Dual‐Active Sites Engineering of N‐Doped Hollow Carbon Nanocubes Confining Bimetal Alloys as Bifunctional Oxygen Electrocatalysts for Flexible Metal–Air Batteries

Since the sluggish kinetic process of oxygen reduction (ORR)/evolution (OER) reactions, the design of highly‐efficient, robust, and cost‐effective catalysts for flexible metal–air batteries is desired but challenging. Herein, bimetallic nanoparticles encapsulated in the N‐doped hollow carbon nanocubes (e.g., FeCo‐NPs/NC, FeNi‐NPs/NC, and CoNi‐NPs/NC) are rationally designed via a general heat‐treatment strategy of introducing NH3 pyrolysis of dopamine‐coated metal–organic frameworks. Impressively, the resultant FeCo‐NPs/NC hybrid exhibits superior bifunctional electrocatalytic performance for ORR/OER, manifesting exceptional discharging performance, outstanding lifespan, and prime flexibility for both Zn/Al–air batteries, superior to those of state‐of‐the‐art Pt/C and RuO2 catalysts. X‐ray absorption near edge structure and density functional theory indicate that the strong synergy between FeCo alloy and N‐doped carbon frameworks has a distinctive activation effect on bimetallic Fe/Co atoms to synchronously modify the electronic structure and afford abundant dual‐active Fe/Co–Nx sites, large surface area, high nitrogen doping level, and conductive carbon frameworks to boost the reversible oxygen electrocatalysis. Such N‐doped carbon with bimetallic alloy bonds provides new pathways for the rational creation of high‐efficiency energy conversion and storage equipment. The hybrid catalysts consisting of bimetallic alloy nanoparticles confined in the N‐doped hollow carbon nanocubes are successfully fabricated through a general heat‐treatment strategy of introducing NH3 pyrolysis of dopamine‐coated metal–organic frameworks, which exhibit remarkable bifunctional catalytic properties toward oxygen reduction reaction and oxygen evolution reaction, and demonstrate to be excellent air electrodes for both flexible Zn/Al–air batteries.