Hydrothermal Growth of Zinc Oxide (ZnO) Nanorods (NRs) on Screen Printed IDEs for pH Measurement Application

Abstract

There is considerable interest in nanostructured materials with interdigitated electrodes (IDEs) platforms to detect and monitor the level of various ions in numerous applications. Herein, we report the design and fabrication of IDEs based pH sensor by using hydrothermal growth of ZnO nanorods (NRs). A four-step deposition of ZnO seed layer followed by a hydrothermal treatment lead to the heavily ordered ZnO NRs patterns on the screen printed IDEs. The structural, chemical compositional and electrical properties of the NRs were investigated and examined by using field emission scanning electron microscopy (FeSEM), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) technique and Keithley 4200 semiconductor characterization system respectively. The sensor capacitance and pH were found to be inversely proportional at a working frequency of 1 kHz. The sensor displayed sensitivity of 1.06 nF/pH in the range of pH 4−10.

Machine learning-assisted ammonium detection using zinc oxide/multi-walled carbon nanotube composite based impedance sensors

“…1 . The Copper (Cu) based IDEs structures were screen printed on the fiber epoxy substrate as described in our previous publication 16 . The CIRCAD software-oriented IDE’s design consist of total 18 fingers and provide a total sensing area of 18 × 15 mm 2 for the NH 4 + analytes.…”

“…Metal electrodes coated with metal oxide ion selective active layers have been used for electrochemical sensing of Ammonium (NH 4 + ) 12 – 14 . The enhanced sensitivity of the ZnO is attributed to its surface to volume ratio, electrical conductivity, fast response, wide band-gap (3.37 eV) 15 , large exciton binding energy (60 meV) 16 , and piezoelectricity 17 . Metal oxide functionalization modulates the physicochemical properties of MWCNT thus increasing their ease of dispersion, manipulation, and process ability.…”

“…Conjugating MWCNT with ZnO have shown to reduce the resistance of the sensing material and metal oxide controls the sensing properties 18 – 19 . Sensitivity of the electrodes are influenced by the chemical composition and microstructure morphology of the ZnO/MWCNT active layer 16 , 20 , 21 . After repeated measurements, metal-oxide integrity is degraded, resulting in a gradual decrease in maximum impedance ( ) values over the period of time 22 .…”

The effect of ZnO/ZnSe core/shell nanorod arrays photoelectrodes on PbS quantum dot sensitized solar cell performance

“…Among these oxides, the nanostructures of TiO 2 and ZnO have been extensity and intensively investigated. [42][43][44][45][46][47][48] Although TiO 2 possesses an almost similar band gap and physical properties as those of ZnO, ZnO is the most suitable semiconductor material for photoanode applications. [44][45][46][47][48] One dimensional (1D) ZnO NRs/ NWs exhibit much higher electron mobility (155 cm 2 V À1 s À1 vs. 10 À5 cm 2 V À1 s À1 ) and large exciton diffusion lengths, 49 low sensitivity to UV degradation and long term stability, which means that ZnO is a good alternative material to TiO 2 .…”

“…[44][45][46][47][48] One dimensional (1D) ZnO NRs/ NWs exhibit much higher electron mobility (155 cm 2 V À1 s À1 vs. 10 À5 cm 2 V À1 s À1 ) and large exciton diffusion lengths, 49 low sensitivity to UV degradation and long term stability, which means that ZnO is a good alternative material to TiO 2 . 43 Importantly, the nanostructures and morphology of ZnO can be simply controlled. 50 A 1D ZnO-NR/NW nanostructure provides a direct pathway for the carrier transportation of photoinduced electrons if it is used as a photoanode, which might suppress charge recombination [51][52][53] and hence the efficiency can be improved via the utilization of controllable nanostructured arrays.…”