Data from: Hydrogen sensing enhancement of zinc oxide nanorods via voltage biasing

The capability of zinc oxide (ZnO) as hydrogen sensing elements has been pushed to its limits. Different methods have been explored to extend its sensing capability. In this paper, we report a novel approach which significantly improves the hydrogen sensing capability of zinc oxide by applying a bias voltage to ZnO nanorods as the sensing elements. Zinc oxide in the form of aligned nanorods were first synthesized on an Au-coated Si(111) substrate using a facile method via the galvanic-assisted hydrothermal process. The sensing performance of the zinc oxide nanorods was investigated in respond to the applied biasing voltage. It was found that the sensitivity, response time as well as detection limit of the ZnO sensing elements were dramatically improved with increasing bias voltage. A 100% increment in sensing response was achieved for detection of 2000 ppm hydrogen gas when the bias voltage was increased from -2 V to -6 V with 70% reduction in response and recovery times. This remarkable sensing performance is attributed to the reaction of hydrogen with chemisorbed oxygen ions on the surface of the ZnO nanorods that served as the electron donors to increase the sensor conductance. Higher reverse bias voltages sweeps the electrons faster across the electrodes. This shortened the response time and, at the same time, depleted the electrons in the sensor elements and weaken oxygen adsorption. The oxygen ions could then be readily removed by hydrogen, leading to higher sensitivity of the sensors. This, therefore, envisage a way for high-speed hydrogen gas sensing with high detection sensitivities.

氧化锌（ZnO）作为氢传感元件的性能已逼近其极限，学界已探索多种策略以拓展其传感能力。本文报道一种新颖方法：通过对作为传感元件的氧化锌纳米棒施加偏置电压，可显著提升其氢传感性能。研究团队首先采用简便的原电池辅助水热法，在金镀膜硅(111)基底上合成了定向排列的氧化锌纳米棒。随后针对施加的偏置电压，探究了氧化锌纳米棒的传感性能。结果发现，随着偏置电压升高，氧化锌传感元件的灵敏度、响应时间与检测限均得到显著改善：当偏置电压从-2 V提升至-6 V时，针对2000 ppm氢气的检测响应提升了100%，同时响应与恢复时间缩短了70%。该优异传感性能可归因于氢气与氧化锌纳米棒表面化学吸附氧离子的反应——此类氧离子作为电子供体可提升传感器电导。更高的反向偏置电压可加速电子在电极间的迁移，缩短响应时间，同时耗尽传感元件内的电子并削弱氧吸附，使得氢气可更轻易地脱除氧离子，进而提升传感器灵敏度。因此，本研究为实现高灵敏度、高速氢气传感开辟了可行路径。