A high-performance flexible NO2 sensor based on WO3 NPs decorated on MWCNTs and RGO hybrids on PI/PET substrates

This study explores the fabrication and evaluation of a flexible NO2 sensor based on a tungsten trioxide nanoparticle-loaded, multi-walled carbon nanotube, reduced graphene oxide hybrid (WO3 NP-loaded MWCNT–RGO) on a polyimide/polyethylene terephthalate (PI/PET) substrate. A viscous gel of the hybrid materials was prepared using α-terpineol. The fabricated sensor exhibits excellent NO2 sensing with a maximum response of 17% to 5 ppm, a limit of detection (LOD) of 1 ppm, and relatively short response/recovery time (7/15 min). The mechanical robustness of fabricated sensor was evaluated systematically at different curvature angles (0–90°) and after various times bending/relaxing (up to 107). The sensor exhibits excellent mechanical flexibility and sensing properties at room temperature without significant performance degradation, even at a curvature angle of 90° and after 106 cycles of the bending/relaxing process. These results and the economical, light-weight and mechanically-robust features indicate that the proposed WO3 NPs–MWCNTs–RGO hybrid sensor is a promising building block for the development of high-performance, flexible NO2 sensors.