Electrokinetics of nitrite to ammonia conversion in the neutral medium over a platinum surface.

Polycrystalline Pt electrode was employed to selectively convert nitrite ions ([[EQUATION]]) into useful nitrogenous compound through electrochemical reduction reaction in neutral medium. According to adsorptive stripping analysis, the reduction process produced nitric oxide (NO) on the surface of Pt electrode. The spectroscopic test and gas chromatographic studies discovered the presence of ammonia (NH3) in the electrolyzed solution, suggesting the transformation of adsorbed NO into NH3 during the reverse scan. Scan rate dependent investigation was performed to elucidate kinetic information relating to this reaction on Pt surface. From Ep vs scan rate (υ) and jp vs υ (logarithmic plot), it was found that the conversion of [[EQUATION]] ion into NO is an irreversible reaction which relies on the diffusion of [[EQUATION]] ions to electrode surface. The Tafel analysis unveiled that the first electron transfer sets the overall reaction rate, having formal reduction potential, E0' = -0.46 V and standard heterogeneous rate constant, k0 = [[EQUATION]] cm s-1. Reductive transfer coefficient (α) is another kinetics parameter, which was found to be approximate 0.77 from the difference between Ep and Ep/2 of the voltammograms obtained over scan rate range 0.005 V s-1 to 0.250 V s-1, indicating a stepwise process.

Facile fabrication of GCE/Nafion/Ni composite, a robust platform to detect hydrogen peroxide in basic medium via oxidation reaction.

Nickel particles alone can oxidize hydrogen peroxide but confronts extreme stability problem which imparts a barrier to act as sensor. The porous Nafion bed on glassy carbon electrode (GCE) surface provides the sureness of incorporating of Ni particles which was further exploited as an electrochemical sensor for H2O2 detection through oxidative degradation process. The simple electrochemical incorporation of Ni particles along the pores of Nafion improves the stability of the sensor significantly. The oxidative pathway of hydrogen peroxide on GCE/Nafion/Ni was probed by analyzing mass transfer dependent linear sweep voltammograms both in static and rotating modes along with chronoamperometry. An electron transfer step determines the overall reaction rate with k°= 2.72 × 10-4 cm s-1, which is supported by the values of transfer coefficient (ß) in between (0.68-0.75). Sensing performance was evaluated by recording differential pulse voltammograms (DPVs) with the linear detection limit (LOD) of 1.8 µM and linear dynamic range (LDR) of 5-500 µM. Real samples from industrial sources were successfully quantified with excellent reproducibility mark GCE/Nafion/Ni electrode as an applicable sensor.