Cu2O sensitized flexible 3D-TiO2 nanotube arrays for enhancing visible photo-electrochemical performance

Cu2O flake and particle modified 3D-TiO2 nanotube arrays (TiO2 NTAs) on flexible Ti meshes were prepared by electrochemical deposition. The phase composition, microstructure and photo-electrochemical property were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV-vis diffusion reflection spectroscopy (DRS) and an electrochemical system. The results indicate that 3D-TiO2 NTAs are covered by a large number of Cu2O flakes and nanoparticles, and the flakes become longer and narrower with increasing electrochemical cycles. Cu2O modified 3D-TiO2 NTAs expand the photo-response range from ultraviolet light to visible light. The Cu2O modified NTAs with 400 pulses possess the highest visible photocurrent density of 0.9 mA cm(-2), however, the Cu2O modified NTAs with 600 pulses possess the largest photocatalytic activity toward degradation of methyl orange (MO) under visible-light irradiation. A mechanism is proposed to explain the difference in photocurrent response and photocatalytic activity.