A natural choice towards water desalination: Improving solar-powered wood interfacial evaporation by lignin-based carbon quantum dots
Renjie Zhang, Jun Guo, Pengfei Zhou, Yue Chai, Xiao Xiao, Jikun Xu
Abstract
Solar-powered seawater desalination offers a promising solution to the urgent issue of water scarcity by utilizing the endless energy of sunlight, yet attaining high-performance wood-structured interfacial evaporation remains elusive. We report a facile approach that combines lignin-based carbon quantum dots (CQDs) and perforated bulk wood to improve the evaporation rate and photothermal conversion, wherein the as-prepared CQDs in the evaporator functions as a intensifier to light adsorption and solar-to-heat conversion. Owing to the photoelectric transition of lignin CQDs, adding lignin CQDs alters the natural structure and properties of wood interface with punched holes, thereby heightening the ratio of intermediate water in the device to lower the enthalpy of water evaporation with salt-tolerance and long-term serviceability. Fluidic simulation reveals that the punched large channels with high water flux provokes the salt concentration gradient in hierarchical pores. In the meantime, the concentrated water at the top layer transports downward by diffusion and convection, thus making the spontaneous horizontal and vertical salt exchange. Through the depositing CQDs onto the surface-carbonized wood, the optimum evaporation performance of 3.722 −4.003 kg m −2 h −1 with over 86 % solar-to-vapor efficiency under one sun irradiation is achieved in 0.05 wt% saline water. Owing to the 3D-interconnected porous channels and CQDs photothermal interfaces, the evaporator could operate stably in highly saline water and practical outdoor scene. This work sketch a blueprint of all-wood-based interfacial evaporators with excellent seawater desalination performance, pointing to a broader future for the coordination of sustainable biomass conversion and water purification. • A lignin CQDs-decorated wood interfacial evaporator for enhanced solar-to-vapor. • The lignin multicolor MCQDs and ECQDs are prepared to intensify photothermal ability. • The evaporator operates stably in highly saline water and practical outdoor scene. • Water evaporation of ∼4.0 kg m −2 h −1 is achieved by drilled holes and CQDs loading. • Fluidic simulation reveals the salt concentration gradient in hierarchical pores.