The enhanced PC and PEC oxidation of formic acid in aqueous solution using a Cu-TIO2/ITO film

The photocatalytic (PC) and photoelectrocatalytic (PEC) activity of Cu-TiO2/ITO films for degrading formic acid in aqueous solution was investigated in this study. Compared with a TiO2/ITO film, the degradation efficiency of formic acid on the Cu-TiO2, films increased markedly in both the PC and PEC oxidation processes. However, it was found that the photodeposited Cu metal on the Cu-TiO2, films could electrochemically dissolute during the PEC reaction, while an electrical bias with the voltage higher than 1.48V was applied. It is believed this is a common problem occurred for several metals deposition on the TiO2 films, which results in a poor stability of the metal-deposited TiO2 electrode in PEC processes. To improve the stability of the Cu-TiO2, electrode, an alternative process between PC and PEC reactions was investigated. It was found that the dissolute Cu metal during the PEC process seas re-deposited on the Cu-TiO2 film again during the PC process. The experiments with repeated runs demonstrated that this alternative process: could not only overcome the loss of Cu, but also enhance the PEC oxidation efficiency of the Cu-TiO2 film. (C) 2004 Elsevier Ltd. All rights reserved.