Application of pyrolyzed Cobalt (II) tetramethoxyphenyl porphyrin based catalyst in metal-air systems and enzyme electrodes

Abstract

This article presents the use of Cobalt (II) tetramethoxyphenyl porphyrin pyrolyzed on active carbon as a highly efficient non-precious metal catalyst (AC/CoTMPP) for oxygen reduction reaction in three types of electrochemical metal-air systems. The presented results cover various metal-air systems: the alkaline system (zinc-air) with aqueous electrolyte; the neutral (magnesium-air) one with aqueous electrolyte and the non-aqueous (lithium-air) one, as well as one with enzyme electrodes. Pyrolysis of the N4-chelate compound on activated carbon has been shown to produce a stable catalyst over time. The achieved long-term operation (3500 h) in the zinc-air system with alkaline electrolyte is due to increased activity of the AC/CoTMPP catalyst for the decomposition of H2O2, generated in the process of electrochemical reduction of the oxygen. The use of this catalyst in a magnesium-air system with a NaCl electrolyte is a novelty. Based on the obtained results were mechanically rechargeable magnesium-air cells developed, generating current of 2.5 A–140 A and power of up to 154 W. A novelty is the catalyst use in lithium-air cells with non-aqueous electrolyte. The application of AC/CoTMPP catalyst for enzyme electrodes allows the creation of highly sensitive sensors, designed to operate under anaerobic conditions. AC/CoTMPP has been shown to exhibit its activity over a wide range of potentials (−0.5 V to +1.1 V vs. SHE) in all investigated electrolytes and is active for both the reduction of oxygen and for the oxidation of H2O2.