Improved Photocatalytic Activity of Copper Heterostructure Composites (Cu-Cu2O-CuO/AC) Prepared by Simple Carbothermal Reduction

Cu-Cu2O-CuO/activated carbon heterostructure composites with visible-light activity have been successfully synthesized by a simple carbothermal reduction procedure using CuSO4 as a single precursor. The resultant samples were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements. The results showed that the Cu-Cu2O-CuO composites with size less than 10 nm dispersed well on the surface of activated carbon. Activated carbon played both a reducing agent and support role in the formation of Cu-Cu2O-CuO/activated carbon heterostructure composites. X-ray photoelectron spectroscopy analysis suggests that the outside of the nanoparticles is CuO and the inside of the nanoparticles is Cu metal and Cu2O. Moreover, the composition of Cu-Cu2O-CuO/activated carbon composites can be tailored by varying the Cu loading, heat-treatment temperature, and heat-treatment time. The photocatalytic activities of the catalysts were investigated by degrading reactive brilliant blue KN-R under visible-light irradiation. The Cu-Cu2O-CuO/activated carbon heterostructure composites showed excellent photocatalytic activity compared with other catalysts (pure CuO, Cu2O, Cu2O/activated carbon, CuO/activated carbon, and Cu2O-CuO/activated carbon), which is ascribed to synergistic action between the activated carbon support and photoactive copper species, and the presence of interfacial structures such as a Cu2O/CuO heterostructure, Cu/Cu2O (or CuO) Schottky barrier, and Cu2O/Cu/CuO ohmic heterojunction.