Adsorptive‐catalytic stripping voltammetry‐enhanced reduction current of adsorbed CoII tetraaza[14]annulene complex in the presence of CO2

Abstract

AbstractThe macrocyclic cobalt(II) complex CoL (LH2 = 5,14dihydrodibenzo[b,i][1,4,8,11] tetraaza[l4]annulene) can be adsorptively preaccumulated on mercury electrodes from highly diluted aqueous solutions. The adsorbed CoII complex undergoes one‐electron reduction with subsequent protonation of [CoL]− to CoLH, also adsorbed on mercury. The electrode covered with adsorbed complex may be used to detect CO2, since upon substitution of argon by CO2 a large catalytic peak is observed at the potentials of CoLH complex reduction. At constant CO2 concentration, the peak first increases proportionally to the extent of coverage of the electrode with the adsorbed complex and then becomes constant when monolayer coverage is attained. At a monolayer covered electrode the catalytic reduction signal increases proportionally to the increase of CO2 concentration. The usefulness of the normal pulse voltammetry version of the adsorptive‐catalytic stripping procedure is also shown.