The Experts below are selected from a list of 30078 Experts worldwide ranked by ideXlab platform

Hubert H Girault - One of the best experts on this subject based on the ideXlab platform.

  • standard ion transfer potential at the water butyronitrile interface
    Journal of Electroanalytical Chemistry, 2019
    Co-Authors: Hubert H Girault, J.s. Riva, Victor Costa Bassetto, Astrid J. Olaya
    Abstract:

    Abstract Butyronitrile is an organic solvent stable enough to be used in photochemical reactions at liquid/liquid Interfaces. However, it provides a rather short polarisation window making the analysis of ion transfer across the water|butyronitrile interface challenging. Here, steady-state cyclic voltammetry, at microhole-supported micro-Interfaces, was used to measure Gibbs energies of transfer. A linear relationship between the standard Gibbs energies of ion partition for the water|butyronitrile interface and the water|1,2-dichloroethane and water|nitrobencene Interfaces was found, making easy to extrapolate the Gibbs energy of other ions from this empiric correlation.

  • Standard ion transfer potential at the water|butyronitrile interface
    Journal of Electroanalytical Chemistry, 2019
    Co-Authors: J.s. Riva, Hubert H Girault, Victor Costa Bassetto, Astrid J. Olaya
    Abstract:

    Abstract Butyronitrile is an organic solvent stable enough to be used in photochemical reactions at liquid/liquid Interfaces. However, it provides a rather short polarisation window making the analysis of ion transfer across the water|butyronitrile interface challenging. Here, steady-state cyclic voltammetry, at microhole-supported micro-Interfaces, was used to measure Gibbs energies of transfer. A linear relationship between the standard Gibbs energies of ion partition for the water|butyronitrile interface and the water|1,2-dichloroethane and water|nitrobencene Interfaces was found, making easy to extrapolate the Gibbs energy of other ions from this empiric correlation.

  • decamethylruthenocene hydride and hydrogen formation at liquid liquid Interfaces
    Journal of Physical Chemistry C, 2015
    Co-Authors: Lucie Rivier, Micheal D Scanlon, Manuel A Mendez, Jane T Stockmann, Pekka Peljo, Marcin Opallo, Hubert H Girault
    Abstract:

    The formation and the dissociation of metal hydrides are key steps within the hydrogen evolution reaction (HER) pathway for photochemical water splitting, but also impacts a wide range of other catalytic, industrial, and biochemical reactions. Herein, we describe our recent work studying HER at the interface between two immiscible electrolyte solutions (ITIES), between water|1,2-dichloroethane. This is a unique platform for evaluating the kinetics/thermodynamics for metallocene hydride formation using decamethylruthenocene. In this approach, an aqueous acid serves as the proton source and is pumped across the ITIES via an externally applied potential or the use of a phase transfer catalyst. Simulated curves developed using COMSOL Multiphysics software and compared to experimental ones, indicate a modified EC′ (electrochemical–chemical) mechanism for the decamethylruthenocene hydride formation. In the proposed pathway, decamethylruthenocene hydride is metastable in 1,2-dichloroethane and persists on the ti...

  • self assembled molecular rafts at liquid liquid Interfaces for four electron oxygen reduction
    Journal of the American Chemical Society, 2012
    Co-Authors: Astrid J. Olaya, Hirohisa Nagatani, Delphine Schaming, Pierrefrancois Brevet, Tomas Zimmermann, Jiri Vanicek, Claude P Gros, Jeanmichel Barbe, Hubert H Girault
    Abstract:

    The self-assembly of the oppositely charged water-soluble porphyrins, cobalt tetramethylpyridinium porphyrin (CoTMPyP4+) and cobalt tetrasulphonatophenyl porphyrin (CoTPPS4–), at the interface with an organic solvent to form molecular “rafts”, provides an excellent catalyst to perform the interfacial four-electron reduction of oxygen by lipophilic electron donors such as tetrathiafulvalene (TTF). The catalytic activity and selectivity of the self-assembled catalyst toward the four-electron pathway was found to be as good as that of the Pacman type cofacial cobalt porphyrins. The assembly has been characterized by UV–visible spectroscopy, Surface Second Harmonic Generation, and Scanning Electron Microscopy. Density functional theory calculations confirm the possibility of formation of the catalytic CoTMPyP4+/ CoTPPS4– complex and its capability to bind oxygen.

  • melittin adsorption and lipid monolayer disruption at liquid liquid Interfaces
    Langmuir, 2011
    Co-Authors: Manuel A Mendez, Zahra Nazemi, Ibrahim Uyanik, Hubert H Girault
    Abstract:

    Melittin, a membrane-active peptide with antimicrobial activity, was investigated at the interface formed between two immiscible electrolyte solutions (ITIES) supported on a metallic electrode. Ion-transfer voltammetry showed well-defined semi-reversible transfer peaks along with adsorptive peaks. The reversible adsorption of melittin at the Liquid-Liquid interface is qualitatively discussed from voltammetric data and experimentally confirmed by real-time image analysis of video snapshots. It is also demonstrated that polarization of the water/1,2-DCE interface results in drastic drop shape variations caused by large variations of the interfacial tension. The experimental data also confirmed that maximum adsorption occurs near the ion transfer potential. Finally, the interaction of melittin with a monolayer of L-alpha-dipalmitoyl phosphatidylcholine (DPPC) was also investigated showing that melittin destabilizes the lipidic monolayer facilitating its desorption. The non-covalent complex formation between melittin and DPPC was confirmed by mass spectrometry.

Astrid J. Olaya - One of the best experts on this subject based on the ideXlab platform.

  • standard ion transfer potential at the water butyronitrile interface
    Journal of Electroanalytical Chemistry, 2019
    Co-Authors: Hubert H Girault, J.s. Riva, Victor Costa Bassetto, Astrid J. Olaya
    Abstract:

    Abstract Butyronitrile is an organic solvent stable enough to be used in photochemical reactions at liquid/liquid Interfaces. However, it provides a rather short polarisation window making the analysis of ion transfer across the water|butyronitrile interface challenging. Here, steady-state cyclic voltammetry, at microhole-supported micro-Interfaces, was used to measure Gibbs energies of transfer. A linear relationship between the standard Gibbs energies of ion partition for the water|butyronitrile interface and the water|1,2-dichloroethane and water|nitrobencene Interfaces was found, making easy to extrapolate the Gibbs energy of other ions from this empiric correlation.

  • Standard ion transfer potential at the water|butyronitrile interface
    Journal of Electroanalytical Chemistry, 2019
    Co-Authors: J.s. Riva, Hubert H Girault, Victor Costa Bassetto, Astrid J. Olaya
    Abstract:

    Abstract Butyronitrile is an organic solvent stable enough to be used in photochemical reactions at liquid/liquid Interfaces. However, it provides a rather short polarisation window making the analysis of ion transfer across the water|butyronitrile interface challenging. Here, steady-state cyclic voltammetry, at microhole-supported micro-Interfaces, was used to measure Gibbs energies of transfer. A linear relationship between the standard Gibbs energies of ion partition for the water|butyronitrile interface and the water|1,2-dichloroethane and water|nitrobencene Interfaces was found, making easy to extrapolate the Gibbs energy of other ions from this empiric correlation.

  • self assembled molecular rafts at liquid liquid Interfaces for four electron oxygen reduction
    Journal of the American Chemical Society, 2012
    Co-Authors: Astrid J. Olaya, Hirohisa Nagatani, Delphine Schaming, Pierrefrancois Brevet, Tomas Zimmermann, Jiri Vanicek, Claude P Gros, Jeanmichel Barbe, Hubert H Girault
    Abstract:

    The self-assembly of the oppositely charged water-soluble porphyrins, cobalt tetramethylpyridinium porphyrin (CoTMPyP4+) and cobalt tetrasulphonatophenyl porphyrin (CoTPPS4–), at the interface with an organic solvent to form molecular “rafts”, provides an excellent catalyst to perform the interfacial four-electron reduction of oxygen by lipophilic electron donors such as tetrathiafulvalene (TTF). The catalytic activity and selectivity of the self-assembled catalyst toward the four-electron pathway was found to be as good as that of the Pacman type cofacial cobalt porphyrins. The assembly has been characterized by UV–visible spectroscopy, Surface Second Harmonic Generation, and Scanning Electron Microscopy. Density functional theory calculations confirm the possibility of formation of the catalytic CoTMPyP4+/ CoTPPS4– complex and its capability to bind oxygen.

J.s. Riva - One of the best experts on this subject based on the ideXlab platform.

  • standard ion transfer potential at the water butyronitrile interface
    Journal of Electroanalytical Chemistry, 2019
    Co-Authors: Hubert H Girault, J.s. Riva, Victor Costa Bassetto, Astrid J. Olaya
    Abstract:

    Abstract Butyronitrile is an organic solvent stable enough to be used in photochemical reactions at liquid/liquid Interfaces. However, it provides a rather short polarisation window making the analysis of ion transfer across the water|butyronitrile interface challenging. Here, steady-state cyclic voltammetry, at microhole-supported micro-Interfaces, was used to measure Gibbs energies of transfer. A linear relationship between the standard Gibbs energies of ion partition for the water|butyronitrile interface and the water|1,2-dichloroethane and water|nitrobencene Interfaces was found, making easy to extrapolate the Gibbs energy of other ions from this empiric correlation.

  • Standard ion transfer potential at the water|butyronitrile interface
    Journal of Electroanalytical Chemistry, 2019
    Co-Authors: J.s. Riva, Hubert H Girault, Victor Costa Bassetto, Astrid J. Olaya
    Abstract:

    Abstract Butyronitrile is an organic solvent stable enough to be used in photochemical reactions at liquid/liquid Interfaces. However, it provides a rather short polarisation window making the analysis of ion transfer across the water|butyronitrile interface challenging. Here, steady-state cyclic voltammetry, at microhole-supported micro-Interfaces, was used to measure Gibbs energies of transfer. A linear relationship between the standard Gibbs energies of ion partition for the water|butyronitrile interface and the water|1,2-dichloroethane and water|nitrobencene Interfaces was found, making easy to extrapolate the Gibbs energy of other ions from this empiric correlation.

David J Fermin - One of the best experts on this subject based on the ideXlab platform.

  • organisation and reactivity of nanoparticles at molecular Interfaces part ii dye sensitisation of tio2 nanoparticles assembled at the water 1 2 dichloroethane interface
    ChemPhysChem, 2003
    Co-Authors: David J Fermin, H Jensen, Jacquesedouard Moser, Hubert H Girault
    Abstract:

    Contactless dye-sensitised nano-photoelectrodes assembled at polarisable liquid|liquid Interfaces exhibit photocurrent responses originating from the heterogeneous photooxidation of ferrocene by the colloids. The photocurrent spectra of the nanoparticle assembly sensitised by alizarin indicate that the photoreaction is initiated by an ultrafast electron injection from the dye into the conduction band of the TiO2 particles, followed by heterogeneous electron transfer from ferrocene to the oxidised dye, as shown.

  • a kinetic model for adsorption and transfer of ionic species at polarized liquid liquid Interfaces as studied by potential modulated fluorescence spectroscopy
    Journal of Physical Chemistry B, 2001
    Co-Authors: Hirohisa Nagatani, David J Fermin, Hubert H Girault
    Abstract:

    Fundamental expressions for analyzing potential modulated fluorescence (PMF) responses were derived within the framework of a phenomenological model for adsorption and transfer of ionic species across polarized liquid|liquid Interfaces. For small periodic perturbations of the Galvani potential difference, PMF signals can be linearized and the contribution of each process can be uncoupled in the frequency domain. The PMF response for kinetically controlled adsorption is expressed as a semicircle in the complex plane in which the characteristic frequency of maximum imaginary component is proportional to the adsorption and desorption rate constants. Considering that the potential dependence of adsorption exhibits opposite sign whether the process take place from the aqueous or organic phase, the corresponding PMF responses appear in different quadrants of the complex plane. The present model delivers useful diagnostic criteria for analyzing the nature of the various processes contributing to the periodic flu...

  • photoinduced electron transfer at liquid liquid Interfaces part ii a study of the electron transfer and recombination dynamics by intensity modulated photocurrent spectroscopy imps
    Physical Chemistry Chemical Physics, 1999
    Co-Authors: David J Fermin, Zhifeng Ding, Dung H Duong, Ois Brevet, Hubert H Girault
    Abstract:

    The dynamics of photoresponses associated with heterogeneous quenching of zinc tetrakis(carboxphenyl)porphyrin (ZnTPPC) and ferrocene derivatives at the water/1,2-dichloroethane interface were studied by intensity modulated photocurrent spectroscopy (IMPS). The contribution arising from the electron injection, recombination–product separation competition and the attenuation associated with the uncompensated resistance and interfacial capacitance (RC) time constant of the cell were deconvoluted in the frequency domain. The flux of electron injection was described in terms of a competition between the relaxation of the porphyrin excited state and the electron transfer step. Experimental results in the presence of ferrocene and diferrocenylethane confirmed that as the Galvani potential difference is increased, the phenomenological electron transfer rate constant increases and the ZnTPPC coverage at the liquid/liquid junction decreases. Furthermore, the recombination rate constant decreases with increasing potentials, while the product separation rate constant did not show a clear potential dependence. Photocurrent studies were extended to the electron donors dimethylferrocene and trianisylamine, as well as to the electron acceptor tetracyanoquinodimethane. The results obtained clearly indicate that the Gibbs energy of activation for the charge transfer process is affected by the Galvani potential difference. It is suggested that the electron transfer dynamics are dependent on the local electric field generation by the specifically adsorbed ZnTPPC. The general expressions for the frequency dependent photocurrents at liquid/liquid Interfaces are also introduced.

Imren Hatay - One of the best experts on this subject based on the ideXlab platform.

  • hydrogen evolution at polarised liquid liquid Interfaces catalyzed by molybdenum disulfide
    Energy and Environmental Science, 2011
    Co-Authors: Imren Hatay, Pei Yu Ge, Heron Vrubel, Xile Hu, Hubert H Girault
    Abstract:

    Molybdenum disulfide microparticles in suspension in an aqueous acidic solution adsorb at the interface with an organic electrolyte solution containing the reducing agent, decamethylferrocene, to catalyse hydrogen evolution. This catalytic process has been investigated by voltammetry at the water/1,2-dichloroethane interface and by biphasic reactions monitored by gas chromatography and UV-visible spectroscopy.

  • oxygen reduction catalyzed by a fluorinated tetraphenylporphyrin free base at liquid liquid Interfaces
    Journal of the American Chemical Society, 2010
    Co-Authors: Imren Hatay, Manuel A Mendez, Claude P Gros, Jeanmichel Barbe, Tony Khoury, Mustafa Ersoz, Clemence Corminboeuf, Melanie Bourdillon, Michel Meyer, Stanislav Zalis
    Abstract:

    The diprotonated form of a fluorinated free base porphyrin, namely 5-(p-aminophenyl)-10,15,20-tris(pentafluorophenyl)porphyrin (H2FAP), can catalyze the reduction of oxygen by a weak electron donor, namely ferrocene (Fc). At a water/1,2-dichloroethane interface, the interfacial formation of H4FAP2+ is observed by UV−vis spectroscopy and ion-transfer voltammetry, due to the double protonation of H2FAP at the imino nitrogen atoms in the tetrapyrrole ring. H4FAP2+ is shown to bind oxygen, and the complex in the organic phase can easily be reduced by Fc to produce hydrogen peroxide as studied by two-phase reactions with the Galvani potential difference between the two phases being controlled by the partition of a common ion. Spectrophotometric measurements performed in 1,2-dichloroethane solutions clearly evidence that reduction of oxygen by Fc catalyzed by H4FAP2+ only occurs in the presence of the tetrakis(pentafluorophenyl)borate (TB−) counteranion in the organic phase. Finally, ab initio computations supp...

  • molecular electrocatalysis for oxygen reduction by cobalt porphyrins adsorbed at liquid liquid Interfaces
    Journal of the American Chemical Society, 2010
    Co-Authors: Bin Su, Imren Hatay, Claude P Gros, Jeanmichel Barbe, Zdenek Samec, Tony Khoury, Antonin Trojanek, Antoine Daina, Pierrealain Carrupt, Hubert H Girault
    Abstract:

    Molecular electrocatalysis for oxygen reduction at a polarized water/1,2-dichloroethane (DCE) interface was studied, involving aqueous protons, ferrocene (Fc) in DCE and amphiphilic cobalt porphyrin catalysts adsorbed at the interface. The catalyst, (2,8,13,17-tetraethyl-3,7,12,18-tetramethyl-5-p-amino-phenylporphyrin) cobalt(II) (CoAP), functions like conventional cobalt porphyrins, activating O2 via coordination by the formation of a superoxide structure. Furthermore, due to the hydrophilic nature of the aminophenyl group, CoAP has a strong affinity for the water/DCE interface as evidenced by lipophilicity mapping calculations and surface tension measurements, facilitating the protonation of the CoAP−O2 complex and its reduction by ferrocene. The reaction is electrocatalytic as its rate depends on the applied Galvani potential difference between the two phases.

  • proton coupled oxygen reduction at liquid liquid Interfaces catalyzed by cobalt porphine
    Journal of the American Chemical Society, 2009
    Co-Authors: Imren Hatay, Manuel A Mendez, Claude P Gros, Jeanmichel Barbe, Zdenek Samec, Tony Khoury, Mustafa Ersoz, Hubert H Girault
    Abstract:

    Cobalt porphine (CoP) dissolved in the organic phase of a biphasic system is used to catalyze O2 reduction by an electron donor, ferrocene (Fc). Using voltammetry at the interface between two immiscible electrolyte solutions (ITIES), it is possible to drive this catalytic reduction at the interface as a function of the applied potential difference, where aqueous protons and organic electron donors combine to reduce O2. The current signal observed corresponds to a proton-coupled electron transfer (PCET) reaction, as no current and no reaction can be observed in the absence of either the aqueous acid, CoP, Fc, or O2.