Black Phosphorous Nanosheets: A Novel Solar Vapor Generator

Solar vapor generation is a promising and whole new branch of photothermal conversion for harvesting solar energy. In this work, a novel solar vapor generator based on black phosphorous (BP) nanosheets is designed for steam generation, desalination, as well as dye removal, using polyurethane (PU) foam as a supporting material. Employing electrostatic layer-by-layer assembly, BP nanosheets and chitosan (CS) are alternately deposited onto the skeleton of the PU foam. After the deposition of BP nanosheets, the hydrophilicity of the PU composite foam is obviously improved, thus facilitating the capillary effect. Even with a spot of BP nanosheets (lower than 5.0 wt%), the as-fabricated PU@(sodium alginate, SA/BP)₆ foam exhibits a surface temperature of ≈70.9 °C and an evaporation rate of 1.082 kg m⁻²h⁻¹ under 1 sun irradiation. Due to the protection effect of CS, the photothermal conversion performance and water evaporation rate do not deteriorate during ten cycles of reusing. In addition, the water evaporation performance of PU@(SA/BP)₆ is also investigated under different conditions, including sun irradiation intensity, metal ions, and dye. In brief, employing a facile and eco-friendly fabrication process, BP nanosheets are first applied to seawater desalination and pollution removal, presenting a tremendous potential for practical solar vapor generation.