A low-cost, high-efficient and robust-mechanical aerogel made of melamine sponge and carbon black for solar interfacial water evaporation

The photothermal conversion efficiency and the mechanical strength of aerogel were the bottlenecks of the photothermal interface evaporation layer, and photothermal materials had been proved to be a feasible strategy to improve the evaporation rate of seawater. In this work, a porous photothermal aerogel called carbonized melamine sponge - carbon black (AMSC) was reported, which was prepared by a cost-effective and scalable method using carbonized melamine sponge (AMS), carbon black (CB), and polyvinyl alcohol (PVA). The AMS provided a porous skeleton that enhances water transport and steam escape, while the crystalline PVA both strengthened the skeleton and allowed carbon black to tightly adhere to the AMS. The carbon black acted as a photothermal material, enhancing light absorption and photothermal conversion. The AMSC aerogel evaporator shown efficient evaporation performance, excellent mechanical properties, and good stability. At room temperature, the water evaporation rate of the aerogel evaporator reached 2.52 kg m−2 h−1 under 1.0 sun illumination (100 mW/cm2), and the collected freshwater could be compliant with the international drinking water standards. Moreover, the AMSC aerogel also maintained a high evaporation rate and purification effect in acid or alkaline solutions. In mechanical tests, the AMSC aerogel retained its structural integrity even in the cases of longitudinal twisting, lateral pulling, and prolonged ultrasonic treatment in water. The outdoor tested results show that the water evaporation rate of the aerogel evaporator was approximately 6 times higher than the natural one of pure water. This study presented an environmental-friendly, cost-effective, and scalable strategy for preparing high-performance photothermal aerogels, expected practical applications in the field of solar seawater desalination.