A typha orientalis-inspired 3D Janus solar evaporator with controllable wettability for highly efficient and stable solar desalination

Solar-powered interfacial evaporators, though promising for seawater desalination and wastewater treatment, but suffer from the problems of monolithic structure and complex preparation. It is of great importance to develop a multi-layered solar evaporator that possesses stable and high-efficiency photothermal performance. Our research employs simple liquid-phase polymerization and chemical deposition methods to achieve this. The objective of this study is to develop a highly efficient solar evaporator, designated as SA/MWCNTs@PPy/MWCNTs-NH 2 @PU (SMPMPU), by integrating stearic acid (SA), multi-walled carbon nanotubes (MWCNTs), polypyrrole (PPy), and aminated multi-walled carbon nanotubes (MWCNTs-NH 2 ) within a polyurethane (PU) matrix. Inspired by typha orientalis, this evaporator boasts a highly antibacterial, self-floating Janus bilayer structure. This double-layered Janus solar evaporator utilizes the capillary adsorption effect to regulate the flow of water. It slows down heat transfer and significantly improves energy utilization efficiency. The resulting SMPMPU solar evaporator demonstrates a solar steam conversion efficiency with an evaporation rate of 2.40 kg·m −2 ·h −1 , which is attributed to the material's efficient absorption of light energy. Its evaporation efficiency under one sun illumination reaches 92.76 %, which can be credited to the Janus interface facilitating the absorption and evaporation of water molecules. The Janus bilayer structured solar evaporator developed in this study holds great promise and is anticipated to find widespread applications in seawater desalination and other related fields.