Enhanced Ethanol-Sensing Properties Based on Modified NiO-ZnO p-n Heterojunction Nanotubes

NiO/ZnO gas-sensing nanotube materials were prepared by electrospinning. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray detection (EDX) and Brunauer-Emmett-Teller (BET) analysis. The template, PAN (peroxyacetyl nitrate) fibers, was completely removed, as evidenced by the EDX results. The final NiO/ZnO composite materials were composed of hexagonal wurtzite ZnO and cubic NiO and exhibited hollow tubular structures. In the composites, p-n heterojunctions were formed at the interface of NiO and ZnO. The results of gas sensitivity tests showed that the incorporation of NiO considerably improved the gas sensitivity of ZnO to ethanol. When the doping ratio was 0.125 mol/mol, the composites exhibited the highest sensitivity to ethanol (100.92 at 300 degrees C) and showed high selectivity.