Electrocatalytic reduction of nitrate ions from water using polyaniline nanofibers modified gold electrode

Polyaniline (PANI) nanofibers were electrochemically synthesized on gold electrode using ethanol as soft template by the cyclic voltammetry technique. The PANI nanofibers were characterized by Fourier transform infrared spectroscopy, UV-visible spectroscopy, and scanning electron microscopy. Linear sweep voltammetry was used to investigate electrocatalytic activity of the PANI nanofibers modified electrode toward the reduction of nitrate ions. Results showed that the electroreduction process strongly depends on the applied potential. At the potential value of about -0.8 V vs Ag/AgCl, the electroreduction of nitrate anions to nitrite anions was identified as the rate-determining step of the electroreduction process. In the potential range of -0.8 to -1.0 V, reduction of nitrite to hydroxylamine occurs, followed by the reduction to ammonia. At potentials more negative than -1.0 V, nitrite is directly reduced to ammonia. This study demonstrates the effectiveness of PANI nanofibers modified electrode in the electroreduction of nitrate ions compared to traditional reduction methods.