Highly Efficient Visible Light Photocatalytic Reduction
of CO<sub>2</sub> to Hydrocarbon Fuels by Cu-Nanoparticle Decorated
Graphene Oxide
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Abstract
The production of renewable solar
fuel through CO<sub>2</sub> 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 CO<sub>2</sub> 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
CO<sub>2</sub> 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 CO<sub>2</sub> to fuel catalytic
efficiency has been demonstrated using Cu/GO-2 (10 wt % Cu) compared
with that using pristine GO