Single (Ni, Fe) atoms and ultrasmall Core@shell Ni@Fe nanostructures Dual-implanted CNTs-Graphene nanonetworks for robust Zn- and Al-Air batteries

To meet the reaction kinetic demands of cathodic electrode in metal-air battery technology, we propose a novel bifunctional catalyst of single iron atoms, single nickel atoms, and core@shell Ni@Fe nanoparticles simultaneously confined in a porous interconnected carbon nanotubes/N-doped graphene nanonetwork (Ni_SAFe_SA-Ni@Fe_NPs/CNTs-NGNS). The optimized Ni_SAFe_SA-Ni@Fe_NPs/CNTs-NGNS catalyst exhibits excellent electrocatalytic activities, affording a positive onset potential of + 0.92 V along with a favorable 4e⁻ pathway for ORR while delivering a low overpotential (η) of 309 mV at 10 mA cm⁻² for OER in alkaline medium. The synergistic effects caused by the enhanced OER and ORR allow the Ni_SAFe_SA-Ni@Fe_NPs/CNTs-NGNS air–cathode to produce high-performance Zn- and Al-air batteries with exceptional cell voltage, power density, and durability, surpassing most materials reported so far. The developed Zn- and Al-air batteries deliver cell voltages of 1.41 and 1.61 V with high power density of 163 and 184 mW cm⁻², respectively. Furthermore, they exhibit a stable cell voltage even after undergoing deformation testing and long-term charge–discharge operation of 170 h. This work suggests a promising candidate for high-performance metal-air battery applications.