1 research outputs found
Ionic Liquid Anion Controlled Nanoscale Gold Morphology Grown at a Liquid Interface
Two different ionic
liquids comprising the tetrabutylphosphonium
cation ([P<sub>4444</sub>]) paired with the strongly coordinating
anions 6-aminocaproate ([6-AC]) or taurinate ([tau]) were prepared
and employed in an aqueous/organic liquid bilayer system to generate
nanoscale gold by AuÂ(OH)<sub>4</sub><sup>–</sup> photoreduction.
Generally, as the concentration of ionic liquid in the organic phase
was increased, the resulting quasi-spherical gold nanoparticles were
smaller in size and presented less aggregation, leading to marked
increases in the catalytic efficiency for 4-nitrophenol reduction
using borohydride. The diffusion of the ionic liquids across the liquid/liquid
interface was also investigated, revealing partition coefficients
of 6.0 and 7.6 for [P<sub>4444</sub>]Â[6-AC] and [P<sub>4444</sub>]Â[tau],
respectively. Control studies elucidated that biphasic interfacial
reduction was necessary to achieve stable nanoparticles possessing
high catalytic activity. When the ionic liquid anion was instead replaced
by the weakly coordinating bisÂ(trifluoroÂmethylÂsulfonyl)Âimide
([Tf<sub>2</sub>N]), photoreduction of AuÂ(OH)<sub>4</sub><sup>–</sup> led to holey, wavy gold nanowires instead of spherical nanoparticles,
indicating the dramatic morphological control exerted by the coordination
strength of the ionic liquid anion. This strategy is straightforward
and simple and opens up a number of intriguing avenues for controllably
preparing plasmonic colloids for a range of applications from catalysis
to optical sensing