Scalable and low-cost synthesis of black amorphous Al-Ti-O nanostructure for high-efficient photothermal desalination

Abstract Sunlight provides us with enough renewable energy resource being potentially converted into heat for steam generation, residential water heating, desalination, and wastewater treatment, while the exploration of low-cost but high-efficiency photothermal materials still remains a grand challenge. We here reported a new Al-Ti-O nanostructure with tunable colors from gray to black, which couples the features of plasmonic effects in Al nanoparticles and high photoactivity in black TiO 2 , enabling the optimized black Al-Ti-O nanostructure shows a broad light absorption capability with almost covering 90.32% of solar spectrum. Inspiringly, the black Al-Ti-O hybrid were assembled into a microporous membrane that can naturally float on the surface of water for photothermal desalination application, manifesting a high efficiency of 77.52% for desalination under simulated solar light irradiance, as well as an outstanding durability upon continuous running. A solar seawater desalination system was designed and manufactured to demonstrate its potential for practical application, which can produce purified water with a rate of ~ 0.50 kg m −2  h −1 , or ~ 4 L m −2  day −1 , given that the effective sunshine time is 8 h per day under current solar irradiation (~ 820 W m −2 ). The numerous advantages in the present black Al-Ti-O hybrid, including high photothermal efficiency, viable scalable synthesis, and low cost, may build step stone for commercial solar desalination application.