In situ study of Au nanoparticle formation in a mechanochemical-aging-based method

As we strive to perform chemical transformations in a more sustainable fashion, enabling solid-state reactions through mechanochemistry has emerged as a highly successful approach. Due to the wide-ranging applications of gold nanoparticles (AuNPs), mechanochemical strategies have already been employed for their synthesis. However, the underlying processes surrounding gold salt reduction, nucleation and growth of AuNPs in the solid state are yet to be understood. Here, we present a mechanically activated aging synthesis of AuNPs, through a solid-state Turkevich reaction. Solid reactants are only briefly exposed to input of mechanical energy before being aged statically over a period of six weeks at different temperatures. This system offers an excellent opportunity for an in situ analysis of both reduction and nanoparticle formation processes. During the aging period, the reaction was monitored using a combination of X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, powder X-ray diffraction and transmission electron microscopy, to gain meaningful insights into the mechanisms of solid-state formation of gold nanoparticles. The acquired data allowed for the establishment of the first kinetic model for solid-state nanoparticle formation.

Automated summary

Mechanochemistry has proven to be a successful approach for sustainable chemical transformations, including the synthesis of gold nanoparticles. However, the processes involved in the solid-state reduction of gold salts and the formation of nanoparticles are not well understood. This study presents a mechanically activated aging synthesis of gold nanoparticles using a solid-state Turkevich reaction. The reaction is monitored over a six-week period at different temperatures, allowing for in situ analysis of both reduction and nanoparticle formation processes. Through various spectroscopic and microscopic techniques, valuable insights into the mechanisms of solid-state formation of gold nanoparticles are obtained, leading to the establishment of the first kinetic model for this process.