Electrochemical rectification at electrode surface modified with poly (acrylic acid) and decane thiol

Abstract

Gold surface modified with a two-component system consisting of poly (acrylic acid) (PAA) by electropolymerizing acrylic acid (AA) and decane thiol (DT), further functionalized with ferrocene monocarboxylic acid (FMC) through covalent linkage, was used to demonstrate mediated electron transfer resulting in a unidirectional flow of current. The electrode surface was modified using two different configurations. In Configuration 1 (Config. 1), electrode surface modified with FMC showed rectification behavior when contacted with a solution containing methylene blue (MB). In Configuration 2, redox-active bilayer was constructed using polyvinyl pyrollidone (PVP) and hexaamineruthernium (II) chloride [Ru(NH₃)₆]²⁺ showed rectification characteristics. The continuous rectification property of the redox-active bilayer is achieved by releasing the trapped [Ru(NH₃)₆]³⁺ in the outer layer using a reductant (ascorbic acid). Spectroelectrochemical measurements were made to study the reduction property of the ascorbic acid. Atomic force microscopic images and impedance measurements were also made on the modified electrode surfaces to explore the compactness of the first layer (PAA and PAA/DT).