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

Carbon nanotube (CNT) has been considered as an ideal channel material for building highly sensitive gas sensors. However, the reported H sensors based on CNT always suffered from the low sensitivity or low production. We developed the technology to massively fabricate ultra-highly sensitive H sensors based on solution derived CNT network through comprehensive optimization of the CNT material, device structure, and fabrication process. In the H sensors, high semiconducting purity solution-derived CNT film sorted by poly9-(1-octylonoyl)-9 H-carbazole-2,7-diyl is used as the main channel, which is decorated with Pd nanoparticles as functionalization for capturing H. 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 H sensors and the very first time to show the sub-ppm detection for H at room temperature. Furthermore, the detection limit concentration can be improved to 89 ppb at 100 °C. The batch fabrication of CNT film H sensors with ultra-high sensitivity and high uniformity is ready to promote CNT devices to application for the first time in some specialized field.