Abstract

RIOS-ESCUDERO, A. et al. Electrochemical reduction of carbon dioxide in the presence of [NiII-5,7,12,14-tetramethyldinaphtho [b,i] [1,4,8,11] tetra aza [14]annulene]++ cation. An. Asoc. Quím. Argent. [online]. 2004, vol.92, n.1-3, pp.63-71. ISSN 0365-0375.

Cyclic Voltammograms of [Ni(II)5,7,12,14-tetrametyldinaphtho[b,i] [1,4,8,11]tetraaza[14]annulene]++ cation complex ([Ni(tmdnTAA)]2+ hereafter) present twoirreversible reduction peaks at -0.70 V y -1.50 V vs. Ag/AgCl in N,N´-dimethylformamide (DMF), while in acetonitrile (MeCN) these peaks are at -0.93V. and-1.80 V vs. Ag/AgCl. When DMF/H2O or MeCN/H2O are used as solvents, the peaks are also shifted with respect to those in pure DMF as solvent. For example, in DMF/ H2O they are-0.76 and -1.04 V respectively. Cyclic voltammograms of the cation complex in CO2 saturated solutions exhibited the catalytic wave of the CO2 reduction, Ecp,at ~ -1.50 V in DMF/H2O and at ~ -1.80 V in MeCN/H2O.Under these conditions, the only product of the bulk electrolysis was hydrogen. Due to the formation of a stable product, the catalytic current for the CO2 reduction of the secondvoltammetric cycle is30% less intense than the current of the first cycle. The stable adduct, [Ni(II)tmdnTAA-CO]++, formed on the electrode was characterizated by spectroeletrochemistry and FT-IR spectroscopy.

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