On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

Abstract

Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles 3 immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag + ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered.

Natural Soil Clays from a Phaeozem to Synthesize a Nanocomposite with Exhausted Coffee Grounds and Ag- and TiO₂-Nanoparticles for Water, Air, or Soil Decontamination

“…The XPS Ag 3d spectrum of those composites exhibit the binding energy of Ag 3d5/2 line at 367.08 eV to composite 8NC with Phaeozem-soil that is characteristic of Ag with oxidation state (0). It is in agreement with the kinetic energy of the Ag M5N45N45 Auger peak at 357.7 eV [18]. Fig.…”

Spontaneous Shape Alteration and Size Separation of Surfactant-Free Silver Particles Synthesized by Laser Ablation in Acetone during Long-Period Storage

“…In the present case, considering the absence of water molecules in the liquids, the OH– formed by the acetone decomposition and reconstruction is one possible candidate to cause the anisotropic growth of Ag particles [ 35 ] via the Ostwald ripening process [ 33 ]. Chemical adsorbed carboxylate (COO–) groups may be another candidate to trigger the selective Ag crystal facet growth during ripening [ 51 ].…”

Interaction of silver nanoparticles with Vancomycin: an UV-vis study

“…Silver reduction with citrate ions is frequently used to obtain AgNPs, and also to stabilize them, but that mechanism in not yet fully understood [33]. The spectra of AgNPs obtained by reduction with trisodium citrate ( C ) and their mixtures with vancomycin hydrochloride (V) solution in different ratios are given in Figure 1.…”