Metal Phthalocyanine Modified Electrode Electrocatalytic Reduction Of Molecular Oxygen

Phthalocyanine cobalt (CoPc), tetrabromophthalocyanine cobalt (CoPcBr₄),tetra-α-(2,2,4-trimethyl-3-pentyloxy)phthalocyanine cobalt (CoPc(OC₈H₁₇)₄) andtetrabromophthalocyanine iron (FePcBr₄) modified glass carbon electrodes wereprepared by the adsorption method in this paper. Electrocatalytic reduction ofmolecular oxygen and H₂O₂ by the modified electrodes was studied in acidic and basicmedia using cyclic voltammetry and linear sweep volammetry. The effect of differentsubstituted groups and central metal ions on the electrocatalytic properties ofmetallophthalocyanines and the kinetic process of O₂ reduction were investigated.In the acidic medium, FePcBr₄ modified electrode was very unstable. CoPcBr₄ hadthe highest electrocatalytic activity. It promoted the reduction of O₂ to H₂O₂ and H₂O₂to H₂O and eventually enabled two steps of two-electron reduction of O₂. In the basicmedium, the four metallophthalocyanines all catalyzed O₂ to produce H₂O viafour-electron path and FePcBr₄ had the highest elelctrocatalytic activity. Thedifferences of electrocatalytic activity resulted from the differences of substitutedgroups and central metal ions. The kinetic process of O₂ reduction was controlled bythe diffusion of O₂ from solution to electrode surface.CoPc(OC₈H₁₇)₄ and MnO₂ dual catalysts modified glass carbon electrode wasprepared by the evaporation method. Electrocatalytic reduction of molecular oxygenby the modified electrodes was studied in basic media using cyclic voltammetry. Theresults indicated that the electrocatalytic activity of dual catalysts was better than anyingredient of them.