Watermelon Flesh‐Derived Carbon Aerogel with Hierarchical Porous Structure for Interfacial Solar Steam Generation
Bo Zhu, Jiangtong Zhao, Yangfan Meng, Zixiao Liu, Nuo Yu, Lisha Zhang, Zhigang Chen
Abstract
Solar‐enabled interfacial steam generation is emerging as a sustainable seawater desalination technology, but its practical application is impeded by the high cost of materials and low evaporation rate. To solve these problems, a three‐dimensional (3D) carbon aerogel (CA) is prepared with hierarchical pores by the hydrothermal‐carbonization/freeze‐drying/carbonization treatment of watermelon flesh. The CA is composed of frizzy carbon thin sheets (thickness: ≈2 μm) and large pores (size: 200–400 μm), deriving from the carbonization of plant cells. Especially, plenty of ≈200 nm nanoparticles are located on these thin sheets, accompanying the formation of nanopores with a size of 200–400 nm. These hierarchical macro/nanopores can act as the “light traps,” conferring the broad (250–2500 nm) and strong photoabsorption (absorbance efficiency: 93%). Then, the CA is inserted into a ring‐like polystyrene foam to construct a 3D evaporator, which can float on seawater. Under the irradiation of simulated sunlight (1 kW m −2 ), the evaporator exhibits a high evaporation rate of 2.32 kg m −2 h −1 and long‐term stability. Therefore, the CA acts as an efficient photothermal material for solar‐enabled desalination and also provides some insights for developing other biomass‐derived evaporators.