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 CeO 2 composites loaded with reduced graphene oxide (rGO, denoted as Er‐doped CeO 2 /rGO) were prepared via a hydrothermal method. The crystal structures, morphological characteristics, and surface physicochemical properties of the as‐prepared Er‐doped CeO 2 /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 CO 2 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 CO 2 to methanol approached 42.5 and 135.6 μmol g −1 cat h −1 for Er‐doped CeO 2 /CuO and Er‐doped CeO 2 /rGO/CuO catalysts under similar conditions in 5 h, respectively. Accordingly, rGO enhances significantly the yield of the photocatalytic reduction of CO 2 to methanol. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 655–662, 2018