Solar evaporation is a sustainable and green strategy to relieve the growing global freshwater crisis. In this strategy, a solar irradiation absorber platform absorbs the sunlight and converts it into heat for water evaporation. Herein, a new class of nitrogen-doped graphene quantum dots (N-GQDs) hydrogels has been developed for highly efficient solar water evaporation via the heat localization mechanism. N-GQDs hydrogels are fabricated via the hydrothermal self-assembly process. Using N-GQDs with different lateral size ranges as the precursor, hydrogels with different structural properties and solar water evaporation efficiencies are prepared. The highest achieved solar steam generation efficiency in this work is 89.7% obtained by employing N-GQDs with the smallest lateral size range in the precursor solution. The steam generation efficiency of hydrogels reduces with increasing the lateral size of synthesized N-GQDs in precursors. The colloidal morphology, high hydrophilicity, hierarchical pore structure, and low thermal conductivity of prepared N-GQDs hydrogels result in the high performance of these structures in solar water evaporation applications.

太阳能蒸发是缓解日益严重的全球淡水危机的可持续绿色战略。在该策略中，太阳辐射吸收器平台吸收阳光并将其转化为热量以蒸发水分。在此，已开发出一类新型掺氮石墨烯量子点 (N-GQD) 水凝胶，用于通过热定位机制高效蒸发太阳能。N-GQDs 水凝胶是通过水热自组装工艺制造的。以不同横向尺寸范围的N-GQDs为前驱体，制备了具有不同结构特性和太阳能蒸发效率的水凝胶。在这项工作中，通过在前体溶液中使用具有最小横向尺寸范围的 N-GQD 获得了 89.7% 的最高太阳能蒸汽产生效率。水凝胶的蒸汽产生效率随着前体中合成 N-GQD 的横向尺寸的增加而降低。制备的 N-GQDs 水凝胶的胶体形态、高亲水性、分级孔结构和低热导率导致这些结构在太阳能水蒸发应用中的高性能。