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Impact of hydrogen concentrations on the impedance spectroscopic behavior of Pd-sensitized ZnO nanorods

Muhammad Kashif1*, Md Eaqub Ali2, Syed M Usman Ali3, Uda Hashim1 and Sharifah Bee Abd Hamid2

Author Affiliations

1 Nano Biochip Research Group, Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis 01000, Malaysia

2 Nanotechnology and Catalysis Research Centre, Universiti Malaya, Kuala Lumpur 50603, Malaysia

3 Department of Electronic Engineering, NED University of Engineering and Technology, Karachi 75270, Pakistan

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Nanoscale Research Letters 2013, 8:68  doi:10.1186/1556-276X-8-68

Published: 11 February 2013


ZnO nanorods were synthesized using a low-cost sol-gel spin coating technique. The synthesized nanorods were consisted of hexagonal phase having c-axis orientation. SEM images reflected perpendicular ZnO nanorods forming bridging network in some areas. The impact of different hydrogen concentrations on the Pd-sensitized ZnO nanorods was investigated using an impedance spectroscopy (IS). The grain boundary resistance (Rgb) significantly contributed to the sensing properties of hydrogen gas. The boundary resistance was decreased from 11.95 to 3.765 kΩ when the hydrogen concentration was increased from 40 to 360 ppm. IS gain curve showed a gain of 6.5 for 360 ppm of hydrogen at room temperature. Nyquist plot showed reduction in real part of impedance at low frequencies on exposure to different concentrations of hydrogen. Circuit equivalency was investigated by placing capacitors and resistors to identify the conduction mechanism according to complex impedance Nyquist plot. Variations in nanorod resistance and capacitance in response to the introduction of various concentrations of hydrogen gas were obtained from the alternating current impedance spectra.

Sol-gel; Pd-sensitized ZnO nanorods; Impedance behavior; Nyquist plot