Characterizations of Nanostructured Films as Responsive Electrode Materials
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Characterizations of Nanostructured Films as Responsive Electrode Materials Nancy Kariuki, Jin Luo, Laura Moussa, Lisa B. Israel, Chuan-Jian Zhong*, Maria Hepel a) Department of Chemistry, State University of New York at Binghamton, Binghamton, New York 13902. a) Department of Chemistry, State University of New York at Potsdam, Potsdam, New York 13676
ABSTRACT Nanostructured thin films were assembled as metal-responsive electrode materials from monolayer-capped gold nanoparticles (2 nm) and carboxylic acid functionalized alkyl thiol linkers via an exchange-crosslinking-precipitation reaction pathway. The network assemblies have open frameworks in which void space forms channels or chambers with the nanometer sized cores defining its size and the shell structures defining its chemical specificity. Such nanostructures were investigated as responsive materials for the detection of metal ion fluxes. Cyclic voltammetry, in–situ electrochemical quartz-crystal nanobalance, and surface infrared reflection spectroscopy techniques were used to characterize the interfacial redox reactivity and mass fluxes at the nanostructured electrode materials. The system showed remarkable reversible mass loading arising from incorporation of ionic species into the film. The diagnostic stretching bands of the carboxylic and carboxylate groups at the shell allowed the identification and assessment of the interfacial carboxylatemetal ion reactivity. INTRODUCTION Nanoparticles and nanostructured materials have numerous commercial and technological applications, including chemical sensors, electronic, optical and mechanical devices, drug delivery and bio-encapsulation1-2 . Extensive researches have been reported for producing nanoparticles of various size ranges3-5 . The use of nanoparticles as building blocks for the construction of highly responsive materials at electrodes with nanoscopic dimensions constitutes one of the most important areas in interfacial electrochemistry1,6. Such nanostructured electrodes are potentially useful for electrochemical experiments that are not sensitive or selective with un- modified electrodes. In the light of the numerous and relevant applications, the characterization of nanosized particles and their assemblies has attracted a lot of interest7,8. In order to employ these nanoparticles as active and stable components in a device, the question on how to interconnect and manipulate them in a controllable way has been very challenging. Molecular linking9-10 and embedding the particles on polymeric or network architecture seem to be some of the viable choices. Research interest in this area has grown rapidly as a result of abundant demonstrations of using self-assembled monolayer as encapsulating shell to protect metallic nanocrystal core and to generate interesting interfacial reactivities5,11-12 . Our study is aimed at the core-shell manipulation of the nanoparticles as building blocks towards responsive electrode materials that can be fine-tuned as individual nanoelectrodes or collective arrays. Part of the m
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