Easy Fabrication of Macroporous Gold Films Using Graphene
Sheets as a Template
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Abstract
We demonstrate a facile new and environmentally
friendly strategy to fabricate monolithic macroporous gold (MPG) films
using graphene sheets as a sacrificial template. Gold nanoparticle
(AuNP) decorated graphene sheets were prepared by a one-pot simultaneous
reduction of graphene oxide (GO) and gold precursor (HAuCl<sub>4</sub>) by sodium citrate. Two thermal annealing methods, direct thermal
annealing in air and a two-step thermal treatment (in N<sub>2</sub> first and subsequently in air), were then employed to remove the
template (graphene sheets), which can both produce macroporous structures,
but with distinctly different morphologies. We additionally investigated
the porosity evolution mechanism as well as the effect of graphene/Au
weight ratio and annealing temperature on the nanoarchitecture. The
two-step treatment has a more significant templating effect than direct
thermal annealing to fabricate MPG films because of the existence
of a preaggregation process of AuNPs assisted by graphene sheets in
N<sub>2</sub>. Moreover, the resulting MPG films were found to exhibit
excellent surface-enhanced Raman scattering (SERS) activity. Our method
can be hopefully extended to the synthesis of other porous materials
(such as Ag, Cu, Pt, and ceramic) and much wider applications