Preparation of Phase‐Change Composites and Their Interfacial Water Evaporation Properties

Materials for the photothermal conversion of solar energy for evaporation have attracted the attention of researchers due to their low energy consumption. However, photothermal conversion materials cannot operate continuously in all weathers due to intermittent solar radiation, which reduces the evaporation efficiency of interfacial evaporated materials. Therefore, this article uses phase‐change materials (PCMs) to improve the evaporation efficiency of traditional interfacial evaporation materials, using polyethylene glycol (PEG) as PCMs, polydopamine (PDA) as light absorption material, acrylamide (AM), bacterial nanocellulose (BC), and sodium carboxymethyl cellulose (CMC‐Na) as matrix raw materials. 3D gel blend (AM/PEG/BC/CMC@PDA) phase transition composite is fabricated using the one‐pot cross‐linking method. Experimental results show that the material achieves 98% light absorption in the entire spectral range. At 1 kW m −2 light, the evaporation rate of the AM/PEG/BC/CMC@PDA phase transition composite reaches 3.44 kg m −2 h −1 . The evaporation rate of the material is equivalent to 8 times that of water, and the photothermal conversion efficiency is 95%. The evaporation rate of the material in the dark is 1.2 kg m −2 h −1 . The material has excellent evaporation rates in various water bodies and meets drinking water standards.