posted on 2022-05-04, 20:06authored byYifan Huang, Fantao Kong, Han Tian, Fenglai Pei, Yafeng Chen, Ge Meng, Ziwei Chang, Chang Chen, Xiangzhi Cui, Jianlin Shi
Developing
high-efficiency and low-cost nonprecious catalysts for
the oxygen reduction reaction (ORR) is important but still challenging.
Herein, a N-doped carbon catalyst embedded with uniformly dispersed
Cu nanoparticles (∼30 nm) is fabricated by the spatial confinement
effect of a nitrogen-rich Salen-based covalent organic framework (Salen-COF),
in which Cu(II) ions are anchored onto open chelate sites of Salen-COF
and isolated by aromatic rings to form uniformly dispersed Cu nanoparticles
embedded in N-doped carbon (Cu NPs/N-C) during pyrolysis. The optimized
Cu NPs/N-C-800 exhibits high ORR catalytic activity in both alkaline
and acidic electrolytes, especially with an onset potential (Eonset) of 1.02 V and a half-wave potential (E1/2) of 0.88 V in an alkaline electrolyte. Attractively,
the Cu NPs/N-C-800-derived Zn–air battery demonstrates a higher
peak-power density (163.5 mW cm–2) and long-term
cycling stability (118 h). The electronic interaction between the
highly concentrated homogeneously dispersed Cu NPs and carbon shell
results in an appropriate d-band center, and the porous graphitized
carbon shell leads to faster electron transfer and mass transport,
which are responsible for the high ORR performance of Cu NPs/N-C-800.
This strategy provides a new prospect to synthesize uniformly dispersed
metal nanoparticle electrocatalysts with more exposed active sites
and efficient catalytic activities for renewable energy conversion
devices.