High-performance salt-resistant solar interfacial evaporation by flexible robust porous carbon/pulp fiber membrane

Abstract

Solar evaporation has emerged as an attractive technology to produce freshwater by utilizing renewable solar energy. However, it remains a huge challenge to develop efficient solar steam generators with good flexibility, low cost and remarkable salt resistance. Herein, we prepare flexible, robust solar membranes by filtration of porous carbon and commercial paper pulp fiber. The porous carbon with well-defined structures is prepared through controlled carbonization of biomass/waste plastics by eutectic salts. We prove the synergistic effect of porous carbon and paper pulp fiber in boosting solar evaporation performance. Firstly, the porous carbon displays a high light absorption, while the paper pulp fiber with good hydrophilicity effectively promotes the transport of water. Secondly, the combination between porous carbon and paper pulp fiber reduces the water vaporization enthalpy by 20%, which is important to significantly improve the evaporation performance. As a proof of concept, the porous carbon/paper pulp fiber membrane possesses a high evaporation rate of 1.8 kg m−2 h−1 under 1 kW m−2 irradiation. Thirdly, the good flexibility and mechanical property of paper pulp fiber enable the solar membrane to work well under extreme conditions (e.g., after 20 cycles of folding/stretching/recovery). Lastly, due to the super-hydrophilicity and superwetting, the hybrid membrane exhibits the exceptional salt resistance and long-term stability in continuous seawater desalination, e.g., for 50 h. Importantly, a large-scale solar desalination device for outdoor experiments is developed to produce freshwater. Consequently, this work provides a new insight into developing advanced flexible solar evaporators with superb performance in seawater desalination.