In-situ constructing cellulose/PVA hydrogel with confinement capillarity for efficient solar interfacial evaporation

Solar-driven interfacial evaporation technology, a potential method of solving freshwater scarcity without any fossil energy consumption and environmental impact, is limited by its core component of photothermal materials. Herein, we fabricated a cellulose/PVA hydrogel with interconnected pores structure via an in-situ method to improve its working capacity in seawater desalination and wastewater purification. The results show that adding hydroxypropyl cellulose and changing light absorbers (CNTs and Chinese ink) can efficiently regulate the evaporation enthalpy to accelerate the evaporation. Integrating the interconnected pores structure with an indirect water supply can achieve confinement capillarity, i.e., upward water transportation along the inner surface of the porous hydrogel instead of being full of all pores, thus obtaining a sharp increase in evaporation interface. Compared to Chinese ink, CNTs particles exhibit an obvious promotion to the mechanical properties and evaporation capacity. Eventually, the evaporation rate of the hydrogel containing CNTs with optimized structure can reach 3.16 kg m−2 h−1 under 1 sun. Besides, the as-prepared hydrogel has impressive performance in working stability and self-cleaning capacity under harsh environmental conditions, such as high-concentration brine, strong acid, and alkaline solution. The regulation strategy will arouse new inspiration from numerous researchers about designing and manufacturing high-performance solar-driven evaporators.