Novel Sponge-Based Carbonaceous Hydrogel for a Highly Efficient Interfacial Photothermal-Driven Atmospheric Water Generator

A high-performance atmospheric water generator based on continuous adsorption–desorption of liquid hygroscopic agents was constructed by applying interfacial photothermal evaporation technology to the field of atmospheric water harvesting. A three-dimensional carbon-containing sponge hydrogel photothermal conversion material with a porous channel structure was designed, which was prepared from melamine foam (MF) and carbon black (CB) cross-linked by sodium alginate (SA). The results showed that the evaporation rate of CB/SA@MF in pure water was 1.90 kg·m–2·h–1, and the photothermal conversion efficiency could reach 85.0%. The multistage pore structures and water transport channels in the A4 configuration device provided an excellent structural basis for material salt resistance and liquid hygroscopic agent regeneration. Using sponge-based CB/SA@MF hydrogel photothermal composites as the evaporation interface and liquid hygroscopic salts as the air–water trapping agent, an interfacial photothermal-driven atmospheric water generator successfully absorbed water at night and produced water during the day. Its water production could reach 2.84 kg·m–2·d–1. The cost of the atmospheric water generator was only $12, and the water quality obtained after 5 cycle tests met WHO/GB 5749-2022. This research was designed to collect fresh water from the air, bringing convenience to inland arid regions as well as remote and scattered areas with limited power resources.