A highly efficient melamine foam-based solar evaporator with double-photothermal-converting and fast water transportation

Melamine foam (MF) has received a lot of attention in the field of solar water evaporation due to its unique structure, hydrophilicity and easy availability. Most previous studies have focused only on either applying MF as photo-thermal conversion (PTC) materials after calcination, or as skeleton matrix for loading other PTC materials. Herein, by utilizing melamine foam as matrix, a composite photothermal conversion based on carbonized melamine foam and polydopamine was achieved through a series of carbonization and coating procedures. Additionally, the infilling of bacterial cellulose prior to the coating of PDA reduced the voids inside the evaporator, thus created more pathways to ensure fast water transportation during evaporation without compromising its salt backflow. As a consequence, very close evaporation rates of 2.28 and 2.24 kg m-2 h-1 were achieved during the evaporation tests in pure water and seawater under 1.0 sun illumination, respectively. Our work presents a methodology to apply melamine foam for efficient solar water evaporation, as well as to guarantee the evaporation rate stability of evaporators in desalination.