CNT/TiO2 core-shell structures prepared by atomic layer deposition and characterization of their photocatalytic properties

Abstract

TiO2 film was coated on acid-treated and pristine multiwall carbon nanotubes (CNTs) with different thicknesses by atomic layer deposition at 100°C to form a CNT/TiO2 core-shell structure. The relationship between oxygen-containing functional groups on the surface of CNTs and growth rate of TiO2 film was studied. The saturation growth rate of TiO2 was 0.55Å/cycle for acid-treated CNTs with sufficient durations of pulse time for the precursors of TiCl4 and H2O. The as-prepared TiO2 film was amorphous, and the anatase and rutile phases of TiO2 were obtained by heating to 300°C and 800°C, respectively. The shell thickness of anatase TiO2 on CNTs was a key factor to determine the efficiency of methylene blue (MB) degradation. The thickness of 22nm exhibited the best efficiency of MB degradation due to lower electron-hole recombination rate and higher amount of hydroxyl group generated on the surface of TiO2 after UV irradiation.