Porphyrin and phthalocyanine transition metal complexes adsorbed on activated carbon fiber nanoporous supports are shown to be effective catalysts for CO2 electroreduction in the form of gas diffusion electrodes, yielding carbon monoxide with current efficiencies up to ca. 70%. A comparison of the efficiency of activated carbon supports with a wide pore size distribution, and activated carbon fibers, with slit-shaped pores of ca. 2 nm width, demonstrates that an increase in the catalyst dimensions results in a decrease in the benefit of the so-called nanospace effect. For bulky molecules, e.g., tetra-tert-butyl-substituted phthalocyanines, activated carbon supports are more effective, with a current efficiency as high as 85% for CO production being achieved. © 2002 The Electrochemical Society. All rights reserved.

Electrochemical behavior of C(60)(CF(2))(n), n = 1, 2 and C(60)(CCl(2)) has been investigated. [6,6]-Opened C(60)(CF(2)) and cis-2-C(60)(CF(2))(2) exhibit reversible reductions at potentials 150 and 145 mV more positive than C(60), unlike the related [6,6]-closed C(60)(CCl(2)), which shows reduction at the potential close to that for C(60). The structures, electron localization and lifetimes of the observed radical anions C(60)(CF(2))(-*) and cis-2-C(60)(CF(2))(2)(-*) have been elucidated by the ESR study and DFT calculations. The protonation pathway of decay of C(60)(CF(2))(-*) yields [6,6]-opened 1,9-dihydro-(1a,1a-difluoro-1aH-1(9)a-homo(C(60)-I(h))fullerene, C(60)(CF(2))H(2), which becomes the first characterized derivative of [6,6]-opened C(60)(CF(2)). DFT calculations of the structure and electron affinity of a number of homofullerene structures have been carried out to rationalize the experimental findings.

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