Preparation and characterization of graphene oxide supported Cu, Cu₂O, and CuO nanocomposites and their high photocatalytic activity for organic dye molecule

A highly efficient synthetic route was successfully developed to prepare crystallized and well dispersed Cu, Cu₂O, and CuO nanoparticles (NPs) on reduced graphene oxide (rGO) by controlling the impregnation condition of a copper-precursor (Cu(NO₃)₂·3H₂O) on graphene oxide (GO) and subsequent thermal treatments. The morphological and chemical structures of the nanocomposites were systemically evaluated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS), and transmission electron microscopy (TEM). The rGO based CuO_x nanocomposites exhibited a much higher catalytic activity than bare CuOx NPs toward the decomposition reaction of dye molecules under visible light illumination. Among the CuO_x/rGO nanocomposites, CuO/rGO showed excellent photocatalytic efficiency and recyclability without significant loss of activity. Based on the XPS, XRD, XAFS, and TEM results, the high photocatalytic efficiency of the CuO/rGO can be attributed to the synergistic combination of dye adsorptivity and electron acceptability of the rGO, the surface hydroxyl species in the CuO/rGO, and the narrow band gap and smaller size of the CuO NPs. This work could be applied to the removal and water treatment of waste dye.