Space-Confined Yolk-Shell Construction of Fe_3O_4 Nanoparticles Inside N-Doped Hollow Mesoporous Carbon Spheres as Bifunctional Electrocatalysts for Long-Term Rechargeable Zinc-Air Batteries

摘要

Development of efficient, durable and inexpensive oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts with accelerated kinetics and high-performance remain a grand challenge in the context of reversible metal-air batteries. Herein, the Fe(3)O(4)nanoparticles inside N-doped hollow mesoporous carbon spheres (N/HCSs) yolk-shell structure (Fe-x@N/HCSs) is constructed as an excellent bifunctional electrocatalyst for ORR and OER via an innovative approach. The N/HCSs effectively control and confine in situ growth of Fe(3)O(4)nanoparticles using the melting-diffusion strategy via capillary force and significantly improve the conductivity and structural stability of the hybrid material. The constructed yolk-shell structured Fe-20@N/HCSs ecosystem with Fe-N(x)active sites exhibits excellent ORR and OER activity and stability, which even surpass commercial grade Pt/C, RuO2, IrO(2)and many reported catalysts. Moreover, the zinc-air battery assembled with Fe-20@N/HCSs as a cathode achieves high open circuit voltage (1.57 V), large power density (140.8 mW cm(-2)), and excellent long-term cycling performance (over 300h), revealing superior performance compared to commercial Pt/C + RuO2. This work provides a new avenue for the design and optimization of other high-performance yolk-shell materials with nanoscale confinement structures.