ZnO decorated flexible and strong graphene fibers for sensing NO2 and H2S at room temperature

ZnO nanoparticles and flowers, grown on flexible graphene fibers, effectively act as catalysts to sense H2S and NO2 gases at room temperature while fibers assist in transferring the charges. [Display omitted] •Flexible graphene oxide fibers were synthesized using a novel, simple and cost-effective process of wet spinning.•Graphene oxide fibers were chemically modified using hydrothermal assisted chemical reduction.•Flexible rGO fibers can detect minimum of 1.5 and 8 ppm of NO2 and H2S, respectively, at room temperature.•ZnO flowers, grown on reduced graphene oxide fibers, enhanced the sensing performance.•Low detection limit, high selectivity and good stability were observed. Here we present toxic gas fiber-based sensor, operating at room temperature, which is important in wearable electronics for monitoring the environment and human health. Continuous strong and flexible graphene oxide (GO) fibers, with aligned GO sheets are synthesized by transforming a prealigned liquid crystalline GO solution using a wet spinning assembly. GO fibers are chemically reduced (rGO) for imparting resistance-based gas sensing. ZnO decorated rGO fibers (ZrGO) are synthesized by hydrothermal-assisted chemical reduction of GO fibers. ZnO nanoparticles and flowers, grown on ZrGO fibers, provided more surface area for adsorption of gas molecules compared to rGO fibers. Furthermore, ZrGO fibers provided more catalytic sites for gas interactions to enhance the sensing performance. The fiber-sensor can detect minimum levels of 1.5 and 8 ppm of NO2 and H2S gas, respectively. Interestingly, the sensing performance of ZrGO fiber-sensor is increased by 8 and 24-fold for NO2 and H2S, respectively, compared to rGO. The fiber-sensor shows fast recovery for H2S compared to NO2 gas. This work opens a new way for the application of robust, lightweight, cheap, and room temperature chemical sensors, that can detect hazardous gases.