Temperature and amino acid-assisted size- and morphology-controlled photochemical synthesis of silver decahedral nanoparticles

Abstract

Stable silver decahedron nanoparticles were produced under the blue light irradiation (lightemitting diodes) of a modified precursor solution that has been previously reported. To improve the formation of the nano-decahedrons under blue light, we proposed the use of amino acids with electrically charged side chains (L-arginine, L-lysine and L-histidine). Our results show that L-arginine and L-lysine are best suited to improve the yield of the decahedrons. We also followed the kinetics of the photochemical synthesis under different irradiance conditions of 80, 50 and 15 mW/cm 2 . The maximum irradiance, 80 mW/cm 2 , resulted in a synthesis that was twice as fast as those associated with lower irradiances, and the corresponding decahedron yield was higher. The optimal temperature of the precursor solution for the improvement of the photochemical synthesis of silver decahedrons with Triton X-100 as a surfactant was also determined.

Demonstrating the Photochemical Transformation of Silver Nanoparticles

“…Increasing the size of the spherical silver NPs will lead to a red shift of the plasmon band, but as size increases, colloidal stability is compromised. In the case of silver colloids, a second plasmon band around 550 nm appears when aggregation of the silver NPs occurs. , Experimentally, anisotropic noble metal NPs, such as rods, cubes, decahedra, disks, prisms, and plates, will present two plasmon bands; ,, in the case of silver nanorods, the second plasmon band can be fine-tuned from 500 to 750 nm, depending on their aspect ratio (width/length) . In silver nanoprisms (of 34 nm in edge length and 4 nm in thickness), the second plasmon band is located at 730 nm. , This red shift will be impossible to achieve by using spherical NPs.…”

“…This experiment will introduce students to nanotechnology, and it shows that anisotropic nanoparticle synthesis methods are not limited to chemical reduction or seed regrowth. Students will synthesize silver nanospheres and transform them into other anisotropic morphologies (decahedral and disks) by means of a photochemical process. − …”

Photochemical Synthesis of Silver Nanodecahedrons under Blue LED Irradiation and Their SERS Activity

“…AgNDs were synthesized in 2 steps: (i) synthesis of AgNPs as seeds and (ii) irradiating the seeds with blue LEDs to grow AgNDs with the aid of L-A [3,11]. The synthesis procedure is described in Figure 1.…”

“…They studied the mechanism of AgNDs formation but did not consider the surface plasmon effect, one of the important surface properties of silver nanomaterials [9]. Cardoso-Avila et al also applied LED irradiation on quartz cuvettes containing AgNPs to synthesize AgNDs; however, neither the reaction mechanism nor the SERS effects were thoroughly investigated [10,11].…”