Enhanced decoloration activity by Cu2O@TiO2 nanobelts heterostructures via a strong adsorption-weak photodegradation process

Abstract

Cu2O@TiO2 heterostructures were synthesized via a room-temperature chemical precipitation method, and were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), UV–vis diffuse reflectance spectra, N2 adsorption–desorption isotherms and Fourier-transform infrared (FTIR) spectra. The decoloration activity of the composite photocatalyst was investigated by adsorbing/degrading methyl orange (MO) solutions in the dark/under visible light irradiation. From FESEM and HRTEM images it is found that, Cu2O nanoparticles are assembled on the rough surface of TiO2 nanobelts, producing Cu2O@TiO2 heterostructures. Comparing with P25, TiO2 nanobelts and pure Cu2O nanoparticles, the as-prepared Cu2O@TiO2 heterostructures exhibit dramatically improved adsorbability in the dark due to the interfacial effect after introduction of Cu2O nanoparticles onto the surface of TiO2 nanobelts. By comparison of decoloration rate of the Cu2O@TiO2 heterostructures in dark and under visible light irradiation, and from the FTIR analysis of MO degradation, it can be concluded that Cu2O@TiO2 heterostructures mainly play the role of adsorbent, and their visible light photodegradation processes are rather slow. Therefore, the excellent decoloration process of the Cu2O@TiO2 heterostructures on MO can be described as a strong adsorption of MO molecules onto the surface of Cu2O, and a weak photodegradation of the adsorbed MO molecules throught the heterostructures.