Highly efficient solar vapour generation via self-floating three-dimensional Ti2O3-based aerogels

To reduce the shortage of water resources, solar-driven water evaporation is considered as a sustainable solution. High efficiency solar steam generation (SSG) with the good light absorption, sufficient water transmission, high thermal management and freely floating photothermal materials is highly desirable. Herein, a simple solar desalination strategy was proposed and a new type three-dimensional Ti2O3-based aerogel with high porosity and low thermal conductivity was prepared. In short, polydopamine (PDA)-modified Ti2O3 nanoparticles were uniformly dispersed in chitosan (CS) solution and a porous Ti2O3-based aerogel was formed after freeze-drying. The evaporation rate of this solar steam generator is as high as 1.31 kg m−2 h−1 at 1.0 solar irradiance (1.0 kW m−2), and the photothermal conversion efficiency is about 81.7%. The optical absorption at 250–2500 nm was 94.49%. In addition, the aerogel has a porosity of 97.50% and a density of 0.025 g cm−3, making it freely float on the surface of water. Besides, its thermal conductivity is 0.037 W m−1 K−1, indicating it has excellent thermal insulation performance. The porous Ti2O3-based aerogel can maintain stable evaporation rate and high evaporation efficiency after 10 repeated evaporation cycles. Additionally, the seawater after desalination was tested and the removal rates of ions and carbon-containing organic matter reached 99.80% and 75.45%, respectively. Therefore, the interfacial water evaporator prepared in this work has excellent photothermal conversion ability and is expected to be a candidate material for solar seawater desalination.