Visualization of Surfactants on Nanostructured Palladium Clusters by a Combination of STM and High-Resolution TEM

Abstract

Scanning tunneling microscopy (STM) and high-resolution transmission electron microscopy (TEM) have been used to determine the dimensions of a series of palladium clusters stabilized by tetraalkylammonium salts. Electrochemically prepared colloids were used in which the average diameter of the inner metal core was varied between 2 and 4 nanometers, and the size of the ammonium ions was adjusted in the series (+)N(n-C(4)H(9))(4) < (+)N(n-C(8)H(17))(4) < (+)N(n-C(18)H(37))(4). The difference between the mean diameter determined by STM and that measured by TEM allows the determination of the thickness of the protective surfactant layer. On the basis of these studies, a model of the geometric properties of ammonium-stabilized palladium clusters has been proposed. Suggestions for the mechanism of the STM imaging process are also made.

Characterization of copper nanoparticles synthesized by a novel microbiological method

“…In a seminal paper based on the combined use of transmission electron and scanning tunneling microscopies, the group of M. Reetz demonstrated that these metal nanoparticles possess a core-shell structure in which the metallic core is stabilized by a monolayer of tetra alkylammonium species, and the thickness of this shell is linearly correlated with the length of the alkyl chains. 19 In the last decade, the electrolytic production of nanoparticles and nanocomposites containing platinum group elements has been extensively studied, due to the strong catalytic properties of these products. 13 ,zQ-25 The electro-synthesis of Cu and Ag colloids, on the other hand, has been the subject of only a few reports.…”

Electrophoretic deposition of Au NPs on CNT networks for sensitive NO&lt;sub&gt;2&lt;/sub&gt; detection

“…During the process, the cell was kept under a nitrogen atmosphere. Since in these systems the NPs shell thickness is roughly proportional to the chain length of the surfactant (Reetz and Helbig, 1994;Reetz et al, 1995), while the core size is mainly influenced by the electrochemical parameters, Au NPs with a shell thickness of about 1.2 nm were synthesized using TOAC. The working potential was set at +1 V corrosion voltages and the electrolysis charge at 300 mC.…”

Temperature-Dependent Size-Controlled Nucleation and Growth of Gold Nanoclusters

“…Electrochemical methods [19][20][21][22] were used to produce transition metal nanoparticles whose size can be controlled by adjusting the current density. In this type of synthesis, tetraalkylammonium salts were used as both supporting electrolyte and stabilizer for the cluster formed.…”