Efficient Solar\nSteam Generation by Multiscale Photothermal\nStructures Derived from Cactus Stems

Solar steam generation (SSG) is a promising technique\nthat may\nfind applications in seawater desalination, sewage treatment, etc.\nThe core component for SSG devices is photothermal materials, among\nwhich biomass-derived carbon materials have been extensively attempted\ndue to their low cost, wide availability, and diversified microstructures.\nHowever, the practical performance of these materials is not satisfactory\nbecause of the multifaceted structural requirements for photothermal\nmaterials in SSG scenarios. In this work, cactus stems, which possess\nabundant and multiscaled pores for simultaneous sunlight gathering\nand water evaporation, are applied as the photothermal structure for\nSSG devices after mild heat treatment. Consequently, the SSG device\nbased on the carbonized cactus stems delivers high performance (an\nabsorption rate of 93.7% of the solar spectrum, an evaporation rate\nof 2.02 kg m<sup>–2</sup> h<sup>–1</sup>, and an efficiency\nof 91.4% under one solar irradiation). We anticipate that the material\ncan be a potential candidate for efficient SSG devices and may shed\nlight on the sustainable supply of water.