Scalable, self-cleaning and self-floating bi-layered bacterial cellulose biofoam for efficient solar evaporator with photocatalytic purification

With the aggravation of water resource shortage, solar-driven interface seawater desalination is considered to be one of the most promising ways to solve the water crisis. However, there still exist enormous difficulties in preparing efficient interface evaporators with self-floating and self-cleaning properties. Herein, we demonstrate a scalable bi-layered bacterial cellulose (BC) biofoam evaporator, in which the CuS/BC composite material is used as the photothermal conversion layer and the regenerated BC biofoam is employed as the water transport and thermal insulation layer. The optimized evaporation rate is as high as 1.44 kg m−2 h−1, and the evaporation efficiency reaches to 83.5%, which are higher than the performances of most reported BC-based solar evaporators. Besides, the bi-layered BC biofoam exhibits the self-floating ability which can keep a stable long-term floatability more than 6 weeks, and displays excellent self-cleaning ability which can clean the salt of 2 g within 120 min at a circle diameter of 4.8 cm. The solar evaporator simultaneously has photocatalytic purification. The lightweight, portable, self-floating and self-cleaning solar evaporator with photocatalytic performance offer possibilities for solar-powered water treatment, dyeing wastewater purification and other advanced solar thermal applications.