Fabrication and characterization of highly sensitive and selective sensors based on porous NiO nanodisks

Herein, we report the synthesis, characterization and alcohol sensing applications of highly porous NiO nanodisks (NiO-NDs). The nanodisks were synthesized via hydrothermal method and were characterized in detail to examine their morphological, structural, compositional, crystalline and optical properties through different techniques. The typical thickness of the nanodisks was in the range of 15 ± 5 nm while the diagonal dimensions were about 100 ± 20 nm. The electrochemical sensing performances of the synthesized NiO-NDs for different alcohols were subsequently measured by fabricating carbon paste modified electrodes in alkaline medium (CPE/NiO-NDs). For excellent sensing results, the fabricated CPE/NiO-NDs electrodes were standardized for NiO composition, scan rate, the concentration of functional electrode materials etc. Various electroanalytical techniques such as cyclic voltammetry, linear sweep voltammetry and amperometry were employed at different applied potentials to examine the sensing performances of the fabricated sensors. The maximum sensitivity was recorded for CPE/NiO-NDs with 15% NiO composition after 40 scan rates in 0.15 M of NaOH/0.1 M KCl supporting electrolyte. The detailed sensing studies confirmed that the CPE/NiO-NDs (15%) electrode was more sensitive for ethanol as compared to other alcohols. Experimental limit of detection (LOD) and linear dynamic range (LDR) were observed to be 1 mM and 1-47 mM, respectively whereas; the sensitivity of the CPE/NiO-NDs (15%) electrode was recorded to be 3.51 μA mM−1 cm−2 towards ethanol.