Investigation of Fiber Laser-Induced Porous Graphene Electrodes in Controlled Atmospheres for ZnO Nanorod-Based NO2 Gas Sensors

This study aims to develop fiber laser-induced graphene (LIG) on polyimide films fabricated under a chamber with air, vacuum, or nitrogen atmospheres. Moreover, ZnO nanorods with a large specific surface area were synthesized by a facile and low-cost hydrothermal method. The ZnO nanorod sensing solution was drop-cast on the LIG surface with porous structures as a sensing layer for the NO2 gas sensor. The characteristics of the LIGs and ZnO nanorods including the surface morphology, elemental content, crystal structure, elemental composition, and chemical bond were investigated. The ZnO gas sensor with LIG electrodes fabricated in air has outstanding sensing performance in a high response (251.71 %), fast response and recovery times (9.5 s and 8.3 s, respectively), and response stability at a NO2 concentration of 1000 ppb. In addition, the ZnO gas sensor with LIG electrodes fabricated in vacuum has an excellent sensitivity. Based on the ZnO nanorod/LIG-based NO2 gas sensor with a high response and sensitivity, the proposed gas sensors can be combined with the Internet of Things and widely used in real-time detecting harmful gases.