Flexible and Highly Efficient Bilayer Photothermal Paper for Water Desalination and Purification: Self-Floating, Rapid Water Transport, and Localized Heat.

TiN nanoparticles/OMS-2 nanorods/carbonized wood composites for simultaneous solar water evaporation and abatement of volatile organic compound from undrinkable water

As a sustainable and clean water production technology, solar thermal water evaporation has been extensively studied in the past few years. One challenge is that upon operation, salt would form on surface of the solar absorbers leading to inefficient water supply and light absorption and thus much reduced water vaporization rate. To address this problem, a simple solar evaporator based on an array of aligned millineedles for efficient solar water evaporation and controlled site-specific salt formation is demonstrated. The maximum solar evaporation rate achieved is 2.94kg m-2 h-1 under one Sun irradiation in brine of high salinity (25wt% NaCl), achieving energy conversion efficiency of 94.5% simultaneously. More importantly, the spontaneously site-specific salt formation on the tips of millineedles endows this solar evaporator with salt harvesting capacity. Rationally separating the clean water and salt from brine by condensation and gravity assistance, this tip-preferential crystallization solar evaporator is not affected by the salt clogging compared with conventional 2D solar evaporators. This study provides new insights on the design of solar evaporators and advances their applications in sustainable seawater desalination and wastewater management.

An efficient solar water evaporator is an important strategy for addressing the problem of water shortage. Constructing high-performance solar interfacial evaporators through bionic design has become a crucial approach for performance enhancement. Through the study of zebra patterns, it has been found that the black-and-white alternating patterns generate vortices on the surface of the zebra's skin, thereby reducing the temperature. By utilizing the vortices brought about by the temperature difference, the design of a solar water evaporator is created based on the bionic zebra pattern, so as to improve its water evaporation performance. In this work, green and sustainable wood is used as the base of the evaporator, and the bionic design of zebra stripes is adopted. Meanwhile, the following research is conducted: The wood is cut into thin slices with dimensions of 30 × 30 × 5 mm3, and a delignification treatment is performed. Tannic acid-Fe ions are used as the photothermal material for functionalization. A series of stable patterned water evaporators based on delignification wood loaded with tannic acid-Fe ion complex (TA-Fe3+) are successfully prepared. Among them, the wood-based solar water evaporator with 3 mm zebra stripes exhibits excellent photothermal water evaporation performance, achieving a water evaporation rate of 1.44 kg·m-2·h-1 under the illumination intensity of one sun. Its water evaporation performance is significantly superior to that of other coating patterns, proving that the bionic design of zebra patterns is effective and can improve water evaporation efficiency. This work provides new insights into the development of safe and environmentally friendly solar interfacial water evaporation materials through bionic design.

Solar energy-driven water evaporation is a promising sustainable strategy to purify seawater and contaminated water. However, developing solar evaporators with high water evaporation rates and excellent salt resistance still faces a great challenge. Herein, inspired by the long-range ordered structure and water transportation capability of lotus stem, a biomimetic aerogel with vertically ordered channels and low water evaporation enthalpy for high-efficiency solar energy-driven salt-resistant seawater desalination and wastewater purification is developed. The biomimetic aerogel consists of ultralong hydroxyapatite nanowires as heat-insulating skeletons, polydopamine-modified MXene as a photothermal material with broadband sunlight absorption and high photothermal conversion efficiency, polyacrylamide, and polyvinyl alcohol as reagents to lower the water evaporation enthalpy and as glues to enhance the mechanical performance. The honeycomb porous structure, unidirectionally aligned microchannels, and nanowire/nanosheet/polymer pore wall endow the biomimetic aerogel with excellent mechanical properties, rapid water transportation, and excellent solar water evaporation performance. The biomimetic aerogel exhibits a high water evaporation rate (2.62kgm-2 h-1 ) and energy efficiency (93.6%) under one sun irradiation. The superior salt-rejecting ability of the designed water evaporator enables stable and continuous seawater desalination, which is promising for application in water purification to mitigate the global water crisis.

Nitrogen-doped graphene quantum dots hydrogels for highly efficient solar steam generation

Duckweeds mimicked self-clean Janus solar evaporator

Janus Co@C/NCNT photothermal membrane with multiple optical absorption for highly efficient solar water evaporation and wastewater purification

Sandwich-type absorber for synergistically enhanced solar water evaporation and photocatalysis

Salt-rejecting 3D cone flowing evaporator based on bilayer photothermal paper for high-performance solar seawater desalination

Highly efficient solar water evaporation of TiO2@TiN hyperbranched nanowires-carbonized wood hierarchical photothermal conversion material

Hierarchically porous nickel foam supported Co-NCNT arrays for efficient solar water evaporation, wastewater purification and electricity generation

Solar water evaporation, which can be utilized for seawater desalination and wastewater treatment, promises freshwater security with renewable energy. Herein, a bionic solar evaporator consisting of a hydrogel solar absorber and bionic microchannels fabricated by the projection microstereolithography based 3D printing technique is proposed. Such a bioinspired solar evaporator achieves a fast water self‐transport speed and a high solar water evaporation rate of 4.12 kg·m−2·h−1 under 1 sun irradiation (1 kW·m−2), and the solar thermal efficiency can be as high as 92.1%. However, both the evaporation rate and solar thermal efficiency are greatly affected by properties of the hydrogel, geometric parameters of microchannels, and intensity of the light source. Most significantly, the bionic solar evaporator is applied for wastewater treatment including the purification of organic dyes, acid and alkali, as well as metal ions. The purification rate can be as high as 99.999%, demonstrating amazing performance for clean water production. The bioinspired water evaporator promises applications for solar energy harvesting, photothermal conversion, as well as environmental engineering, such as solar vapor generation, thermophotovoltaic cell, sewage disposal, and desalination of seawater.

Wastewater accounts for a large part of the water body on the earth. Solar water evaporation is an effective way to produce fresh water from seawater or polluted water. However, the co-evaporation or deposition of contaminants may reduce the efficiency and freshwater quality during water evaporation. In this work, a self-cleaning solar water evaporator is developed based on the natural lignocellulose fibers (NCF), polyaniline (PANI), and TiO2, which shows great advantages of wide-range light absorption, super hydrophilicity, and low thermal conductivity. Nanofibrous PANI is polymerized on the surface of NCF to form a mesoporous network by adding the NCF to the polymerization solution. P25 TiO2 nanoparticles as photocatalysts are dispersed into the above reaction to form the hybrid PANI/TiO2/NCF composite disc by simply filtration. Owing to the synergistic effect between the photothermal PANI and the photocatalytic degradation of TiO2 nanoparticles in the solar water evaporator device, the water evaporation rate can reach 2.36 kg m−2 h−1 (under 1 sun irradiation), and the contaminant (100 ppm tetracycline) can be efficiently degraded. Interestingly, the solar water evaporator device still maintains a constant solar evaporation rate after working for 10 h, and no contaminant is accumulated. The bifunctional solar water evaporation device, which combines photocatalytic and photothermal effects, has great potential application in organic contaminant water with a self-cleaning effect.

The scarcity of fresh water is a pressing issue globally, and solar water evaporation technology has emerged as a leading method for producing fresh water. However, the preparation of solar evaporators is hindered by high costs, complexity, and environmental concerns. In this work, a solar evaporator with hierarchical porous structure is prepared using a simple, low‐cost, and environmentally friendly dissolution manufacturing strategy. Excellent photothermal conversion capability and salt drainage performance are found owing to its hierarchical porous structure. The prepared sample exhibits a water evaporation rate of 2.19 kg m−2 h−1 and achieves evaporation efficiency of 84.3% under one sun. Furthermore, the evaporation rates of the samples in seawater and methylene blue are 2.04, and 1.98 kg m−2 h−1, respectively. The evaporation rate remains stable after ten evaporation cycles. The strategy also overcomes the dimensional limitations of traditional methods, as large‐size samples prepared by this strategy are successfully evaluated for evaporation experiments with natural seawater under sunny weather, and the quantity of water collected is ≈170 g in 6 h. The proposed strategy will offer not only sustainable water purification technologies, but also new routes for solar water evaporation, solar steam generation, and photothermal drive fields.

Solar water evaporation is considered one of the most sustainable and environmentally friendly technologies. To achieve good evaporation performance, a combination of materials with good photothermal conversion efficiency and good evaporation structure is required. In this study, we used carbon nanodots as a photothermal material made that synthesis by hydrothermal of urea and citric acid. At the same time, luffa possessing advantages such as good water transport and easy attachment of carbon nanodots was chosen as the evaporation structure. The results showed that carbon nanodots material had an average size of less than 5 nm and a good absorption range in the wavelength of 200-800 nm. The absorption range of the material has expanded to the near-infrared region (NIR region), increasing the ability to absorb sunlight and convert it into heat energy, subsequently, improving the evaporation efficiency. The carbon nanodots/ luffa composite structure showed a high evaporation rate of 1.25 kg.m-2h -1 under 1 sun irradiation (1 kW.m-2).