In situ integration of Co5.47N and Co0.72Fe0.28 alloy nanoparticles into intertwined carbon network for efficient oxygen reduction

Abstract

Cost-effective electrocatalysts with excellent oxygen reduction reaction (ORR) activity are requisite for the commercial application fuel cells and zinc-air batteries. Herein, we prepare a series of carbon-based non-precious metal catalysts by simply carbonizing the mixture of FeCo-ZIF, melamine and soya-bean oil. The microstructure and electrochemical activity of the prepared catalysts highly depend on the adding amount of FeCo-ZIF. With proper addition, the FeCo-ZIF are transformed into Co5.47N and Co0.72Fe0.28 alloy nanoparticles, which are embedded in the in situ formed carbon network consisted of nitrogen-doped graphene-like carbon nanosheets and interwoven carbon nanotubes. The resulted catalyst (FeCo@NCs-0.15) with considerable specific surface area and high pore volume demonstrates a superior ORR catalytic activity than commercial Pt/C with a half-wave potential (E1/2) of 0.83 V (vs. RHE), onset potential (Eonset) of 0.97 V (vs. RHE) and 4-electron dominated reaction path. The durability and methanol resistance are also better than that of commercial Pt/C in alkaline solution. This study provides an inexpensive, facile and scalable strategy to simultaneously realize non-precious metal-based active sites, nitrogen-doping, porosity and highly conductive carbon matrix in one electrocatalyst by one step.