阶装饰是电化学基础知识的应用，具有在清洁石墨表面上自然发生的已知台阶特征。 石墨为电化学生长的金属线的受控生长提供模板。 纳米线具有相对于线中的金属原子数量而言非常高的表面积。 由于这个原因，导电性取决于附着在表面的分子的数量和种类，使纳米线成为新一代传感器的逻辑组件。

The Analytical and Surface Chemistry Program supports this project by Prof. Reginald Penner at the University of California at Irvine on the synthesis of nanowires of various metals and an evaluation of their use as chemical sensors. Nanowires are to be fabricated by the procedure of electrochemical step decoration, which has been demonstrated for molybdenum to make wires that are up to 150 micrometers in length, hemicylindrical in cross-section, and removable from the surfaces on which prepared. The high-aspect ratio nanowires, with diameters ranging from 10 to 500 nanometers, can be prepared size-selective on stepped graphite surfaces, transferred to a polystyrene film, and then electrodes attached. The conductivity is similar to that of bulk metal. As a sensor, the nanowires function by exposure of the metal surface to an analyte while measuring the electrical conductivity of the nanowires. For example, molybdenum wires are reactive with oxygen yielding a substantial, but stable drop in conductivity as a metal oxide coating is made. The future research directions include preparation of noble metal nanowires. One synthetic scheme to be tested is metal wire preparation via a mercury amalgam. Then, sensors are to be fabricated with nanowires, either bare metal or with a metal oxide overlayer. Yet to be determined is the physical model to connect analyte concentration with the change in metal nanowire conductivity. New generation chemical sensors will have a wide range of applications, from biomedical to pollution control. As nanotechnology moves from the laboratory to practical applications, the synthesis of devices must be improved; faster, cheaper, better. There is a great need for reliable and efficient synthesis of nanowires. Electrochemical step decoration is an application of fundamental knowledge of electrochemistry with the known step features naturally occurring on a clean graphite surface. The graphite provides a template for the controlled growth of an electrochemically grown metal wire. The nanowires have an extremely high surface area in relation to the number of metal atoms in the wire. For this reason, electrical conductivity depends upon the number and kind of molecules attached to the surface, making nanowires a logical component of new generation sensors.