A lotus leaf like vertical hierarchical solar vapor generator for stable and efficient evaporation of high-salinity brine

Abstract Interfacial solar vapor generation is promising and sustainable for seawater desalination. However, the performance degradation caused by salt accumulation has hindered the development of the interfacial solar vapor generator severely. In this paper, we have designed a lotus leaf like vertical hierarchical solar vapor generator (LSG) for stable evaporation of high-salinity brine. The LSG is assembled by Si/PPy-PVA sponge and multi-root columnar PVA sponge by mimicking the structure of the lotus leaf. The Si/PPy-PVA sponge is fabricated by successively depositing the PPy layer and silane layer on the PVA sponge and acts as the absorber of LSG. LSG enables a stable evaporation rate of 1.35 ± 0.02 kg m−2 h−1 out of 26.6 wt% brine under 1 sun for over 15 days. Besides, LSG demonstrates high efficiency of 92.6% under 0.25 sun. LSG is also tested to treat different industrial dyeing wastewater with the highest evaporation rate of 1.38 ± 0.01 kg m−2 h−1. The condensed water produced by LSG has reached the Class IV Surface Water Standards. Our work provides a new guideline to design high-efficiency solar vapor generators for stable evaporation of high-salinity brine.