Ultrasensitive and selective hydrazine determination in water samples using Ag-Cu heterostructures-grown indium tin oxide electrode via environmentally benign methods

The present study describes the facile and fast growth of Ag-Cu dendritic nanostructures (D-AgCuNSs) via an environmentally benign electro-electroless deposition method and determination of hydrazine (HZ) in water samples using the resultant D-AgCuNSs-grown indium tin oxide (ITO) electrode. HZ was also successfully determined with the aid of Raman spectroscopy, in which the Raman signal was enhanced 15-fold at D-AgCuNSs in the presence of HZ, in contrast to bare ITO. Initially, CuNSs were grown on the ITO substrates at different applied potentials and the resultant substrates were used in the galvanic displacement reaction with Ag⁺ ions and thereby grown D-AgCuNSs on the ITO substrate. The growth of D-AgCuNSs was followed by scanning electron microscopy (SEM), with respect to time and Ag⁺ concentration. The D-AgCuNSs grown on ITO substrates were further characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive spectroscopy (EDS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. XPS shows that the grown D-AgCuNSs contain zerovalent Ag and Cu. Furthermore, the D-AgCuNSs-modified ITO electrode was utilized for carcinogenic HZ determination and excellent catalytic activity was observed at this electrode, in contrast to bare and Cu-modified ITO electrodes. The amperometric determination was accomplished with a wide range of HZ concentrations, from 20 × 10^-9 M to 50 × 10^-6 M (correlation coefficient of R² = 0.9934). Furthermore, the ITO/D-AgCuNSs electrode detects HZ with the superior selectivity of 2500-fold in the presence of common interfering ions and biological compounds. The lowest limit of detection (0.12 nM (signal-to-noise (S/N) ratio of 3)) and superior sensitivity (3722 μA mM^-1 cm^-2) were achieved toward HZ. In addition, the present sensor was exploited for the determination of HZ in environmental samples and exhibits excellent recovery.