Carbon electrodes with phthalocyanine catalyst in acid medium

The catalytic properties of polymeric phthalocyanines with Fe and Co as central atoms for the electroreduction of oxygen in 0.5–2.3m H₂SO₄ were studied. No noticeable dependence of the electrode potential on the concentration of H₂SO₄ was found. The electroactivity of the catalyst with a central Fe atom undergoes considerable deterioration under the given conditions, whereas the stability of the catalyst with a central Co atom is very good and the potential of an electrode containing 30% catalyst in the active mass is 100 mV more positive than that of an electrode with 13% platinum, both at 40 mA cm^–2. The electrode performance depends markedly on the sort of carbon substrate, showing a parallelism with respect to oxygen electrodes in alkaline medium. The gold mesh current collector can be replaced by the addition of carbon black to the active layer.