Molecular-assembly route to fabricate a robust flexible hydrogel membrane for high-efficient and durable solar water purification

• A PVA/PEDOT: PSS hydrogel-carbonized melamine foam (PPPH-CF) was fabricated. • The PPPH-CF membrane shows great flexibility, hydrophilicity and light absorption. • Solar water evaporation rate reaches 2.06 kg m −2 h −1 with an efficiency of 96.9%. • The PPPH-CF membrane exhibits a superior rejection of diverse contaminants. • The PPPH-CF membrane can be repeatedly used via rinse due to favorable elasticity. Freshwater scarcity is threatening the health and life of people. As a portable water purification route, solar-driven water evaporation has attracted great attention. Although diverse light absorber materials were achieved for interfacial water evaporation, it is still desired to design robust and high-efficient photothermal materials. Herein, we employed a molecular assembly method to accomplish a PVA/PEDOT: PSS composite hydrogel (PPPH) into a carbonized melamine foam (CF) for the fabrication of PPPH-CF membrane, which is flexible, stretchable, and reusable for solar water evaporation. The water evaporation rate can reach 2.06 kg m −2 h −1 with an amazing photothermal conversion efficiency of 96.9% under one sun. The as-prepared PPPH-CF membrane was also utilized for water purification, which exhibits an outstanding rejection ratio of salts, heavy metals, dyes, and bacteria. This facile, low-cost, and high-efficient water purification procedure can be envisioned for the large-scale and one-step water treatment with renewable solar energy, meeting people’s freshwater demands.