Slide-shaped cotton-based photocatalytic solar evaporator with dual mutually strengthening functions for simultaneous desalination and dynamic fast dye removal.

High-salt dyeing wastewater would do harm to both the environment and people's health. Herein, a photocatalytic solar evaporator with bifunctions of photothermal evaporation and photocatalysis was prepared by loading MnO 2 and TiO 2 on the cotton fabric, aiming at simultaneous pure water derivation and dye degradation. The evaporator was positioned in a slide-shaped configuration that uses downward capillary force and gravity-assisted water transportation for a sufficient water supply, avoiding salt accumulation during photothermal evaporation and realizing a fast dynamic dye removal via photocatalysis. Interestingly, the loaded TiO 2 enhances the photothermal activity of the loaded MnO 2 by increasing light absorption. While MnO 2 also enhances the photocatalytic activity of TiO 2 by charge transfer and heat generation. It was exciting to find that the solution streaming down dynamically through the slide-shaped evaporator into the downstream container was completely colorless, which was in sharp contrast with the blue dye solution at the upstream. Under one sunlight, the evaporator showed a evaporation rate of 1.65 kg m−2 h−1, a photothermal conversion efficiency of 96.65 % and a methylene blue removal efficiency of >95 % during the 8-day evaporation. This study realizes the synergistic effect of photothermal evaporation and photocatalysis, providing a novel strategy for the treatment of high-salt dyeing wastewaters. [Display omitted] • Slide-shaped cotton-based photocatalytic solar evaporator with MnO 2 and TiO 2 for simultaneous desalination and dye removal • TiO 2 strengthened by MnO 2 in photocatalytic activity via charge transfer and heat generation • MnO 2 strengthened by TiO 2 in photothermal evaporation via enhanced light absorption • Zero salt aggregation via capillary effect and gravity-assisted water supply in a slide-shaped structure • Fast dynamic degradation of the dye solution flowing through the slide-shaped evaporator during solar evaporation [ABSTRACT FROM AUTHOR]