Synthesis, characterization and mechanism of electrospun carbon nanofibers decorated with ZnO nanoparticles for flexible ammonia gas sensors at room temperature

A flexible gas sensor based on ZnO nanoparticles decorated carbon nanofibers (ZnO@CNF) was fabricated by electrospinning, preoxidation, oxidation and carbonization to detect ammonia at room temperature. SEM, TEM, EDS, XPS, XRD and Raman spectra were used to analyze the morphology, structure and composition of the composite. By using electrospinning technology, preoxidation at 220 °C in air, oxidation at 410 °C and carbonization at 600 °C in argon, ZnO@CNF with a diameter of about 200 nm were synthesized. The preoxidation stage includes cyclization, dehydrogenation and oxidation of PAN, while the carbonization was contributed to the decreasing of carbon nanofiber diameter. The gas sensing test results show that ZnO@CNF has higher response, better selectivity than CNF to ammonia at room temperature, while greatly reducing the optimum working temperature of pure ZnO. The flexibility test of ZnO@CNF shows that the composite of metal oxides and carbon materials has a certain degree of flexibility. With the advantages of flexibility, room temperature operation and good response to ammonia, gas sensors based on ZnO@CNF are expected to become a potential candidate for the detection of ammonia in exhaled gas of patients with gastrointestinal diseases or kidney diseases in the future.