Room temperature selective sensing of aligned Ni nanowires using impedance spectroscopy

Abstract

Room temperature gas sensing behavior of arrayed one-dimensional (1D) nickel nanowires (Ni NWs) are investigated using impedance spectroscopy. Ni nanowires synthesized via electrochemical deposition method based on anodic aluminum oxide (AAO) templates. Their structural characterization verified by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) analysis. Impedance spectroscopy as an essential technique utilized to understand the mechanism of gas interaction with the wires through the changes in their electronic behavior. Bode and Nyquist plots with the real and imaginary impedances are plotted versus frequency range of 500 Hz to 2 MHz at different relative humidity values (varying from 30% to 70%) and ethanol vapor concentrations (varying from 2 to 18 ppm). The equivalent circuits are proposed and simulated for impedance responses to both humidity and ethanol vapors. The impedance plots indicate the increase in resistance of the aligned nanowires at low frequencies by the adsorption of water and ethanol molecules.