Bioinspired Synthesis of Photocatalytic Nanocomposite Membranes Based on Synergy of Au-TiO₂ and Polydopamine for Degradation of Tetracycline under Visible Light

A bioinspired photocatalytic nanocomposite membrane was successfully prepared via polydopamine (pDA)-coated poly(vinylidene fluoride) (PVDF) membrane, as a secondary platform for vacuum-filtrated Au-TiO₂ nanocomposites, with enhanced photocatalytic activity. The degradation efficiency of Au-TiO₂/pDA/PVDF membranes reached 92% when exposed to visible light for 120 min, and the degradation efficiency of Au-TiO₂/pDA/PVDF membranes increased by 26% compared to that of Au-TiO₂ powder and increased by 51% compared to that of TiO₂/pDA/PVDF nanocomposite membranes. The degradation efficiency remained about 90% after five cycle experiments, and the Au-TiO₂/pDA/PVDF nanocomposite membranes showed good stability, regeneration performance, and easy recycling. The pDA coating not only served as a bioadhesion interface to improve the bonding force between the catalyst and the membrane substrate but also acted as a photosensitizer to broaden the wavelength response range of TiO₂, and the structure of Au-TiO₂/pDA/PVDF also improves the transfer rate of photogenerated electrons; the surface plasmon resonance effect of Au also played a positive role in improving the activity of the catalyst. Therefore, we believe that this study opens up a new strategy in preparing the bioinspired photocatalytic nanocomposite membrane for potential wastewater purification, catalysis, and as a membrane separation field.