Portal de Periódicos da CAPES

Aminopyridyl cation radical method for bridging between metal complex and glassy carbon: cobalt(II) tetraphenylporphyrin bonded on glassy carbon for enhancement of CO2 electroreduction

1997; Elsevier BV; Volume: 437; Issue: 1-2 Linguagem: Inglês

10.1016/s0022-0728(97)00080-6

1873-2569

Hideaki Tanaka, Akiko Aramata,

Electrochemical sensors and biosensors

Aminopyridyl compound immobilization on glassy carbon (GC) was carried out by amine cation radical formation through electro-oxidation at GC in ethanol solution, and subsequently by chemical bonding of the radical to GC. The aminopyridyl group immobilized on GC takes part as a bridge between cobalt tetraphenylporphyrin (Co(II)TPP) and GC, where the nitrogen of the pyridyl group is coordinated as a fifth ligand of Co(II)TPP, being perpendicular to the porphyrin plane. The Co(II)TPP modified GC electrode was thus prepared by a bridging amine of 4-aminopyridine, 4-aminoethylpyridine, or imidazole in the electrochemical and chemical processes, which is denoted 'CoTPP bonded GC'. Whereas Co(II)TPP physically attached to GC, denoted CoTPP|GC, was not able to reduce CO2 atE = −1.1V(SCE) in pH 6.3 phosphate buffer solution, 'CoTPP bonded GC' gave CO from CO2 electroreduction at that potential with 60% current efficiency. By polarization of 'CoTPP bonded GC' at hydrogen evolution potentials, Co(II)TPP stacked on 'CoTPP bonded ' is suggested to be converted to HCo(II)TPP, but Co(II)TPP on CoTPP|GC remains the same. Hydrogenated 'CoTPP bonded GC' is suggested to play an important role as one of the intermediates of CO2 electroreduction.