Efficient Bifunctional Oxygen Electrocatalysts for Rechargeable Zn-air Batteries Derived from Ni-modified Prussian Blue

The rational design and exploration of efficient, low-cost and durable bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key to the development of rechargeable metal-air batteries. Here, we report a novel approach to in-situ synthesize Fe0.64Ni0.36 nanoalloy encapsulated in nitrogen-doped porous carbon nanotubes (FeNi@N-CNTs) as bifunctional electrocatalyst derived from Ni-modified Prussian blue, on which the ORR/OER can be promoted by the N-CNTs surface due to the electron modulation caused by electron transfer from the inner FeNi nanoalloy to the N-CNTs surface. The abundant wide-size range of mesopores in N-CNTs can offer rapid mass transport channels to facilitate the catalytic reactions. In addition, the encapsulation structure endows the outer N-CNTs acting as a "shield" to prevent the inner FeNi nanoalloy from corrosion in strong basic medium. Thanks to the synergistic effect between the N-CNTs and FeNi nanoalloy, the obtained FeNi@N-CNTs exhibits excellent bifunctional oxygen catalytic activity together with outstanding performance and cycling durability in rechargeable Zn-air battery. This work will open new avenues for the development of advanced bifunctional electrocatalysts for other metal-air batteries. Fe0.64Ni0.36 nanoalloy encapsulated in nitrogen-doped porous carbon nanotubes as bifunctional oxygen electrocatalyst for zinc-air batteries was obtained from Ni-modified Prussian blue. The electron transfer from inner nanoalloy to the N-CNT surface can modulate its electron state to boost ORR/OER catalysis. Meanwhile, the N-CNTs act as a "shield" to prevent the inner nanoalloy from corrosion in strong basic medium.image