Synthesis Of Mn:ZnO Nanofibers/ Small-sized ZnO Nanoparticles And The Study Of Their Gas-sensing Properties For Acetone

Zinc oxide(Zn O) nanofibers doped with manganese(Mn) are synthesized by electrospinning followed by calcinations at 580°C for 150 min. The structure, morphology and element-composition are investigated using X-ray diffraction(XRD), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). The results show that the doping with Mn has obviously effects on Zn O nanofibers. The result of XRD presents that the diffraction peaks are indexed as hexagonal wurtzite structure Zn O and the intensity of characteristic diffraction peaks decrease with the contents of Mn. XPS spectrum indicates that Mn2+ ions exist in divalent state. The Mn doping makes the Zn O nanofibers concave-convex and rough, which is conducive to absorb the gas. The Mn doping plays a significant role in controlling the morphology of the Zn O nanofibers and gas sensitivity of the Zn O nanofibers. As a result, 2.0 wt% Mn-doped Zn O nanofibers can be a promising material for acetone sensors.However, two groups of different Zn O nanoparticles are synthesized by precipitation and precipitation-hydrothermal method and compared their properties, structures and gas-sensing. It can be seen that Zn O nanoparticles of former method synthesis own higher superiority than previous on gas-sensing properties. When a Zn O crystal grew, a surfactant film could form at the interface between solution and Zn O crystal to reduce the interface energy. And the film is floating, and surfactant molecules carrying the growing units will release them at the surface of Zn O single crystal. Therefore, it leads to restrain the growing or agglomeration of Zn O crystal. The results of BET(Brunauer-Emmett-Teller) surface areas and pore size of all samples show that it has bigger BET, larger porosity, lower operating temperature, higher response and shorter response(recovery) time than others for S4. The most probable reasons for this higher performance of gas sensing can be attributed to the unique morphology, the higher crystallinity degree, smaller particle size and larger surface areas. Zn O nanoparticles of S4 are supposedly the origins of this better sensing performance.