High-efficiency solar-driven water desalination using a thermally isolated plasmonic membrane

This study presents an experimental demonstration of a highly efficient solar-driven interfacial evaporation system for potable water production. The engineered evaporation system consist of a photothermal structure (plasmonic titanium nitride nanoparticles (TiN NPs) coated on a hydrophilic porous membrane), and a thermally insulating nano silica aerogel. During the solar-driven vapor generation test, a hydrophilic membrane functioned as a porous support and drew underlying water to the surface through its microporous channels; the TiN NPs coated on a membrane surface functioned as a photothermal layer and generated localized heat at the water–vapor interface upon light irradiation; and an aerogel mat positioned between the photothermal membrane and the underlying bulk water served as a thermally insulating barrier, to suppress parasitic heat dissipation. The results reveal that the optimized TiN photothermal membrane when tested in a thermally-insulated system, efficiently produced clean water at a rate of 1.34 kgm⁻²h⁻¹ that corresponds to a solar-thermal conversion efficiency of 84.5% under 1 sun. A superior efficiency of the system was primarily attributed to the broadband light absorption and superior light to heat conversion properties of plasmonic TiN NPs, as well as to the suppressed heat loss from the heated surface to the underlying water. It is believed that the application of TiN-membranes fabricated via a simple and scalable method presents a concrete step for solar-assisted off-grid desalination, particularly at remote locations with limited or no access to electricity.