Cobalt pyridinoporphyrazine film as a platinum group metal-free mediator in hydrogen electrochemistry

Abstract

The cobalt pyridinoporphyrazine film deposited on basal plane highly oriented pyrolytic graphite (HOPG) and Au(111) electrodes exhibited electrocatalytic activity to hydrogen oxidation reaction compared to the bare electrode surfaces. The deposition performed by spontaneous adsorption of the cobalt pyridinoporphyrazine complex from its aqueous solution led on basal plane HOPG to the formation of a uniform homogeneous film with simultaneous reduction of cobalt centre, while at Au(111) electrode preferential aggregation of pyridinoporphyrazine complex took place without any change of reduction state of cobalt. Accordingly, both substrates affected the pathway of electrocatalytic hydrogen oxidation. Potentiometric detection of hydrogen based on equilibrium potential of pyridinoporphyrazine Co(II)/Co(I) electrode upon alternation presence of hydrogen and argon in solution was examined.