MOF-Derived Carbon Materials Mounted with Highly Dispersed Ru and MoO3 for Rechargeable Li–O2 Cathode Yield Enhanced Cyclability

A composite cathode catalyst for Li–O2 batteries using ruthenium and molybdenum trioxide loaded on MOF-derived carbon materials (MDC) is designed and prepared by an impregnation and hydrogen reduction process. The catalyst exhibits high capacity and excellent cycling stability, and the Ru nanoparticles (NPs) and MoO3 significantly enhance the catalyst’s performance. For our optimal catalyst, Ru-MoO3/MDC, the first discharge capacity and charge capacity reach up to 5343 and 5950 mAh g–1 at a discharge rate of 100 mA g–1, with a discharge voltage plateau of 2.6 V. It also exhibits excellent cycling stability over 160 cycles at a limited capacity of 600 mA h g–1. The addition of Ru NPs greatly improves the cathode’s capacity and effectively reduces the battery’s charge overpotential. The further addition of MoO3 significantly improves the material’s cycling stability, although it seems to have no influence on the cathode’s capacity. The morphology of the discharge products changes from donut to yo-yo shaped with further MoO3 loading. We ascribe the high performance of our composite catalyst to the high surface area of the MDC’s rich porous structure, which is ideal for the discharge products; the addition of Ru and MoO3, which enhance the catalyst’s activity and stability; and synergetic effects between carbon, Ru, and MoO3.