An in situ SAXS investigation of the formation of silver nanoparticles and bimetallic silver-gold nanoparticles in controlled wet-chemical reduction synthesis

Author(s)

Garcia, Paulo R. A. F. ^[1] ; Prymak, Oleg ^{[2, 3]} ; Grasmik, Viktoria ^{[2, 3]} ; Pappert, Kevin ^{[2, 3]} ; Wlysses, Wagner ^[1] ; Otubo, Larissa ^[4] ; Epple, Matthias ^{[2, 3]} ; Oliveira, Cristiano L. P. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Phys, Rua Matao 1371, BR-05508090 Sao Paulo - Brazil

^[2] Univ Duisburg Essen, Inorgan Chem, Univ Str 5-7, D-45117 Essen - Germany

^[3] Univ Duisburg Essen, Ctr Nanointegrat Duisburg Essen CeNIDE, Univ Str 5-7, D-45117 Essen - Germany

^[4] IPEN CNEN SP, Inst Pesquisas Energet & Nucl, LMM, BR-05508000 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: NANOSCALE ADVANCES; v. 2, n. 1, p. 225-238, JAN 1 2020.
• Web of Science Citations: 0

Abstract

We present a study on the formation of silver (Ag) and bimetallic silver-gold (AgAu) nanoparticles monitored by in situ SAXS as well as by ex situ TEM, XRD and UV-vis analysis in a flow reactor at controlled reaction temperature. The formation mechanism of the nanoparticles is derived from the structural parameters obtained from the experimental data. The evolution of the average particle size of pure and alloyed nanoparticles shows that the particle growth occurs initially by a coalescence mechanism. The later growth of pure silver nanoparticles is well described by Ostwald ripening and for the alloyed nanoparticles by a process with a significantly slower growth rate. Additionally, the SAXS data of pure silver nanoparticles revealed two major populations of nanoparticles, the first one with a continuous crystal growth to a saturation plateau, and the second one probably with a continuous emergence of small new crystals. The particle sizes obtained by SAXS agree well with the results from transmission electron microscopy and X-ray diffraction. The present study demonstrates the capability of an in situ investigation of synthesis processes using a laboratory based SAXS instrument. Online monitoring of the synthesis permitted a detailed investigation of the structural evolution of the system. (AU)

• FAPESP's process: 18/16092-5 - Investigating colloidal systems by scattering methods
• Grantee: Cristiano Luis Pinto de Oliveira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/24531-3 - Structural and biophysics properties of native and modified lipoproteins
• Grantee: Antonio Martins Figueiredo Neto
• Support Opportunities: Research Projects - Thematic Grants