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| Home > Publications database > In situ - ATR-SEIRAS study of adsorption and phase formation of trimesic acid on Au(111-25nm) film electrodes |
| Journal Article | PreJuSER-37536 |
; ; ;
2004
NRC Research Press
Ottawa, Ont.
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Please use a persistent id in citations: doi:10.1139/V04-118
Abstract: The adsorption and phase formation of 3 mmol L-1 trimesic acid (TMA) on Au(111-25 nm) film electrodes in contact with aq. 0.1 mol L-1 HClO4 electrolyte have been investigated by in situ ATR-SEIRAS, cyclic voltammetry, chronoamperometry, and STM measurements. Depending on the applied electrode potential, TMA molecules assemble in three distinctly different 2D ordered adlayers. In the range 0.10 < E < 0.50 V, planar-oriented molecules form an open ring honeycomb pattern (phase I) stabilized by directional hydrogen bonds. Interfacial water molecules are being replaced. A close-packed, physisorbed adlayer II forms at higher potentials in the range 0.58 < E < 0.75 V. Further increase of the electrode potential causes an orientation change. An initially disordered phase transforms into an ordered, stripe-like chemisorbed adlayer III of perpendicularly oriented TMA molecules (0.90 < E < 1.20 V). One carboxylate group per molecule is bound to the electrode surface, while the two other protonated carboxyl groups are directed toward the electrolyte, and act as structure-determining components of a hydrogen-bonded molecular ladder network. Strongly hydrogen-bonded and isolated water species are co-adsorbed. The potential-induced formation of chemisorbed TMA proceeds in two steps: (i) orientation change from planar to a disordered tilted and (or) perpendicular phase IIIa (tau < 5 ms) according to a Langmuir-type kinetics; (ii) subsequently, the chemisorbed TMA molecules align into a highly ordered, stripe-like phase IIIb with co-adsorbed water species.
Keyword(s): J ; ATR-SEIRAS (auto) ; trimesic acid (auto) ; Au(111) (auto) ; supramolecular assembly (auto)
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