Preparation and characterization of titanate nanotubes/carbon composites

Titanate nanotubes/carbon composites(TNT/CCs) were synthesized by allowing carbon-coated TiO2 (CCT) powder to react with a dense aqueous solution of NaOH at 120 °C for a proper period of time. As-prepared CCT and TNT/CCs were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectrometry. The processes for formation of titanate nanotubes/carbon composites were discussed. It was found that the TiO2 particles in TiO2-carbon composite were enwrapped by a fine layer of carbon with a thickness of about 4 nm. This carbon layer functioned to inhibit the transformation from anatase TiO2 to orthorhombic titanate. As a result, the anatase TiO2 in CCT was incompletely transformed into orthorhombic titanate nanotubes upon 24 h of reaction in the dense and hot NaOH solution. When the carbon layers were gradually peeled off along with the formation of more orthorhombic titanate nanotubes at extended reaction durations (e.g., 72 h), anatase TiO2 particles in CCT were completely transformed into orthorhombic titanate nanotubes, yielding TNT/CCs whose morphology was highly dependent on the reaction time and temperature.