Solid-state reference electrodes based on carbon nanotubes and polyacrylate membranes

A novel potentiometric solid-state reference electrode containing single-walled carbon nanotubes as the transducer layer between a polyacrylate membrane and the conductor is reported here. Single-walled carbon nanotubes act as an efficient transducer of the constant potentiometric signal originating from the reference membrane containing the Ag/AgCl/Cl− ions system, and they are needed to obtain a stable reference potentiometric signal. Furthermore, we have taken advantage of the light insensitivity of single-walled carbon nanotubes to improve the analytical performance characteristics of previously reported solid-state reference electrodes. Four different polyacrylate polymers have been selected in order to identify the most efficient reservoir for the Ag/AgCl system. Finally, two different arrangements have been assessed: (1) a solid-state reference electrode using photo-polymerised n-butyl acrylate polymer and (2) a thermo-polymerised methyl methacrylate:n-butyl acrylate (1:10) polymer. The sensitivity to various salts, pH and light, as well as time of response and stability, has been tested: the best results were obtained using single-walled carbon nanotubes and photo-polymerised n-butyl acrylate polymer. Water transport plays an important role in the potentiometric performance of acrylate membranes, so a new screening test method has been developed to qualitatively assess the difference in water percolation between the polyacrylic membranes studied. The results presented here open the way for the true miniaturisation of potentiometric systems using the excellent properties of single-walled carbon nanotubes

Single-Molecule Electrochemical Transistor Utilizing a Nickel-Pyridyl Spinterface

Using a scanning tunnelling microscope break-junction technique, we produce 4,4′-bipyridine (44BP) single-molecule junctions with Ni and Au contacts. Electrochemical control is used to prevent Ni oxidation and to modulate the conductance of the devices via nonredox gatingthe first time this has been shown using non-Au contacts. Remarkably the conductance and gain of the resulting Ni-44BP-Ni electrochemical transistors is significantly higher than analogous Au-based devices. Ab-initio calculations reveal that this behavior arises because charge transport is mediated by spin-polarized Ni <i>d</i>-electrons, which hybridize strongly with molecular orbitals to form a “spinterface”. Our results highlight the important role of the contact material for single-molecule devices and show that it can be varied to provide control of charge and spin transport

Metal-supported cathodically activated graphite via self-reduction as electrocatalysts for efficient hydrogen evolution reaction

International audienc

Variations of Diffusion Coefficients of Redox Active Molecules in Room Temperature Ionic Liquids upon Electron Transfer

International audienc

Reactivity of platinum metal with organic radical anions from metal to pt negative oxidation states

J. Amer. Chem. Soc., 2007, 129, 6654-666

Facile Electrochemical Characterization of Core/Shell Nanoparticles. Ag Core/Ag 2 O Shell Structures

ABSTRACT We report in this paper a facile approach for the formation and electrochemical characterization of silver−silver oxide core−shell nanoparticles (NPs). Thus, thermal treatment at temperatures between 200 and 360°C of Ag NP, in the gas phase or in an organic solvent, has been used to achieve the formation Ag@Ag 2 O NP. The evidence of formation of such a core−shell structure was obtained by cyclic voltammetry using a Nafion modified electrode (where Nafion containing carbon particles is used as the matrix to encapsulate the core−shell NP). Initial positive scans measure free Ag. Initial negative scans measure Ag 2 O, with the following positive scan, compared to the initial one, providing a measure of &quot;trapped&quot; or core Ag. The results presented demonstrate the utility of this approach in characterizing core−shell structures, like Ag@Ag 2 O, which could be extended to other core−shell forms, such as bimetallic core−shell NP