Batch Fabrication of Ultrasensitive Carbon Nanotube Hydrogen Sensors with Sub-ppm Detection Limit

Mengmeng Xiao, Shibo Liang, Jie Han, Donglai Zhong, Jingxia Liu, Zhiyong Zhang, Lianmao Peng

Index: 10.1021/acssensors.8b00006

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Abstract

Carbon nanotube (CNT) has been considered as an ideal channel material for building highly sensitive gas sensors. However, the reported H2 sensors based on CNT always suffered from the low sensitivity or low production. We developed the technology to massively fabricate ultra-highly sensitive H2 sensors based on solution derived CNT network through comprehensive optimization of the CNT material, device structure, and fabrication process. In the H2 sensors, high semiconducting purity solution-derived CNT film sorted by poly[9-(1-octylonoyl)-9H-carbazole-2,7-diyl](PCz) is used as the main channel, which is decorated with Pd nanoparticles as functionalization for capturing H2. Meanwhile, Ti contacts are used to form a Schottky barrier for enhancing transferred charge-induced resistance change, and then a response of resistance change by 3 orders of magnitude is achieved at room temperature under the concentration of ∼311 ppm with a very fast response time of approximately 7 s and a detection limit of 890 ppb, which is the highest response to date for CNT H2 sensors and the very first time to show the sub-ppm detection for H2 at room temperature. Furthermore, the detection limit concentration can be improved to 89 ppb at 100 °C. The batch fabrication of CNT film H2 sensors with ultra-high sensitivity and high uniformity is ready to promote CNT devices to application for the first time in some specialized field.