Heterostructured Mo₂C-MoO₂ as highly efficient catalyst for rechargeable Li-O₂ battery

Li-O-2 batteries has been widely investigated for its ultra-high capacity as next generation batteries. Nevertheless, some problems like sluggish kinetic reaction and instability hugely impede the practical use of Li-O-2 batteries. In this work, Mo2C/MoO2@RGO heterostructures was fabricated by in-situ growth of Mo2C between MoO2 and RGO during calcination and being employed as cathode to explore the synergistic effect in Li-O-2 batteries. As a result, Mo2C/MoO2@RGO exhibits good specific capacity with 2365 mAh g(-1), high round-trip efficiency (89% at first cycle) and improved cycling performance. Density functional theory calculations indicated that the Mo2C/MoO2@RGO heterostructures have better capability of oxygen adsorption than sole constituent (Mo2C@RGO or MoO2@RGO), which triggers the formation of film-like amorphous discharge products, leading to lower over-potential and stable performance. Our study reveals the important role of heterostructures in Li-O-2 batteries system and demonstrates a promising design strategy for heterostructured catalyst.