Simple Electrochemical Method for Deposition and Voltammetric Inspection of Silver Particles at the Liquid−Liquid Interface of a Thin-Film Electrode

摘要

A novel experimental methodology for depositing and voltammetric study of Ag nanoparticles at the waternitrobenzeneud(W-NB) interface is proposed by means of thin-film electrodes. The electrode assembly consistsudof a graphite electrode modified with a thin NB film containing decamethylferrocene (DMFC) as a redoxudprobe. In contact with an aqueous electrolyte containing Ag+ ions, a heterogeneous electron-transfer reactionudbetween DMFC(NB) and Ag+ud(W) takes place to form DMFC+ud(NB) and Ag deposit at the W-NB interface.udBased on this interfacial reaction, two different deposition strategies have been applied. In the uncontrolledudpotential deposition protocol, the electrode is immersed into an AgNO3 aqueous solution for a certain periodudunder open circuit conditions. Following the deposition step, the Ag-modified thin-film electrode is transferredudinto an aqueous electrolyte free of Ag+ ions and voltammetrically inspected. In the second protocol theuddeposition was carried out under controlled potential conditions, i.e., in an aqueous electrolyte solutionudcontaining Ag+ ions by permanent cycling of the electrode potential. In this procedure, DMFC(NB) isudelectrochemically regenerated at the electrode surface, hence enabling continuation and voltammetric controludof the Ag deposition. Hence, the overall electrochemical process can be regarded as an electrochemical reductionudof Ag+ud(W) at the W-NB interface, where the redox couple DMFC+/DMFC acts as a mediator for shuttlingudelectrons from the electrode to the W-NB interface. Ag-particles deposited at the W-NB interface affectudthe ion transfer across the interface, which provides the basis for voltammetric inspection of the metal depositudat the liquid-liquid interface with thin-film electrodes. Voltammetric properties of thin-film electrodes areudparticularly sensitive to the deposition procedure, reflecting differences in the properties of the Ag deposit.udMoreover, this methodology is particularly suited to inspect catalytic activities of metal particles deposited atudthe liquid-liquid interface toward heterogeneous electron-transfer reactions occurring at the at the liquidliquidudinterface.