Hussain Ghulam, Ge Mengchen, Zhao Chuan, Silvester Debbie S
Curtin Institute for Functional Molecules and Interfaces, School of Molecular and Life Sciences, Curtin University, GPO Box U1987, Perth, 6845, WA, Australia.
School of Chemistry, Faculty of Science, The University of New South Wales, Sydney, 2052, Australia.
Anal Chim Acta. 2019 Sep 23;1072:35-45. doi: 10.1016/j.aca.2019.04.042. Epub 2019 Apr 21.
From a safety perspective, it is vital to have fast responding gas sensors for toxic and explosive gases in the event of a gas leak. Amperometric gas sensors have been developed for such a purpose, but their response times are often relatively slow - on the order of 50 seconds or more. In this work, we have developed sensors for hydrogen gas that demonstrate ultra-fast response times. The sensor consists of an array of gold microchannel electrodes, electrodeposited with platinum nanoparticles (PtNPs) to enable hydrogen electroactivity. Very thin layers (∼9 μm) of room temperature ionic liquids (RTILs) result in an extremely fast response time of only 2 s, significantly faster than the other conventional electrodes examined (unmodified Pt electrode, and PtNP modified Au electrode). The RTIL layer in the microchannels is much thinner than the channel length, showing an interesting yet complex diffusion pattern and characteristic thin-layer behavior. At short times (e.g. on the timescale of cyclic voltammetry), the oxidation current is smaller and steady-state in nature, compared to macrodisk electrodes. At longer times (e.g. using long-term chronoamperometry), the diffusion layer is large for all surfaces and extends to the liquid/gas phase boundary, where the gas is continuously replenished from the flowing gas stream. Thus, the current response is the largest on the microchannel electrode, resulting in the highest sensitivity and lowest limit of detection for hydrogen. These microchannel electrodes appear to be highly promising surfaces for the ultrafast detection of hydrogen gas, particularly at relevant concentrations close to, or below, the lower explosive limit of 4 vol-% H.
从安全角度来看，在发生气体泄漏时，拥有对有毒和易爆气体快速响应的气体传感器至关重要。电流型气体传感器就是为此目的而开发的，但其响应时间通常相对较慢——在50秒或更长时间的量级。在这项工作中，我们开发了用于氢气的传感器，其展示出超快的响应时间。该传感器由金微通道电极阵列组成，电沉积有铂纳米颗粒（PtNPs）以实现氢电活性。非常薄的室温离子液体（RTILs）层（约9μm）导致仅2秒的极快响应时间，明显快于所研究的其他传统电极（未修饰的铂电极和PtNP修饰的金电极）。微通道中的RTIL层比通道长度薄得多，呈现出有趣但复杂的扩散模式和特征性的薄层行为。在短时间内（例如在循环伏安法的时间尺度上），与宏观圆盘电极相比，氧化电流较小且本质上处于稳态。在较长时间内（例如使用长期计时电流法），所有表面的扩散层都很大，并延伸到液/气相边界，气体从流动的气流中不断补充。因此，微通道电极上的电流响应最大，从而对氢气具有最高的灵敏度和最低的检测限。这些微通道电极似乎是用于超快检测氢气的极具前景的表面，特别是在接近或低于4体积％H的爆炸下限的相关浓度下。
