Electrochemical non-enzymatic urea sensing using polyvinylpyrrolidine derived highly electrocatalytic NiCo₂O₄ nanowires

It is highly desirable to use non-enzymatic urea sensors in the clinical, biomedical, agricultural, and food industries. Thus, we have utilized polyvinyl-pyrrolidine (PVP) to tune the shape, particle and electrochemical properties of NiCo₂O₄ nanowires during hydrothermal processes. NiCo₂O₄ nanowires were investigated under alkaline conditions 0f 0.1 M NaOH in relation to their electrochemical activity in detecting urea using PVP. NiCo₂O₄ nanowires were analyzed using different analytical techniques to determine their structure, chemical composition, and crystallinity. The PVP has strongly changed the morphology of NiCo₂O₄ from nanorod to thin nanowires with diameter of 150 nm to 250 nm and the grain size was also reduced. A cubic phase crystal system displayed a typical spinel structure in NiCo₂O₄ nanowires. NiCo₂O₄ nanowires prepared with 50 mg of PVP show a wide linear range of urea concentrations between 1 and 16 mM with a limit of detection of 0.01 mM. In addition to this, the stability, selectivity, and reproducibility of the experiment were all satisfactory. Consequently, NiCo₂O₄ nanowires may perform better because they have a smaller particle size, a smaller grain size, are exposed to more catalytic sites, and have a higher electrical conductivity. The newly developed NiCo₂O₄ nanowire-bussed enzyme-free sensor was also examined for practicality.