Low-temperature, facile fabrication of ultrafine Cu2O networks by anodization on TiO2nanotube arrays

A green and facile process was developed to fabricate ultrafine p-type Cu2O single crystal nanowires by anodizing copper (Cu0) particles preloaded on TiO2?nanotube arrays. The Cu2O nanowires with a diameter of less than 5?nm were assembled on the top surface of n-type TiO2?nanotube arrays, constructing a novel p?n junction heterostructure with larger specific surface area compared to the unmodified TiO2?nanotube arrays. X-ray diffractometer (XRD) and high-resolution transmission electron microscopy (HRTEM) were employed to demonstrate that the resulting Cu2O was single crystalline. The composite Cu2O/TiO2?nanotube arrays exhibited significantly enhanced response to the visible light, resulting from Cu2O with a narrow-band gap. Furthermore, under visible light irradiation, enhanced efficiency in separating photogenerated hole?electron pairs was achieved due to the potential difference generated on the p?n interface. A possible mechanism was proposed to explain the formation of crystal Cu2O nanowires.