Fabrication of a TiO2/carbon nanowall heterojunction and its photocatalytic ability

A two-dimensional TiO2/carbon nanowall composite material was fabricated by growing carbon nanowalls on a Ti sheet with hot filament chemical vapor deposition, followed by metal–organic chemical vapor deposition using titanium isopropoxide as TiO2 precursor and argon as carrier gas. Scanning electron microscopy showed that TiO2 was uniformly coated on the entire carbon nanowall and a TiO2/carbon nanowall composite was obtained. Raman spectroscopy and X-ray diffraction indicated that the crystal phase of the TiO2 coating was anatase. The asymmetry of the current-voltage plot for the material revealed that a heterojunction was formed between the TiO2 and the carbon nanowall. As a result of this heterojunction, enhanced separation of photogenerated electrons and holes was confirmed by surface photovoltage and photocurrent measurements. The investigation of photocatalytic ability showed that the TiO2/carbon nanowall had a higher photocatalytic activity than TiO2 nanotubes for the degradation of phenol under UV light irradiation.