Simple size-controlled synthesis of Au nanoparticles and their size-dependent catalytic activity

Abstract

The controlled preparation of Au nanoparticles (NPs) in the size range of 6 to 22 nm is explored in this study. The Au NPs were prepared by the reduction of tetrachloroauric acid using maltose in the presence of nonionic surfactant Tween 80 at various concentrations to control the size of the resulting Au NPs. With increasing concentration of Tween 80 a decrease in the size of produced Au NPs was observed, along with a significant decrease in their size distribution. The size-dependent catalytic activity of the synthesized Au NPs was tested in the reduction of 4-nitrophenol with sodium borohydride, resulting in increasing catalytic activity with decreasing size of the prepared nanoparticles. Eley-Rideal catalytic mechanism emerges as the more probable, in contrary to the Langmuir-Hinshelwood mechanism reported for other noble metal nanocatalysts.

The Effect of Poly(vinylpyrrolidone) (PVP) on the Au Catalyzed Reduction of p–nitrophenol: The Fundamental Role of NaBH4.

“…Decrease in p‐NP consumption rate during δ regime (k app,δ < k app,β ) suggests the occurrence of partial saturation or blocking of the active sites by the reaction product, p‐AmP, in the last part of the process. Similar behavior has been recently reported by Suchomel et al . for gold NPs obtained in presence of Tween 80 (specifically for formulations containing the two highest concentrations of the surfactant that correspond to the two smallest NPs sizes obtained, 14.1 and 6.2 nm in diameter respectively).…”

“…This is a clear indication that the intermediate and, to a lesser extent, the p‐AmP, contribute to the absorbance of the peak observed at around 300 nm. To our knowledge, only a few works have identified different stages for this reaction ,,. Gu et al.…”

“…Despite these advantages, the nature and origin of some features observed during p‐NP reduction are still a matter of debate and make this reaction not so well understood. First of all, the p‐NP reduction kinetics has been described in terms of a Langmuir‐Hinshelwood or an Eley‐Rideal mechanism in different research studies ,,,,,. Systematic changes in reactant concentrations are required to distinguish between these two models .…”

Nano-based approach to combat emerging viral (NIPAH virus) infection

“…65 The unique property of AuNPs contributing to these applications is different from its bulk form that is, Surface Enhanced Raman Scattering (SERS). 66 (Table 1). 64…”

Multilayer‐Functionalized Reduced Graphene Oxide Decorated with Gold Nanoparticles as a Designed Nanonanocatalyst for the Selective Oxidation of Cyclohexene by Molecular Oxygen in a Solvent‐Free System

“…Compared to other noble metals, supported Au nanoparticles exhibit higher stability toward oxygen deactivation and higher selectivity to allylic oxidation, being a promising catalyst for such application. According to many different studies, the catalytic activity and selectivity of supported Au nanoparticles depend largely on the size and the shape of the Au nanoparticles and the nature of the supports and preparation methods . Carbon‐based materials have been widely used as catalyst supports such as graphene, reduced graphene oxide, carbon nanotubes, carbon nanofibers, mesoporous carbon nitride and mesoporous carbon and their hybrids .…”