Effect of different electrodes on the transport properties of ZnO nanofibers under humid environment

Abstract

Relative humidity (RH) sensing properties of zinc oxide nanofibers (ZNF), synthesized using electrospinning technique, were studied by impedance spectroscopy. RH sensors were fabricated with two different electrodes (Au and Ni) using lithography on top of the nanofibers deposited on Si/SiO2 substrate. Compare with the Ni electrode sensor, Au electrode sensor exhibits larger sensitivity and quicker response/recovery. Capacitance, electrical conductivity and electrical modulus were studied at 40%-90% RH as a function of the frequency of the applied AC signal in the frequency range of 10−2-106 Hz. The corresponding response and recovery times are 3s and 5s for Au, and 6s and 10s for Ni electrode sensor, respectively. The sensors exhibited a reversible response with small hysteresis of less than 4% and 12% for Au and Ni electrodes respectively. Stability of the sensor device with Au electrode was confirmed by testing the device for 13 days. The excellent sensing characteristics and comparison of sensors with different electrode materials may offer an effective route for designing and optimizing RH sensors.

Recent Advances in the Synthesis of Metal Oxide Nanofibers and Their Environmental Remediation Applications

“…In the case of electrospinning from an inorganic precursor, the high-temperature calcination process causes a reduction in the diameter of the fibers as the sacrificial polymer template is selectively removed. Consequently, by reason of calcination, the resultant nanofibers become fragile owing to their thinner cross sections and the thermomechanical stress generated from the reduction in size [105,[120][121][122]. There have been many efforts made in recent times towards the production of metal oxide nanofibers by the electrospinning route.…”

Study of electric conduction mechanisms in bismuth silicate nanofibers

“…Different type of interfaces can play a vital role in our conduction mechanism e.g. interface region between nanofibers, interface between nanofibers and contact region and interface of nanofibers with the environment 35 .…”

Silanization of ZnO nanofibers by tetraethoxysilane

“…29 This solution was also magnetically stirred at room temperature (at 250 rpm) for 1 h to have a homogeneous mixture of PVP in ethanol. This solution was magnetically stirred at room temperature at 250 rpm for 40 min.…”

“…PVP weighing 1.5 g was dissolved in 8 mL of ethanol in a separate beaker. 29 This solution was also magnetically stirred at room temperature (at 250 rpm) for 1 h to have a homogeneous mixture of PVP in ethanol. These two solutions namely zinc acetate dihydrate in water and PVP in ethanol were mixed and continuously stirred magnetically at a speed of 250 rpm for 2 h. As a result, a viscous homogeneous solution of ZnO/PVP was obtained.…”