Recycling\nSpent Ternary Cathodes to Oxygen Evolution\nCatalysts for Pure Water Anion-Exchange Membrane Electrolysis

Recycling\nspent lithium-ion batteries (LIBs) to efficient water-splitting\nelectrocatalysts is a promising and sustainable technology route for\ngreen hydrogen production by renewables. In this work, a fluorinated\nternary metal oxide (F-TMO) derived from spent LIBs was successfully\nconverted to a robust water oxidation catalyst for pure water electrolysis\nby utilizing an anion-exchange membrane. The optimized catalyst delivered\na high current density of 3.0 A cm<sup>–2</sup> at only 2.56\nV and a durability of >300 h at 0.5 A cm<sup>–2</sup>, surpassing\nthe noble-metal IrO<sub>2</sub> catalyst. Such excellent performance\nbenefits from an artificially endowed interface layer on the F-TMO,\nwhich renders the exposure of active metal (oxy)hydroxide sites with\na stabilized configuration during pure water operation. Compared to\nother metal oxides (i.e., NiO, Co<sub>3</sub>O<sub>4</sub>, MnO<sub>2</sub>), F-TMO possesses a higher stability number of 2.4 ×\n10<sup>6</sup>, indicating its strong potential for industrial applications.\nThis work provides a feasible way of recycling waste LIBs to valuable\nelectrocatalysts.