Fabrication of TiO₂−Pt Coaxial Nanotube Array Schottky Structures for Enhanced Photocatalytic Degradation of Phenol in Aqueous Solution

Abstract

Well-aligned TiO 2 −Pt coaxial nanotube array schottky structures on Ti substrate (TiO 2 −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 TiO 2 −Pt coaxial nanotube array, and the outer TiO 2 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 TiO 2 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 TiO 2 −Pt coaxial nanotube array exhibited a much higher photocatalytic efficiency (up to 87%) than did the TiO 2 nanotube array, and the kinetic constant of it was 2.3 times as great as that of the TiO 2 nanotube array.