Photoelectrochemical characterization and application of direct-grown nanostructured anatase film via hydrothermal reactions

The nanostructured anatase film (NAF), consisted of nanoparticles or nanowires, was fabricated directly on Ti substrate by a two-step hydrothermal approach. The film obtained after the initial hydrothermal reaction was composed of titanate nanotubes or nanowires by regulating the temperature of hydrothermal treatment. Then both the precursor films were readily transformed into corresponding NAFs (nanoparticles and nanowires) via a secondary hydrothermal treatment with 0.05 M HNO3 solution at 120 °C. The NAFs exhibited remarkably high surface photovoltage (SPV) responses and photocurrent densities in UV region, suggesting the enhanced separation ability of photogenerated electrons and holes compared with the compact titania film (CTF) prepared by calcining the TiO2 sol film. The photoelectrocatalytic (PEC) activities of the NAFs were evaluated using phenol as a test substance under UV light irradiation. The kinetic constants of PEC degradation towards phenol with NAF-nanoparticles and NAF-nanowires were 2.2 and 3.4 times as great as the values with CTF, respectively. A significant PEC synergetic effect between the photocatalytic (PC) and electrochemical (EC) processes was also observed.