Design of house centipede-like MoC–Mo₂C nanorods grafted with N-doped carbon nanotubes as bifunctional catalysts for high-performance Li–O₂ batteries

Developing effective bifunctional catalysts to promote Li₂O₂ oxidation and to realize high-performance Li–O₂ batteries with long cycle life is a key challenge. Herein, a house centipede-like bifunctional catalyst consisting of a molybdenum carbide nanorod grafted with N-doped carbon nanotubes (denoted as MoC–Mo₂C/NCNTs) is developed for enhancing the performance of Li–O₂ batteries. This nanocatalyst is successfully fabricated by the post-treatment of MoO₃ nanorods coated with a Co-based zeolitic imidazolate framework (ZIF-67). The obtained MoC–Mo₂C/NCNT nanorods have a unique structure with a body comprising small MoC–Mo₂C nanocrystals and Co@NCNTs extending like legs from it. This structural architecture not only provides numerous catalytic active sites and sufficient space for accommodating Li₂O₂ but also facilitates electron transport through the catalytically active NCNT conductive pathways. Consequently, the MoC–Mo₂C/NCNTs show substantially improved electrocatalytic performance in Li–O₂ batteries with a significantly reduced discharge–charge overpotential (0.50 V), high specific discharge capacity (34,862 mA h g⁻¹ at 200 mA g⁻¹), and long cycle stability (up to 162 cycles at current density of 200 mA g⁻¹) and cut-off capacity of 500 mA h g⁻¹. Preliminary results suggest that the MoC–Mo₂C/NCNT nanorod is an efficient, stable bifunctional catalyst for Li–O₂ batteries.