Non-pyrolyzed cobalt-porphyrin cathode catalyst on carbon support as an efficient electrocatalyst for oxygen reduction reaction in basic medium
Owing to their high energy efficiency, reduced pollution, and minimal maintenance cost, fuel cells have been regarded as one of the most promising energy conversion devices. The commonly used effective electrocatalysts are platinum-based materials. The development of fuel cell electrodes with non-noble metal catalysts to lessen the use of Pt-based materials has been the focus of this study. The cathode catalysts were synthesized using the sodium borohydride reduction method. Catalyst inks were prepared and subjected to electrochemical characterization that included linear sweep voltammetry (LSV) and cyclic voltammetry (CV). Optimization of the metal loading and metal salt shows that the non-precious metal catalyst, 20% cobalt porphyrin (2,3,7,8,12,13,17,18-Octaethyl-21H, 23H-porphine cobalt (II)) supported on carbon black (CoP/C), gave the highest catalytic activity having a current density of 2.23 mA cm–2 compared to the commercially available 20% Pt/C (Premetek, USA) (1.46 mA cm–2) in basic medium. The retained current for the CoP/C was 58.15% while for the 20% Pt/C catalyst (Premetek (USA), it was 21.23%. The electrochemical impedance spectroscopy (EIS) showed enhanced electron transfer kinetics for CoP/C than the commercially available 20% Pt/C (Premetek, USA). The morphological and surface characterization were obtained using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis that confirmed the ~20% metal loading of the catalyst.
Keywords: cobalt porphyrin, cathode catalyst, fuel cell, oxygen reduction reaction