TiO2 nanotube arrays were prepared by the electrochemical anodization on pure Ti surfaces, and their photoelectrochemical activity was examined. The photoelectrocatalytic property of Ti/TiO2 electrode was evaluated by the degradation of phenol aqueous solution and compared with its photocatalytic performance. The results demonstrated that the photoelectrocatalytic degradation rate of phenol solution for Ti/TiO2 electrode was higher than its photocatalytic degradation rate. The highest photoelectrocatalytic level could be achieved when the bias potential of 0.6 V was applied on the Ti/TiO2 electrode. The results of EIS analyses revealed that the surface reaction step was the only rate limiting step either for the photocatalytic process or for the photoelectrocatalytic process. The extra bias potential could decrease the values of the electron-transfer resistance and increase the separation efficiency of photogenerated electron-hole pairs
