A wood-inspired bimodal solar-driven evaporator for highly efficient and durable purification of high-salinity wastewater

Abstract

Solar-driven interfacial evaporation has great potential for energy-efficient purification of high-salinity wastewater, but there is a long-standing trade-off to achieve ultrahigh water evaporation while assuring salt resistance performance. Here, inspired by the leaves-on-stem architecture and transpiration of natural balsa wood, a wood-inspired bimodal evaporator (WBE) with both high evaporation and durable self-salt-discharge in high-salinity brine was prepared via an ice-template method. The hierarchical design and a bimodal porous structure configuration of the WBE provide efficient heat energy confinement, controllable vaporization enthalpy, and abundant salt exchange sites, as revealed by numerical simulations and demonstrated by experiments. The designed WBE achieved ultrahigh water evaporation capacity (3.02 kg m⁻² h⁻¹, 91.8% pure water efficiency) and long-term salt resistance (continuous 100 h in 20 wt% brine) under 1 sun irradiation. Especially, the bimodal design endowed the WBE with remarkable long-term structure reliability even after 1000 repeated compressions at 80% deformation. This work provides a promising approach to achieve durable and efficient purification of high-salinity wastewater.