(Digital Presentation) The Optimization of Polypyrrole Concentration to Synthesize Hollow Fe, Co, and Nitrogen Doped Carbon Spheres with Improved Oxygen Reduction Reaction Performance

Abstract

Transition metal and nitrogen co-doped carbon materials (M-N-C, M=Fe, Co, Ni, etc.) have recently emerged as front runners to replace commercial Pt/C for the oxygen reduction reaction (ORR) due to their natural availability and excellent electrocatalytic activity. The development of M-N-C materials with optimized active sites using a secondary nitrogen source has attracted a lot of attention as ORR catalysts for their high activity and excellent durability. Polypyrrole (PPy) has become an attractive secondary nitrogen source for increased nitrogen doping and metal dispersion. Herein, we developed hollow Fe, Co, and nitrogen-doped carbon (H-FeCo-NC) spheres using the composites of metal-organic frameworks (MOFs) materials and PPy. Based on X-ray absorption fine spectroscopy analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy, the active centers and the role of PPy for ORR catalytic performance are explored. The H-FeCo-NC not only displayed remarkable ORR performance in alkaline media, with a half-wave potential of 0.903 V, but also showed excellent stability and durability. The results outperformed the commercial Pt/C catalyst, demonstrating the potential of utilizing PPy for improved ORR performance.