https://doi.org/10.1002/solr.202300026

Abstract：Solar-driven steam generation is considered one of

the most promising techniques to obtain freshwater. Under the same projection

area, 3D evaporator has a larger evaporation area and can get more energy from

the environment, resulting into better evaporation performance. 3D evaporators are often hindered by complex and dangerous

fabrication process, special and expensive equipment, and costly raw materials. Herein, we propose a simple method

to prepare a low-cost and highly efficient 3D solar evaporator using chalk and ink that are common in

classrooms. This method does not involve expensive raw materials and

any equipment, and the manufacturing process is simple and fast, especially

suitable for less developed regions. Thanks

to the excellent hydrophilicity of chalk and the strong sunlight absorption of

black ink, the ink-stained chalk (ISC)

shows up to 20.49 kg m-2 h-1 of the evaporation rate under one sun

illumination. When treating real seawater sample, ISC prepared from

broken or used chalks show highly efficient (8.97-19.91 kg m-2 h-1) and stable (24 h)

solar desalination. The ink-stained

chalk presented in this work

offers a new avenue to develop 3D solar evaporator for

low-cost and high-efficient seawater desalination, which is especially attractive for

remote and less developed areas.