Transition metal coordinated framework porphyrin for electrocatalytic oxygen reduction

Oxygen reduction reaction (ORR) constitutes the core process of many clean and sustainable energy systems including fuel cells and metal-air batteries. Developing high-performance and cost-efficiency ORR electrocatalysts is of great significance to the practical applications of the above-mentioned energy storage devices. Transition metal coordinated porphyrin electrocatalysts are highly considered as a promising substitution of noble-metal-based electrocatalyst because of their high ORR reactivity, where the ORR performances of the porphyrin-based electrocatalysts are highly dependent on the transition metal center. Herein a series of framework porphyrin electrocatalysts coordinated with different transition metal centers (M-POF, where M is Mn, Fe, Co, Ni, Cu, or Zn) was designed, synthesized, and evaluated in regards of electrocatalytic ORR performances. Among all, the Co-POF electrocatalyst exhibits the best ORR performances with the highest half-wave potential of 0.81 V vs. RHE and the lowest Tafel slope of 53 mV/dec. This contribution affords an optimized high-performance ORR electrocatalyst and provides instructions for further rational design of porphyrin-based ORR electrocatalysts for sustainable energy applications.