Photochemical Synthesis in Formamide and Room-Temperature Coulomb Staircase Behavior of Size-Controlled Gold Nanoparticles

Abstract

An effective photochemical route is reported here for size-controlled synthesis of nonaqueous colloidal gold particles in a highly polar and viscous medium, formamide in the presence of poly(vinylpyrrolidone). The effective photoreduction of AuCl4 -in the nonaqueous system is attributed to the higher degree of dissociation of AuCl4 -in formamide and the direct reduction by the photogenerated free radicals from the coordinated formamide molecules. Evident photochemical formation of gold particles was not achieved in dimethylformamide because AuCl4 -cannot be dissociated in dimethylformamide, having no amino group but an aldehyde group as in formamide. Under similar conditions, uniform gold particles were prepared much more easily in formamide than in water, and the photoreduction of AuCl4 -was also carried out much more completely in formamide than in water. A Coulomb staircase was clearly observed at room temperature on the nonaqueously grown uniform gold particles of 12 nm, but this behavior did not occur on the aqueously grown gold particles of similar size. This new photochemical route is also very effective to produce other uniform transition-metal particles such as silver, palladium, and platinum.

Uniform Magnetic Chains of Hollow Cobalt Mesospheres from One‐Pot Synthesis and Their Assembly in Solution

“…11). The protective polymer, PVP, is widely used as a stabilizer to prevent nanoparticles from aggregation in chemical preparations of noble metal nanoparticles, including gold, [32] silver, [33] palla- …”

Photochemical synthesis of gold nanoparticles by the sunlight radiation using a seeding approach

“…In previous published investigations of preparing colloidal gold particles by the photochemical reduction method, the UV lamp-house was widely used (29)(30)(31)(32)(33)(34)(35). In fact, the light source can provide UV-A, -B and -C band irradiation and has a certain wavelength range.…”

“…extend far beyond imaging. As concerns the preparation of the colloidal gold nanoparticles which were widely used as precursors, various chemical routes, including the use of chemical reductants in both aqueous and nonaqueous solvents (13)(14)(15)(16)(17)(18)(19)(20), electrochemical method (21)(22)(23)(24)(25), sonochemical method (26,27) radiolytic (28) and photochemical method (29)(30)(31)(32)(33)(34) have been widely studied for different purposes of application. For producing monodisperse colloidal gold particles of 10-20nm in diameter in aqueous solution, the citrate-reduced method developed by G. Frens (13) is quite effective, which was most widely adopted or improved in a lot of published papers.…”

“…In order to prevent the aggregation of the particles, the same as other chemical preparations, it is usually requisite to add protective agents such as soluble polymers, surfactants and dendrimers in the photochemical methods (29)(30)(31)(32)(33)(34)(35). The authors have studied the preparation of the colloidal gold nanoparticles by UV irradiation using linear polymer poly (ethylene glycols) (PEG) as the protective agent (34).…”

Nanohybridized Synthesis of Metal Nanoparticles and Their Organization

“…One-dimensional (1D) nanostructures have attracted much attention due to their optical and electronic properties for potential uses as interconnects or active components in fabricating nanodevices [167]. Various chemical methods have been established to accomplish 1D growth of nanostructures [168], among which template-directed synthesis is the most widely used method for generating metallic or metal oxide nanowires [169].…”