In situ self-growing CuO nanoclusters on titanium dioxide for high-efficient photocatalytic degradation of norfloxacin under visible light

The selection of simple and effective photocatalysts is a challenge for removing Norfloxacin (NOR) from water. This study successfully synthesized CuO nanoclusters and titanium dioxide (CuO/TiO₂) Z-scheme heterojunction using the facile in situ self-growing method and used for photocatalytic degradation of NOR. The 1.4 % CuO/TiO₂ system achieves an 84.88 % NOR degradation efficiency in 60 min and maintains over 78.42 % efficiency after five cycles when exposed to visible light, which is higher than that of CuO and TiO₂, respectively. The internal electric field established between them expedited the separation and transfer of electron-hole pairs, thereby boosting photocatalytic activity. Moreover, the active species that take part in the photocatalytic reaction were identified as ·O₂⁻, ·OH, and h⁺ radicals. According to the mass spectrometry (MS) test, the possible three photocatalytic degradation pathways of NOR were investigated. Finally, the heterojunction formation and charge transfer mechanism of CuO/TiO₂ are proposed and validated with DFT calculation. This study applies simple, low-cost CuO/TiO₂ for efficient NOR degradation under visible light, providing an insight into the scale-up removal of NOR from water.