Bio-inspired solar evaporators for stable and efficient desalination of high-salinity brine with zero liquid discharge.

Abstract

Solar-driven interfacial evaporation has shown great potential for achieving desalination with high energy conversion efficiency. However, maintaining a high evaporation rate is challenging due to salt accumulation on solar evaporators (SEs), leading to a long-standing trade-off between stable evaporation and salt accumulation in conventional SEs. Inspired by the salt secretion and brine transport mechanisms in mangroves, we present a bio-inspired solar evaporator (BSE) featuring an external photothermal layer and an internal water supply channel. This design enables efficient and continuous evaporation from near-saturated brine using less photothermal material. The BSE exhibits high evaporation performance (3.98 kg m^-2 h^-1 for 25 wt% brine), effcient salt collection (1.27 kg m^-2 h^-1 for 25 wt% brine), long-term durability (7 d in 25 wt% brine), and zero liquid discharge desalination. Notably, the BSE achieves a record-high water production rate of 3.50 kg m^-2 h^-1 in outdoor tests. Furthermore, it can purify World Health Organization-standard freshwater from various types of contaminated water. Importantly, the universality of BSE design is validated by extending it to other solar desalination systems. This work demonstrates a universal SE design, providing key insights into the design of next-generation SEs for efficient and stable evaporation in continuous high-salinity brine desalination.