School of Electrical Engineering, Korea University, Seoul, Korea.
Nanotechnology. 2011 Feb 25;22(8):085502. doi: 10.1088/0957-4484/22/8/085502. Epub 2011 Jan 18.
We have successfully demonstrated a ZnO nanorod-based 3D nanostructure to show a high sensitivity and very fast response/recovery to hydrogen gas. ZnO nanorods have been synthesized selectively over the pre-defined area at relatively low temperature using a simple self-catalytic solution process assisted by a lithographic method. The conductance of the ZnO nanorod device varies significantly as the concentration of the hydrogen is changed without any additive metal catalyst, revealing a high sensitivity to hydrogen gas. Its superior performance can be explained by the porous structure of its three-dimensional network and the enhanced surface reaction of the hydrogen molecules with the oxygen defects resulting from a high surface-to-volume ratio. It was found that the change of conductance follows a power law depending on the hydrogen concentration. A Langmuir isotherm following an ideal power law and a cross-over behavior of the activation energy with respect to hydrogen concentration were observed. This is a very novel and intriguing phenomenon on nanostructured materials, which suggests competitive surface reactions in ZnO nanorod gas sensors.
我们成功地展示了一种基于氧化锌纳米棒的 3D 纳米结构，该结构对氢气表现出高灵敏度和非常快速的响应/恢复。使用简单的自催化溶液工艺和光刻法，在相对较低的温度下，选择性地在预定义区域上合成了氧化锌纳米棒。在没有任何添加剂金属催化剂的情况下，随着氢气浓度的变化，氧化锌纳米棒器件的电导显著变化，对氢气表现出高灵敏度。其优异的性能可以通过其三维网络的多孔结构和高表面积与体积比导致的氢分子与氧缺陷的增强表面反应来解释。结果发现，电导的变化遵循依赖于氢气浓度的幂律。观察到遵循理想幂律的朗缪尔等温线和与氢气浓度的交叉行为的激活能。这是关于纳米结构材料的一个非常新颖和有趣的现象，表明在氧化锌纳米棒气体传感器中存在竞争的表面反应。
