Metal oxide-based nanomaterials are of growing interest owing to their inimitable properties, distinctive performance, and extensive relevance in various fields especially in sensor technology which is a forefront technology because of its prominent role in environmental, industrial, medicinal, and clinical monitoring [1–3]. The extensive applications of nanomaterials as sensing materials are generally considered due to their small size, particular shape, high active surface-to-volume ratio, and high surface activity. These properties make nanomaterials attractive in many fields and especially in sensor technology [4–6]. The small particle size and active surface area of nanomaterial make them capable to detect and investigate sensing analytes in very low concentration, and therefore, nanomaterials are capable to detect and monitor the toxic chemicals and organic pollutants in the environment at very low concentration which is impossible for a sensor with microstructure materials. Therefore, nanomaterials have created a center of interest for their use in chemical sensor fabrication [7, 8].
Zinc oxide (ZnO) (wurtzite structure and large bandgap (3.37 eV) and high exciton binding energy (60 meV)) has been explored for various applications such as fabricating solar cells, sensors, catalysts, etc. ZnO has shown electrical, optical, and sensing properties which are largely dependent on the structural behaviors of ZnO that normally change due to the intrinsic defects which exist in ZnO and cause divergence of ZnO from the stoichiometry [9–11]. However, to expand the applications of ZnO to convene the rising desires for different purposes, there is a need to modify the features of ZnO. Doping of nanomaterials by adding dopant is a well-known and momentous method to alter the features of the nanomaterials. Doped nanomaterials have recently shown excellent properties in various sectors. Doping process increases the surface area and trims down the size of nanomaterials and, as a result, enhances physical and chemical performance of nanomaterials [12–15].
Nowadays, the world is facing environmental pollution problem, and industrial development is mainly responsible for this environmental issue [1–4]. The industrial development is only beneficial if there is intelligent monitoring and proper control of the pollutant discharge to the environment as result of industrial process. These industries discharge various pollutants in gas and liquid form to the environment which are responsible for the environmental pollution [5–7]. One of these pollutants is waste liquid which causes contamination, eutrophication, and perturbation in aquatic life. Waste liquid discharges various organic pollutants to the environment such as hydrazine derivatives, liquid ammonia, dyes, phenols, etc. Hydrazine and its derivatives such phenyl hydrazine are well-known organic pollutant and industrial chemicals which discharge to the environment from their uses in industries and as aerospace fuels [16, 17]. It is one of the great challenges to control these pollutants in the environment and protect the human and aquatic life.
Various techniques and materials have been used to develop susceptible and consistent analytical technique to monitor and protect the environment from toxic nature of phenyl hydrazine. Among these techniques, electro-analytical method using various redox mediators has proven itself as one of the simple and well-organized technique for the recognition of various pollutants [10–12]. Here, we proposed ZnO composite nanorods as a sensor material for the detection of phenyl hydrazine by electrochemical method to overcome the lower over potential of the conventional electrode and show good performance in terms of sensitivity by improving electrochemical oxidations. Metal oxide nanostructures have been used as a redox mediator to overcome the lower over potential of the conventional electrodes used in electro-analytical method and have shown good performance in terms of sensitivity by improving electrochemical oxidations [1–3]. Several reports in literature are related to pure and doped nanomaterials, but there is no literature about electrochemical properties of composite nanomaterials for phenyl hydrazine detection in aqueous phase. To get the utmost profit of the assets of nanomaterial, several methods have been established. However, we have used simple, low-cost, and low-temperature hydrothermal method for the synthesis of composite nanorods.
The aim of this involvement was to prepare, characterize, and investigate chemical sensing performance of composite nanorods based on Ag/Ag2O3/ZnO. The morphological, structural, and optical properties of the prepared nanorods were characterized by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–vis) spectroscopy. Chemical sensing property was studied by simple I-V technique and detected phenyl hydrazine in aqueous solution with high sensitivity and selectivity.