Clean Technology 2011
K.R. Wu, C.H. Hung, C.W. Yeh, J.C. Sun, C.J. Hsu
National Kaohsiung Marine University, TW
TiO2, Cu2O, heterojunction, photocatalytic degradation
In this study, a p/n-type photoelectrocatalytic (PEC) cell was used to enhance the photocatalytic (PC) and PEC activities towards the degradation of methylene blue (MB) solution under ultraviolet (UV) irradiation. The PEC cell consists of a p-type Cu2O (Eg=2.2 eV) electrode and a wide band gap n-type TiO2 (Eg=3.2 eV) thin film of which was electrically connected via a home-made potentiostat. The p-type Cu2O electrode was prepared by radio frequency sputtering using a pure cupper target under various O2 flow rates (2-6 sccm). Due to proper positioned band edges of the p/n heterojunction, the separation of photo-induced charges both in Cu2O and TiO2 electrodes under UV irradiation could be significantly improved as compared with one electrode used alone. Thus, the PC activity was greatly increased towards the degradation of MB solution under UV irradiation. The Cu2O electrode prepared at a flow of 5 sccm exhibited the highest photocatalytic activity among five different flow rates. This is attributable to the electron transport favored (111) plane of the Cu2O oxide. This p/n heterojunction structure offers an efficient way for photogenerated electron transport from the n-type TiO2 to the p-type Cu2O electrode rendering enhanced PC and PEC activities under UV irradiation.