Superior solar water purification achieved by the excellent photothermal conversion and thermal management of porous plasmonic TiN nanoparticles

Abstract

Solar photothermal steam generation promises decentralized water purification, but the lack of materials that have strong sunlight absorption in wide spectral range, superior thermal management, large specific surface area as well as good water wettability limits the overall solar water purification efficiency. Herein, porous TiN nanospheres are prepared for solar water purification. The monodispersed porous TiN nanospheres are prepared through the wet-chemistry synthesis of TiO2 and followed nitridation. The prepared porous TiN nanospheres have relatively large specific surface area and very good hydrophilicity. In comparison with solid TiN nanospheres, the porous counterparts have stronger light absorption and better thermal management. The optimum solar evaporation film prepared with the porous TiN nanospheres and filter membrane (TiN/FM) exhibits a reflectance smaller than ∼ 19% in the entire solar spectrum. All these merits of the porous TiN nanospheres give rise to a water evaporation rate of 1.68 kg m-2 h−1 and a solar-steam conversion efficiency of 93.4% under AM 1.5 irradiation. Both seawater and polluted water can be purified to potable water with TiN/FM. Our work not only provides a preparation approach for monodispersed porous TiN nanospheres but also demonstrates the great potential of porous plasmonic nanoparticles for the future development of solar water purification.