Waste tobacco-derived N, P dual-doped porous carbon loaded with heterostructured CoFe/CoFe2O4 nanoparticles for efficient oxygen electrocatalysis and Zn-air batteries

Bifunctional oxygen reduction/oxidation reaction (ORR/OER) electrocatalysts can be derived from waste biomass for implementing rechargeable Zn–air batteries, which not only turns waste into wealth, but also provides a novel approach for solving the energy crisis and promoting environmental restoration. Herein, heterostructured CoFe/CoFe2O4 nanoparticles grown on waste tobacco-derived N,P-co-doped carbon (CoFe/CoFe2O4@PNC) are constructed. Benefiting from the accelerated electron transfer due to the synergistic effect of CoFe and CoFe2O4 along with the enlarged active area owing to N,P-codoping, the CoFe/CoFe2O4@PNC electrocatalysts exhibit remarkable OER/ORR activity, reaching a half-wave potential of 0.86 V for ORR solution and driving 10 mA cm−2 by OER overpotential of 360 mV in 1.0 M KOH. Moreover, the zinc-air battery assembled with CoFe/CoFe2O4@PNC can reach a power density of 141.5 mW cm−2 and exhibit impressive durability for exceeding 300 h, which are superior to the power density and stability of zinc-air batteries assembled with precious metal-based materials. This work opens up new possibilities for preparing advanced ORR/OER catalysts for efficient Zn-based batteries.