Seamlessly integrated flexible Janus membranes enabling water-heat-salt synergy for solar desalination and wastewater treatment

Solar-driven interfacial evaporation presents a promising approach to address global freshwater scarcity. Current challenges in photothermal membrane design lie in achieving concurrent optimization of high solar absorption, low thermal conductivity, and water transport, where existing materials fail to establish effective “water-heat-salt” synergistic regulation at the evaporation interface. This study develops a seamlessly integrated Janus membrane through growing hydrophilic Cu_2−xS nanostructure on a hydrophobic carbon cloth substrate with carbon black coating (CB/CC). By precisely engineering the submicron pore architecture within the Cu_2−xS layer, we established a synergistic optimization mechanism for interfacial water transport, heat management, and salt rejection. The resulting Janus membrane demonstrates a high evaporation rate of 2.22 kg m⁻² h⁻¹ under 1 sun with an energy efficiency of about 88.4 %. Notably, the system maintains stable operation in hypersaline environments (20 wt% NaCl) and achieves continuous 5-h salt-resistant evaporation. Moreover, the Janus membranes can effectively purify various industrial wastewater, including acidic, alkaline, and organic pollutants. This study provides a new strategy for developing high-efficiency portable desalination systems through interfacial engineering of pore architecture.