Nano-engineering of prussian blue analogues to core-shell architectures: Enhanced catalytic activity for zinc-air...

To substitute precious metal with non-precious electrocatalysts, that can work efficiently, still remains a great challenge. Herein, we fabricated the series of nitrogen doped carbon (NC) and CoFe-NC core-shell architectures to produce dual-functionality towards oxygen reduction/evolution reactions and ultimately for Zn-air battery. The addition of NC tends to prevent the reduction of Co/Fe nanoparticles during pyrolysis which not only provide improved catalytic sites but also boost the specific surface area, graphitization degree, electron and mass transfer capacity. With distinctive core-shell morphology, the as-synthesized CoFe-NC/NC shows superior OER performance with low overpotential (270 mV) than IrO₂ (340 mV) at 10 mA cm^-2 and nearly close ORR activity with respect to Pt/C. When fabricated as zinc-air battery application, CoFe-NC/NC shows 58 mW cm^-2 higher peak power density than that of air-cathodes made of Pt/C and IrO₂. Further, our catalyst shows good durability due to the synergistic effect of Fe/Co and NC shell.