Polypyrrole (PPy) nanowire modified electrode was prepared and its electrocatalytic behavior towards nitrate reduction was characterized.The electrode surfaces were investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The electrocatalyticactivity of modified graphite electrode was compared with graphite, copper (Cu) and platinum (Pt) electrode. The nitrite concentrationproduced at PPy modified electrode is lower than that at any other electrodes, and its changing tendency is opposite to any other electrodes. ThePPy nanowire modified electrodes were further modified by electrodeposition of Cu. The results show that the produced nitrite concentrationgets higher with the increase of Cu content. The primary experimental results show that the modified electrode has promise use in the removeof nitrate from water.

In this paper, the electrochemical solid-phase extraction (EC-SPE) and amperometric determination of nitrite with polypyrrole (PPy)nanowire modified electrode was reported. The PPy nanowire modified electrode was prepared by template-free method in a mixture ofsodium carbonate and sodium bicarbonate aqueous solution and then conditioned in 0.10M perchlorate acid for 24 h. EC-SPE (preconcentration)of nitrite ions was conducted under the condition of applied potential 0.800V for 300 s. The electroreduction of nitrite wasconducted under the condition of −0.200V for 100 s in the solution of 0.50M H2SO4. The length of nanowires, the temperature and thepH of the test solution, the EC-SPE potential and time have significant effects on the corresponding current. Under a certain condition, therelationship between nitrite concentration and corresponding current density is in good linearity. The determination sensitivity may be variedaccording to the modification parameters. Under the experimental condition, the highest corresponding sensitivity is 55.84 mA/M cm2,and may be further improved by modification the electrode with longer polypyrrole nanowires.

In this paper, the electrochemical behavior of polypyrrole nanowire modified electrode is described. The modified electrode has very goodactivity toward nitrite electroreduction. The electroreduction current is linearly dependent on the concentration of nitrite. The experimentalparameters such as thickness of polypyrrole film, pH, and temperature of the test solution, and scan rate which have effects on the reductioncurrent were examined. The result shows that the electroreduction current increases with the increasing of the polypyrrole film thickness,acidity of electrolyte solution, temperature, and scan rate. The good linearity between the electroreduction current and the concentrationof nitrite makes it possible to determine nitrite concentration accurately in the range of 2.28 × 10−4 to 0.020 M.

The behavior of the polypyrrole (PPy) fibrils modified electrode during hydrogen evolution process is reported. The experimental resultsshow that the hydrogen evolution current density could be significantly increased on the PPy fibrils modified electrode. The hydrogenevolution current density on the modified electrode increases with PPy fibrils getting longer. The hydrogen evolution current density onfibrillar PPy modified electrode is higher than that on electrode modified with PPy with cauliflower form. Redoping PPy fibrils with metalcomplex could further increase the hydrogen evolution current density.

The potentiometric pH responses of novel fibrillar polypyrrole modified electrodes were studied. The effects of the film thickness and thescan rate were examined. The results show that the film thickness has little effect on the potentiometric response for the one-dimensionalgrowth pattern of polypyrrole. This makes it easy to obtain electrodes with the same potentiometric pH response slope. The scan rateinfluences the potentiometric pH response. The highest response slope is 53.0 mV/pH, which was measured on the electrode prepared at ascan rate of 25 mV/s.

Polypyrrole nanowires growing with two-dimensional instantaneous nucleation and one-dimensional growth pattern were realized ongraphite/paraffin composite electrode in phosphate buffer solution.