Superhydrophilic carbon nanofiber membrane with a hierarchically macro/ meso porous structure for high performance solar steam generators

The utilization of solar energy for water evaporation to obtain fresh water shows potential applications in addressing water scarcity issues. It remains great challenges to develop light absorber materials with high photothermal conversion efficiency, large specific surface area and excellent corrosion resistance. Here, we demonstrate a hierarchically mesoporous and superhydrophilic carbon nanofiber membrane (CNF) based on the sublimation of the terephthalic acid from the polyacrylonitrile nanofibers during the calcination. The porous structure enhances the light absorption (94.2% in a broadband from 280 to 2500 nm). Furthermore, the mesopores in the individual CNF as well as the macropores in the membrane could not only significantly improve the interfacial evaporation area and the hydrophilicity but also reduce the thermal conductivity and hence the thermal lose. The porous membrane with hydrophilicity possesses good salt rejection performance. When used for interfacial solar water evaporation, the CNF membrane exhibits a high solar energy efficiency and evaporation rate of 89.5% and 1.36 kg m- 2 h-1 under one sun illumination, respectively. In addition, the superhydrophilic CNF membrane with excellent corrosive resistance can even be used for solar desalination of sea water containing acid or alkali and also the oil-in-saline water emulsions.

Automated summary

A highly efficient solar water evaporation technology has been developed using a porous carbon nanofiber membrane with high photothermal conversion efficiency, providing a stable production of fresh water under sunlight.