Preparation of a tetraphenylporphyrinatocobalt(II)-poly(3,4-azopyridylene) complex and its oxygen enrichment effect at an oxygen electrode

The reversible oxygen-binding properties of tetraphenylporphyrinatocobalt(II) (CoTPP) complexed with poly(3,4-azopyridylene) (PAP) were established. The CoTPP complexes functioned as oxygen carriers at the surface of a cathode to enhance the current for the reduction of oxygen. PAP was synthesized by the oxidative polymerization of 3,4-diaminopyridine in a DMF solution at 25 °C using a Cu/pyridine catalyst. The combination of the CoTPP complex and the conventional Pt/C catalyst resulted in a significant increase in the steady-state current for the four-electron reduction of O ₂, particularly at small overpotentials where typical fuel cells operate, based on the facilitated transport of O₂ from the atmosphere to the catalyst at the electrode surface.