The deposition of iron and silver nanoparticles in graphene-polyelectrolyte brushes.

The high surface area of graphene nanosheets (GNs) enables them to load metal nanoparticles (NPs) for various applications such as catalysis, sensors and biomedicine. To optimize the performance, it is desired to establish an effective approach that can tune the morphology of metal nanoparticles (NPs) on GNs. We here demonstrate that GN-poly(acrylic acid) (GN/PAA) brushes can control the size and spatial distributions of iron and silver NPs. Results of Raman, Fourier transform infrared and x-ray photoelectron spectroscopy confirm the covalent bonding between PAA chains and GNs. Thermogravimetric analysis reveals a PAA grafting density of ~0.055 chain nm(-2). Transmission electron microscopy is used to study the effect of PAA chain length and precursor concentration on the morphology of the metal NPs deposited on PAA brushes and graphene oxide (GO). Short PAA brushes are found to be effective for controlling the spatial and size distributions of the NPs, resulting in small particle sizes and homogeneous distributions compared to those deposited on GO. The concentration of precursors has a limited effect on the dimension of the NPs in the brushes due to the key role that polyelectrolyte brushes play in controlling the growth of NPs.