N-Doped ZnWO₄ Nanorods Decorated on N-Doped Reduced Graphene Oxide Sheets for Electrochemical Detection of Diphenylamine

In this study, facile simultaneous nitrogen (N)-doped zinc tungstate nanorod-decorated N-doped reduced graphene oxide nanosheets (referred to as N-ZnWO 4 /N-rGO or N-ZWR- x ) were prepared by a one-pot hydrothermal method. Here, urea serves as a structural orienting agent, a source of N, and a buffer to maintain the pH medium throughout the synthesis process. The successful formation of the crystalline nanocomposite was confirmed through X-ray diffraction, Fourier transform infrared spectroscopy, Raman, N 2 physisorption, field emission scanning electron microscopy, field emission transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. The modified electrode (N-ZWR-1/GCE) was also successfully applied for the electrochemical detection of diphenylamine (DPA). It exhibited a dynamic linear range (LR: 0.2–841 μM), a limit of detection (LOD: 0.0083 μM), and an acceptable sensitivity (SEN: 1.4746 μA μM –1 cm –2 ) with good stability. This is due to its large surface area, mass and ionic transport, synergetic effect, and chemical stability. Moreover, this nanocomposite yields admirable reproducibility, storage stability, and selectivity and is also a promising electrocatalyst to quantify DPA in fresh fruit samples in practical analysis.