Growth, structure and photocatalytic properties of hierarchical Cu–Ti–O nanotube arrays by anodization

Abstract

Recently p-type Cu–Ti–O nanotubes have been explored in water-splitting photoelectrochemical pn-junction diodes to significantly improve the photoconversion efficiency. We reported on the growth and characterization of Cu–Ti–O nanotube arrays by anodizing directly Cu–Ti (30:70 wt%) alloy substrate. As-anodized hierarchical Cu–Ti–O nanotube arrays consist of two distinct Ti-rich and Cu-rich nanotube regions. It was found that mechanical stresses induced by copper doping resulted in the difference in the microstructure evolution of Cu-rich and Ti-rich regions. The oxygen vacancies induced by the high concentration Cu dopant into the Cu–Ti–O nanotube play a crucial role in determining the phase stabilization of anatase phase. The absorption edge of TiO 2 nanotube arrays was extended into the visible region by Cu doping. In degrading Methyl orange (MO), 21.2% MO was removed using Cu–Ti–O nanotube arrays after 240 min UV illumination. This result indicates the photocatalytic activity of Cu–Ti–O nanotube arrays to MO is reasonably high.