Sustainable Recovery of CO₂ by Using Visible-Light-Responsive Crystal Cuprous Oxide/Reduced Graphene Oxide

A simple solution-chemistry method has been investigated to prepare crystal cuprous oxide (Cu2O) incorporated with reduced graphene oxide (designated as Cu2O-rGO-x, where x represents the contents of rGO = 1%, 5% and 10%) in this work. These Cu2O-rGO-x composites combine the prospective advantages of rhombic dodecahedra Cu2O together with rGO nanosheets which have been studied as visible-light-sensitive catalysts for the photocatalytic production of methanol from CO2. Among the Cu2O-rGO-x photocatalysts, the methanol yield photocatalyzed by Cu2O-rGO-5% can be observed to be 355.26 μmol g−1cat, which is ca. 36 times higher than that of pristine Cu2O nanocrystal in the 20th hour under visible light irradiation. The improved activity may be attributed to the enhanced absorption ability of visible light, the superior separation of electron⁻hole pairs, well-dispersed Cu2O nanocrystals and the increased photostability of Cu2O, which are evidenced by employing UV-vis diffuse reflection spectroscopy, photoluminescence, scanning electron microscopy/transmission electron microscopy and X-ray photoelectron spectroscopy, respectively. This work demonstrates an easy and cost-effective route to prepare non-noble photocatalysts for efficient CO2 recovery in artificial photosynthesis