Sustainable recovery Co₃O₄-based catalysts from spent lithium-ion batteries for preferential CO oxidation

Retired Lithium-ion batteries (LIBs) present significant challenges related to environmental pollution, making the recycling of battery materials essential for environmental sustainability and energy recovery. Cobalt has been identified as an effective catalyst for oxidation reactions; accordingly, Co₃O₄ was recovered from batteries directly for use in preferential CO oxidation (CO-PROX). To enhance the low-temperature catalytic activity, supported CuO/Co₃O₄ catalysts were synthesized, resulting in a remarkable boost in catalytic performance, with thorough CO conversion (T_100%) at 160 °C. However, the way a reaction occurs remains unclear, and the active sites for CO adsorption require further investigation. Characterization techniques and density functional theory (DFT) calculations indicated that CuO/Co₃O₄ exhibits higher lattice oxygen (O_latt) content and strong metal-support interactions, which facilitate CO adsorption while suppressing hydrogen activation. Moreover, in-situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS) analysis was used to analyze reaction intermediates, verifying that CuO/Co₃O₄ significantly enhances both CO conversion and CO₂ selectivity. This research presents a viable strategy for the recycling of retired LIBs and the advancement of efficient catalysts for CO-PROX.