Detection of Nitrate/Nitrite Using BDD Electrodes Coated with Metal Nano-Catalysts

Abstract

The aim of this work is to investigate the mechanisms of nitrate and nitrite ions electro-reduction in neutral solution at boron doped diamond (BDD) electrodes modified with metal catalyst nanoparticles. The electrode preparation consists in sputtering a thin metal layer onto polycrystalline BDD by a physical vapor deposition method, followed by a dewetting heat treatment at 700 °C under oxygen-free atmosphere. Such a process leads to a stable population of nanosized metal particles as characterized by scanning electron microscopy (SEM) and cyclic voltammetry. Electro-reduction of NO2− and NO3− was characterized both on a bare BDD electrode and on BDD electrodes decorated with platinum-gold, ruthenium-gold and ruthenium nanoparticles in the range 4 to 25 mM. The amperometric response was enhanced by the presence of the nanoparticles, the most sensitive electrode being Pt-Au/BDD and Ru-Au/BDD for nitrite and nitrate ions, respectively.

Keywords

• boron doped diamond
• nano-catalysts
• nitrate/nitrite detection