Solar-driven Interfacial Evaporation Research Articles

Large-area, low-cost, highly durable solar evaporators for sustainable solarizing seawater

Conventional solarizing seawater technology faces significant challenges including a large footprint, time-consuming processes, and inefficient energy utilization. Solar-driven interfacial water evaporation (SIWE) technology, offers a promising approach for sustainable solarizing seawater, facilitating the production of solid salt with reduced time and land requirements. Nevertheless, the urgent challenge lies in the development of low-cost, large-area solar evaporators that are highly salt-resistant and adaptable, enabling efficient and sustainable solar desalination for solid salt production. As such, a large-area, affordable, and highly durable melamine foam/reduced graphene oxide/sodium alginate (MGS) solar evaporator is proposed for continuous solarizing seawater using a simple method of “immersion-crosslinking-reduction”. Among them, hydrophilic melamine foam serves as the supportive framework, immersed with graphene as light absorption material, and hydrophilic sodium alginate polymeric network for fixing graphene sheets and regulating water evaporation enthalpy. As such, MGS solar evaporator can be prepared in a large-area of 0.5 m × 0.5 m at the cost prices as low as $2.91 m−2. The optimized MGS solar evaporator achieves a high water evaporation rate of 2.30 kg m−2h−1 with the photothermal conversion efficiency of 89.2 % under one sun irradiation. In outdoor environments, MGS allows for timely convective/diffusive salt discharge through its macropores, thus allowing for prolonged seawater solarization without obvious solid salt accumulation. Notably, the original seawater can be highly concentrated until all the water evaporates and solid salt precipitates. This developed MGS solar evaporator offers a novel perspective on efficient seawater solarization, conserving both time and land.

Multifunctional MoS2 membrane for integrated solar-driven water evaporation and water purification

Solar-driven interfacial water evaporation shows great potential to address the global water crisis, but its efficient implementation in the presence of organic wastewater remains challenging. Here, we achieved integrated water evaporation and organic compound degradation by designing a multifunctional MoS2 membrane. Under 1.0 sun irradiation, the membrane exhibits an evaporation rate of 2.07 kg m−2 h−1 and 82% degradation efficiency of organic pollutants, with negligible organic pollutant residues in the condensate. The high performance is attributed to the thermal energy generated by the evaporation process of MoS2 membrane. This promotes an increase in the rate constant of interfacial electron transfer during the photocatalytic reaction, accelerating the generation of free radicals and facilitating the removal of organic pollutants. The study demonstrated that fresh water can be collected from high-salinity wastewater at a rate of 1.56 kg m−2 h−1. The MoS2 membrane provides a sustainable approach to addressing the water crisis.

Versatile GO/ANFs Aerogel for Highly Efficient Solar-Powered Water Purification in Wide Environments.

Solar-driven interfacial evaporation is a very promising choice for producing clean water. Despite the considerable investigation of pure NaCl brine purification, solar-driven complex water purification, such as real-world seawater desalination as well as domestic and industrial wastewater treatment, has rarely been investigated, mainly due to its compositions being much more complicated than NaCl brine. Herein, we developed a graphene oxide/aramid nanofiber (GO/ANFs) aerogel by a freeze-drying process. The GO/ANFs aerogel combined opened porous microchannels, superhydrophilicity, anti-oil-fouling capacity, enhanced broad-spectrum light absorption (more than 92%), and good solar/heat management. These integrated properties enabled the GO/ANFs aerogel to be an advanced solar interfacial evaporator for efficient freshwater production with the characteristics of localized heat conversion, quick water transport, and salt crystallization inhibition, and the rate of steam production rate was as high as 2.25 kg m-2 h-1 upon exposure to 1 solar irradiation. Importantly, the high-water-vapor generation rate was maintained even under complicated conditions, including real-world seawater, dye water, emulsions, and corrosive liquid environments. Considering its promising adaptability to a wide range of environments, this work hopes to inspire the development of brine desalination, wastewater purification, clean water production, and solar energy utilization.

Facile preparation of a novel basalt fiber fabric-based photothermal material for high salinity wastewater treatment and solar interface evaporation

Solar-driven interfacial evaporation (SIE) is a sustainable, efficient, and environmentally friendly desalination technology. It has great potential for solving the shortage of clean water and environmental pollution that humanity faces. Nevertheless, low strength, inadequate efficiency, and complicated preparation process of photothermal materials continue to be primary barriers to achieving the widespread application of SIE technology. Therefore, in the present work, a low-cost and eco-friendly photothermal material was prepared successfully by using multi-walled carbon nanotubes (MWCNTs), sodium alginate (SA) hydrogel, and basalt fiber (BF) fabric for obtaining purified/drinking water from seawater/brackish water. The results indicated that newly developed MWCNTs-SA/BF fabric had better wettability, evaporation performance, and purification capability. The evaporation rate of MWCNTs-SA/BF evaporator using simulated high salinity seawater could reach 1.48 kg m−2h−1 and 2.5 kg m−2h−1, under 1 and 2 suns illumination, respectively, and solar energy utilization efficiency is 91.6 % under 1 sun irradiation. Additionally, cyclic evaporation test results show that fabrics are highly durable for long-term solar evaporation. Furthermore, an excellent water purification performance of MWCNTs-SA/BF fabrics was also demonstrated by evaluating the purity of water samples and determining the changes in the four major ions (Na+, K+, Ca2+, and Mg2+) in seawater before and after evaporation experiments. This work provides a simple, practical, and economical approach to preparing a novel BF fabric-based evaporator that utilizes abundant solar energy potential for large-scale desalination and wastewater treatment.

3-aminopropyltriethoxysilane modified MXene on three-dimensional nonwoven fiber substrates for low-cost, stable, and efficient solar-driven interfacial evaporation desalination

Recently, the solar-driven interfacial evaporation desalination has attracted more and more attentions due to the advantages of low cost, zero energy consumption, and high water purification rate, etc. One of the bottlenecks of this emerging technique lies in a lack of simple and low-cost ways to construct three-dimensional (3D) hierarchical microstructures for photothermal membranes. To this end, a two-step strategy is carried out by combining surface functionalization with substrate engineering. Firstly, a silane coupling agent 3-aminopropyltriethoxysilane (APTES) is grafted onto an ideal photothermal material of Ti3C2Tx MXene, to improve the nanochannel sizes and hydrophilicity, which are attributed to enlarged interspaces of MXene and introduced hydrophilic group e.g., –NH2 and –OH, respectively. Secondly, a low-cost and robust nonwoven fiber (NWF) substrate, which has a 3D micron-sized mesh structure with interlaced fiber stacks, is employed as the skeleton to load enough APTES-grafted MXene by a simple soaking method. Benefited from above design, the Ti3C2Tx-APTES/NWF composite membrane with a 3D hierarchical structure shows enhanced light scattering and utilization, water transport and vapor escape. A remarkable evaporation rate of 1.457 kg m−2 h−1 and an evaporation efficiency of 91.48 % are attained for a large-area (5 × 5 cm2) evaporator, and the evaporation rate is further increased to 1.672 kg m−2 h−1 for a small-area (2 × 2 cm2) device. The rejection rates of salt ions and heavy metal ions are higher than 99 % and 99.99 %, respectively, and the removal rates of organic dye molecules are nearly to 100 %. Besides, the composite photothermal membrane exhibits great stabilities in harsh conditions such as high salinities, long cycling, large light intensities, strong acid/alkali environments, and mechanical bending. Most importantly, the photothermal membrane shows a considerable cost-effectiveness of 89.4 g h−1/$. Hence, this study might promote the commercialization of solar-driven interfacial evaporation desalination by collaboratively considering surface modification and substrate engineering for MXene.

Recycling waste carbon fibers for solar-driven clean water production by one-step electrochemical process

Waste carbon fibers (WCF), as a co-product of carbon-based textile material, presented a high recycling value. However, it is difficult to utilize the short carbon fibers by traditional process, recycling and using these WCF effectively has thus attracted increasing attention. Herein, we propose a novel strategy that utilizes simultaneous electrochemical exfoliation and deposition processes to convert WCF into photothermal materials. Stainless steel felt (SS) was selected as the substrate to verify this strategy. Through this strategy, the reduced graphene oxide-coated SS (rGO-SS) was obtained. The 2D solar-driven interfacial evaporator based on rGO-SS enabled stable evaporation in actual wastewater with an excellent rate of 1.44 ∼ 1.50 kg m−2 h−1 under 1 sun. Additionally, by constructing a 3D evaporation structure, rGO-SS performed a high evaporation rate of ∼16.88 kg m−2 h−1 under 1 sun. Finally, this work proposes a novel method for the waste carbon fibers and gives new insights into fabricating a novel solar-driven interfacial evaporator.

Dual-Interface Solar Evaporator with Highly-Efficient Thermal Regulation via Suspended Multilayer Design.

Facing the increasing global shortage of freshwater resources, this study presents a suspended multilayer evaporator (SMLE), designed to tackle the principal issues plaguing current solar-driven interfacial evaporation technologies, specifically, substantial thermal losses and limited water production. This approach, through the implementation of a multilayer structural design, enables superior thermal regulation throughout the evaporation process. This evaporator consists of a radiation damping layer, a photothermal conversion layer, and a bottom layer that leverages radiation, wherein the bottom layer exhibits a notable infrared emissivity. The distinctive feature of the design effectively reduces radiative heat loss and facilitates dual-interface evaporation by heating the water surface through mid-infrared radiation. The refined design leads to a notable evaporation rate of 2.83kg m-2 h-1. Numerical simulations and practical performance evaluations validate the effectiveness of the multilayer evaporator in actual use scenarios. This energy-recycling and dual-interface evaporation multilayered approach propels the design of high-efficiency solar-driven interfacial evaporators forward, presenting new insights into developing effective water-energy transformation systems.

A self-floating integrated hydrogel evaporator with efficient salt resistance and thermal localization for efficient solar water desalination

Solar-driven interfacial evaporation technology was considered a promising way to effectively alleviate the global freshwater crisis. However, it is still a major challenge to design evaporators with efficient thermal management, salt resistant and self-floating ability to realize efficient clean water production. Here, we design a double-layer hydrogel evaporator with self-floating system. The evaporator is prepared from expanded polystyrene board, poly (vinyl alcohol), polyvinylpyrrolidone, agar and conductive carbon black. The structural design of the evaporator improves water transport capacity of the evaporation system and effectively reduces heat loss, so that the evaporator has efficient salt resistance and thermal localization. The evaporator demonstrates an outstanding evaporation rate and evaporation efficiency of 2.77 kg m-2h−1 and 94.25 % under 1 kW m−2 illumination. Additionally, the evaporator exhibits good stability in the 10-cycle solar evaporation experiment. Furthermore, the evaporator exhibits excellent salt resistance in 3.5 wt% NaCl solution during continuous evaporation for 9 h at 1 kW m−2 illumination. Moreover, the purification rates of the organic wastewater 4-nitrophenol and methylene blue by the evaporator reached 99.8 % and 100 %, respectively. This evaporator has stable and efficient capability of solar water purification, providing a new way for large-scale solar desalination and water purification.

Three-dimensional NiO/Ni self-floating porous composite materials for efficient solar interfacial evaporation

The scarcity of freshwater resources and energy crisis are major challenges to the progress of human society. Recently, solar-driven interfacial water evaporation utilizes photothermal conversion materials to convert solar energy into thermal energy, which possesses great application potential in seawater desalination and sewage treatment. Here, we fabricated porous nickel sponge (NSP) composite photothermal material (NiO-NSP) containing abundant NiO nanoneedles array. This in situ-grown NiO with enhanced bonding between photothermal material and substrate can be used as a solar absorber directly without consuming additional photothermal material compared to conventional coating and cladding on the carrier surface. Due to the multi-scattering induced light trapping effect of the semiconductor NiO nanoneedles array on the surface of nickel fibers, resulting in light absorption up to 96.5 %. NiO-NSP evaporators have an abundance of interconnected porous channels for water supply, which results in strong capillary action to pump water to the evaporation interface efficiently. Moreover, the highly dispersed nanoneedles array expand the evaporation surface area. Consequently, the NiO-NSP evaporator delivers an excellent evaporation rate of 1.78 kg m−2 h−1 and a photothermal conversion efficiency of 84.7 % at one sun radiation. In addition, the micron-sized porous mesh structure of NiO-NSP dissolve salt crystals and diffuse them downward into the bulk brine, exhibiting excellent salt resistance and remarkable seawater desalination stability. Moreover, NiO-NSP solar evaporators has been demonstrated to possess excellent ability to purify dye and heavy metal ion wastewater. Therefore, the NiO-NSP high-performance evaporator produced by straightforward process proved to be suitable for solar seawater desalination and wastewater purification.

A robust and low-cost blended-fiber-based evaporator with high efficiency for solar desalination

The solar-driven interfacial evaporation (SDIE) is a clean and efficient technology to mitigate freshwater shortages. A robust and low-cost evaporator is essential for the practical implementation of SDIE systems. Herein, we design a fantastic blended-fiber-based evaporator using weaving techniques. This mixture fabric is crafted using polyethylene terephthalate fibers and linen threads. It makes full use of the excellent light absorption, tensile strength, and corrosion resistance of polyethylene terephthalate fibers. Meanwhile, the mixture fabric reserves exceptional air permeability and water supply capability of linen thread. We optimize the density of the mixture fabric by adjusting the reed count and the weft count. It is found that the combination of the 40 reed and a single weft yarn produces the most effective and stable evaporator. The optimized mixture fabric makes a good trade-off between the water supply to the evaporator and solar-thermal evaporation. As a result, the evaporator achieves a high evaporation rate and efficiency (~1.53kg/m2/h, ~ 90%) under 1 sun illumination, which surpasses most of the existing two-dimensional evaporators based on metal nanomaterials, polymers, carbon-based materials, and fabrics. Our work opens a new horizon for the development of efficient, scalable, flexible, low-cost, corrosion-resistant, and stable evaporators.

Flexible Janus Black Silicon Photothermal Conversion Membranes for Highly Efficient Solar-Driven Interfacial Water Purification.

Photothermal conversion materials are critical in the development of solar-driven interfacial evaporation techniques; however, achieving a high energy conversion efficiency remains challenging owing to the high cost and instability of light-absorbing materials, in addition to the difficulties of simultaneously improving light absorption while suppressing heat loss. A black silicon (Si) powder with a porous structure was prepared by chemical etching of a low-cost commercial micron-sized Al-Si alloy, and a flexible Janus black Si photothermal conversion membrane was constructed. The partially broken spherical particles and porous structure obtained after etching enhanced the refraction of light from the Si powder, imparting the prepared membrane with an average light absorption rate of 95.95% over the solar spectrum. Evaporation from the membrane increased the intermediate water content and reduced the equivalent evaporation enthalpy. The thermal conduction loss was inhibited through a one-dimensional water transport structure, and the membrane achieved a water evaporation rate of 2.17 kg m-2 h-1 and a photothermal efficiency of 94.95% under 1 sun illumination. Benefiting from the broadband absorption and high photothermal efficiency of black Si powder, surface modification of hydrophobic polydimethylsiloxane, and directional salt-out structure design, the evaporation rate of the Janus black Si membrane-based system in a 10% NaCl solution was maintained >2.10 kg m-2 h-1 after 7 days of continuous evaporation cycles. The removal rate of metal ions from simulated seawater and from practical wastewater containing complex heavy metals reached >99.9%, indicating the promising potential of black Si membrane for application in solar-driven interfacial water purification.

Preparation of nanoporous TiOx powder and its enhanced photocatalytic N2 to NH3 conversion by solar-driven interfacial water evaporation

At present, the limited efficiency in ammonia generation poses significant challenge to the widespread practical implementation of photocatalytic nitrogen reduction to ammonia (PNRN). In this study, we synthesized a nanoporous TiOx powder (Alloy-RTO) by rapid breakdown anodization of TA13 alloy and subsequent magnesiothermic reduction. The Alloy-RTO exhibited superior photothermal and photocatalytic properties owing to its multicomponent and interconnective nanoporous structure, and the electronic band structure is suitable for efficient PNRN. Notably, through synergistic integration of PNRN with solar-driven interfacial water evaporation technology (SDIWE), the ammonia production rate was further enhanced, and a multifaceted role of SDIWE in enhancing PNRN was proposed: (1) increasing temperature of Alloy-RTO to promote PNRN; (2) raising temperature to accelerate ammonia water decomposition and facilitate PNRN; and (3) generating plenty of gaseous water to accelerate PNRN. This study presents an effective strategy for preparing nanoporous TiOx and highlights the pivotal role of SDIWE in promoting PNRN.

Novel cellulose-based films with highly efficient photothermal performance for sustainable solar evaporation and solar-thermal power generation

Solar-driven interfacial evaporation has received substantial attention in a variety of applications, including water purification, seawater desalination, and energy production. However, creating a straightforward, adaptable, and scalable method for correctly integrating hybrid solar-thermal systems continues to be a challenging task. Herein, we propose an economical, scalable, and environmentally friendly approach for achieving synergistic coupling of interfacial solar energy conversion for evaporation and low-grade thermal energy conversion to electricity by incorporating zinc oxide (ZnO) nanoparticle-modified MXene (ZNM- MXene) into cellulose nanofiber (CNF) films. The vacuum filtering approach produces CNF@ZNM-MXene composite films with enhanced photothermal conversion efficiency, capillary hydrophilicity, and thermal localization. Because of its rapid water transport capability, excellent sunlight absorption, and efficient solar-thermal conversion under 1 kW m−2 irradiance, the CNF@ZNM-MXene solar evaporator's evaporation rate reaches 1.27 kg m−2 h−1, and the solar-vapor conversion efficiency is as high as 82.15%, outperforming most previously reported solar evaporators. Moreover, when compared to a standalone thermoelectric (TE) module, the output power of the solar thermal conversion system coupled with a CNF@ZNM-MXene composite films and a TE module is boosted by 15.32 times. This work offers a practical and effective method for simultaneously capturing solar energy and desalinating saltwater.

Sandwiched solar interfacial evaporation system: Integrating phase change material/hydrogel/NiCo2O4 nanoflower for superior desalination

Solar-driven interfacial evaporation is a kind of sustainable and eco-friendly method of water treatment to alleviate the global water crisis. Here we demonstrate a novel sandwiched solar interfacial evaporator integrating phase change material (PCM), sodium alginate hydrogel (SA), and NiCo2O4 nanoflower featuring superb evaporation and glorious thermal energy management to achieve efficient energy utilization and long-term evaporation stability. After being combined with filter paper, NiCo2O4 nanoflower composites are adopted as the light absorber on the top layer, which can achieve an absorption of about 96.5 % in the full spectral range. SA hydrogel has been used as an intermediate layer for rapid water supply to the evaporation interface and to prevent salt deposition. Under one sun irradiation (1 kW m−2), the evaporator exhibits a high evaporation rate (1.94 kg m-2h−1) and excellent endurance in the treatment of high salt-concentration water. In particular, benefiting from the rational combination of PCM, the water production reached up to 12.13 kg m−2, which is 2.23 kg m-2higher than that of the evaporator without PCM under natural solar irradiation for 9 h. This work presents a promising concept for maximally utilizing intermittent solar irradiation energy and prolonged salt-free deposition desalination.

Recent Advances in High-Rate Solar-Driven Interfacial Evaporation.

Recent advances in solar-driven interfacial evaporation (SDIE) have led to high evaporation rates that open promising avenues for practical utilization in freshwater production and industrial application for pollutant and nutrient concentration, and resource recovery. Breakthroughs in overcoming the theoretical limitation of 2D interfacial evaporation have allowed for developing systems with high evaporation rates. This study presents a comprehensive review of various evaporator designs that have achieved pure evaporation rates beyond 4kgm-2h-1, including structural and material designs allowing for rapid evaporation, passive 3D designs, and systems coupled with alternative energy sources of wind and joule heating. The operational mechanisms for each design are outlined together with discussion on the current benefits and areas for improvement. The overarching challenges encountered by SDIE concerning the feasibility of direct integration into contemporary practical settings are assessed, and issues relating to sustaining elevated evaporation rates under diverse environmental conditions are addressed.

Flexible nanofiber composite solar evaporator for simultaneous interfacial evaporation and heavy metal ion adsorption

Solar driven interfacial evaporation (SDIE) is promising in harvesting fresh water because of its low cost, environmental friendless and sustainability; however, it is desirable but still difficult to achieve high efficiency heavy metal ion removal during SDIE. Here, we develop a superhydrophilic and stretchable nanofiber composite solar evaporator via carbon nanofiber (CNF) assembly on polymer fiber surface and then polydopamine (PDA) modification. The evaporation rate reaches as high as 1.456 kg m−2 h−1 with the evaporation efficiency of 91.40 %. The functional groups of PDA endow the nanofiber composite with good heavy metal ion adsorption performance that is proved to be an endothermic process, and SDIE can induce the increase of interface temperature and localized ion concentration and hence promote the Cr (VI) adsorption. One the other hand, NaCl ions are able to diffuse into body water without salt precipitation by virtue of powerful water transportation capability of the evaporation device. The dual Cr (VI) adsorption and NaCl ion diffusion channels ensure simultaneous and high efficiency Cr (VI) removal and seawater interface evaporation. SDIE accelerated heavy metal ion adsorption and the dual ion channel model provide inspiration to design multifunctional solar evaporator materials for waste water purification.

Black Silver-Decorated liquid metal nanofillers coupled with Glycerol-Modified hydrogel composites for high efficiency solar steam generation and thermoelectric conversion

Solar-driven interfacial evaporation (SDIE) holds great potential in alleviating global freshwater scarcity, which requires the design of efficient energy conversion devices. Herein, a quadruply engineered hydrogel-based evaporator is developed based on multipath regulation of the four key processes involved in SDIE, i.e., heat generation, energy utilization, water transportation, and evaporation. Surface-tailored liquid metal nanoparticles (EGaIn@Ag NPs) with a high photothermal conversion efficiency (PCE) of 30.4 % serve as the nanofiller to produce heat efficiently. Vertically aligned microchannels are constructed in the poly(vinyl alcohol) (PVA) hydrogel through directional freezing to accelerate water transportation. Glycerol is introduced to the PVA matrix to synergistically a) prevent heat loss from the interface to bulk water, and b) modulate the bonding state of water in the hydrogel to reduce the vaporization enthalpy. Such an elaborate design achieves a rather high evaporation rate of 3.26 kg m−2h−1 under 1 sun illumination. The hydrogel evaporator (EGaIn@Ag/PVAG) is applicable in treating real seawater and dye-contaminated sewages, showing favorable desalination durability and self-cleaning property. The synergistic design also imparts the hydrogel with thermoelectric power generation capabilities. This work offers a new insight into the synergistic design of SDIE devices, which is expected to inspire innovations in solar energy conversion and utilization.

A novel hierarchical chromium black membrane prepared by electroplating for desalination

Solar-driven interfacial evaporation (SDIE), a technology for local solar energy conversion through photothermal materials, has been greatly developed. The metal oxide semiconductors have excellent photothermal conversion performance and are considered the most promising materials for photothermal conversion. Hierarchical structure with large surface area is beneficial to improve the photothermal conversion efficiency through the light-trapping effect and reduces the evaporation enthalpy of water. Herein, chromium black (Cr, Cr2O3, CrO3-x) photothermal membranes (CBPM) with ganoderma-like hierarchical structure were prepared by electrochemical oxidation. Due to the small interlayer spacing of the ganoderma-like structure, the light absorption of CBPM (M7) can reach 78.53 %, which in turn promotes the conversion of solar energy due to the low thermal conductivity of the chromium black layer, resulting in a high evaporation rate of 1.64 kg m−2 h−1. The solar-to-vapor conversion efficiency is up to 90.39 % under 1 sun irradiation. Meanwhile, the superhydrophilicity of the membrane is conducive to salt redissolution at night, so there was not much performance degradation after 24 cycles. This study provides a new solution for water treatment using chromium black as a photothermal material with great potential for solar production of fresh water.

Novel mushroom-like cotton-based evaporator for simultaneous freshwater production and salt harvesting via edge-preferential crystallization

Solar-driven interfacial evaporation (SDIE) has emerged as a promising technology to alleviate the global freshwater scarcity. However, the simultaneous collection of water and salt as resources while maintaining stable evaporation rate without salt contamination at the evaporation interface remains a huge challenge. Herein, we report a novel mushroom-like cotton-based evaporator, inspired by the vertical stem and inclined caps of mushrooms, for simultaneous freshwater production and salt harvesting. By depositing polyaniline (PANI) and carbon nanotubes (CNTs) onto the cotton fabric (CF), an evaporation rate of 1.88 kg m−2h−1 and a high solar evaporation efficiency of 99.4 % can be achieved in 3.5 wt% NaCl solution under one solar irradiation. Furthermore, a significant water collection efficiency of 70.2 % and a high salt harvesting rate of 42.1 g m−2h−1 can be derived. Even exposed to high-concentration (15 wt%) brine, our design still effectively prevents salt contamination. The distinctive edge-preferential crystallization not only avoids the salt contamination but also promotes the salt harvesting, due to the capillary force, the criss-cross water channels from the nature of cotton cloth, as well as the gravity-assisted water transport of the “mushroom cap” during evaporation. In addition, the low thermal conductivity (0.163 W m−1 K−1) of the photothermal layer with the integration of PANI and CNTs, as well as the vertical water upward transport via the “mushroom stem” effectively reduce the heat loss. This research holds great potential for seawater desalination applications with the comprehensive utilization of seawater resources.

Harnessing overlapped temperature-salinity gradient in solar-driven interfacial seawater evaporation for efficient steam and electricity generation

Solar-driven interfacial water evaporation (SIWE) offers a superb way to leverage concentrated solar heat to minimize energy dissipation during seawater desalination. It also engenders overlapped temperature-salinity gradient (TSG) between water-air interface and adjacent seawater, affording opportunities of harnessing electricity. However, the efficiency of conventional SIWE technologies is limited by significant challenges, including salt passivation to hinder evaporation and difficulties in exploiting overlapped TSG simultaneously. Herein, we report self-sustaining hybrid SIWE for not only sustainable seawater desalination but also efficient electricity generation from TSG. It enables spontaneous circulation of salt flux upon seawater evaporation, inducing a self-cleaning evaporative interface without salt passivation for stable steam generation. Meanwhile, this design enables spatial separation and simultaneous utilization of overlapped TSG to enhance electricity generation. These benefits render a remarkable efficiency of 90.8% in solar energy utilization, manifesting in co-generation of solar steam at a fast rate of 2.01 kg m−2 h−1 and electricity power of 1.91 W m−2 with high voltage. Directly interfacing the hybrid SIWE with seawater electrolyzer constructs a system for water-electricity-hydrogen co-generation without external electricity supply. It produces hydrogen at a rapid rate of 1.29 L h−1 m−2 and freshwater with 22 times lower Na+ concentration than the World Health Organization (WHO) threshold.