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In recent years, pursuing a high evaporation rate of solar steam generation (SSG) has been the focus of research for relieving the freshwater shortage. Scientists struggled to find perfect photothermal materials while the importance of substrate during the steam generation was often overlooked. Therefore, in this work, an aerogel substrate composed of polyvinyl alcohol (PVA) and chitosan (CS) has been designed for solar steam generation. The compounded aerogels synthesized via freeze‐drying method not only retain the inherent characteristics of lightweight, porosity, and high specific surface area, but also inherit the advantages of PVA in water lock effect as well as CS in moisture absorption. The obtained PVA/CS/CuO aerogel coupling with high light absorption of CuO exhibited excellent steam generation capabilities, largely benefited from the superiority of the aerogel substrate. Under 1 sun solar illumination (1 kW m–2), it realized an evaporation rate as high as 2.14 Kg m–2 h–1, which is superior to recently reported semiconductor solar evaporation system. The solar‐to‐vapor energy conversion efficiency of 87.1% is obtained. Due to the versatility of CuO, PVA/CS/CuO aerogel not only has excellent light‐to‐heat conversion performance, but also has good effects in antibacterial. [ABSTRACT FROM AUTHOR]

Solar steam generation is an environmentally friendly water treatment method that produces clean water using solar energy. However, it is still a challenge to effectively prevent the performance deterioration when most photothermal conversion materials are used to evaporate high‐concentration salt‐containing wastewater or strong acid/alkali solution. Herein, a stable and effective solar evaporator is designed using natural sugarcane, where sucrose is simply dehydrated into carbon particles by hydrothermal reaction in sulfuric acid. With a honeycomb structure, it not only enables water transport capacity but also promotes sunlight absorption. Sulfuric acid hydrothermal carbonized sugarcane (SHCSC) can reach up to 95.36% solar absorption in a wide wavelength range (200–2500 nm) and a high evaporation rate of 2.32 kg m−2 h−1 under 1 sun illumination. More importantly, SHCSC has an excellent adsorption capacity with ion removal rate of 99.9% even under artificial wastewater containing 1000 mg L−1 of mixed metal ions. SHCSC also can perform efficiently and stably at a high evaporation rate above 2.2 kg m−2 h−1 in strong acidic or alkaline wastewater. These findings suggest that SHCSC can be potentially applied to the efficient harvest of clean water from the high‐concentration wastewater containing acid, alkali, and mixed metal ions. [ABSTRACT FROM AUTHOR]

The solar‐assisted desalination generator (SADG) shows great potential for solving water scarcity problems. However, salt precipitation and accumulation is still a challenge for SADG, which slows down solar steam generation performance of evaporator during operation. Here, a facile integrative evaporator featuring stable and high evaporation performance breaks this bottleneck. By using a rational design in which amorphous carbon particles are evenly composited within the porous chitosan aerogel, the evaporator not only integrates excellent light absorption, heat management, and water transportation abilities but also endows a large vapor escape space. Upon desalination, salt concentration ingredients between carbon particles and chitosan membranes can be quickly balanced by water transport in interconnected chitosan chains, and thus salt precipiation on the evaporator surface would be avoided. Compared to other salt‐rejection evaporators, the integrative evaporator can operate in 3.5 wt% brine for 60 days without salt precipiation and exhibits a stable evaporation rate (1.70 kg m−2 h−1), indicating its potential for practical applications in seawater desalination and the harvest of clean drinking water. [ABSTRACT FROM AUTHOR]

Highly efficient solar steam generation (SSG) relies on excellent light absorption, adequate water transportation, a large evaporation area, and high thermal management capability in coherent photothermal materials. However, there is not yet a general means of integrating these functions on a monolith with design flexibility in chemical compositions and pore structure. Here, we design and demonstrate a versatile chitosan (CS) aerogel that is easily compatible with other photothermal materials for high-efficiency SSG. The CS aerogel was synthesized through liquid-phase one-pot freeze drying without any cross-linkers. CS composite aerogels not only preserved the initial characteristics of the CS aerogel but also integrated biocompatible, hydrophilic and high thermal insulation properties, as well as enhanced light absorption ability based on the designed porous structure through the effects of light trapping and multiple scattering. Carbonized pomelo peel particles composited with the CS aerogel and freeze dried by lyophilizer (PP 0.1 CS 1.5 -L) exhibited excellent SSG performance with an evaporation rate of up to 1.78 kg m−2 h−1, which is far beyond that attainable by two-dimensional SSG systems under normal solar irradiation of 1 kW m−2. This research opens up a new avenue for the facile fabrication of reusable, low-cost, nontoxic, and high-performance functional aerogels. Image 1 • Photothermal material aerogel integrated the enhanced light absorption, convenient water transport, and improved heat management ability. • The evaporation rate of up to 1.78 kg m−2 h−1 is far beyond that attainable by two-dimensional SSG systems under normal solar irradiation of 1 kW m−2. • The chitosan aerogel is easily compatible with other photothermal materials for high-efficiency solar steam generation. • The pore sizes and structures of composite aerogels can be easily controlled by adjusting ice formation direction and freezing temperature. [ABSTRACT FROM AUTHOR]