Plant-Mimetic Vertical-Channel Hydrogels for Synergistic Water Purification and Interfacial Water Evaporation

Abstract

The integration of renewable solar energy-driven interfacial evaporation and photocatalysis has recently emerged as one of the most promising technologies for simultaneous freshwater production and pollutant removal. However, the construction of an advanced integrated system with the merit of a fast supply of water and pollutant molecules remains challenging for efficient solar-driven evaporation and photocatalytic performance. Herein, inspired by the transpiration of plants, we fabricate a biomimetic, vertically channeled polypyrrole/foam-like carbon nitride/poly(vinyl alcohol) hydrogel (PCH) by directional freeze-drying. We prove that the vertically aligned channels not only reduce heat loss and improve energy conversion efficiency but also facilitate the transport of water and organic pollutants to the air−water interface. Benefiting from the advantages above, the PCH evaporator presents a high solar evaporation efficiency of 92.5%, with the evaporation rate achieving 2.27 kg m −2 h −1 under 1 kW m −2 irradiation, exceeding many advanced interfacial solar-driven evaporators. Meanwhile, PCH reaches a degradation efficiency of 90.6% within 1 h when dealing with tetracycline (a typical antibiotic)-polluted water, remarkably higher than that of the hydrogel without vertically aligned channels (68.6%). Furthermore, the as-formed reactive oxygen species effectively kill Grampositive and Gram-negative bacterial in the source water, achieving the all-round water purification. In an outdoor experiment, after 11 h of sunlight irradiation, the tetracycline degradation efficiency and freshwater production of the PCH evaporator rise to 99.0% and 6.2 kg m −2 , respectively. This work highlights the novel biomimetic approach to fabricate multifunctional photothermal materials for simultaneous freshwater production and polluted-water remediation.

A melanin-inspired robust aerogel for multifunctional water remediation

“…In particular, the emerging solar desalination strategy has been developed by locally heating up the water at the air/liquid interface to achieve efficient freshwater production. [8][9][10][11][12][13][14] Although solar desalination usually can effectively deal with seawater, contaminants such as oils, dyes, and heavy metal ions are prone to clog the water transportation channels of photothermal materials, thus reducing the water evaporation efficiency and even damaging the device. [15][16][17] Therefore, it is highly desirable to develop advanced photothermal materials with excellent multifunctional properties to treat multicomponent wastewater effectively.…”

Highly Efficient, Antibacterial, and Salt-Resistant Strategy Based on Carbon Black/Chitosan-Decorated Phase-Change Microcapsules for Solar-Powered Seawater Desalination

“…An evident decline in the concentrations of the four representative ions was observed from the clean water after seawater desalination using the developed evaporator (Figure a). Such low ion concentrations can satisfy the specific requirements of the World Health Organization (WHO) and U.S. Environmental Protection Agency (EPA) standards . The detection report for the water quality also exhibits extremely low concentrations of the volatile organic compounds (VOCs) and synthetic detergents as seen in Table S3 in the Supporting Information.…”

“…Such low ion concentrations can satisfy the specific requirements of the World Health Organization (WHO) and U.S. Environmental Protection Agency (EPA) standards. 39 The detection report for the water quality also exhibits extremely low concentrations of the volatile organic compounds (VOCs) and synthetic detergents as seen in Table S3 in the Supporting Information. Moreover, there is no coliform colony detected in the evaporated water.…”

MXene-decorated flexible Al2O3/TiO2 nanofibrous mats with self-adaptive stress dispersion towards multifunctional desalination

“…Since the double-layer structures are both hydrophilic, water may be quickly pushed through the microchannels and be used to generate steam efficiently. 36…”