Plasmonic silver nanoparticles embedded in flexible three-dimensional carbonized melamine foam with enhanced solar-driven water evaporation

Abstract Solar-driven water evaporation is a promising method to address the growing freshwater crisis. Materials with excellent photothermal conversion property and their incorporation into high-efficiency devices are the key to solving such crisis. Herein, a flexible architecture featuring uniformly distributed Ag nanoparticles within three-dimensional (3D) carbonized melamine foams (CMF) is proposed, which combines the merits of CMF's porous structure and Ag's plasmonic optical property to efficiently convert light to heat. Packing such 3D CMF@Ag with a melamine foam (MF) as the water absorption layer, solar-driven water evaporation with high efficiency is achieved. With 1 kW m−2 solar illumination on pure tap water, wet fine sand and xalsonte, the fully packed device exhibits evaporation rates of 2.12, 2.14 and 2.39 kg m−2 h−1 and photothermal efficiency of 102.99%, 105.83% and 119.46%, respectively. The enhanced water evaporation performance is ascribed to the synergistic effect of the efficient photothermal conversion of CMF@Ag layer, the strong water absorption/transfer ability of the MF layer, the tightly integrated CMF/MF interface and the environmental energy-assisted means. Equivalently important is the 3D porous structure of CMF that increases the scattering of light and reduces the water vaporization enthalpy. By demonstrating this unique design capable of scalable processing and packing, we expect it to be a promising candidate for efficient water purification applicable to various water sources.