A comparative study of the catalytic activity between Ag nanoparticles and Ag flower-like particles synthesized by the Sedum praealtum aqueous extract

This work shows that using Sedum praealtum extract, silver nanoparticles (AgNPs) and flower-like silver self-assemblies (AgFLs) can be synthesized by varying only the concentration of AgNO3. In addition, the comparison of its catalytic activity on the degradation of the methylene blue dye (MB) was evaluated. SEM showed spherical AgNPs of similar to 15 nm at 5 mM (AgNO3) concentration, and AgFLs are formed at 10 mM (AgNO3). XRD patterns confirmed the fcc crystal structure of the materials. FTIR spectroscopy determined that glycoside compounds are the main participants as reducing agents, stabilizers, and binders. UV-Vis spectroscopy confirmed the obtaining of Ag nanomaterials through the characteristic resonance band of the surface plasmon (RSP). In addition, the value of the band-gap was determined to measure the catalytic activity in the degradation of MB. The photocatalytic activity was mainly favored by smaller sizes of AgNPs, over the texture and surface porosity of AgFLs. However, it is independent of the morphology, and the use of an external reducing agent (NaBH4) since a 90% degradation is obtained after 24 h of reaction due to the combined action of photocatalysis and dye adsorption.

Automated summary

This work demonstrates the synthesis of silver nanoparticles (AgNPs) and flower-like silver self-assemblies (AgFLs) using Sedum praealtum extract by adjusting the concentration of AgNO3. The catalytic activity of these materials in the degradation of methylene blue dye (MB) was evaluated. The experimental results show that AgNPs with an average size of 15 nm are formed at 5 mM (AgNO3) concentration, while AgFLs are formed at 10 mM (AgNO3). The photocatalytic activity is mainly influenced by the size of AgNPs rather than the morphology of AgFLs.