Study On Preparation And Characterization Of Cu₂O-loaded TiO₂Nanotube And Its Photoelectric Properties

With the development of society and economy, energy shortage and environmental pollution are gradually becoming top two global issues which require to be solved urgently. Many research institutions and scientists were dedicated to solve these issues. Using semiconductor materials to achieve the conversion of solar energy and the degradation of organic pollutants having been researched extensively in recently years. Up to now, TiO2becoming one of the mostly researched functional semiconductor materials due to its non-toxic, low cost, excellent chemical stability and high photocatalytic property. The specific surface of conventional TiO2particles will drastically deceases after loaded on substrate and the easy recombination of photoinduced electron-hole pairs in application gradually becoming the critical factors which greatly hamper its application. In addition, TiO2absorbs only the ultraviolet light which accounts for only3～4%of the total incident sunlight due to its wide bandgap (3.2eV and3.0eV for anatase and rutile, respectively). Therefore, fabrication of novel morphology of TiO2and its visible light modification to improve efficiency for solar energy becoming one of most important projects in TiO2photocatalytic semiconductor research field.Considering the shortages of TiO2particles mentioned above, we proposed the vision that fabricating tubular TiO2nanomaterial and coupling with narrow bandgap semiconductor to improve its visible light response. First, the highly ordered TiO2nanotube arrays films were fabricated by anodic oxidation of titanium foil substrates. And then, Cu2O particles were loaded on TiO2nanotube arrays via galvanostatic pulse electrodeposition. As a result, Cu2O-TiO2nanotube arrays heterojunction composite films were obtained. The influence of the situation of electrolyte (standing, magnetic agitating and ultrasonic stirring) and the deposition current density values (0.2mA/cm2-1.5mA/cm2) during the processing of depositing Cu2O on the morphology, microstructure and photoelectric properties of the composite films were investigated by field emitting scanning electron microscopy (FESEM), X-ray diffraction (XRD), diffuse reflectance UV-Vis spectrometer (UV-Vis) and photocurrent test.The analysis of the morphology and the microstructure of the samples demonstrated that the prepared TiO2nanotube arrays was highly order and uniformly distributed; the diameter and length of the TiO2nanotube were about100nm and400nm, respectively. The morphologies of the Cu2O crystals in the composite films change from irregular branched clusters, regular branched truncated octahedrons, and dispersive truncated octahedrons gradually to dispersive overlapped octahedrons with increasing deposition current densities; the morphology evolution of the deposited Cu2O in magnetic agitating and ultrasonic stirring electrolyte lag behind than that of in standing slution, while the former electrolyte conditions are favorable to obtain pure Cu2O phase.The diffuse reflectance UV-Vis absorption spectra and the photocurrent properties measurements shown that the prepared Cu2O-loaded TiO2nanotube arrays films exhibit remarkable visible light responses than that of TiO2nanotube arrays films under simulated visible light illumination; the optimal visible light absorption and photocurrent properties were obtained for the Cu2O-TiO2nanotube arrays heterojunction composite films which fabricated by using1.0mA/cm2of the pulse deposition current density to deposite Cu2O.