Antibacterial and photocatalytic PVDF foam for simultaneous interface evaporation and water purification

Abstract

Water evaporation and purification have been extensively employed as a viable approach to address the global freshwater crisis. However, the capacity of evaporators to procure potable freshwater from seawater, sewage, and other aqueous environments is limited by challenging conditions. Herein, self-floating PVDF/TiO₂/GO foam with micro/nanostructure (MNPFG) and interconnected vapor escape channels is prepared economically and efficiently by combining compression molding and spray coating. The surface micro/nanostructures and inherent properties of PVDF allow the MNPFG to maintain a robust superhydrophobic state under dynamic impacts, extreme temperatures, and acidic, alkaline, or saline solutions, demonstrating a contact angle of 158° and a rolling angle of 9°. The combination of superoxide ions, photothermal effect, and physical puncture effect inhibits bacterial growth and reproduction, resulting in remarkable antibacterial activity (99.9%) against Escherichia coli. Moreover, the MNPFG exhibits catalytic and degradation rates of 0.019 min^–1 and 99%, respectively. The MNPFG with self-cleaning, antibacterial, and catalytic degradation properties is sufficient for simultaneous interface evaporation and water purification, with the purified water meeting the freshwater standards set by the World Health Organization without any detectable organic or microbial residues. The proposed approach offers an industrialized methodology for the large-scale production of solar evaporators suitable for freshwater generation and purification.