Two-Dimensional Flexible Bilayer Janus Membrane for Advanced Photothermal Water Desalination

Solar water evaporation is thought to be a promising solution to address the issues of global water scarcity. However, it is particularly difficult to achieve an idealized photothermal conversion membrane with all of the required structure characteristics such as wide spectrum absorption, ultrathin and porous, low thermal conductivity, and ease to scale up, thus leading to reduced water evaporation efficiency. Here, we designed a large-area bilayer Janus film by assembling gold nanorod (AuNR) onto the interconnected single-walled carbon nanotube (SWNT) porous film. The combined characteristics of high solar spectrum absorption, enhanced photothermal performance, thermal insulating feature, interconnected porous structure, and excellent mechanical performance enable the bilayer Janus film with a nearly 94% water evaporation efficiency under 5 kW m–2 solar irradiation and stable water generation capability during long-term illumination cycles as a water desalination membrane. Construction of the bilayer Janus film represents an effective strategy for developing multifunctional membranes for advanced desalination applications.