A voltammetric carbon paste sensor modified with NiO nanoparticle and ionic liquid for fast analysis of p-nitrophenol in water samples

p-Nitrophenol is a water pollutant with wide applications in petrochemistry, synthesis of dyes and pesticides. The material has however been reported to harmful effects on humans. Accordingly, the present work focused on developing a voltammetric sensor for the determination of p-nitrophenol using a modified carbon paste electrode (CPE) as the working electrode. The modification of the CPE was performed using NiO nanoparticles (NiONPs) and N-hexyl-3-methylimidazolium hexafluorophosphate (NH3MPF6). The resulting sensor showed very good performance in the analysis of p-nitrophenol in water samples. MAP, energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), atomic force microscopy (AFM), UV–vis and field emission scanning electron microscopy (FESEM) analyses confirmed the presence of high-purity NiONPs with a diameter size of 22.0 nm in the modified electrode. It was concluded that NiONPs and NH3MPF6 act as high-performance modifiers in the working electrode matrix and hence create a voltammetric sensor for nano-molar determination of p-nitrophenol. Validation of the applicability of the sensors was performed through the determination of p-nitrophenol in different water samples, and the results indicated respective LDR and LOD values of ~0.01–280 μM and ~7.0 nM for p-nitrophenol.