Durable Antibacterial Photothermal Membrane Using Melanin-Inspired Cu-Doped Polynorepinephrine for Water Remediation

Solar-driven interfacial evaporation is an efficient approach to addressing water scarcity due to its environmental sustainability. However, the prolonged use of solar evaporators causes microbial contamination from wastewater. Inspired by the antifouling properties of polydopamine, we develop a series of mono- and dual-metal-loaded poly(norepinephrine) (PNE) nanoparticles by pre-doping multiple metal ions. Metal doping enhances the photothermal conversion efficiency (∼60%) of PNE by reducing the energy bandgap and imparts antimicrobial properties. Cu²⁺-loaded PNE (Cu-5) combined with laser achieves a 99.72% bactericidal rate against both E. coli and S. aureus. The Cu-5-coated cellulose membrane (Cu-5@CM) realized an evaporation rate of 2.21 kg m^-2 h^-1 under one sun with an evaporation efficiency of 97.4%. Cu-5@CM exhibits remarkable anti-biofouling properties, maintaining its surface integrity and evaporation performance even after 15 days of immersion in a bacterial environment. Its stable evaporation rate and long-lasting antimicrobial performance offer a promising solution to the biofouling challenges in seawater desalination.