Modulation of gas sensing properties of chitin-based carbon fibers and Fe3O4/carbon fibers by controlling carbonization temperature

Chitin-based carbon fibers (CCFs) and Fe3O4/CCFs composites are prepared by simple carbonization at different temperatures, which are used as gas sensors for the first time. The effect of carbonization temperatures on the morphology, functional groups, composition, defects, conductivity and gas sensing performance of CCFs and Fe3O4/CCFs was investigated. The formation of Fe3O4 nanoparticles and the conversion of chitin to carbon material during carbonization were also analyzed. It was found that the structure and gas sensing performance of CCFs and Fe3O4/CCFs could be controlled by adjusting carbonization temperature. Furthermore, compared with CCFs, the Fe3O4/CCFs composite showed better gas sensitivity due to the lots of heterojunctions between Fe3O4 and CCFs. The response time and recovery time of the optimized sensor are no more than 30 s and 5 s, respectively. By controlling the carbonation temperature, the controlled CCFs and Fe3O4/CCFs showed good long-term stability, and the degradation of response is less than 10% within three months. What’s more, due to the different gas sensing performances, the CCFs and Fe3O4/CCFs materials prepared at different temperatures were prepared into sensor arrays, which realized the discriminative detection of a variety of target analytes at normal temperature.