The photocatalyst generates hydrogen peroxide in situ under visible and UV light, which facilitates efficient metal extraction from battery cathodes. The process achieved high leaching efficiency (>94%) under solar irradiation conditions (T = 25°C, P = 1 atm, I = 0.58 μE cm−2 s−1) for valuable metals (Li, Co, Ni, Al, Mn) from various commercial cathode materials, including LCO, NCM, and NCA.
Electron spin-resonance spectroscopy confirmed the generation of hydroxyl radicals (·OH) and superoxide radicals (·O2−), while specific molecular probes (THA and NBT) verified their production. The continuous generation of H2O2 during the photocatalytic reaction was confirmed using horseradish peroxidase assay. Since the photocatalytic charge transport occurs without molecular structure degradation, the catalyst can be recovered and reused multiple times. The photocatalyst maintained its structural stability and performance across multiple recycling cycles, demonstrating 95-97% of original leaching efficiencies.
Process modeling and economic assessment revealed significant advantages over conventional methods. At commercial scale (10,000 tons annually), the photocatalytic approach yields estimated profits of $10.2 per kg of processed batteries, exceeding both pyrometallurgical ($6.7/kg) and hydrometallurgical methods ($7.8/kg). Environmental assessment showed 65% lower greenhouse gas emissions compared to pyrometallurgical processes and 38% lower than conventional hydrometallurgical methods.
Additionally, the total energy consumption (8.54 MJ per kg cathode) is substantially reduced—34% lower than hydrometallurgical approaches and 77% lower than pyrometallurgical methods. These results establish this ambient sunlight-driven photocatalytic system as a promising sustainable platform for large-scale battery recycling.