Photocatalytic Activity of Cu2O and Bilayer Cu2O/TiO2 Films Prepared by

Cu2O, TiO2 and composite Cu2O/TiO2 films were deposited on slide glass by direct current (DC) reac- tive magnetron sputtering. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive spectrometry (EDS) were applied to characterize crystal structure, morphology and composition of the films, re- spectively. Photocatalytic activity was evaluated by the degradation of methylene blue (MB) with Xenon lamp. XRD results show that besides the initial (111) crystal plane at sputtering time of 5 min, (110) and (220) crystal planes gradually develop on the Cu2O film with the increase of sputtering time. Our calculation result indicates that (111) crystal plane is more beneficial to absorption of O2 than other crystal planes. The photocatalytic activity of the Cu2O/TiO2 composite films first increases with increasing Cu2O-deposited content, and then reaches the highest value when the deposited content of Cu2O is 2.6mol%, and successively undergoes a drop. The enhancement of the photocatalytic activity is mainly attributed to alleviate the recombination of electron-hole pairs. Excessive Cu2O will prolong the time for transferring of electrons to Cu2O/TiO2 interface and holes to surface, which increases the