Gas sensing properties of cotton-based carbon fibers and ZnO/carbon fibers regulated by changing carbonization temperatures

Renewable waste cotton was carbonized into hollow carbon fibers (CFs) and ZnO/CFs composite by a simple carbonization method, which was studied as gas sensing materials for the first time. It was found that the carbonization destroyed the hydrogen bonds within the cotton fiber and changed their microstructure. Meanwhile, high temperature promoted the decomposition of zinc acetate adsorbed to cotton fibers into ZnO, forming lots of heterojunctions between ZnO and CFs, which further improved the gas sensitive properties. Accordingly, the gas sensing properties of CFs and ZnO/CFs were effectively tailored by controlling the carbonization temperatures, achieving the differential response to the target gases. The sensor array based on CFs and ZnO/CFs displayed the rapid, discriminative detection to target gases at room temperature. The response time and recovery time of sensor array are no more than 15 s and 4 s, respectively. The theoretical limit of detection of controlled CFs and ZnO/CFs to CH2O vapor was determined to be 0.45 ppb and 0.17 ppb, respectively. This work extended the application of cotton to the field of gas sensors and enriched the family of gas sensing materials.