Enhanced Interfacial Solar Evaporation through Formation of Micro-Meniscuses and Microdroplets to Reduce Evaporation Enthalpy

Interfacial solar water evaporation, a promising way to address water shortages and water pollution, has attracted increasing attention. However, low evaporation rates limit its practical applications. Reducing evaporation enthalpy is one of the most efficient ways to improve the evaporation rate. In this study, micro-meniscuses and microdroplets (MMDs) are found and observed on the surface of the polypyrrole nanoarrays on hydrophilic carbon cloth. The MMDs can reduce the evaporation enthalpy of the system, thus resulting in a high evaporation rate of 2.16 kg m(-2) h(-1) in pure water under 1 sun. Dynamic calculations imply that the evaporation rate of MMDs is approximately at least 1.7 times and 1.8 times that of a flat liquid film, respectively. Under 1 sun, the evaporators with MMDs enable stable evaporation in continuous 72 h in 10.0 wt% NaCl solution, simulated seawater, and actual wastewater, with an evaporation rate of 1.86, 1.99, and 1.82 kg m(-2) h(-1), respectively. As far as it is known, these evaporation rates are the highest reported values for the 2D interfacial solar evaporator in high-salinity brine or wastewater. It is believed that this work provided a novel pathway for designing an evaporator with low evaporation enthalpy and high evaporation performance.

Automated summary

Interfacial solar water evaporation is a promising way to address water shortages and pollution, but its low evaporation rate has limited practical applications. In this study, micro-meniscuses and microdroplets (MMDs) were found on the surface of polypyrrole nanoarrays, which significantly reduced the evaporation enthalpy and resulted in high evaporation rates even in high-salinity brine or wastewater.