MOF-derived SnO2@ZnO ethanol sensors with enhanced gas sensing properties

In this work, we synthesized Sn@Zn MOF composites with different Sn/Zn molar ratios by one-step solvothermal method, and then calcined to obtain SnO2@ZnO composites with Zinc oxide (ZnO) nanoparticles grown on the surface of stannic oxide (SnO2) quadrangular prism. The structure, morphology and gas sensing performance of prepared products were investigated by XRD, SEM, XPS, TEM and gas sensing measurements. Compared with pure SnO2, the optimum operating temperature of SnO2@ZnO composites was reduced from 200 °C to 160 °C. Among them, the gas sensor fabricated by the sample SnO2@ZnO0.33 had a response of up to 51 for 100 ppm ethanol at 160 °C, which is 5 times the response of pure SnO2, and its response-recovery time (37–44 s) is acceptable. The enhanced gas sensing mechanism of SnO2@ZnO composite materials was also discussed, which may be due to the further increase of barrier height caused by Fermi level equilibrium and band bending at the heterojunction interface.