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

Abstract

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 high-performance 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 MoO 2 /Mo 2 C nanocrystals (MoO 2 /Mo 2 C@3D NCF). Here, recombinant proteins (ELK16-FLAG) facilitated the self-assembly of metal precursors and provided a carbon source for Mo 2 C formation. The as-prepared MoO 2 /Mo 2 C@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 MoO 2 and Mo 2 C 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.