Recent progress on MN ₄ macrocycle-derived oxygen reduction reaction electrocatalysts for polymer electrolyte fuel cell applications

macrocycle-derived oxygen reduction reaction (ORR) electrocatalysts for proton exchange membrane fuel cells (PEMFCs) and anion exchange membrane fuel cells (AEMFCs), and summarizes the viability in energy applications, including their stability issues. This review aims to discuss the various factors that influence the fuel cell performance of cathode catalysts based on transition-metal macrocyclic complexes (metal porphyrins and phthalocyanines).