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^-1 cat, 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.