Metal Phthalocyanine-Porphyrin-based Conjugated Microporous Polymer-derived Bifunctional Electrocatalysts for Zn-Air Batteries.

Conjugated microporous polymers (CMPs) as emerging porous materials with diverse structures and tunable building-units have attracted much attention in the electrochemical field. Herein, we designed phthalocyanine-porphyrin-based conjugated microporous polymers as precursors for fabrication of Co, Fe, N tri-doped graphene composites towards oxygen reduction and evolution reaction (ORR/OER). As expected, the elements cobalt and iron are well dispersed in graphene carbon and interact with the nitrogen sites, thereby providing extra electrocatalytic active sites and enhancing its overall conductivity. Benefiting from its unique design and structure, the obtained catalyst affords a superior bifunctional catalytic activity with a positive onset potential of 0.957 V for ORR, and a low overpotential of 0.36 V for OER. More attractively, the CoFeNG is employed as an air cathode catalyst in Zn-air batteries, showing a maximum current density of 215 mA cm and good cycle stability for 20000 s. The rational design of phthalocyanine-porphyrin-based derivatives provides a feasible route for the construction of high-performance ORR/OER catalysts.