title: Liquid / liquid ion-transfer processes at the dioctylphosphoric acid (N,N-didodecyl-N',N'-diethylphenylenediamine) / water (electrolyte) interface at graphite and mesoporous TiO2 substrates.
abstract: Biphasic electrode systems are studied for the case of the oxidation of the water-insoluble liquid N,N-didodecyl-N',N'-diethylphenylenediamine (DDPD) neat and dissolved in bis(2-ethylhexyl) phosphate (HDOP) and immersed in aqueous electrolyte media. The oxidation process in the absence of HDOP is accompanied by transfer of the anion (perchlorate or phosphate) from the water into the organic phase. However, in the presence of HDOP, oxidation is accompanied by proton exchange instead. This electrochemically driven proton exchange process occurs over a wide pH range. Organic microdroplet deposits of DDPD in HDOP at basal plane pyrolytic graphite electrodes are studied by voltammetric techniques and compared in their behavior to organic microphase deposits in mesoporous TiO2 thin films. The mesoporous TiO2 thin film acts as a host for the organic liquid and provides an alternative biphasic electrode system compared to the random microdroplet/graphite system. Two types of mesoporous TiO2 thin-film electrodes, (i) a 300-400-nm film on ITO and (ii) a 300-400-nm film on ITO sputter-coated with a 20-nm porous gold layer, are investigated.
authors.affiliation: Department of Chemistry, Loughborough University, Loughborough, Leicestershire, UK.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Stott
authors.forename: Katy J
authors.initials: KJ
authors.lastname: McKenzie
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Mortimer
authors.forename: Colin M
authors.initials: CM
authors.lastname: Hayman
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Buckley
authors.forename: Philip C
authors.initials: PC
authors.lastname: Bulman Page
authors.forename: Frank
authors.initials: F
authors.lastname: Marken
authors.forename: Galyna
authors.initials: G
authors.lastname: Shul
authors.forename: Marcin
authors.initials: M
authors.lastname: Opallo
mesh_terms: D004563:Electrochemistry; D004566:Electrodes; D004573:Electrolytes / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D015394:Molecular Structure; D010755:Organophosphates / Q000737:chemistry*; D010084:Oxidation-Reduction; D016062:Porosity; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D004573:Electrolytes; D007477:Ions; D010755:Organophosphates; D014867:Water; C009495:titanium dioxide; C007377:di-2-(ethylhexyl)phosphoric acid; D006108:Graphite; D014025:Titanium