Electrocatalytic effects of thionyl chloride reduction by polymeric Schiff base transition metal(II) complexes

Abstract

Electrocatalytic effects for the reduction of thionyl chloride in LiAlCl 4/SOCl 2 electrolyte solution containing polymeric Schiff base M(II) (M: Ni and Cu) complexes were evaluated by determining kinetic parameters with cyclic voltammetry at a glassy carbon electrode. The charge transfer process during the reduction of thionyl chloride was affected by the concentration of the catalyst. The catalytic effects were demonstrated from both a shift of the reduction potential for the thionyl chloride in a more positive direction and an increase in peak currents. The reduction of thionyl chloride was found to be diffusion-controlled. Catalytic effects are larger in thionyl chloride solutions containing (PVPS)M(II)(SALPR) rather than in those containing (PVPS)M(II)(SALPE). Such results are opposite to those for monomeric Schiff base complexes. Significant improvements in the cell performance were found in terms of both thermodynamics and kinetic parameters for the thionyl chloride reduction. An exchange rate constant, k o, of 1.62×10 −8 cm/s was found at a bare electrode, while larger values of (4.69–8.18)×10 −8 cm/s were observed at the catalyst-supported glassy carbon electrode.