Ultrathin Boundary-Less SnO<sub>2</sub> Films with Surface-Activated Two-Dimensional Nanograins Enable Fast and Sensitive Hydrogen Gas Sensing
Zhiwei Li, Yahua He, Jiawei Huang, Zhan Zhu, Yang Yang, Lei Jiang, Shulin Yang, Zhao Wang, Linfeng Fei, Haoshuang Gu, John Wang
Abstract
Fast and reliable semiconductor hydrogen sensors are crucially important for the large-scale utilization of hydrogen energy. One major challenge that hinders their practical application is the elevated temperature required, arising from undesirable surface passivation and grain-boundary-dominated electron transportation in the conventional nanocrystalline sensing layers. To address this long-standing issue, in the present work, we report a class of highly reactive and boundary-less ultrathin SnO 2 films, which are fabricated by the topochemical transformation of 2D SnO transferred from liquid Sn–Bi droplets. The ultrathin SnO 2 films are purposely made to consist of well-crystallized quasi-2D nanograins with in-plane grain sizes going beyond 30 nm, whereby the hydroxyl adsorption and grain boundary side-effects are effectively suppressed, giving rise to an activated (101)-dominating dangling-bond surface and a surface-controlled electrical transportation with an exceptional electron mobility of 209 cm 2 V –1 s –1 . Our work provides a new cost-effective strategy to disruptively improve the gas reception and transduction of SnO 2 . The proposed chemiresistive sensors exhibit fast, sensitive, and selective hydrogen sensing performance at a much-reduced working temperature of 60 °C. The remarkable sensing performance as well as the simple and scalable fabrication process of the ultrathin SnO 2 films render the thus-developed sensors attractive for long awaited practical applications in hydrogen-related industries.