Ultrathin CuZnCr-LDH nanosheets for photo-Fenton synergistic degradation of ciprofloxacin and methylene blue

The extensive use and improper disposal of antibiotics and organic dyes have resulted in their substantial release into the natural environment, posing a grave threat to both the ecological system and human health. This study successfully synthesised an ultra-thin CuZnCr layered ternary hydrotalcite (CuZnCr-LDH) nanosheet, exhibiting remarkable photo-Fenton properties, through a streamlined one-step coprecipitation method. When the ratio of Cu⁺ to Zn²⁺ is 2:1, methylene blue (MB) degradation efficiency reaches 96.5% after 70 min, and that of CIP attains 75% after 3 h, and the mineralization rate can be as high as 81.3% and 64.7%. The key to enhancing its performance is that the ultrathin structure is conducive to carrier migration, a large number of photogenerated electrons are conducive to the recovery of valence states of Cu and Cr ions to promote Fenton reaction cycle, and the rich active species actively participate in the reaction. Furthermore, electron paramagnetic resonance (EPR) signaling and active material capture experiments have shown that photogenerated superoxide radicals (‧O₂^-), hydroxyl radicals (‧OH) and holes (h⁺) as active species play a crucial role in the degradation process. And the cyclic pattern of the high-priced metal was verified by X-ray photoelectron spectroscopy (XPS) testing, which is a key factor in the photo-Fenton synergy. Based on the experimental results, the photo-Fenton degradation mechanism is proposed. This study holds important promise in addressing the pressing problem of water pollution caused by antibiotics and organic pollutants.