Pierre-Louis Taberna

Electrochemical Characteristics and Impedance Spectroscopy Studies of Carbon-Carbon Supercapacitors

This paper presents the results obtained on the electrochemical behavior of electrochemical capacitors assembled in nonaqueous electrolyte. The first part is devoted to the electrochemical characterization of carbon-carbon 4 cm 2 cells systems in terms of capacitance, resistance, and cyclability. The second part is focused on the electrochemical impedance spectroscopy study of the cells. Nyquist plots are presented and the impedance of the supercapacitors is discussed in terms of complex capacitance and complex power. This allows the determination of a relaxation time constant of the systems, and the real and the imaginary part of the complex power vs. the frequency plots give information on the supercapacitor cells frequency behavior. The complex impedance plots for both a supercapacitor and a tantalum dielectric capacitor cells are compared.

Studies and characterisations of various activated carbons used for carbon/carbon supercapacitors

Various activated carbons from the PICA Company have been tested in supercapacitor cells in order to compare their performances. The differences measured in terms of specific capacitance and cell resistance are presented. Porosity measurements made on activated carbon powders and electrode allowed a better understanding of the electrochemical behaviour of these activated carbons. In this way, the PICACTIF SC carbon was found to be an interesting active material for supercapacitors, with a specific capacitance as high as 125 F/g.

Synthesis and characterization of well aligned Ru nanowires and nanotubes

Arrays of well aligned Ru nanowires and nanotubes were prepared by electrodeposition through porous anodic aluminum oxide membranes. It is shown that Ru nanowires are formed at low cathodic deposition overpotential, while nanotubes are prepared at higher cathodic overpotential. The inner diameter of the nanotube can be controlled by the deposition potential, and it varies from 0 to 70% of the outer diameter as the deposition potential is changed from -0.30 to -0.45 V vs SCE.

Single electron transfer photoinduced oxidation of piperidine and pyrrolidine derivatives to the corresponding lactams

Irradiation by visible light of various N-arylaminopiperidines or N-arylaminopyrrolidines in presence of a catalytic amount of photosensitizer led with good yields to the corresponding N-arylaminolactams under mild conditions. This reaction proceeds by two consecutive photooxidations, the first in presence of trimethylsilyl cyanide and the second one in presence of water. Voltammetric investigations demonstrated clearly that hydrazines are more readily oxidised than tertiary amines, and as a consequence it is possible to obtain by photooxidation a wider range of oxidised compounds.