Fe,
N‑Doped
Hollow Porous Carbon Spheres Decorated
with Ultrasmall Co NPs as Efficient Bifunctional Electrocatalysts
for Rechargeable Zinc–Air Batteries
posted on 2024-01-11, 20:14authored byJiayao Peng, Ting Liu, Liqi Ou, Yueqi Feng, Yiyi Qiu, Yan Chen, Jianlin Huang
Developing dual-function electrocatalysts
that improve
oxygen reduction/evolution
reaction (ORR/OER) kinetics and durability is strongly desirable but
still challenging. Herein, ultrasmall Co nanoparticles (NPs) embedded
into hollow hierarchically porous Fe, N-codoped carbon spheres (denoted
as Co/Fe-NC) are prepared through one-step pyrolysis of trimetallic
ZnCoFe-ZIFs composites. The hierarchically porous structure of Co/Fe-NC
demonstrates that the micropores possess strong capability to O2 capture and contribute large specific surface area, the mesopores
provide numerous channels for the electrolyte infiltration, and the
hollow holes allow more available active sites when used as cathodes
of Zn–air batteries (ZABs). Consequently, the optimized Co/Fe-NC
catalyst demonstrates satisfactory activities with a half-wave potential
(E1/2 = 0.91 V) and onset potential (E0 = 1.04 V), higher than that of the benchmark
Pt/C catalyst (E0 = 0.90 V and E1/2 = 0.85 V) for ORR. Moreover, a rechargeable
ZAB assembled by the Co/Fe-NC electrode displays a large specific
capacity of 836.2 mA h g–1, a power density of 136
mW cm–2, and excellent durability (maintaining 99%
of its initial activity after 1195 cycles). The outstanding catalytic
activity of the Co/Fe-NC is attributed to its multicomponent active
dopants (Co, Fe, and N), and hollow hierarchical porous nanostructure.