A comprehensive study on electrocatalytic current of urea oxidation by modified carbon paste electrode with Ni(II)-clinoptilolite nanoparticles: Experimental design by response surface methodology

In this work, the electrocatalytic oxidation of urea in alkaline medium was studied by the modified carbon paste electrode (CPE) with clinoptilolite nanoparticles (CNP) ion-exchanged with Ni(II) cations (Ni(II)-CNP/CPE) in cyclic voltammetry technique (CV). X-Ray diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray spectroscopy (SEM-EDX) and FT-IR methods were used for characterization of the samples. Interactions of the experimental factors were studied by designing the experiments via response surface methodology (RSM). The proposed electrode showed reasonable electrocatalytic effect in oxidation of urea, so the oxidation of urea on surface of the proposed electrode had lower overvoltage about 700 mV less positive than the conventional Pt electrodes. Surface coverage concentration of the electrode was about 3.97 x 10(-6) mol Ni(OH)(2) cm(-2). The apparent charge transfer rate constant and the cathodic charge transfer coefficient for the modified electrode were respectively obtained as 0.39 s(-1) (ks) and 0.18 (alpha(c)) in the absence of urea, while alpha(a) was 0.7 in the presence of urea.