Transition metal-doped carbon sphere as enhanced catalysts for oxygen reduction

Abstract

Herein, carbon sphere (CS-T) were successfully prepared by pyrolyzation melamine formaldehyde resin. And then different transition metals (Fe, Co, Ni) were doped on carbon sphere (CS-M-900). The scanning electron microscopes and elemental mappings prove that the transition metal particles are uniformly doped on the carbon sphere. Meanwhile, the X-ray photoelectron spectrum prove that the transition metals are zero-valence. Furthermore, the electrochemical testings showed the CS-Co-900 had more positive onset potential (0.93 V), half-wave potential (0.84 V), and peak potential (0.81 V). Furthermore, the CS-Co-900 had lower charge transfer resistance (44 Ω) and smaller Tafel slope (65 mV/dec). Most importantly, the oxygen reduction reaction on the CS-Co-900 turned out to be a four electron procedure with excellent methanol tolerance. The improved electrochemical properties towards oxygen reduction reactions of carbon sphere via cobalt doping suggested a design strategy towards future high-performance electrochemical devices.