Synthesis and electrochemical properties of TiO2/nanodiamond nanocomposite

Undoped nanodiamond (ND) powders were coated with TiO2 through two steps: firstly Ti lay was deposited by cycled vacuum-feeding chemical vapour deposition from gaseous TiCl4/H2, and secondly an oxidation treatment was carried out in air. The structure and the morphology of the TiO2/ND composite were characterized by Raman spectrum and transmission electron microscopy. The electrochemical properties of the TiO2/ND powder electrode in a solution containing [Fe(CN)6]3−/4− or NO2− were investigated. The results showed that a continuous coating consisting of Ti nanoparticles covered on ND particle after the deposition. The following oxidation at 500 °C resulted in the formation of anatase phase TiO2 nanoparticles of about 10 nm. The electrochemical results confirmed that the TiO2/ND powder electrode exhibited higher electrochemical activity than the pristine ND electrode, especially higher catalytic ability toward the oxidation of nitrite anions. Moreover, the TiO2/ND powder electrode presented fast response towards nitrite oxidation with a detection limit of 0.55 µM and a linear range of 0.05 to 1.0 mM.