Highly Efficient Visible Light Photocatalytic Reduction of CO₂ to Hydrocarbon Fuels by Cu-Nanoparticle Decorated Graphene Oxide

The production of renewable solar fuel through CO₂ photoreduction, namely artificial photosynthesis, has gained tremendous attention in recent times due to the limited availability of fossil-fuel resources and global climate change caused by rising anthropogenic CO₂ in the atmosphere. In this study, graphene oxide (GO) decorated with copper nanoparticles (Cu-NPs), hereafter referred to as Cu/GO, has been used to enhance photocatalytic CO₂ reduction under visible-light. A rapid one-pot microwave process was used to prepare the Cu/GO hybrids with various Cu contents. The attributes of metallic copper nanoparticles (∼4–5 nm in size) in the GO hybrid are shown to significantly enhance the photocatalytic activity of GO, primarily through the suppression of electron–hole pair recombination, further reduction of GO’s bandgap, and modification of its work function. X-ray photoemission spectroscopy studies indicate a charge transfer from GO to Cu. A strong interaction is observed between the metal content of the Cu/GO hybrids and the rates of formation and selectivity of the products. A factor of greater than 60 times enhancement in CO₂ to fuel catalytic efficiency has been demonstrated using Cu/GO-2 (10 wt % Cu) compared with that using pristine GO