Multi-Metal Metal-Organic Framework Electrocatalysts Recycled From Spent Li-Ion Batteries for Efficient Oxygen Evolution.

Developing efficient and stable transition metal oxygen evolution reaction (OER) catalysts is crucial for clean energy technologies, while recycling spent lithium-ion batteries (LIBs) faces challenges of high energy consumption and low added value. Herein, we propose a green strategy to recover valuable metals from spent LIBs and convert them into high-performance OER catalysts. Using spent LiNi0.33Co0.33Mn0.33O2 (NCM111) cathodes as raw material, metal ions were extracted by acid leaching, followed by a one-step hydrothermal synthesis on nickel foam to fabricate a MnFeCoNiCu metal-organic framework catalyst (MFCNC-X). The results demonstrate that MFCNC-150 synthesized at 150 °C exhibits a unique petal-like stacked morphology, high specific surface area, and excellent hydrophilicity. Benefiting from the regulation of the electronic structure induced by the multi-metal synergistic effect and interactions among multi-metal active sites, MFCNC-150 exhibits outstanding OER activity in 1 M KOH electrolyte, with an overpotential of only 237 mV at a current density of 10 mA cm-2, a Tafel slope of 56.35 mV dec-1, and long-term stability exceeding 120 h. Electrochemical characterization and post-reaction analysis reveal surface restructuring during OER process, forming active metal hydroxide sites. This work offers novel insights for high-value recycling of spent LIBs and development of efficient transition metal OER catalysts.