Janus Poly(Vinylidene Fluoride) Membranes with Penetrative Pores for Photothermal Desalination.Solar-driven desalination has been considered as a promising technology for producing clean water through an abundant and pollution-free energy source.  It is a critical challenge to reasonably design the porous morphology and the thermal management of photothermal membranes for enabling efficient energy conversion and water production.  In this work, a Janus poly(vinylidene fluoride) membrane was fabricated in combination of penetrative pore structure, asymmetric surface wettability with proper thermal management for high-efficiency solar desalination.  The unique feature of hydrophobic upper layer/hydrophilic lower layer enables the photothermal membranes to self-float on the water surface and rapidly pump water from the bulk to the surface.  The resulting Janus membrane exhibits a satisfactory light absorbance as high as 97% and a photothermal conversion efficiency of 62.8% under one-sun irradiation in a direct contact mode.  The solar-to-vapor efficiency rises up to 90.2% with the assistance of a thermal insulator adopted beneath.  Therefore, Janus membranes with directly penetrative pores and photothermal surfaces shine a light on the development of high-performance solar evaporators for the practical application in solar seawater desalination.
THERM