Abstract
Herein, a strategy is reported for the fabrication of NiCo2O4-based mesoporous nanosheets (PNSs) with tunable cobalt valence states and oxygen vacancies. The optimized NiCo2.148O4 PNSs with an average Co valence state of 2.3 and uniform 4 nm nanopores present excellent catalytic performance with an ultralow overpotential of 190 mV at a current density of 10 mA cm−2 and long-term stability (700 h) for the oxygen evolution reaction (OER) in alkaline media. Furthermore, Zn–air batteries built using the NiCo2.148O4 PNSs present a high power and energy density of 83 mW cm−2 and 910 Wh kg−1, respectively. Moreover, a portable battery box with NiCo2.148O4 PNSs as the air cathode presents long-term stability for 120 h under low temperatures in the range of 0 to −35 °C. Density functional theory calculations reveal that the prominent electron exchange and transfer activity of the electrocatalyst is attributed to the surface lower-coordinated Co-sites in the porous region presenting a merging 3d–eg–t2g band, which overlaps with the Fermi level of the Zn–air battery system. This favors the adsorption of the *OH, and stabilized *O radicals are reached, toward competitively lower overpotential, demonstrating a generalized key for optimally boosting overall OER performance.
Original language | English |
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Article number | 2001651 |
Journal | Advanced Materials |
Volume | 32 |
Issue number | 39 |
DOIs | |
Publication status | Published - 1 Oct 2020 |
Keywords
- mesoporous nanosheets
- oxygen evolution reaction
- oxygen vacancies
- valence electron regulation
- Zn–air batteries
ASJC Scopus subject areas
- General Materials Science
- Mechanics of Materials
- Mechanical Engineering