Four-birds-with-one-stone: A multifunctional Ti-based material for solar-driven water evaporation

Sustainable, environmentally friendly and low-energy desalination materials have important research value for the increasing demand of freshwater year by year. However, it is a huge challenge to maintain high heat energy transfer efficiency without reducing the heat conversion capacity of specific solar photothermal conversion materials. Moreover, their efficiency and durability are greatly limited by the problems of seawater corrosion, oil, and bacteria pollutions. Till now, no related work has been reported to solve all the aforementioned problems via a simple four-birds-with-one-stone strategy. Herein, a class of multifunctional porous photothermal silver (Ag) modified Ti foams (Tf-TA/Ag series materials) is prepared for the development of advanced solar water evaporation devices, and provides alternative materials for alleviating freshwater crisis and treating sewage. The oil contact angle (OCA) changes from 41° to 180°, which significantly reduces the adhesion of oil. In addition, Tf-TA2/Ag sample also shows an excellent and sustained antibacterial effect, which maintains above 99.9% of antibacterial rate after repeated 5 times. The surface temperature of the Tf-TA2/Ag sample reaches 52.5 °C after simulated sun irradiation for 20 min, which is significantly higher than that of the contact groups (water: 36.4 °C, Ti foam: 38.2 °C and Tf-TA2: 40.9 °C). The capacity of seawater evaporation and salt removal is enhanced due to the excellent photothermal properties, low reflectance, and uniform heat dissipation pores. The water production efficiency of Tf-TA2/Ag sample is 1.41 kg·m⁻²·h⁻¹ in artificial seawater and 0.76 kg·m⁻²·h⁻¹ in oily sewage under simulated sun irradiation. Furthermore, the hydrophilic and oleophobic properties of Tf-TA2/Ag are critical to extracting water from oil/water mixture in diverse water environments. Ultimately, this four-birds-with-one-stone approach provides a new perspective for the improvement of solar seawater desalination performance.