Efficient photochemical water splitting and organic pollutant degradation by highly ordered TiO2 nanopore arrays

We synthesized highly ordered TiO2 nanopore arrays (TNPs) with controllable pore size and good uniformity by anodization at low temperature in fluorinated dimethyl sulfoxide (DMSO) solution with a post-sonication treatment. TNPs possess excellent separation and transport properties of photo-generated electron/hole pair and hence reveal enhanced photocurrent response and photochemical properties for water splitting and organic compound degradation. The TNPs present maximum photo-conversion efficiency for water splitting of 0.28% under AM1.5 irradiation. This value compares favorably with a maximum photo-conversion efficiency of 0.21% for TiO2 nanotube arrays (TNAs) under the same conditions. When illuminated with 1.0 mW cm(-2) UV light, the maximum photo-conversion efficiency can be increased to 22% for TNPs, which is 5% higher than TNAs. The kinetic constant of photoelectrocatalytic (PEC) degradation of methyl orange (MO) for TNPs is found to be 1.27 times as high as that for TNAs when biased at 0.5 V. The visible light response of TNPs might be further improved by relevant surface modification technology. (C) 2008 Elsevier B.V. All rights reserved.