Department of Chemistry, University of California Irvine, CA 92697, USA.
Small. 2010 Jul 5;6(13):1422-9. doi: 10.1002/smll.201000145.
The properties of a single heated palladium (Pd) nanowire for the detection of hydrogen gas (H(2)) are explored. In these experiments, a Pd nanowire, 48-98 microm in length, performs three functions in parallel: 1) Joule self-heating is used to elevate the nanowire temperature by up to 128 K, 2) the 4-contact wire resistance in the absence of H(2) is used to measure its temperature, and 3) the nanowire resistance in the presence of H(2) is correlated with its concentration, allowing it to function as a H(2) sensor. Compared with the room-temperature response of a Pd nanowire, the response of the heated nanowire to hydrogen is altered in two ways: First, the resistance change (DeltaR/R(0)) induced by H(2) exposure at any concentration is reduced by a factor of up to 30 and second, the rate of the resistance change - observed at the beginning ("response") and at the end ("recovery") of a pulse of H(2) - is increased by more than a factor of 50 at some H(2) concentrations. Heating nearly eliminates the retardation of response and recovery seen from 1-2% H(2), caused by the alpha --> beta phase transition of PdH(x), a pronounced effect for nanowires at room temperature. The activation energies associated with sensor response and recovery are measured and interpreted.
研究了单根钯（Pd）纳米线用于氢气（H(2)）检测的特性。在这些实验中，一根长 48-98 微米的 Pd 纳米线并行执行三个功能：1）焦耳自加热将纳米线温度升高高达 128 K，2）在没有 H(2)的情况下使用 4 接触线电阻来测量其温度，以及 3）纳米线在 H(2)存在下的电阻与其浓度相关联，使其可以作为 H(2)传感器。与 Pd 纳米线在室温下的响应相比，加热纳米线对氢气的响应有两种变化方式：首先，任何浓度下暴露于 H(2)所引起的电阻变化（DeltaR/R(0)）减小了 30 倍，其次，在 H(2)脉冲的开始（“响应”）和结束（“恢复”）处观察到的电阻变化率 - 在某些 H(2)浓度下增加了 50 倍以上。加热几乎消除了 PdH(x)的 alpha --> beta 相转变引起的 1-2% H(2)中响应和恢复的滞后，这是室温下纳米线的一个显著效应。测量并解释了与传感器响应和恢复相关的激活能。
