A Hybrid of the Fe4N-Fe Heterojunction Supported on N-Doped Carbon Nanobelts and Ketjen Black Carbon as a Robust High-Performance Electrocatalyst.

Herein, an extremely simple l-alanine-assisted pyrolysis method was proposed for the construction of a novel hierarchically porous hybrid of Fe4N-Fe supported on N-doped carbon nanobelts and Ketjen black carbon (denoted as Fe4N-Fe@N-C/N-KB). It has been found that the participation of l-alanine in pyrolysis can dramatically increase the total pyridinic-N/graphitic-N content in Fe4N-Fe@N-C/N-KB, which is peculiarly conducive to the enhancement of ORR performance. The in-site formation of the Fe4N-Fe heterojunction via the thermal reduction and decomposition of Fe3N as well as the introduction of cheap KB can significantly improve the ORR performance. As a result, the activity, durability, and methanol tolerance of this hybrid are comprehensively better than those of commercial 20 wt % Pt/C, promising future applications in practical devices. Density functional theory calculations disclose that the highly improved ORR activity of Fe4N-Fe@N-C/N-KB also benefits from the favorable electron penetration and excellent electronic conductivity between the Fe4N nanoparticles and the N-incorporated carbon frameworks.