Novel core-shell CuMo-oxynitride@N-doped graphene nanohybrid as multifunctional catalysts for rechargeable zinc-air batteries and water splitting

Highly efficient and durable multifunctional catalysts with attractive nanoarchitectures remain challenging for next-generation rechargeable metal-air batteries and water splitting devices. Herein, for the first time, a novel copper molybdenum oxynitride anchored nitrogen-doped graphene (CuMo₂ON@NG) is synthesized by a simple, scalable, and cost-effective pyrolysis method. The rational design of CuMo₂ON encased in NC shells anchored onto the NG matrix to enhance the electroactive sites and boost the electron-transport behaviors for oxygen reduction/evolution reactions (ORR/OER) and hydrogen evolution reaction (HER). The optimal CuMo₂ON@NG reveals tremendous trifunctional activities, outperform benchmark Pt/C and IrO₂. First-principles calculations demonstrate that the excellent catalytic activity of CuMo₂ON@NG is owing to the synergistic electron transfer between the active CuMo₂ON nanoparticles, doped N species, and graphitic carbon. Formation of the O* intermediates on CuMo₂ON lattice in the core-shell CuMo₂ON@NG nanohybrid is an energetic rate-determining step to attain ORR and OER activities. The CuMo₂ON@NG air-cathode based rechargeable quasi solid-state zinc-air battery delivers an ultra-high specific capacity of 736 mAh g_zn⁻¹, an exceptional energy density of 800.75 Wh kg⁻¹, a record power density of 176.3 mW cm⁻², and excellent reversibility (330 h at 10 mA cm⁻²). Furthermore, the CuMo₂ON@NG-based water splitting device achieves a cell voltage of 1.49 V at a current density of 10 mA cm⁻² and excellent reversibility of 120 h at a high current density of 100 mA cm⁻², outperforming the benchmark Pt/C||IrO₂ (~1.53 V at 10 mA cm⁻²) and reported state-of-the-art catalysts.