Mapping Transition Metal-MN4 Macrocyclic Complex Catalysts Performance for the Critical Reactivity Descriptors

There has been a significant progress towards the development of highly active and stable platinum group metal-free (PGM-free) electrocatalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFC), promising a low-cost replacement for Pt group electrocatalysts. However, the success of such developments depends on the implementation of PGM-free electrocatalysts that are not only highly active but importantly, they also exhibit long-term durability under PEFC operating conditions. This manuscript is an overview of the current status of a specific, most advanced class of PGM-free electrocatalysts: transition metal-nitrogen-carbon (M-N-C) ORR catalysts. We present an overview for the understanding of catalysts’ performance descriptors for M-N-C materials.