Superhydrophilic and mechanically robust phenolic resin as double layered photothermal materials for efficient solar steam generation

Solar steam generation has been emerged as one of efficient and green technologies for harvesting solar energy for seawater desalination and wastewater treatment. Herein, we demonstrate a facile approach for scalable fabrication of phenolic aldehyde foams (PAFs), which were synthesized by polymerization of formaldehyde with phenol and hydroquinone through one-step hydrothermal method, as double layered photothermal materials for efficient solar steam generation. The resulting PAFs show high porosity of higher than 93.6%, low apparent density (0.152-0.167 g cm(-3)), low thermal conductivity (0.034 -0.054 W m(-1) k(-1)) and a good mechanical strength (0.07 MPa under 30% strain). The presence of close-packed open channels, by combination with their surface superhydrophilicity (water contact angle similar to 0 degrees), ensure the PAFs a rapid transportation of water molecules. After facile coating a thin layer of carbon soot on PAFs, a double layered photothermal materials with enhanced light absorption (similar to 90%) was fabricated (named as CPAFs). Under 1 sun irradiation, the CPAFs possess a high water evaporation rate of 1.4922 kg m(-2) h(-1) and a solar conversion efficiency of 87.86%, making it promising candidate as solar generators for efficient solar desalination. By combining with their simple, scalable and cost-efficient manufacture process, it is suggested that such CPAFs may have great potentials for real applications. (C) 2019 Elsevier Ltd. All rights reserved.