Bioinspired Synthesis of Hierarchically Porous MoO2/Mo2C Nanocrystal Decorated N-Doped Carbon Foam for Lithium-Oxygen Batteries

The lithium oxygen (Li-O-2) battery is one of the most promising technologies among various electrochemical energy storage systems. The challenge to develop a highperformance Li-O-2 battery lies in exploring an air electrode with optimal porous structure and high efficient bifunctional electrocatalyst. The present work demonstrates a bioinspired synthesis route for the preparation of high performance Li-O-2 air electrode materials that are made out of N-doped carbon foams decorated with heteronanostructured MoO2/Mo2C nanocrystals (MoO2/Mo2C@3D NCF). Here, recombinant proteins (ELK16-FLAG) facilitated the self-assembly of metal precursors and provided a carbon source for Mo2C formation. The as-prepared MoO2/Mo2C@3D NCF showed superior electrocatalytic activity in both oxygen evolution reaction and oxygen reduction reaction mechanisms with a high round-trip efficiency of 89.1% (2.77 V/3.11 V) at 100 mA g(-1) as well as exceptional rate performances and good cyclability in Li-O-2 battery. The desirable electrochemical performance can be attributed to the unique hierarchical porous structure of the 3D carbon foam and the intimate contact between MoO2 and Mo2C nanocrystals. We demonstrate that the novel, facile, environmentally friendly bioinspired approaches would open new avenues for the synthesis of 3D nitrogen doped carbon supported advanced functional materials with excellent electrochemical performances.