Complex-surfactant-assisted hydrothermal synthesis of one-dimensional ZnO nanorods for high-performance ethanol gas sensor

One-dimensional (1D) ZnO nanorods (ZNRs) were synthesized by a facile and effective hydrothermal method using the mixture of sodium dodecyl sulfate (SDS) and polyethylene glycol 400 (PEG400) with a molar ratio of 1:1 as the complex surfactant. The microstructure and morphology were characterized using of X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results demonstrated that the ZNRs are of a single crystal hexagonal wurtzite structure, having a larger length-to-diameter ratio with more regular surface morphology compared with the ZnO products obtained in the presence of only SDS or PEG400. A possible growth mechanism was proposed based the mediation reaction of the complex surfactant. Gas sensing measurements indicated that the ZNRs assisted by the complex surfactant demonstrated excellent ethanol sensing properties at an optimal operating temperature of 300 degrees C, which could be ascribed to their large length-to-diameter ratio, one-dimensional structure, and numerous surface defects of oxygen vacancies.