Photocatalytic activity of erbium-doped CeO2 enhanced by reduced graphene Oxide/CuO cocatalyst for the reduction of CO2 to methanol

A series of erbium-doped CeO2 composites loaded with reduced graphene oxide (rGO, denoted as Er-doped CeO2/rGO) were prepared via a hydrothermal method. The crystal structures, morphological characteristics, and surface physicochemical properties of the as-prepared Er-doped CeO2/rGO composites were characterized through X-ray diffraction, transmission electron microscopy, Raman spectroscopy, ultraviolet–visible diffuse reflection spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic activities of the composite samples were further evaluated by reducing CO2 to methanol. Results show that erbium (III) doping caused a red shift of the response spectrum from 392 nm to 451 nm, and that rGO loading induced a response spectrum shift to 467.9 nm. The corresponding reduction yields of CO2 to methanol approached 42.5 and 135.6 μmol g−1cat h−1 for Er-doped CeO2/CuO and Er-doped CeO2/rGO/CuO catalysts under similar conditions in 5 h, respectively. Accordingly, rGO enhances significantly the yield of the photocatalytic reduction of CO2 to methanol. © 2017 American Institute of Chemical Engineers Environ Prog, 2017