Co-CoF2 heterojunctions encapsulated in N, F co-doped porous carbon as bifunctional oxygen electrocatalysts for Zn-air batteries

The structural design and atomic adjustment of the catalyst are the main factors that regulate the intrinsic electrocatalytic activity. Herein, we report a novel and facile strategy of synthesizing three-dimensional porous carbon network by polymer-assisted molding strategy. The porous carbon framework with Co-CoF2 and carbon nanotubes (PCF@CCFCNT) was directly obtained by the calcination, in which Co-CoF2 heterojunctions uniformly dispersed in the interconnected holes. Benefiting from the special hierarchical porous morphology, the dual-function catalytic activity of Co-CoF2 heterojunctions and existence of Co-N-x species, the as-obtained PCF@CCFCNT composites exhibit excellent performance in the oxygen evolution reaction (eta = 300 mV@10 mA cm(-2)), as well as outstanding oxygen reduction reaction performance in alkaline medium (E-1/2 = 0.852 V, vs RHE). Moreover, as an air electrode in Zn-air batteries (ZABs), PCF@CCFCNT demonstrates a large peak power density of 184 mW cm(-2) and superior long-term stability, which is much more stable than the one consisting of commercial Pt/C. This finding not only shows a simple composite design to achieve high-performance ZABs but also may stimulate the rapid development of 3D hierarchical porous electrocatalysts for advanced energy technologies.