Robert A. Reed

Application of a polymer solid electrolyte for the vapor-phase electrocatalysis of dioxygen reduction by some cobalt porphyrins

Abstract An electrochemical cell suitable for the study of dioxygen reduction electrocatalysis by films of cobalt metalloporphyrins on electrodes in the absence of liquid electrolytes is described. The glassy carbon disk of a (stationary) ring-disk electrode is coated with either an electropolymerized film of cobalt tetra(o-aminophenyl)porphyrin or an adsorbed multimolecular layer of a dicobalt cofacial porphyrin, Co2 FTF4. Then the disk, the ring (serving as an auxiliary electrode), and a peripheral silver wire (serving as a pseudo-reference electrode) are coated with a thin film of an ionically conducting polymer: poly(ethyleneoxide) containing a 16:1 ether oxygen/Li+ concentration of lithium triflate. Bathing this solid state cell in moist, acidic or neutral bathing gases containing dioxygen produces electrocatalytic currents for dioxygen reduction. The fraction of the reduction leading to H2O2 was determined with a twin electrode sandwich modification of the above cell in which a Au film electrode atop a Nucleopore membrane is contacted to the top surface of the PEO16·Li(CF3SO3) film. No H2O2 was produced in the case of the Co2FTF4 catalyst in a neutral bathing gas; this electrocatalysis was also quite stable.

Kinetics of electron transfer mediated oxidations of methyl benzenes by ruthenium(III) tris-bipyridine

Abstract Methyl substituted benzenes can be electrocatalytically oxidized in acetonitrile solvent by electrogenerated [Ru(bpy)3]3+ in the presence of an electroinactive base, tosylate, or radical scavenger, styrene. The kinetics of the step in which the methyl benzene is oxidized to a radical cation by the metal complex are measured by rotated disk electrode voltammetry, for the faster reactions, and by controlled potential electrolysis, for the slowest reactions. The reaction rates vary systematically with the free energy.