Biomass photothermal structures with carbonized durian for efficient solar-driven water evaporation

Solar evaporation is emerging as a promising technology to address the fresh water scarcity issue. Nevertheless, the complicated fabrication process and high cost of artificial photothermal structures hindered its wide applications. Evaporators with biomass or natural plants are of relatively low water evaporation rate and energy conversion efficiency. Herein, a novel solar evaporator with three-dimensional photothermal structures is developed by carbonizing waste plants of durian skin. The carbonized durian with macroscale three-dimensional pyramid and microscale porous and petal-like structures contributes to ideal light trapping and absorption, and provides an extremely high solar spectrum absorption of 99%. The rich porous microstructures inside carbonized durian provide excellent capillary effect for sufficient water supply. It exhibits an outstanding water evaporation rate of 2.22 kg/m2h and energy conversion efficiency of 93.9% under one sunlight illumination. It also presents good salt resistance and self-cleaning ability. The daily freshwater amount in outdoor solar desalination (4.8-6.1 kg/m2 on sunny days, 3.5-4.2 kg/m2 on cloudy days) can meet water demand of more than 26 adults. These findings are believed to provide inspiration for the future development of high performance solar desalination devices with high evaporation efficiency, good salt resistance, easy production, low cost, and environmental friendliness.