Use of a Titanium Nitride for Electrochemical Inactivation of Marine Bacteria

A titanium nitride (TiN) electrode with very low resistance and good electrochemical stability was constructed and used for electrochemical inactivation of the marine Gram-negative bacterium Vibrio alginolyticus. Specific resistance of the TiN electrode, which was formed by reactive sput tering, was 1.1 × 10-4 Ω·cm. When cyclic voltammetry of the TiN electrode-attached V. alginolyticus cells of 4.2 × 105 cells/cm2 was carried out at a scan rate of 20 mV/s in seawater, an anodic peak current appeared around 0.68 V vs Ag/AgCl. In all, 98.7% of V. alginolyticus cells attached onto the electrode were inactivated by applying a potential of 0.8 V vs Ag/AgCl in seawater for 30 min. Changes in pH and chlorine concentration were not observed at 0.8 V vs Ag/AgCl. The TiN electrode was oxidized by applying potential of a 0.8 V vs Ag/AgCl and passivated by formation of TiO2 onto the electrode surface. The TiO2 thin layer formed on the TiN electrode surface did not impede electrochemical inactivation of marine bacteria. These results show that the TiN electrode can be used as an electrode for electrochemical inactivation of marine bacteria.