Architecting of All-Cellulose-Based Wicking Fabric for a Large-Scale, Low-Cost, and Highly Efficient Solar Desalination Evaporator

Interfacial solar vapor generation (ISVG) technology has been considered a promising and sustainable strategy for seawater desalination and wastewater treatment. However, its practical application is greatly limited due to severe salt accumulation and poor long-term evaporation stability. Herein, an all-cellulose-based wicking fabric (CB@CA/CF) is fabricated via a breath figure template (BFT) method for high-performance and stable desalination. The abundant porous structure of carbon black@cellulose acetate (CB@CA) endows the evaporator with high light absorption (∼96.9%) and rapid steam escape. The hydrophilic CA network also changes the hydration state and greatly reduces the water evaporation enthalpy. More importantly, the unique double-layer porous structure of CB@CA and cotton fabric (CF) produces a rapid antigravitational wicking effect, providing sufficient water supply for vapor generation and preventing salt accumulation on the evaporator surface. As a result, the CB@CA/CF evaporator can achieve high evaporation rates of 2.08 kg m^–2 h^–1 in pure water and 1.98 kg m^–2 h^–1 in a 3.5 wt % NaCl solution under one-sun irradiation, without any salt accumulation over 8 h. Moreover, the designed floating evaporation system can obtain a high freshwater collection of 8.39 kg m^–2 per day under natural environmental conditions. This work provides an effective path for developing stable and highly efficient freshwater acquisition and shows great prospects in the field of seawater desalination and wastewater treatment.