Bimetal Oxides Anchored on Carbon Nanotubes/Nanosheets as High-Efficiency and Durable Bifunctional Oxygen Catalyst for Advanced Zn-Air Battery: Experiments and DFT Calculations.

To meet increasing requirement for innovative energy storage and conversion technology, it is urgent to prepare effective, affordable, and long-term stable oxygen electrocatalysts to replace precious metal-based counterparts. Herein, a two-step pyrolysis strategy is developed for controlled synthesis of Fe 2 O 3 and Mn 3 O 4 anchored on carbon nanotubes/nanosheets (Fe 2 O 3 -Mn 3 O 4 -CNTs/NSs). The typical catalyst has a high half-wave potential (E 1/2 = 0.87 V) for oxygen reduction reaction (ORR), accompanied with a smaller overpotential (η 10 = 290 mV) for oxygen evolution reaction (OER), showing substantial improvement in the ORR and OER performances. As well, density functional theory calculations are performed to illustrate the catalytic mechanism, where the in situ generated Fe 2 O 3 directly correlates to the reduced energy barrier, rather than Mn 3 O 4 . The Fe 2 O 3 -Mn 3 O 4 -CNTs/NSs-based Zn-air battery exhibits a high-power density (153 mW cm -2 ) and satisfyingly long durability (1650 charge/discharge cycles/550 h). This work provides a new reference for preparation of highly reversible oxygen conversion catalysts.