Waste cigarette butts-templated synthesis of in-situ graphitic carbon-doped ZnO fibers boosting dual-selectivity NO2/butanone at different temperatures

How to build a dual-selective ZnO-based gas sensor remains challenging due to the fact that the great majority of reported gas sensors were designed to monitor only a single given harmful gas. Herein, discarded cigarette butts were chose as template, and dipped in zinc nitrate solution. Then, the obtained precursors were calcined to synthesize two types of ZnO-based fibers with V-shaped grooves. Among, the fiber component (GC/ZnO, GC being graphitic carbon) calcined at 400 °C composes of 7.02 wt% GC and small nanoparticles, which possesses multistage mesopores, large specific surface area and abundant oxygen vacancies. These factors not only optimize the percentage and state of oxygen species adsorbed in sensing layer, but also expose more active sites and facilitate surface chemical reactions, thereby providing a dual-selective platform for different gases. The GC/ZnO sensor shows high response of 624 for 10 ppm NO2 at 92 °C, and good response of 22.5 for 100 ppm butanone at 170 °C. Also, it has reversible response-recovery, low detection limit, as well as satisfactory stability and humidity resistance. This is the first report on a conductometric sensor that achieves the rapid and accurate detection of above harmful gases. In addition, its temperature-controlled dual-functional sensing mechanism was also analyzed.