Designing iron carbide embedded isolated boron (B) and nitrogen (N) atoms co-doped porous carbon fibers networks with tiny amount of BN bonds as high-efficiency oxygen reduction reaction catalysts.

In this paper, polyvinylpyrrolidone (PVP) and 4-hydroxybenzeneboronic acid (o-HPBA) are polarized in alkaline solution and then employed as boron (B) and nitrogen (N) sources. Fe(AC)2/o-HPBA/PVP/DMF(N,N-Dimethylformamide) slurries are first electrospunned into three-dimensional (3D) networks. Due to the electrostatic repulsion between negatively charged O- groups surrounding N and B atoms, N and B atoms can be kept far away from each other. Upon optimizing o-HPBA dosages, the maximum amount of isolated B and N atoms are successfully doped into the 3D porous iron carbide (Fe3C) embedded B and N co-doped carbon fibers (Fe3C@B1.0NPCFs) networks with tiny BN clusters. Electrochemical measure results demonstrate that Fe3C@B1.0NPCFs exhibit much better oxygen reduction reaction (ORR) activity than 20 wt% Pt/C in alkaline electrolyte. In acidic electrolyte, Fe3C@B1.0NPCFs also displays ORR activity comparable to Pt/C (its onset and half-wave potentials are just 40 and 50 mV more negative than those of Pt/C). Moreover, Fe3C@B1.0NPCFs show better stability and methanol tolerance ability than Pt/C for ORR in both alkaline and acidic solutions. This work opens new avenues for intentionally preventing the malignant combination of B and N atoms and boosting the electrocatalytic activity of B and N co-doped and Fe3C embedded carbon catalysts.