Effect of Self-Assembled Monolayers on the Locally Electrodeposited Silver Thin Layers

Abstract

The localized electrodeposition of silver on gold coated with self-assembled monolayers (SAMs) by scanning electrochemical microscopy (SECM) is reported. The SAMs were ω-functionalized alkanethiols of the form X−(CH 2 ) 2 SH, X = OH, NH 2 , CO 2 H, SO 3 H, as well as 4-mercaptobenzoic acid. The SAMs were characterized by X-ray photoelectron spectroscopy (XPS) and cycling voltammetry (CV). The anodic dissolution of a Ag microelectrode, which was held within a few microns from the Au surface, formed a well-controlled flux of Ag + . Deposition of silver nanostructures was driven by the electrochemical reduction of the Ag + on the Au surface. The effect of the functional group on the Ag local deposition was studied and compared with bulk deposition on the same SAMs. For bulk deposition, we found that the interaction between Ag + ions and the functional group of the alkanethiols slowed the kinetics of Ag deposition, shifting the deposition to potential that is more negative and caused the formation of large, well-faceted Ag crystals. A clear correlation between the potential shift value and the morphology of deposited Ag was observed. The local deposition of Ag showed distinct difference compared to bulk deposition. We found that a continuous and homogeneous Ag film was formed locally below the Ag microelectrode in the presence of a 3-mercaptopropionic acid monolayer. This was observed when a 120 s delay between the electrogeneration of the silver ions and the application of a negative potential to the gold surface was applied. Moreover, the potential applied to the Au surface also affected deposition. The deposited silver was recollected by the Ag microelectrode by stripping the silver from the Au surface while holding the microelectrode in the same position. This enabled calculating the thickness of the Ag film deposited on the Au coated with 3-mercaptopropionic acid. Additional experiments clearly indicated that the mechanism of deposition involved complexation of silver ions by the SAM and their local reduction, which commenced prior to applying a negative potential to the Au surface.

The long-range effect induced by untying hydrogen bonds for single cell test using SECM

“…This suggests enormous potential of the functional SAMs for clinical applications. The physical adsorption, covalent and covalent coordinate bond methods have been developed for molecules immobilization onto SAM [16,17], such as covalent immobilization of proteins [18]. Among the intermolecular interactions developed for molecules immobilization on SAM, those based on weak interactions still need to explore [19].…”

Control of Crystal Growth in Local Electroless Gold Deposition by Pyridinium Based Surfactants

“…Metallic nanoparticles (NPs) are commonly prepared in solution. , Yet, it is possible to form metallic NPs directly on surfaces. − The latter is of special importance in a variety of fields, such as (electro)­catalysis, sensing, energy, etc. , In growing NPs on either conducting or nonconducting surfaces, the particle–surface interaction plays a major role. , Furthermore, one of the reasons for growing NPs directly on surfaces is to control their location and density for further applications, e.g., catalysis. , Key factors affecting the growth and properties of the NPs at the solid–liquid interface comprise the nature of the NPs and the surface (including surface defects) and their crystallinity . Numerous synthetic approaches for the formation of metallic NP arrays on different surfaces have been reported. , They can be divided into parallel and serial methods.…”

“…Others and we have shown the applicability of SECM as a patterning tool for the local deposition, etching, polymerization, and additional chemical and electrochemical reactions . Recently, we have shown that SECM enables controlling the crystal growth of metal NPs deposited locally on conducting surfaces. ,, We have demonstrated two approaches of controlling the growth of NPs locally on conducting surfaces (Scheme ). The surfactant-based method (Scheme A) involves the addition of shape affecting agents to the solution and generating a flux of metallic ions that are electrochemically reduced on the surface.…”

Scanning Electrochemical Microscopy versus Scanning Ion Conductance Microscopy for Surface Patterning

“…Scanning electrochemical microscopy (SECM), a scanning probe technique with high spatial resolution was evolved as a means of imaging, studying interfacial processes or modifying surfaces. [14][15][16][17] Indeed, SECM has been used to form metallic patterns of Au, [18][19][20][21] Ag, [22] Co [23] and other metals on various surfaces using different modes, e. g. feedback and generation/ collection. [24] Other approaches, including scanning probe microscopy, [25] chemical etching, [26] laser irradiation [27] and electrochemistry using masks [28] have been reported to achieve micrometer resolution through local deposition followed by electroless metal deposition on different substrates.…”