Enhancing the Stability of a Pt‐Free ORR Catalyst via Reaction Intermediates

Abstract

AbstractFinding a platinum‐free cathode catalyst that effectively models the oxygen reduction reaction (ORR) of a proton‐exchange membrane (PEM) fuel cell cathode better than the current commercial Pt/C catalyst has been a major shortcoming in fuel cell technology. Overall, a promising platinum‐free cathode catalyst must offer great ORR activity, ORR selectivity, and acid stability. Due to their enticing ORR activity and selectivity to the preferred four‐electron ORR pathway, the possible dissolution reactions and oxygen‐intermediate reactions of iron phthalocyanine monolayer supported on a pristine graphene (GFePc) and boron‐doped graphene substrate (BGFePc) have been studied to determine the stability as a function of potential and pH through spin‐polarized density functional theory (DFT) calculations at both infinitesimally low (10−9 m) and 1 m Fe2+/Fe3+ ionic concentrations. BGFePc offers higher stability in both concentrations than GFePc. In both cases, the oxygen‐intermediates are more stable than the bare catalytic surface due to the metal d‐band center shifting further away from the Fermi level in the valence band state (higher energy of antibonding). Moreover, at an Fe2+ ionic concentration, both catalysts would be stable in the potential and pH regions at the operating conditions of rotating disk electrode (RDE) experiments and PEM fuel cells.