Lithium-ion battery waste as a robust oxygen evolution reaction electrocatalyst for seawater splitting

Electrocatalytic seawater splitting seems to be the most promising and urgent demand strategy for clean hydrogen energy production. Utilizing low-cost electrocatalysts is pivotal in the hydrogen economy, as seawater splitting can be made highly efficient and more economical. To meet these expectations, we proposed a novel utilization for the black carbon mass left over from hydrometallurgical metal recovery as an efficient and stable electrocatalyst for oxygen evolution reaction (OER) performed in alkaline media. The SEM-EDS, XPS, XRD, XRF, and Raman analyses revealed that the composition and structure of the post-leached battery powders depend on the hydrometallurgical waste recycling conditions, which in turn affect their OER electrocatalytic activity. In particular, the material leached with sulfuric acid (BAT 1) retained a higher content of cobalt-based compounds (mainly LiCoO₂ and Co₃O₄) embedded within a porous carbon matrix and, resulting in the best catalytic performance among all samples. The enhanced performance of BAT 1 is attributed to the synergy of its cobalt-based phases and the well-developed porous carbon structure, which collectively result in a high electrochemically active surface area. The electrochemical tests proved that Li-ion battery waste has remarkable OER catalytic performance with an overpotential of 226 mV and 225 mV, reaching 10 mA cm^{- 2} in water splitting and in seawater splitting, respectively, which is only 14 mV and 95 mV higher than for benchmark RuO₂ in water splitting and seawater splitting, respectively.