Voltammetry of Electroactive Oil Droplets:  Electrochemically-Induced Ion Insertion, Expulsion and Reaction Processes at Microdroplets ofN,N,N‘,N‘-Tetraalkyl-para- phenylenediamines (TRPD, R =n-Butyl,n-Hexyl,n-Heptyl andn-Nonyl)

Abstract

The electrochemistry of microdroplets, shown to be nearly monodisperse, of N,N,N‘,N‘-tetraalkyl-para-phenylenediamine oils (TRPD, R = n-butyl, n-hexyl, n-heptyl, and n-nonyl) immobilized on a basal plane pyrolytic graphite electrode and immersed into aqueous electrolyte solution is studied using cyclic voltammetry. Upon oxidation of the TRPD droplet to the cation radical TRPD+•, anion uptake from, or cation loss into the aqueous solution takes place, so as to maintain electroneutrality within the oily deposit. The former process is shown to produce an ionic liquid, with the anion insertion taking place at the triple phase boundary of electrode |TRPD oil| aqueous electrolyte; the latter process, in contrast, takes place at the interface between the two immiscible liquids, and with two-thirds-order kinetics. The possibility of a chemical reaction taking place between the electrogenerated and inserted ions at the three-phase junction, viz. redox-catalysis or otherwise, is illustrated via reference to two systems (azide and iodide).

Electrochemical Studies of Vitamin K1Microdroplets: Electrocatalytic Hydrogen Evolution

“…The voltammetric reduction of 5.7 nmol vitamin K 1 , which is immobilised on a 4.9-mm-diameter bppg electrode in the form of a random array of probably micron-sized droplets [25,32] and immersed into aqueous 0.1 M HCl, measured at a scan rate of 0.1 V s…”

“…Based on earlier work in other redox liquids, [25] the electrochemical process likely takes place at the three-phase boundary of electrode j vitamin K 1 j aqueous electrolyte, since in dilute aqueous acid (with a pH value approximately one) the quinoid moiety of vitamin K 1 is not protonated, [28] and thus the oil droplets are electrically insulating. Contact between the vitamin K 1 droplets, the conductive aqueous electrolyte, and the electrode at the triple-phase junction provides a means for electron transfer from the electrode to the vitamin K 1 droplets, because this is the only place where an electrical double layer can form.…”

“…In previous work, we showed that for electrochemical processes that take place at three-phase junctions as in this case, this increase is limited; further addition of redox oil causes the observed current peak to decrease. [25] For a given coverage, the voltammetric response of a droplet-modified electrode depends approximately on (scan rate)…”

Electrodeposition of Metal Nanostructures by Galvanic Displacement Powered with Insoluble Crystals of a Ferrocene Derivative

“…[18] Herein, we report that overlayers of two ferrocene derivatives, when deposited on HOPG surfaces, are capable of driving the electrochemical deposition of metal nanoparticles and nanowires. We propose that the mechanism responsible for this metal deposition, shown in Scheme 1, is a galvanic displacement driven by the coupled oxidation of these organic crystals.…”

“…[14][15][16] Hydrophobic aromatic amines and ferrocene derivatives figure amongst the molecules studied using this approach. [15,17,18] The hydrophobic molecules deposited on the electrode surfaces can be present as pure liquids or in solutions of appropriate organic solvents. [17] In the latter case, since the electron-transfer process is coupled to interfacial ion transfer, the voltammetric response can be used to determine the energetics of ion transfer across immiscible liquid phases.…”