Large-Area Printed Oxide Film Sensors Enabling Ultrasensitive and Dual Electrical/Colorimetric Detection of Hydrogen at Room Temperature
Henok Getachew Girma, Ka Yeon Ryu, Xiaowu Tang, Gi‐Seong Ryu, Rixuan Wang, Yejin Kim, Jae Ook Choi, Hye Min Lee, Seungju Jeon, Seo‐Hyun Jung, Jong Mok Park, Yu Jin Jung, Jin Young Kim, Do‐Hoon Hwang, Yong‐Young Noh, Bogyu Lim, Hoyoul Kong, Se Hyun Kim
Abstract
Commercial hydrogen (H 2 ) sensors operate at high temperatures, which increases power consumption and poses a safety risk owing to the flammable nature of H 2 . Here, a polymer–noble metal–metal oxide film is fabricated using the spin-coating and printing methods to realize a highly sensitive, low-voltage operation, wide-operating-concentration, and near-monoselective H 2 sensor at room temperature. The H 2 sensors with an optimized thickness of Pd nanoparticles and SnO 2 showed an extremely high response of 16,623 with a response time of 6 s and a recovery time of 5 s at room temperature and 2% H 2 . At the same time, printed flexible sensors demonstrate excellent sensitivity, with a response of 2300 at 2% H 2 . The excellent sensing performance at room temperature is due to the optimal SnO 2 thickness, corresponding to the Debye length and the oxygen and H 2 spillover caused by the optimized coverage of the Pd catalyst. Furthermore, multistructures of WO 3 and SnO 2 films are used to fabricate a new type of dual-signal sensor, which demonstrated simultaneous conductance and transmittance, i.e., color change. This work provides an effective strategy to develop robust, flexible, transparent, and long-lasting H 2 sensors through large-area printing processes based on polymer–metal–metal oxide nanostructures.