Fabrication of TiO2-Pt coaxial nanotube array schottky structures for enhanced photocatalytic degradation of phenol in aqueous solution

Well-aligned TiO2-Pt coaxial nanotube array schottky structures on Ti substrate (TiO2-Pt/Ti) were successfully fabricated by direct current (DC) electrodeposition using anodic aluminum oxide (AAO) templates and the subsequent atmospheric pressure chemical vapor deposition (APCVD) technique. Environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy-dispersive X-ray spectra (EDX), and X-ray diffraction patterns (XRD) indicated that the as-prepared samples were a vertically well-aligned TiO2-Pt coaxial nanotube array, and the outer TiO2 nanotube was anatase with the preferential orientation of (101) plane. The asymmetry of the current-voltage (I-V) curve revealed that a schottky barrier had been formed between TiO2 and Pt. The enhanced separation of photogenerated holes and electrons was demonstrated by surface photovoltage (SPV) and photocurrent measurement. For the degradation of phenol under UV light irradiation, the TiO2-Pt coaxial nanotube array exhibited a much higher photocatalytic efficiency (up to 87%) than did the TiO2 nanotube array, and the kinetic constant of it was 2.3 times as great as that of the TiO2 nanotube array.