Edge defects-regulated FeCo metalic sites confined in N-doped carbon polyhedron as an efficient ORR catalyst for durable Zn-air battery

Abstract

Metal sites or nanoparticles immobilized on MOF-derived porous carbon matrix have gained enormous attention for oxygen electroreduction reaction (ORR), but they still suffered from the insufficient catalytic performance. Herein, we introduced edge defects to regulate the ORR performance of N-doped carbon polyhedron-supported FeCo bimetallic catalysts via a facile NaCl/KCl-assisted pyrolysis. HR-TEM, HAADF-STEM, Raman spectra, XPS and EPR analysis confirmed the existence of uniform FeCo atoms and edge defects within N-doped porous carbon polyhedrons and their mutual effect helped promoting ORR performance. The resulting FeCo-NC-30 exhibited more excellent ORR activity with E1/2 of 0.86 V, and faster kinetic process with a higher kinetic current density, Jk,E = 0.85V = 7.15 mA/cm2. As a cathode catalyst, it delivered a desirable power density of 196.9 mW/cm2, comparable to Pt/C, in home-made Zn-air batteries. Our findings demonstrated that the electronic tuning effect caused by carbon edge defects and synergistic bimetallic interactions is beneficial for enhancing ORR activity.