Hydrothermal synthesis and gas sensing properties of single-crystalline ultralong ZnO nanowires

Ultralong ZnO nanowires were successfully synthesized by a simple hydrothermal reaction of Zn foil and aqueous Na2C2O4 solution at 140°C. The as-synthesized ZnO nanowires are single crystalline with the wurtzite structure and grow in the [0001] direction. The role of Na2C2O4 in the formation of ultralong ZnO nanowires was investigated, and a possible mechanism was also proposed to account for the formation of the ultralong ZnO nanowires. The gas sensor fabricated on the basis of the ultralong ZnO nanowires showed excellent response characteristics towards NH3 and N(C2H5)3 vapors with low concentration, and its detection limits for NH3 and N(C2H5)3 are about 0.2 and 0.15 ppm at the working temperature of 180°C, respectively. This result suggests potential applications of the ultralong ZnO nanowires in monitoring flammable, toxic and corrosive gases.