Solar‐driven interface evaporation (SDIE) technology is considered an effective way to alleviate the world's water resources scarcity problem, and the development of structurally stable and high‐performance photothermal materials is the key to SDIE technology. Black titanium dioxide (TiO 2 ) has excellent light absorption capacity and good chemical stability, rendering it a desirable candidate for SDIE technology. Herein, a black TiO 2 nanoparticle was prepared by calcining a colloidal titanium dioxide precursor, and then a black TiO 2 /calcium alginate composite hydrogel (PUCA‐TiO 2 ) was obtained by an impregnation cross‐linking technique using a polyurethane sponge as a backbone. The PUCA‐TiO 2 evaporator exhibited excellent evaporation performance at one solar light intensity (1 kW m −2 ) with an evaporation rate of 3.331 kg m −2 h −1 and a photothermal conversion efficiency of 92.79%. Notably, the material was able to maintain an efficient evaporation rate of 2.876 kg m −2 h −1 even in a high brine concentration of 25 wt%. Real seawater desalination tests further confirmed its excellent seawater desalination capacity and long‐term salt stability. The developed PUCA‐TiO 2 composite hydrogel breaks through the bottleneck of traditional TiO 2 photothermal applications and has great potential in solar interface evaporation applications.
Guo et al. (Fri,) studied this question.