Vapor Interface Research Articles

Silk-based polyelectrolyte evaporator with excellent salt resistance for high-rate and stable solar desalination

Solar-driven interfacial evaporation technology is a promising solution to solve global freshwater shortages through desalination. However, salt accumulation in the evaporator affects light absorption and reduces evaporation efficiency, thereby significantly reducing the service life and operating efficiency of the evaporator. Herein, we propose a strategy for sustainable salt resistance that enables strong salt resistance and rapid water delivery by in situ polymerization of sodium acrylate (PAAS) on the directional channel. As a result, the as-prepared SF/rGO@PAAS can achieve a high evaporation rate of up to 2.31 kg m−2 h−1 and high evaporation efficiency of up to 98% under one sun, benefiting from the inherent hydrophilicity of silk fibroin (SF), the directional channel design of water transport layer, and the efficient solar light absorption in full spectrum of reduced graphene oxide (rGO). More importantly, due to the electrostatic effect of PAAS, the evaporator showed excellent salt resistance, with no salt precipitation for 5 days of continuous evaporation in simulated seawater (3.5 wt%) while maintaining the high evaporation rate. This salt resistant evaporator provides an effective solution to the salt accumulation and addresses a key challenge in sustainable desalination.

Self-adaptive interfacial evaporation for high-efficiency photovoltaic panel cooling

Self-adaptive interfacial evaporation for high-efficiency photovoltaic panel cooling

Facile fabrication of superhydrophobic carbon-doped nanofibrous mat for solar-driven desalination

Recently, solar-driven localized heating interfacial evaporation for desalination has attracted much attention to draw freshwater from sewage or seawater. However, salt scaling resulted from concentration polarization, as well as the subsequently deterioration of evaporation rate and energy efficiency, are the major obstacles for the application of solar desalination. In this work, carbon-doped nanofibrous mat with photothermal and superhydrophobic properties were facilely fabricated via incorporation of activated carbon (AC) nanoparticles and hydrophobic modification with polydimethylsiloxane (PDMS). The obtained nanofibrous mat exhibited outstanding light absorption (> 93.0%), superhydrophobic characteristics (> 155°) and high porosity (> 82%). Solar-driven evaporation experiments demonstrated that evaporation rate of the nanofibrous mat reached up to 1.2kg·m-2·h-1 with energy efficiency of 82.1%. Moreover, crystal nucleation and growth on the superhydrophobic carbon-doped mat were dramatically suppressed, whose lifespan was prolonged from 4h to as long as 19h with near-saturated NaCl solution as the feedwater. Therefore, the fabricated superhydrophobic carbon-doped nanofibrous mat might find its applications in stable solar-driven evaporation for seawater desalination or wastewater reclamation.

Three birds with one stone: Constructing Janus multilayer carbon fabric to boost solar-driven interfacial evaporation, electrical power generation and inhibit VOCs volatilization

Solar-driven interfacial evaporation technology has great potential to address both the freshwater and energy crises in a low-cost, environmentally friendly, and sustainable method. How to achieve highly efficient freshwater and energy harvesting simultaneously is still challenging. Here, a Janus-structured multilayer carbon fabric (JMCF) solar evaporator is proposed to effectively overcome the bottleneck in the cogeneration of fresh water and electricity. The Janus structure of the multilayer fabric effectively controls water supply upwards, improves light absorption and photothermal conversion, increases evaporation surface area, facilitates water vapor escape and inhibits VOCs volatilization. Accordingly, the optimized JMCF solar evaporator can achieve a high evaporation rate of 3.12 kg m-2h−1 and an output voltage of 0.577 V in 3.5 wt% seawater under 1 sun irradiation. In addition, the JMCF evaporation system also demonstrates good working stability, self-cleaning capacity, environmental adaptability, and economic feasibility. This work provides new ideas and inspiration for the design of high efficiency solar-driven interfacial evaporation system to address the freshwater scarcity, energy crisis, global change problem, etc.

Hierarchical Ti3C2Tx MXene@Honeycomb nanocomposite with high energy efficiency for solar water desalination

The utilization of solar-driven interfacial evaporation holds immense promise in enhancing energy efficiency and establishing sustainable methods for seawater desalination and water purification. While designing the materials to achieve high evaporation efficiency, the tuning of materials with porosity and surface chemistry is very crucial. Novel sustainable materials are of great importance for solar water desalination applications since clean water production is utmost important in the current era. There exists a lack of exploration in modifying the surface wettability states of solar evaporators to expedite the vapor generation rates. In this study, we showcase a hydrophilic Ti3C2Tx MXene-coated carbonized honeycomb (CHC) (Ti3C2Tx MXene@CHC) nanocomposite-based hexagonal-shaped evaporator surface. This is the first-time report on the effective utilization of hierarchical CHC for the preparation of solar absorber comprising of Ti3C2Tx MXene@CHC nanocomposite, particularly for the solar water desalination. The Ti3C2Tx MXene@CHC nanocomposite evaporator achieves an impressive water evaporation rate of 1.6 kg m−2 h−1 with 90% efficiency under 1 sun illumination. The augmented thickness of the water layer in the hydrophilic surface of the Ti3C2Tx MXene@CHC nanocomposite helps in facilitating the rapid escape of water molecules. The relatively elongated contact lines in the hydrophobic region simultaneously ensure substantial water evaporation, significantly enhancing the water desalination process. The Ti3C2Tx MXene@CHC nanocomposite exceeds stringent quality benchmarks, signaling its potential for solar water desalination.

Advancing thermohydraulic performance of micro-grooved flat heat pipes through a combined numerical-experimental approach

A combined numerical-experimental model has been developed to predict the thermohydraulic characteristics of micro-grooved flat heat pipes (FHPs). This model uses a limited number of experimental data for calibration with two parameters, βexp,1 and βexp,2, which account for uncertainties in the accommodation coefficients used to determine evaporation and condensation mass fluxes. This calibration, which is a key feature of the developed model, addresses the uncertainties and challenges in determining these coefficients. Moreover, the model incorporates the effects of interfacial shear stress, axial wall conduction, heat transfer in the liquid block region, and the contact angle of the liquid–vapor interface. Furthermore, the evaporation mass flux from the curved liquid–vapor interface is calculated using a separate multiscale approach developed in two recent works for analyzing evaporation from the extended meniscus in microchannels, considering thin-film evaporation. The model demonstrates high accuracy in predicting the maximum heat transport capacity (Qmax) and wall temperature distribution across various input heat powers, with a maximum error of less than 0.5 % in wall temperature predictions, as validated against experimental data. The validated model is then used to explore a new micro-grooved wick structure featuring converging/diverging microchannels. In this structure, the channel width is constant and equal to Wf2 in the first half of the heat pipe, from the condenser end to the midpoint, and then it decreases or increases to Wf1 by the end of the evaporator section. Results indicate that a flat heat pipe with a converging micro-grooved wick structure (Wf1 = 200 µm and Wf2 = 160 µm) can enhance Qmax from 53 to 70 W, 70.8 to 91.8 W, and 91.2 to 116.5 W at working temperatures of 60 °C, 70 °C, and 80 °C, respectively. This means the new converging micro-grooved wick structure can boost flat heat pipe performance by more than 25 % compared to a flat heat pipe with a straight micro-grooved wick (Wf1 = Wf2 = 200 µm) without increasing the occupied space.

Polyzwitterionic hydrogel using waste biomass as solar absorbent for efficient evaporation in high salinity brine

Solar-driven interfacial vapor generation (SVG) is a promising strategy for brine purification. However, the effective combination of functional evaporator backbones and solar absorbers for SVG enhancement remains challenging in high-salinity brines (≥10 wt%). Herein, a biomass-based polyzwitterionic hydrogel (PZH) was developed to improve the SVG performances in 10 wt% brine. Zwitterions with specific anti-polyelectrolyte effects served as backbones for accelerating H2O transportation, with fewer salt deposits and macropore channels. The biomass of straw prepared at a pyrolysis temperature at 600 ℃ was the most effective solar absorber. The synthesis of So600-PZH-8mm yielded the optimal solar evaporator with a low evaporation enthalpy of 877.79 J·g−1, a remarkable solar-to-vapor energy efficiency of 87.1 %, and a high evaporation rate of 3.57 kg·m−2·h−1 under 1 sun irradiation and a relative humidity of 30 %. Multi-cycle evaporation tests further verified the high quality of the steam water, high salt resistance, reliability, and durability of So600-PZH-8mm in practical applications. Furthermore, density functional theory calculations of the binding energies of charged groups and ions verified the anti-polyelectrolyte effect and swelling behavior of the PZHs. Overall, this study demonstrated the effectiveness of waste biomass as solar absorber for high-efficiency solar adsorption and water activation, which opens a new perspective to inspire the up-conversion of waste biomass in more valuable and meaningful ways.

Bionic solar-Driven interfacial evaporator for synergistic photothermal-Photocatalytic activities and salt collection during desalination

Solar-driven interfacial evaporation plays an essential part in the production of potable water. Nevertheless, the intricate water conditions in real-world scenarios continue to pose limitations on its utilization. This study prepared a novel bionic PPy/BiVO4-PI/MXene aerogel composite material with radial center structure through directional freezing as the evaporator, which integrates both photothermal and photocatalytic properties into the evaporation system. In order to evaluate the efficacy of photocatalytic degradation and salt collection during interfacial evaporation, high-concentration saline water, simulated seawater and dyeing wastewater were employed as substitutes for real contaminated water bodies. After being exposed to 1 kW/m−2(−|-) of irradiation, the PPy/BiVO4-PI/MXene composite exhibits an evaporation rate of 1.64 kg m-2h−1 and achieves a photothermal efficiency of 96.77 %. In high-concentration saltwater containing 20 wt% NaCl, the PPy/BiVO4-PI/MXene exhibited an evaporation rate of 1.32 kg m-2h−1 and a photothermal conversion efficiency of 77.41 %. Furthermore, approximately 26.7 g of salt can be collected after 15 days’ continuous evaporation. Furthermore, the PPy/BiVO4-PI/MXene demonstrated exceptional photocatalytic capabilities to organic dyes such as MB, RhB, CR and MG with removal efficiencies of 79.28 %, 70.96 %, 76.70 % and 80.95 %, respectively. This study realizes the synergistic effect of interfacial evaporation, photocatalysis and salt collection, providing a highly promising choice for the treatment of high-salt dyeing wastewaters.

Exceeding the theoretical limit of interfacial evaporation efficiency by using the carbon-based aerogel evaporator with cold evaporation surface

Solar-driven interfacial evaporation technology has shown significant potential in the field of water treatment. Heat loss is still inevitable during the SIE process, since the temperature at the evaporation interface surpasses both the ambient temperature and the temperature of the water below. In this study, we presented a study on an aerogel composed of reduced graphene oxide (rGO), multi-walled carbon nanotubes (MWCNTs) and polypyrrole (PPy). The self-aggregation effect of rGO was mitigated through π-π interactions with MWCNTs and PPy, resulting in the formation of a three-dimensional porous structure. This provided the aerogel with a large specific surface area for pollutant adsorption and ample pore volume for photo-induced degradation and photothermal water purification. Using infrared thermography, thermocouples and numerical simulation, it was demonstrated that introducing a cold evaporation surface resulted in thermal flow reversal. This process allowed the evaporator to extract energy from bulk water, thereby enhancing solar evaporation. Due to this gain, under one sun illumination, the aerogel reached an evaporation rate as high as 3.31 kg·m−2·h−1 and achieved an evaporation efficiency of 135.6 %. Simultaneously, the aerogel exhibited a photocatalytic efficiency of over 90 % for various organic pollutants (methylene blue trihydrate, trypan blue and tetracycline hydrochloride). Moreover, it also demonstrated excellent purification ability for combined wastewater, including high-salinity water, seawater and lubricant/water emulsions. Therefore, high-performance interfacial evaporators hold great promise for achieving sustainable wastewater purification and serve as a valuable reference for the development of new solar energy conversion systems.

Nano-structured urchin-like photothermal covalent organic frameworks for efficient Solar-Driven interfacial water evaporation

Solar-driven interfacial water evaporation is a promising sustainable technology to alleviate the global energy crisis and clean water shortage. The design of advanced photothermal materials play the critical role to utilize photothermal heat for water evaporation. Covalent organic frameworks (COFs) as a new class of crystalline porous polymer semiconductor materials have been deemed as an ideal nanoscale platform for designing photothermal materials with notable features like highly ordered structures, porous open channels, and tunable structure and functionality. In this work, we focus on the regulation of the multi-scale structure of COFs and design hierarchically nano-structured photothermal COFs for efficient solar-driven interfacial water evaporation. At the molecular scale, we synthesize a photothermal functionalized COF-366-OH using photosensitive 5,10,15,20-tetrakis(4-aminophenyl) porphyrin (TAPP) and 2,5-dihydroxyterephthalaldehyde (DHTA) as building blocks. At the micro-nano scale, we introduce the π-conjugated catechol molecule 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) to regulate COF polycondensation and assembly, which enable the shaping of COF-366-OH into urchin-like nano-morphologies (namely UCOF-366-OH). The synthesized UCOF-366-OH exhibits high crystallinity, large surface area, excellent photothermal conversion capacity, and strong hydrophilicity. Furthermore, UCOF-366-OH is processed into a photothermal composite membrane. With localized solar heating and optimized water transport at the water evaporation interface, a high evaporation rate of 2.51 kg m−2h−1 with solar-to-vapor efficiency of 97.3 % is achieved. This work paves a new way for the multi-scale structural design of COF-based photothermal materials and highlights their innovative application in solar water evaporation.

Synergistic Effect Between 0D CQDs and 2D MXene to Enhance the Photothermal Conversion of Hydrogel Evaporators for Efficient Solar Water Evaporation, Photothermal Sensing and Electricity Generation.

Solar-powered interfacial water evaporation is a promising technique for alleviating freshwater stress. However, the evaporation performance of solar evaporators is still constrained by low photothermal conversion efficiency and high water evaporation enthalpy. Herein, 0D carbon quantum dots (CQDs) are combined with 2D MXene to serve as a hybrid photothermal material to enhance the light absorption and photothermal conversion ability, meanwhile sodium carboxymethyl cellulose (CMC)/polyacrylamide (PAM) hydrogels are used as a substrate material for water transport to reduce the enthalpy of water evaporation. The synergistic effect in 0D CQDs/2D MXene hybrid photothermal materials accelerate the carrier transfer, inducing efficient localized surface plasmon resonance (LSPR) effect. This results in the enhanced photothermal conversion efficiency. The integrated hydrogel evaporators demonstrate a high evaporation rate (1.93 and 2.86kgm-2h-1 under 1 and 2 sunlights, respectively) and low evaporation enthalpy (1485Jg-1). In addition, the hydrogel evaporators are applied for photothermal sensing and temperature difference power generation (TEG). The TEG device presents an efficient output power density (230.7mWm-2) under 1 sunlight. This work provides a feasible approach for regulating and controlling the evaporation performances of hydrogel evaporators, and gives a proof-of-concept for the design of multipurpose solar evaporation systems.

Photothermal/magnetothermal coupled polyphenylene sulfide composite membranes for ultra-efficient and continuous seawater desalination

As the population continues to expand and industrialization gathers pace, the rate at which freshwater resources are dwindling is alarming. Solar desalination technology has shown encouraging results in generating clean water. However, solar-driven interfacial evaporation technology still faces a series of major challenges, specifically manifested in its low efficiency, poor chemical stability, and the tendency for salt crystallization to accumulate on the evaporation surface during operation. In this work, we proposed a novel magneto/photo-thermal coupled evaporator based on polyphenylene sulfide (PPS) fibrous membrane, which showed excellent high temperature and corrosion resistance. This non-contact responsive interfacial evaporator exhibited outstanding photothermal and magnetothermal conversion performance properties. Under one solar illumination, the evaporation rate of this evaporator could reach 1.52 kg m−2 h−1, corresponding to an evaporation efficiency of 91.84 %. In addition, under a magnetic field power of 2 kW m−2, the evaporator could achieve a remarkable evaporation rate of 4.2 kg m−2 h−1 under one solar illumination, with an evaporation efficiency of up to 93.77 %. Moreover, it also exhibited superb salt resistance, great mechanical properties, long-term operational stability, and outstanding dye purification property. Furthermore, by integrating the thermoelectric generator with the evaporator and utilizing the waste heat from the evaporation process to generate electricity, the efficiency of energy utilization has been improved. The interfacial evaporator opens up vast prospects for efficient and rapid clean water production, demonstrating significant potential and advantages.

Energy and exergy analysis of a novel solar-powered passive multi-stage osmosis desalination system for sustainable water production

Climate change and population growth constantly exacerbate global water scarcity, and seawater desalination technology is crucial to addressing this crisis. Conventional fossil-fuel desalination poses environmental and economic challenges, especially in remote, water-scarce regions. Renewable energy offers sustainable options for seawater desalination; however, most related technologies face challenges in flexible deployment. Among passive technologies, interfacial evaporation still confronts issues of salt accumulation impacting desalination efficiency. Therefore, this study investigates a novel solar-powered passive multi-stage osmosis device that emulates mangroves’ transpiration and natural osmosis processes. Harnessing solar energy, it employs hydrophilic nanoporous membranes for water movement and evaporation and an osmosis membrane for solute retention, aiming for efficient seawater desalination without external power and pressure. Energy and exergy analyses reveal key efficiency factors. Results reveal significant pressure gradients across the osmosis membrane as a challenge. Optimizing salinity and adjusting the area ratio of the nanoporous membrane to the osmosis membrane is vital for stability and performance. Moreover, potential increases in water production from 0.97 kg/m2/h to 3.53 kg/m2/h with a five-stage setup, though benefits diminish with additional stages due to heat/exergy losses. The exergy efficiency increases from 0.14 % for a five-stage device to 0.18 % for a ten-stage system. This study demonstrates the solar-powered passive multi-stage osmosis device’s dependence on solar flux and highlights the importance of optimizing the air gap thickness and insulation to boost efficiency.

Fe-MOF derived Fe3O4/C-based hydrogel for efficient solar-driven photothermal evaporation

Solar-driven interfacial photothermal evaporation (SIPE) has been considered as a green and sustainable technology for obtaining fresh water, and the exploring efficient photothermal materials is crucial. Nanocomposite derived from metal-organic framework exhibits high light absorption properties and excellent chemical stability, making it an ideal candidate in the SIPE. Herein, Fe3O4/C nanocomposite was obtained using MIL-101 (Fe) as a precursor, and Fe3O4/C-based porous hydrogel (Fe3O4/C-PH) was subsequently prepared through chemical crosslinking foaming polymerization. The obtained Fe3O4/C-PH exhibited an evaporation rate of 3.33 kg m−2 h−1 under one sun intensity. Fe3O4/C-PH demonstrated outstanding desalination and salting out resistance when treating real seawater. Moreover, it could remove over 99 % of dyes from wastewater. The photothermal mechanisms are molecular thermal vibration of C component and semiconductor relaxation of Fe3O4. Meanwhile, the hydrophilic and porous skeleton structure of the hydrogel ensure Fe3O4/C-PH to transport water rapidly and exhibit good light absorption properties. This research broadens the candidate of photothermal materials for applications in SIPE, and also provides new avenues for desalination and wastewater purification.

Salt-resistant MXene-charge gradient hydrogel evaporator with boosted water transport for efficient photothermal desalination

Solar interfacial evaporation represents a highly promising approach for generating potable water from seawater utilizing clean, abundant, and sustainable solar energy. MXene-based materials exhibit outstanding photothermal conversion in desalination applications but face challenges in water transport and salt removal. Here, we introduce an effective MXene-charge gradient hydrogel (MCGH) evaporator that leverages the Donnan effect for salt rejection and internal osmotic pressure for water conveyance. The MCGH evaporator achieved 3.1 kg m−2 h−1 evaporation rate in 3.5 wt% NaCl under 1 sun irradiation. It also operates effectively in concentrated brines, reaching a notable 2.1 kg m−2 h−1 evaporation rate in 20 wt% NaCl solutions. This work introduces a new approach for salt-tolerant MXene photothermal evaporators, holding great promise for sustainable solar desalination applications.

Numerical and experimental investigation of floating wick solar still with a porous-media system

Wick-based solar desalination and solar-driven interfacial evaporation have attracted significant attention for their high efficiency in evaporation and salt removal. This study presents both experimental and numerical models for wick solar desalination. Cotton fabric, coated with black carbon for enhanced radiation absorption, was used as the evaporation medium in experiments due to its superior desalination, capillary, and salt rejection properties. Experimental results showed an evaporation rate of 1.57 kg/m2·h and efficiency of 81 % with freshwater. For saltwater (3.6 % salinity), the evaporation rate and efficiency were 1.24 kg/m2·h and 71 %, under 1000 W/m2 radiation. After validating the numerical model, the effects of porosity, capillary pressure, wick thickness, and thickness of the fabric’s upper (solar absorber) layer were examined. Results showed that reducing the solar absorber fabric thickness (from 9 mm to 0.6 mm), lowering porosity (from 0.97 to 0.3), and increasing wick thickness (from 1.5 mm to 10.5 mm) improved evaporation rates by 58.6 %, 27 %, and 28.4 %, respectively. Capillary pressure and fabric submerged length had minimal effects on evaporation. The model estimates that in real conditions at Jask coastal port (Iran), a configuration with greater wick thickness (6 mm vs. 3 mm), reduced solar absorber fabric thickness (1 mm vs. 1.5 mm), and lower porosity (0.75 vs. 0.93) could increase annual freshwater output by 26.6 % (from 796.6 to 1008.4 kg/m2). The cost per liter of produced water in the best-case scenario is estimated to be $0.0045.

3D printed degradable hydrogel evaporator for high-efficiency, environmental-friendly solar alkaline-water evaporation

Solar evaporation is a simple, cost-effective method for producing clean water that does not require complex infrastructure and fossil energy. Although there have been significant advances in hydrogel solar evaporators, their widespread applications are still hampered by challenges related to customizing the structures to optimize solar evaporation rates and managing the pollution associated with waste hydrogel evaporators. To address these issues, we construct a customizable in structure, highly efficient and degradable interfacial solar evaporator using three-dimensional (3D) printing technique. The complex 3D microstructures can significantly enhance sunlight absorption through multiple surface reflections and anti-reflection effects, which can achieve customized evaporation performance. The optimized tree-shaped hydrogel evaporators can achieve a high evaporation rate of 2.41 kg m–2 h−1 under 1 sun. Importantly, the hydrogel evaporators exhibit degradation properties in alkaline liquids. These components can be integrated into the environment, reducing their impact on the environment and achieving sustainable utilization, offering a promising solution for alkaline wastewater purification and demonstrating the potential of environmental-friendly solar evaporator technology.

Correlation effect between the capillary flow and evaporation rate of water in a 2-D photothermal membrane

To shed light on the correlation effect between the capillary flow and phase transition of water in photothermal evaporation, the non-equilibrium molecular dynamics (NEMD) simulations were employed to investigate the evaporation of water in Multilayered graphene oxide membranes. It was initially found that water molecules need to overcome strong energy barriers to migrate upward by layers before evaporation, with the energy barrier increasing with the reduction in nanogap, hydroxyl content, or increase in layer spacing of graphene sheets. The strong energy barrier accordingly results in dramatic sensible heat conversion and high evaporation temperature. It was shown that the enhanced temperature and hydrophilicity both weaken the hydrogen bond strength of water molecules confined in 2-dimensional channels, contributing to the reduced evaporation enthalpy. The preferential pathways in graphene channels or the weakened hydrogen bonds in hydroxyl-functionalized graphene of water molecules were found to be important influences on capillary flow energy consumption, leading to differences in evaporation energy supply. In combination with these effects, the evaporation rate could be increased by up to 2 folds and an interfacial enthalpy of evaporation below 1500 kJ kg−1 could be achieved by properly tuning the configuration and chemical properties of the graphene membrane. Our findings lay a theoretical foundation for providing a strategy to improve the interfacial evaporation performance in desalination.

High-efficiency electrospun PVDF@MXene composite membrane with covalent bonding and well-dispersed internal materials for solar-driven seawater desalination

Environmentally friendly and efficient solar-driven interfacial evaporation (SDIE) has been increasingly applied to seawater desalination, and the easy-to-operate electrospinning technology has attracted more and more attention. However, photothermal materials such as MXene are often combined with polymers suitable for spinning through ordinary blending. The inherent difficult dispersion of it may lead to the instability of spinning and decrease the performance of evaporators, further hindering their production and application. To address these challenges, this work designs a covalent bonding PVDF@MXene composite as the spinning raw material. Using the electrospinning technology, the high-efficiency membrane-based evaporator with well-dispersed internal materials and strong homogeneity is successfully fabricated. The membrane performance is optimal when the MXene content is 25 %, achieving an evaporation rate of 1.88 kg·m−2·h−1 and an efficiency of 94.06 % under one sun. Besides, it exhibits remarkable salt resistance, maintaining an evaporation rate of 1.81 kg·m−2·h−1 even at the salinity of up to 20 wt%. More importantly, the membrane can be immersed in oxidative reagents for 24 h without degradation or reduced performance, demonstrating its good environmental stability. Overall, this research not only provides a rational idea for addressing the dispersion issue of MXene, but also presents a potential solution to deal with the global freshwater shortage emergency.

Interfacial solar‐driven steam and electricity co‐generation using Hydrangea‐like graphene by salt‐assisted carbonization of waste polylactic acid

AbstractThe interfacial solar steam generation and water evaporation–driven power generation are regarded as promising strategies to address energy crisis. However, it remains challenging to construct low‐cost evaporators for freshwater and electricity co‐generation. Herein, we report a salt‐assisted carbonization strategy of waste polylactic acid to prepare Hydrangea flower–like graphene and build a bi‐functional graphene‐based evaporator. The evaporator presents merits of good sunlight absorption, photo‐to‐thermal conversion property, water transport, good thermal management capability, and negatively charged pores for the continuous diffusion of ions. Hence, it achieves the evaporation rate of 3.0 kg m−2 h−1 and output voltage of 0.425 V, surpassing many advanced evaporators/generators. Molecular dynamics simulation result proves that more Na+ ions are attracted by functional groups, especially –COOH/C–OH, to promote Na+ selectivity in nanochannels. This work offers new opportunities to construct multifunctional evaporators for freshwater and electricity co‐generation.