CuCo Bimetallic Oxide Quantum Dot Decorated Nitrogen-Doped Carbon Nanotubes: A High-Efficiency Bifunctional Oxygen Electrode for Zn–Air Batteries

5 years ago

CuCo Bimetallic Oxide Quantum Dot Decorated Nitrogen-Doped Carbon Nanotubes: A High-Efficiency Bifunctional Oxygen Electrode for Zn–Air Batteries

Zhao-Qing Liu, Hui Cheng, Nan Li, Chang-Yuan Su, Mei-Ling Li

The large-scale production of metal–air batteries, an appealing solution for next-generation energy storage, requires low-cost, earth-abundant, and efficient oxygen electrode materials, yet insights into active catalyst structures and synergistic reactivity remain largely unknown. Here, a new bifunctional oxygen electrode based on nitrogen-doped carbon nanotubes decorated by spinel CuCo2O4 quantum dots (CuCo2O4/N-CNTs) is reported, outperforming the benchmark of state-of-the-art noble metal catalysts. Combining spectroscopic characterization and electrochemical studies, a prominent synergetic effect between CuCo2O4 and N-doped carbon nanotubes is uncovered: the high conductivity, large active surface area, and increase in the number of catalytic sites induced by Cu doping (i.e., Cu2+ and CuN) can be beneficial to the overall electrocatalytic activities. Remarkably, the native flexibility of CuCo2O4/N-CNTs allows its direct use as reversible oxygen electrodes in Zn–air batteries either with liquid alkaline electrolyte or in the all-solid-state configuration. The prepared devices demonstrate excellent discharging/charging performance, large energy density (83.83 mW cm−2 in liquid state, 1.86 W g−1 in all-solid-state), and long lifetime (48 h in liquid state, 9 h in all-solid-state), holding great promise in the practical application of rechargeable metal–air batteries and other fuel cells. Advanced Cu Co bimetallic oxide are decorated on nitrogen-doped carbon nanotubes to serve as the bifunctional oxygen catalyst. A strong synergetic coupling in CuCo2O4/N-CNTs is proposed, which provides advantaged local chemical environment and enriched catalytic sites. Benefiting from these features, CuCo2O4/N-CNTs with reversible oxygen catalytic activity is capable of operating the new-generation rechargeable zinc–air batteries.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adfm.201701833