Nitrogen, Fluorine, and Phosphorus Tri-Doped Porous Carbon with High Electrical Conductivity as an Excellent Metal-Free Electrocatalyst for Oxygen Reduction Reaction

Abstract

Today's oxygen reduction reaction (ORR) depends on the precious metal Pt-based catalysts, limiting the large commercialization of promising energy conversion technologies such as proton exchange membrane fuel cells (PEMFCs) and metal-air batteries. Therefore, the rational design of low-cost and highly efficient electrocatalysts for ORR is strongly desired. Herein, we report a porous carbon doped with nitrogen, fluorine, and phosphorus (N, F, P tri-doped carbon) prepared via only a heating process using low-cost glycine, ammonium fluoride, and phytic acid as precursors. X-ray photoelectron spectroscopy (XPS) analysis revealed the existence of pyridinic-N and the co-existence of graphitic-N and oxidized graphitic-P, which can be active sites, with semi-ionic C−F bonds highly boosting ORR activity. Remarkably, the resultant N, F, P tri-doped carbon exhibited outstanding activity for the ORR with an onset potential comparable to that of commercial 20 wt % Pt/C catalyst, the half-wave potential superior to that of the Pt/C catalyst, and the electron transfer number close to 4.