Resource recovery from spent lithium manganese oxide batteries for the fabrication of high-performance manganese-based catalysts in toluene degradation: A structure-activity relationship study

To address the dual environmental and health challenges posed by spent lithium manganese oxide batteries (LMO) and volatile organic compounds (VOCs), this study developed a 3D-structured composite manganese oxide catalyst for toluene degradation by uniquely integrating resource recovery with functional catalyst design, offering an innovative solution that combines environmental sustainability with exceptional catalytic performance. The effects of leachate pH on the crystal structure and catalytic performance of the catalysts were systematically investigated, and the relationship between structural parameters and catalytic activity was thoroughly analyzed. Manganese oxide derived from spent LMO exhibited superior performance compared to similar catalysts from chemical reagents. Notably, the composite crystalline LMO-α@δ-MnO₂ featured a 3D structure with numerous oxygen vacancies, resulting in higher low-valence manganese and surface-adsorbed oxygen. This material also had the smallest grain size, largest pore volume, specific surface area, and highest redox capability, contributing to its superior catalytic activity for toluene oxidation, achieving a T₉₀ of 218°C. Furthermore, the potential degradation mechanism of toluene over LMO-α@δ-MnO₂ was proposed. This study provides new insights into the sustainable resource utilization of spent LMO and the development of high-performance catalysts for VOCs degradation.