An efficient sensing system using ion-selective membrane on Ni2O3/rGO nanocomposite for electrochemical detection of nitrate ions

A simple, cost-effective, and efficient Ni2O3/rGO nanocomposites (NNGC) were synthesized by hydrothermal method. The NNG samples exhibited superior electrochemical performance towards the detection of nitrate ions due to the synergistic effect between Ni2O3, and rGO nanomaterials in terms of electroactive surface area. The crystallographic structure of the hybrid nanocomposite examined by X-ray diffraction (XRD) analysis confirms the presence of NiO and Ni2O3 in the nanocomposite. A nitrate ion-selective electrode (NO3--ISE) was developed based on tetradodecylammonium nitrate as an ion exchanger and 2-nitrophenyl octyl ether as a plasticizer. Ion-selective membrane (ISM) coated thin wrinkled layered structure of rGO together with the flaky layered structure of nickel oxide enabled the hybrid material towards electrochemical detection of nitrate ions. Microscopic studies and energy-dispersive X-ray analysis (EDS) spectra confirmed the formation of hybrid nanostructures. Raman and FTIR analysis results further corroborate the formation composite with significant D and G bands in NNG samples, which is in accordance with XRD results. Cyclic Voltammetry measurements were carried out with ISM-NNGC composite to record the changes in the detection of nitrate ions. The prepared ISM-NNGC sensing material showed a significant change in CV peak current in a linear range from 1 ppm to 200 ppm with a limit of detection (LOD) of 23.59 mg/L and sensitivity of 13.3 μA/(mg/L)/cm2. Thus, the ISM-NNGC electrode has a significant potential to be employed for detecting nitrate ions as required in the soil during crop cultivation, according to reproducibility and interference experiments.