title: Facile tuning of plasmon bands in hollow silver nanoshells using mild reductant and mild stabilizer.
abstract: Hollow silver nanoshells with tunable plasmon bands have been synthesized using Ag2O nanoparticles at an optimized temperature of 20 °C. The plasmon peak has been tuned in a wide range from 460 nm to 605 nm employing a combination of mild reductant and a mild stabilizer, hydrazine hydrate and sodium citrate, respectively. In contrast, the combination of strong reductant and strong stabilizer, NaBH4 and hydrophilic thiols, resulted in limited plasmon tunability (455-510 nm). The differential behaviour is attributed to the change in dynamics of the diffusion-reaction process. For thiols, the effect of free end-groups was quite evident as plasmon peak shifted from 449 nm to 470 nm on replacing thioglycolic acid (HS-CH2-COOH) with mercaptoethanol (HS-CH2-CH2-OH). Transmission electron microscopy (TEM) revealed that the aspect ratio [outer diameter (d)/shell thickness (t)] was 2.8 (d: 40.0 ± 1.6 nm, t: 14.0 ± 1.3 nm) and 5 (d: 84 ± 2.3 nm, t: 16.8 ± 1.9 nm) for the nanoshells exhibiting a plasmon peak at 460 nm and 605 nm, respectively. The crystal phase of nanoshells was found to be face centered cubic (fcc) as deduced from HR-TEM and electron diffraction data. Using the same Ag2O template, morphological transformation from non-porous to mesoporous has also been achieved by simply reversing the order of addition.
authors.affiliation: Department of Applied Chemistry, Birla Institute of Technology, Mesra, Ranchi-835215, India.
authors.forename: Satarupa
authors.initials: S
authors.lastname: Pattanayak
authors.forename: Amiya
authors.initials: A
authors.lastname: Priyam
authors.forename: Pradip
authors.initials: P
authors.lastname: Paik