Enhanced TiO₂/SiC_x Active Layer Formed In Situ on Coal Gangue/Ti₃C₂ MXene Electrocatalyst as Catalytic Integrated...

The pursuit of efficient cathode catalysts to improve cycle stability at ultra-high rates plays an important role in boosting the practical utilization of Li-O₂ batteries. Featured as industrial solid waste, coal gangue with rich electrochemical active components could be a promising candidate for electrocatalysts. Here, a coal gangue/Ti₃C₂ MXene hybrid with a TiO₂/SiC_x active layer is synthesized and applied as a cathode catalyst in Li-O₂ batteries. The coal gangue/Ti₃C₂ MXene hybrid has a tailored amorphous/crystalline heterostructure, enhanced active TiO₂ termination, and a stable SiC_x protective layer; thereby, it achieved an excellent rate stability. The Li-O₂ battery, assembled with a coal gangue/Ti₃C₂ MXene cathode catalyst, was found to obtain a competitive full discharge capacity of 3959 mAh g^-1 and a considerable long-term endurance of 180 h (up to 175 cycles), with a stable voltage polarization of 1.72 V at 2500 mA g^-1. Comprehensive characterization measurements (SEM, TEM, XPS, etc.) were applied; an in-depth analysis was conducted to reveal the critical role of TiO₂/SiC_X active units in regulating the micro-chemical constitution and the enhanced synergistic effect between coal gangue and Ti₃C₂ MXene. This work could provide considerable insights into the rational design of catalysts derived from solid waste gangue for high-rate Li-O₂ batteries.