Coupling of Fe-Nx sites and Fe nanoparticles on nitrogen-doped porous carbon for boosting oxygen electroreduction in Zn-air batteries

• Published in: Journal of energy storage 2024-08, Vol.96, p.112672, Article 112672
• Main Authors: Zha, Sujuan, Wang, Dan, Li, Xiaosong, Wang, Jibiao, Chu, Yuan, Mitsuzaki, Naotoshi, Chen, Zhidong
• Format: Article
• Language: English
• Subjects: Fe-Nx sites; Metallic nanoparticles; Oxygen reduction reaction; Two-step pyrolysis; Zinc-air batteries
• ISSN: 2352-152X
• DOI: 10.1016/j.est.2024.112672

Fe and nitrogen co-doped carbon (Fe-N-C) catalysts have emerged as attractive materials to substitute Pt-based catalysts for the oxygen reduction reaction (ORR) in Zn-air batteries (ZABs). However, the Fe-N-C catalysts with monotypic active component usually endow suboptimal catalytic performance and stability under both acid and alkaline medium. Herein, a nano ZnO template and two-step pyrolysis co-assisted strategy is proposed to achieve the coupling of Fe-Nx sites and metallic Fe nanoparticles in hierarchically porous N-doped carbon for ORR. The nano ZnO template contributes to the formation of meso/macropores structure, while the secondary pyrolysis is beneficial to the creation of more micropores. Besides the advanced hierarchical porosity, the combination of dispersed Fe-Nx sites and dominated metallic Fe nanoparticles is also conducive to boost ORR activity in both acid and alkaline solution. Impressively, the prepared Fe@FeHPNC-P2 electrocatalyst exhibits an excellent half-wave potentials (E1/2) of 0.88 V and 0.79 V in alkaline and acidic electrolyte, respectively. Meanwhile, the assembled liquid Zn-air battery using Fe@FeHPNC-P2 delivers a peak power density of 149.3 mW cm−2 and a maximum energy density of 957.1 Wh kgZn−1 along with long-term stability for 1000 cycles. •A nano ZnO template and two-step pyrolysis co-assisted strategy is proposed.•The coupling of two size-asymmetric active sites can boost ORR performance.•The nano ZnO template and secondary pyrolysis contribute to hierarchical pores.•Fe@FeHPNC-P2 exhibits excellent ORR performance in alkaline and acidic media.