Modulation of the surface humidity with dual convection structure towards highly efficient and stable solar desalination

Solar-driven interfacial evaporation has emerged as a promising sustainable technology to address global water scarcity. Notwithstanding significant advancements in photothermal materials, substrates, and their combinations, these strategies to enhance evaporation efficiency seem to have reached a bottleneck for the oversight of the important factor of thermal convection on the performance of the evaporator. Herein, a wood-based evaporator featuring a dual convection structure was developed by creating a central cavity in a wood block and integrating MXene photothermal materials. Specifically, without the need for special materials or complex structural designs, the evaporator achieves an outstanding evaporation rate of 2.16 kg·m⁻2·h-1 with a photothermal conversion efficiency of 118%. Simulation results indicated that the engineered dual-convection structure effectively modulates the heat distribution and reduces the humidity above the evaporation surface, thereby increasing the evaporation rate and the overall photothermal conversion efficiency. Additionally, the device demonstrates excellent salt resistance and long-term operational stability even under extreme pH conditions (e.g., strong acid (pH=2) and strong alkali (pH=12) environments). This study not only provides new insights into the design of efficient, structurally simple solar interfacial evaporators but also expands the potential applications of wood-based materials in solar-driven evaporation systems.