ϵ-Fe3N@N-doped carbon core-shell nanoparticles encapsulated in bamboo-like carbon nanotubes for oxygen reduction reaction electrocatalyst

Exploring economically efficient electrocatalysts with robust oxygen reduction catalytic activities and developing appropriate structures are necessary to understand fuel cells with high open-circuit voltages and long lifespans. In this work, a high-performance ORR catalyst was prepared with a one-spot method by pyrolysis of a urea, FeCl3, and NaCl mixture. The surface element distribution was studied by XPS etching, showing the active sites ϵ-Fe3N with active Fe–N bonding. Benefiting from the double layer protection, in which the ϵ-Fe3N nanoparticles were covered by an N-doped carbon layer encapsulated in carbon bamboo-like nanotubes, the catalysts showed abnormal stability with 5000 cycles, a negative shift of only 15 mV by the CV test and a 3% attenuation after 60,000 s of operation. The onset potential is found to be 0.96 V, which is a positive shift of 12 mV compared to that of the state-of-the-art Pt/C catalyst. The ORR kinetic analysis indicates that the catalyst shows a Tafel slope of 82 mV decade−1 at high potential and 130 mV decade−1 at low potential close to that of the reference catalyst, suggesting a similar reaction mechanism. Therefore, successfully synthesized nonnoble electrocatalysts offer a novel strategy and promising candidates to promote the further development of clean energy devices. •ϵ-Fe3N@N-doped carbon core-shell nanoparticles encapsulated in bamboo-like nanotube is prepared by a facile method.•The active sites ϵ-Fe3N nanoparticles are protected by double N-doped carbon layers and show excellent stability.•The nanotube structure can enhance the electrocatalytic performance.•The FN@NC catalyst shows excellent ORR catalytic activities with a Tafel slope of 82 mV decade−1 at high potential.