Facile synthesis of carbon nanosheet arrays decorated with chromium-doped Co nanoparticles as advanced bifunctional catalysts for Zn-air batteries

The development of low-cost electrochemical catalytic nanomaterials for efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through structural and composition control is a great challenge. Herein, a 3D hybrid structure is designed by an in-situ approach for growing 2D leaf-like nanosheet arrays on 1D electrospun nanofibers. The resultant catalysts composed of Cr-doped Co nanoparticle decorated N-doped carbon nanosheet and carbon nanofiber are synthesized by subsequent Cr 3+ impregnation and heat treatment. The excellent properties of the as-prepared cathode benefit from the novel establishment of the 3D structure and the regulating mechanism of the electron density of Co after Cr doping, which simultaneously increases the mass and charge transfer process during the catalytic reaction. Consequently, Cr 0.10 -Co@NC exhibits excellent catalytic performance for the ORR (with a half-wave potential of 0.84 V) and OER (with an overpotential of 370 mV). When used in a homemade ZAB for evaluating their practical reversible performance, the device exhibits a higher open-circuit voltage (1.45 V) and a smaller potential gap (0.73 V) with excellent cycle durability of 110 h. This work offers a well-designed structure and development for synthesizing efficient and durable electrocatalysts in electrochemical energy conversion technologies. • 3D hybrid structure was synthesized by growing 2D MOF on 1D electrospun nanofibers. • Cr-doped Co@NC has much-enhanced mass transfer and electrical conductivity. • Cr 0.10 -Co@NC has an excellent bifunctional catalytic performance of the ORR and OER. • The excellent stability of Cr 0.10 -Co@NC toward ORR and OER was confirmed. • Cr 0.10 -Co@NC exhibits outstanding performance in Zinc-air batteries.