A Plant-Leaf-Inspired Solar Evaporator

The interfacial solar evaporator has emerged as a leading solution to mitigate the global water scarcity challenge. Current research predominantly concentrates on augmenting the evaporator efficiency through enhanced light absorption, improved water transport, and superior heat insulation. Nonetheless, the evaporation process is a water vapor transport process driven by gas diffusion theory, which involves a concentration gradient and airflow along with boundary layer effects. Inspired by highly efficient water vapor diffusion in plant leaf stomata, we propose a leaf-inspired design for solar evaporators. In this study, simulation and calculation by COMSOL were utilized to identify the optimal configuration for the array pore arrangement. Subsequently, a poly(vinyl alcohol) (PVA) sponge is employed to replicate the characteristics of leaf mesophyll, while a polyimide film featuring a meticulously engineered array of pores is applied onto the sponge to mimic the structure of leaf stomata. Our experimentation on seawater desalination tests has revealed an enhancement in the evaporation rate of the evaporator (1.69 kg m–2 h–1 under 1 sun irradiation for a 3.5 wt % NaCl solution), representing an impressive 11.9% increase compared to the uncovered evaporator (1.51 kg m–2 h–1). Remarkably, the evaporator also showcases exceptional stability and resistance to salt deposition. The outcomes of our study provide a direction for designing highly efficient solar evaporators.