Ice templated and ice seed tailored hydrogels for highly efficient solar evaporator

• Published in: Desalination Vol. 575; p. 117292
• Main Authors: Qian, Jiahong, Guo, Jiangbo, Li, Yajuan, Yu, Xudong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 16.04.2024
• Subjects: Anisotropic hydrogel; Ice-templating; Photothermal conversion; Solar vapor generation; Tunable; Tunable; Anisotropic hydrogel; Ice-templating; Photothermal conversion; Solar vapor generation
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2024.117292

In recent years, freshwater resources have become a global concern, and solar vapor generation (SVG) has garnered significant attention from researchers. Herein, a novel hydrogel solar evaporator was prepared by incorporating lignin and CuS-rGO into a chitosan-gelatin matrix. The anisotropic and isotropic morphologies of the hydrogel were prepared by pathway control on the solidification velocities of ice crystals and ice seeds. It presented that the anisotropic morphology can improve the refraction of light and increase the utilization rate of light by forming a light trap, leading to higher water evaporation rate. Additionally, ice seed was introduced during the freezing process, producing an anisotropic hydrogel with curled layer structure that endowed lower enthalpy of water evaporation and faster water transfer rate, resulting in high evaporate of 3.62 kg m−2 h−1 under one solar irradiation with photothermal conversion efficiency of 97.7 %. Finally, the gel also demonstrated good mechanical properties, long-term working stability and harsh environment tolerance, which make it ideal for outdoor applications. The hydrogel evaporator had potential to generate 25.24 kg m2 water per day that could meet the huge demand for freshwater as sources. Three kinds of gel evaporators were prepared by controlling the cooling rate, and the anisotropic hydrogel with ice seed were mainly studied. [Display omitted] •A novel hydrogel-based solar evaporator was designed via ice templated method.•Three kinds of morphologies were obtained by solidification velocity control.•The anisotropic hydrogel demonstrated highest evaporation rate up to 3.62 kg m−2 h−1.•The average evaporation capacity of outdoor evaporation was 25.24 kg m−2 water in a day.