Metal-coordinated porous polydopamine nanospheres derived Fe <sub>3</sub>N-FeCo encapsulated N-doped carbon as a highly efficient electrocatalyst for oxygen reduction reaction
Fanjuan Guo, Mingyue Zhang, Shicheng Yi, Xuxin Li, Rong Xin, Mei Yang, Bei Liu, Hongbiao Chen, Huaming Li, Yijiang Liu
Abstract
The exploration of high-efficiency, long-durability, and cost-effectiveness transition metal doped carbon materials to replace the commercial Pt/C in oxygen reduction reaction (ORR) is greatly desirable for promoting the advancement of sustainable energy devices. Herein, the Fe<sub>3</sub>N and FeCo alloy decorated N-doped carbon hybrid material (denoted Fe<sub>3</sub>N-FeCo@NC) is prepared and applied as the ORR catalyst, which is derived from the two-step pyrolysis of an intriguing complex consisted of metal-coordinated porous polydopamine (PDA) nanospheres (i.e., Fe-PDA@Co) and melamine. The resulting Fe<sub>3</sub>N-FeCo@NC delivers outstanding ORR activity with an onset potential (<i>E</i><sub>on</sub>) of 1.05 V, a half-wave potential (<i>E</i><sub>1/2</sub>) of 0.89 V, as well as excellent long-term stability and methanol resistance over Pt/C. Interestingly, the home-made Zn-air battery with Fe<sub>3</sub>N-FeCo@NC as the air-cathode demonstrates much higher open-circuit voltage (1.50 vs. 1.48 V), power density (141 vs. 113 mW·cm<sup>−2</sup>) and specific capacity (806.6 vs. 660.6 mAh·g<sub>Zn</sub><sup>−1</sup>) than those of Pt/C counterpart. Such a remarkable ORR activity of Fe<sub>3</sub>N-FeCo@NC may stem from the synergistic effect of Fe<sub>3</sub>N and FeCo active species, the large surface area, the hierarchical porous structure and the exceptional sphere/sheet hybridized architecture.