Interfacial Solar Evaporation Research Articles

MXene nanosheets coated conjugated microporous polymers hollow microspheres incorporating with phase change material for continuous desalination

The inevitable intermittency of solar illumination during the interfacial evaporation process can cause a reduction in the evaporation performance of solar evaporators. Here, we report the fabrication of a new solar-driven interfacial evaporator using MXene nanosheets as the photothermal layer, modifying them with conjugated microporous polymer hollow microspheres, and then compounding them with the phase change material, in this case, cetyl alcohol, to form a composite evaporator (CE) that can perform all-weather solar interfacial evaporation. By combining interfacial evaporation photothermal conversion with energy storage, the evaporator achieves an evaporation rate of 1.57 kg⋅m−2⋅h−1 at a light intensity of 1 kW⋅m−2 and 2.79 kg⋅m−2⋅h−1 at a light intensity of 2 kW⋅m−2. In addition, the evaporator attains an excellent solar evaporation efficiency of over 91% in both cases and even in salt water. In addition, interestingly, our CE exhibits excellent continuous evaporation ability, e.g., the mass of evaporated water was increased by 0.36 kg⋅m−2 at a light intensity of 2 kW⋅m−2 compared to the cavity evaporator without the phase change material (PCM) when solar light was turned off. These results could be attributed to the fact that the energy released by the incorporated phase change material allows the evaporator to maintain stable evaporation under conditions of insufficient or intermittent solar irradiation, potentially providing a new opportunity for addressing the intermittent problem of evaporation at the solar interface due to unstable light intensity, thus showing great potential for practical continuous desalination.

Hierarchical Co3S4 nanostructure coupling with macroporous nickel foam: A robust interfacial solar evaporator for efficient desalination and sustainable freshwater production

Interfacial solar water evaporation (ISWE) technology provides a green, energy-saving and economical way to sustainably produce freshwater from various water sources for addressing the impending water shortage. However, the low evaporation rate, complex manufacturing process and harmful surface salt accumulation for ISWE are still challenging and considerably restricted the practical applications. Herein, we design and fabricate a robust ISWE based on the hierarchical Co3S4 nanostructure as a photothermal absorber and three-dimensional (3D) nickel foam (NF) as a primary structure with macroporous networks. The as-fabricated Co3S4/NF not only introduces sufficient photothermal centers to convert solar energy into heat, but also provides abundant channels for water transportation and steam escape. The Co3S4/NF evaporator exhibits a high evaporation rate of 1.56 kg m−2 h−1 and a photothermal conversion efficiency up to 94.18 % under one-sun illumination. Moreover, such evaporator shows the long-term durability and good salt-resistant ability, which can sustainably produce freshwater from various water sources including seawater, saline water, lake water and other contaminated water. The photothermal Co3S4/NF evaporator would provide a promising platform for the production of drinkable water in a safe and sustainable manner.

Evolution of Morphology and Distribution of Salt Crystals on a Photothermal Layer during Solar Interfacial Evaporation.

Solar interfacial evaporation (SIE) by leveraging photothermal conversion could be a clean and sustainable solution to the scarcity of fresh water, decontamination of wastewater, and steam sterilization. However, the process of salt crystallization on photothermal materials used in SIE, especially from saltwater evaporation, has not been completely understood. We report the temporal and spatial evolution of salt crystals on the photothermal layer during SIE. By using a typical oil lamp evaporator, we found that salt crystallization always initiates from the edge of the evaporation surface of the photothermal layer due to the local fast flux of the vapor to the surroundings. Interestingly, the salt crystals exhibit either compact or loose morphology, depending on the location and evaporation duration. By employing a suite of complementary analytical techniques of Raman and infrared spectroscopy and temperature mapping, we followed the evolution and spatial distribution of salt crystals, interfacial water, and surface temperature during evaporation. Our results suggested that the compact crystal structure may emerge from the recrystallization of salt in an initially porous structure, driven by continuous water evaporation from the porous and loose crystals. The holistic view provided in this study may lay the foundation for effective strategies for mitigation of the negative impact of salt crystallization in solar evaporation.

Functional upcycling of waste polyester into Cr-MOF towards synergistic interfacial solar evaporation and organic pollutant degradation

The development of hybrid photothermal materials coupling interfacial solar-driven water evaporation with advanced oxidation process has recently aroused extensive attention to simultaneously realize freshwater production and wastewater purification. However, designing advanced hybrid photothermal materials with high specific surface areas and robust active sites remains challenging to meet the distinct requirements of photothermal conversion and photocatalysis. Herein, we report the waste-to-metal-organic framework (MOF) strategy for converting waste poly(ethylene terephthalate) [PET] into Cr-MOF hexahedron with abundant active sites and large specific surface area (896.1 m2/g), and subsequently fabricate multifunctional chromium-based metal-organic frameworks (Cr-MOF)/carbon nanotube (CNT) composite solar evaporators in a cost-effective, scalable manner towards simultaneous interfacial solar-driven steam generation and stubborn contaminant removal. First, the composite evaporator presents high light absorption (98%), high photothermal conversion efficiency, super-hydrophilicity, low thermal coefficient (0.087 W/(m/K)) and low vaporization enthalpy. Accordingly, the composite evaporator not only holds a high evaporation rate (2.46 kg/(m2/h)), superior to most of advanced solar evaporators, but also owns good flexibility and long-term stability. Subsequently, according to density functional theory (DFT) calculation and COMSOL results, chromium sites of Cr-MOF and local solar heat contribute to the peroxymonosulfate (PMS) activation to produce various reactive species. Thereupon, the composite evaporator exhibits good tetracycline (TC) degradation activity. Finally, in the practical freshwater production and photocatalytic degradation, the freshwater production amount is 7.3 kg/m2 per day, along with the tetracycline degradation efficiency of 92.4%. This work provides an ingenious strategy to massively synthesize hybrid evaporators and concurrently advances freshwater production and pollutant elimination.

Engineering High-Tortuosity 3D Gradient Structure and CFD-Assisted Multifield Analysis for Solar Interfacial Evaporation.

Solar interfacial evaporation is a promising method for solving the global shortage of fresh water. While 2D evaporators can efficiently localize solar-converted heat at the thin layer of the water-air interface, 3D solar evaporators can maximize energy reutilization while maintaining effective mass transport ability, few studies are conducted to explore the effect of gradient porosity on evaporation performance. In this study, a multifield assisted strategy based on a gradient 3D structure with high tortuosity is proposed, which creates a thermal field environment for efficient evaporation through high absorption of sunlight and excellent photothermal conversion and uses the gradient structure to optimize the internal pressure field to enhance water evaporation and transport. This hierarchically nanostructured solar absorber, with porosity inhomogeneity-induced pressure gradient and optimized temperature management, is a valuable design idea for manufacturing a more efficient 3D solar evaporator in the field of seawater desalination. Owing to the understanding of optimizing the dimension by various simulation parameters, the evaporation efficiencies of such structures are found to be 165.7%, suppressing the most evaporator. Moreover, it can provide new ideas and references for the fields of mass transfer and thermal management.

Bio-inspired selective filtration of sphagnum for efficient solar driven purification of high salinity seawater

Solar-driven interfacial evaporation has emerged as an efficient and sustainable way to generate freshwater from seawater to address the crisis of drinkable water. Though rational designs of photothermal materials and structures are essential to the interfacial solar evaporation process, the salt accumulation remains a challenge to the long-term operation of seawater desalination. Here, we report a high-yield and low-cost natural sphagnum as solar steam generator with ultra-fast water transportation, unique microstructure to prevent salting out, and high evaporation rates. The carbonized sphagnum based photothermal evaporator exhibits a strong broad-band light absorption (>97.0 %). During the solar steam generation, a high evaporation rate of 3.53 kg m−2 h−1 was achieved under 1.0 sun illumination. More significantly, the 3D sphagnum evaporator shows excellent selective filtration of salt ions and cycling stability in actual sea water even high salinity solution (10 wt.% NaCl) for 7 days. This work provides an environmentally friendly and cost-effective photothermal material for large-scale seawater desalination, and treatment of waste water with high ions concentration.

Polypyrrole Coated Textiles as Photothermal Material for Interfacial Solar Evaporation

Polypyrrole Coated Textiles as Photothermal Material for Interfacial Solar Evaporation

Experimental analysis of patterned floating absorbers integrated thermal storage facilitating interfacial evaporation

Conventional solar-driven desalination methods yield low water productivity as a portion of the available energy is wasted for bulk heating. Furthermore, like any solar device, desalination is restricted by the availability (i.e., during night-time) and intermittent nature of solar flux. As a remedy, in this work, (a) interfacial evaporation, which is one of the best emerging energy-efficient technology that can help rectify the drawback of the conventional methods, and (b) the inclusion of thermal energy storage materials, which can supplement the energy needed for evaporation during the off-sunshine hours are selected for further investigations. The cumulative impact of the Solar Interfacial Evaporation (SIE) system incorporated with Phase Change Material (PCM) and different patterned floating absorbers is presented. As an extension, the system is introduced with Thermoelectric Generator (TEG) modules for cogeneration (i.e., desalination and open circuit voltage (OCV)). Primarily, under a controlled environment, this system is subjected to three different solar flux conditions, and the resulting water production is determined. Under 2-Sun conditions, the SIE-PCM approach yielded a higher evaporation rate of 2.3 kg/m2-h, 59 % higher than the SIE system without PCM. Also, under off-sunshine conditions, the SIE-PCM system yielded the highest evaporation rate of 0.5 kg/m2-h. Energy and exergy analysis indicated that the 36 square patterned absorbers yielded higher efficiencies than other tested configurations. The findings revealed that the cogeneration strategy yielded a low OCV showing its lack of potential in the proposed system.

Study of Metal–Graphene Aerogel for Efficient Solar Energy Interface Evaporation Based on One‐Step Thermal Reduction Method

Freshwater resources can be sustainably harvested through interfacial evaporation by solar energy. To enhance the efficiency of solar interfacial evaporation, a metal–graphene alcohol gel is synthesized using a one‐step thermal reduction technique. Subsequently, a metal–graphene aerogel (GA) is produced using freeze‐drying technology. The hydrothermal treatment method is applied to introduce asymmetric moisture and roughness on the upper and lower surfaces of the aerogel. The unique structure of the aerogel plays a significant role in facilitating continuous water transport to the interface for evaporation. The top layer, being hydrophobic, and the bottom layer, being hydrophilic, contribute to this process. Importantly, the top layer's design ensures that an excessively thick water film does not form, thereby preventing any adverse effects on light‐absorption efficiency. The aerogel exhibits that an outstanding water‐evaporation rate is 1.75 kg m−2 h−1 and a remarkable photothermal conversion efficiency (PTCE) is 93.17% under one solar radiation intensity. This is because the aerogel has a unique 3D structure. This special 3D structure has an interconnected microporous‐like appearance inside, which increases the evaporation area. Metal–GA is based on the electric field dielectric evaporation mechanism of metal nanoparticles localized surface plasmon resonance effect and the thermal mediated evaporation mechanism of graphene full spectrum. Under the double action, the PTCE is significantly improved. The meticulously created metallic GA performs exceptionally well at evaporating water. As a result, it presents a promising and practical avenue for exploring effective solar interfacial evaporation.

Polydopamine/Fe3O4 modified wood-based evaporator for efficient and continuous water purification

Solar interfacial evaporation is a highly promising technology for seawater desalination and wastewater treatment, while the simple preparation processes and efficient production of clean water based on biomass interfacial evaporators still need further exploration and development. Here, we reported a wood-based evaporator (PFDW) loaded with Fe3O4 and polydopamine (PDA) after simple immersion treatment at room temperature for efficient and continuous water purification. The synergistic photothermal effect of PDA coating and Fe3O4 particles enables the evaporator to achieve high photothermal conversion efficiency in the longer wavelength range, while combined with the rapid water transport capacity endowed by the vertically aligned microporous structure of natural wood, it achieved an evaporation rate of 1.70 kg m-2h−1 and an energy efficiency of 98.0% under 1 kW m−2 irradiation. In addition, the prepared PFDW exhibited sustainable desalination stability and excellent removal efficiency for different water sources including organic dye wastewater, heavy metal effluent, oil–water emulsion and river water. This work provides a new avenue for efficient salt-tolerant portable evaporators.

Economical, Simple‐to‐Prepare, and Salt‐Resistant Evaporator Based on Porous Activated Carbon for Sustainable Solar Evaporation

Interfacial solar vapor evaporation is expected to be an emerging technology to solve the scarcity of freshwater due to its sustainability and high efficiency. However, the present application of evaporators is mainly limited by the complex preparation process, expensive cost of raw material, and poor structure. Herein, based on coconut shell activated carbon (CSC) and ultrahigh molecular weight polyethylene (UHMWPE), a cost‐effective and robust CSC/UHMWPE (CSC/PE) evaporator is prepared through sintering in a mold. Benefiting from high light absorptance (≈90%) and excellent thermal localization, the CSC/PE evaporator exhibits an evaporation rate of 1.340 kg m−2 h−1 and an evaporation efficiency of 80.57% in 3.5 wt% brine under 1 sun irradiation. Moreover, by regulating the component ratios, the CSC/PE evaporator achieves superhydrophilicity and proper water transportation rate, and shows long‐term stability with an average evaporation rate of 1.309 kg m−2 h−1 in natural seawater for 10 h. Specifically, the high porosity CSC/PE facilitates the salt resistance in high salinity brine (15 wt%). Importantly, the cost‐effectiveness of CSC/PE is 53.43 g h−1 $−1, which is economical compared to other reported evaporators. Therefore, the economical, simple‐to‐prepare, and durable CSC/PE evaporator has enormous potential in interfacial solar vapor evaporation for freshwater production.

A Review: Electrospinning Applied to Solar Interfacial Evaporator

The emerging solar interfacial evaporation (SIE) technology is an effective measure to address freshwater resources. An efficient and stable solar interfacial evaporator cannot be achieved without the synergy of three key factors: water transport, solar thermal conversion, and thermal management. The performance of a solar interfacial evaporator can be improved through the rational selection of materials and the structural design of these three key factors. Due to superior nanostructures, electrospun nanofibrous materials often exhibit some unique properties that facilitate the construction of solar interface evaporators with good performance. So far, electrospinning has been used to prepare structures such as solar absorbers, water transportation, and thermal insulation in various solar interfacial evaporators. This review presents the fundamental research and technological development in the application of electrospinning techniques to solar interfacial evaporators on structures, morphology, and properties. Then, the latest advances in the use of electrospinning technology in solar interfacial evaporators are summarized and the current issues facing the application of electrospinning technology to solar interfacial evaporators are presented. These systematic discussions can provide ideas and approaches for the rational design of electrospun nanofiber materials for solar interfacial evaporators in the future.

An interfacial solar evaporation enabled autonomous double-layered vertical floating solar sea farm

Water, energy, and food security are the three most critical elements for achieving the 2030 United Nations' Sustainable Development Goals. While much effort has been focused on the development of interfacial solar evaporation technology for seawater desalination, limited effort has been directed towards potential sustainable agricultural applications. This work addresses this gap by developing a self-sustaining and solar-driven offshore double-layered sea farm system to address growing global shortages in clean water, agricultural land resources and food supply. During a long-term field test, this unique design was used to successfully germinate and grow, with a survival rate of 80%, three common vegetable crops (broccoli, lettuce, and Pak Choi) on seawater surfaces without maintenance nor additional clean water irrigation. Thus, this design could potentially make a significant contribution to sustainable agriculture production in the seawater-energy-food nexus.

Establishing a transient model of double-layer porous media interfacial evaporation system to reveal the relationship between porous media parameters and evaporation performance

The solar interfacial evaporation system can generate steam efficiently by localizing solar thermal energy to heat air–water interface, which has great application potential in seawater desalination, sewage treatment, and other fields. At present, the solar absorption layer and substrate of the interfacial evaporation system are mainly made of carbon materials, sponges, foams, and other porous media materials. However, the transient interfacial evaporation heat and mass transfer model and the influence of the physical parameters of porous media on evaporation performance have rarely been investigated. Based on heat and mass transfer theory of porous media, a transient theoretical model of porous media interfacial evaporation system is established in this paper. Moreover, the effects of physical parameters such as the porosity and thermal conductivity of porous media on evaporation performance are analyzed, and the accuracy of the model is verified through outdoor experiments. Based on the model calculation, as the porosity of the substrate increases, the evaporation rate and efficiency of the evaporator first increase and then decrease. The lower the thermal conductivity of the substrate and the higher the porosity and thermal conductivity of the solar absorption layer are, the better the evaporation performance is, but the growth rate gradually decreases. Therefore, the relationship between the improvement of evaporation performance and the increased cost caused by the improvement of material properties needs to be considered. The model and related theoretical analysis results can provide a theoretical basis for system structure optimization, material selection and other aspects of future research on double-layer porous media interfacial evaporation system.

An efficient interfacial solar evaporator featuring a hierarchical porous structure entirely derived from waste cotton

Interfacial solar evaporators are widely used to purify water. However, photothermal materials commonly constituting most interfacial solar evaporators remain expensive; additionally, the inherent structure of the evaporators limits their performance. Furthermore, the large amount of waste cotton produced by the textile industry is an environmental threat. To address these issues, we propose an interfacial solar evaporator, H-CA-CS, with a hierarchical porous structure. This evaporator is made entirely of waste cotton and uses carbon microspheres (CMS) and cellulose aerogel (CA) as photothermal and substrate materials, respectively. Additionally, its photothermal layer (CS layer) has large pores and a high porosity, which promote light absorption and timely vapor escape. In contrast, the water transport layer (CA layer) has small pores, providing a robust capillary effect for water transport. Combined with the outstanding light absorption properties of CMS, H-CA-CS exhibited superior overall performance. We found that H-CA-CS has an excellent evaporation rate (1.68 kg m−2 h−1) and an efficiency of 90.6 % under one solar illumination (1 kW m−2), which are superior to those of many waste-based solar evaporators. Moreover, H-CA-CS maintained a mean evaporation rate of 1.61 kg m−2 h−1, ensuring sustainable evaporation performance under long-term scenarios. Additionally, H-CA-CS can be used to purify seawater and various types of wastewater with removal efficiencies exceeding 99 %. In conclusion, this study proposes a method for efficiently using waste cotton to purify water and provides novel ideas for the high-value use of other waste fibers to further mitigate ongoing environmental degradation.

Manufacturing robust MXene-based hydrogel-coated cotton fabric via electron-beam irradiation for efficient interfacial solar evaporation

Herein, a robust Ti3C2Tx MXene-based hydrogel-coated cotton fabrics (MHCFs) was facilely prepared by electron beam (E-beam) irradiation induced crosslinking under mild condition, which efficiently combined the outstanding light absorption and photothermal conversion performance of MXene with the excellent water transport capacity and good mechanical property of cotton fabrics (CFs). The novel MHCFs deservedly achieved not only high solar absorption, but also excellent water evaporation rate (1.65 kg m−2h−1 under 1-sun irradiation), which breaks through the theoretical limit of planar evaporators (1.47 kg m−2h−1). It also shows great stability and no salt accumulation in long-time continuous solar evaporation of 3.5 wt% NaCl solution, which remained its evaporation rate around 1.49 kg m−2h−1 under 1-sun irradiation after 12 cycles. Moreover, the covalent crosslinking among the Ti3C2Tx MXene sheets, PVA and cellulose of CF induced by E-beam irradiation also endowed the MHCFs with good tolerance to acidic and ultrasonic treatments. In addition, the MHCFs were facilely assembled as a 3D evaporator with cylindrical structure, which not only exhibits 3.74 kg m−2h−1 of water evaporation rate under 1-sun irradiation, but also achieves 2.46 kg m−2h−1 of averaged rate from 3.5 wt% solution after 5 cycles of continuous long-time evaporation test. This study opens a pave to fabricate robust hydrogel-coated photothermal fabrics in continuous and large-scale manner, and expands the application of solar-driven interfacial evaporation (SDIE) to the seawater desalination, wastewater treatment and evaporative crystallization, and so on.

Bifunctional photothermal membrane for high-temperature interfacial solar steam generation and off-grid sterilization

High-temperature solar steam generation is a promising sustainable strategy to alleviate the global clean water shortage. However, it is challenging to scale up the high-temperature steam generation under ambient conditions for water purification and steam sterilization simultaneously. Herein, we develop a solar-powered steam generating system to produce high-temperature steam for interfacial solar steam evaporation and off-grid sterilization. A three-layered photothermal membrane made of polystyrene foam, bubble wrap, and reduced graphene oxide (rGO) coated cloth produces high-temperature steam that can be condensed to clean water as well as sterilize microbes efficiently. The hybrid device configuration and higher solar light-absorbing capability of rGO result in high temperature steam generation (∼90 °C) to sterilize microorganisms such as S.aureus, E.coli, and G.stearothermophilus. Such a bifunctional device with high temperature steam generation and solar-steam evaporation capability could be a promising development for sustainable clean water generation and sterilization in remote areas.

Oriented porous hydrogel with excellent anti-salt and antibacterial properties for high-performance interfacial solar steam generation

In recent years, solar interfacial evaporation has drawn substantial attention in wastewater and seawater treatment, but it still requires intensive development in high-performance evaporators, particularly simultaneous with high anti-salt and antibacterial abilities to supply freshwater. In this work, a directionally channeled evaporator with excellent resistance to salt crystallization and microbial was designed and synthesized by using silver nanoparticles (AgNPs) / polydopamine (PDA) hydrogel via a simple freeze-dried method. The novel structure was proposed to enhance convection and accelerate water transport that prevents salt crystallization. PDA and AgNPs were deposited to achieve superb optical absorption, photothermal conversion and anti-biofouling ability. Therefore, the evaporation rate of the AgNPs-PDA hydrogel achieved 1.70 kg m−2 h−1 with a light-to-heat conversion efficiency of 90.3 %. Based on the efficient evaporation ability and especially structure of the AgNPs-PDA hydrogel, the evaporator presented a tolerance to high salt water and the stable evaporation performance of actual seawater evaporation during long-time application. Simultaneously, the addition of AgNPs endowed the AgNPs-PDA hydrogel evaporator with excellent antibacterial ability. Thus, these favorable properties endowed the special AgNPs-PDA hydrogel evaporator a great potential for obtaining efficient evaporation and simultaneously solving the fouling problem, especially to waterborne pathogens and salt crystallization in tanglesome applications.

A scalable and anti-fouling silver-nickel/cellulose paper with synergy photothermal effect for efficient solar distillation

Solar interfacial evaporation is one of the most efficient and environmentally-friendly clean freshwater production technologies. Plasma metal nanoparticles are excellent optical absorption materials, but their high cost and inherent resonance narrow bandwidth absorption limit their application. In this work, commercial cellulose papers are used as substrates to synthesize Ag-Ni/cellulose paper by the seed-mediated method. The Ag-Ni/cellulose paper exhibits high light absorption at the full wavelength (200–2500 nm) resulting from the synergistic effect of localized surface plasmon resonance (LSPR) of Ag NPs and the interband transitions (IBTs) of Ni. Under one-sun irradiation (1 kW m−2), the energy utilization efficiency of Ag-Ni/cellulose paper is as high as 93.8%, and the water evaporation rate is 1.87 kg m−2 h−1. Diffusion inhibition experiment results show that the Ag-Ni/cellulose paper exhibits excellent antibacterial performance, and the antibacterial performance is highly related with Ag NPs content. These provide new opportunities for commercial production of competitive cost, green, and portable solar evaporators for different application sceneries.

High-performance Janus evaporator based on self-healing hydrogels for salt-rejecting interfacial solar desalination

The solar interfacial evaporation is considered as an innovate and promising technology to overcome the water scarcity crisis. However, an army of problems are being presented in evaporator applicate on open water, which formats and deposits of salt crystallization at its surface during long-term evaporation and permanents damage causing by wave impact. In this study, a self-floating and durable Janus interfacial solar evaporator (ISE) based on self-healing hydrogel with salt-rejecting was demonstrated for the efficiency production of clean water. Benefiting from the decrease of water evaporation enthalpy in hydrogel-based ISE, water evaporation rates over 2.096 kg·m−2·h−1 and solar efficiency of 85.50 % are attained under 1 sun. Additionally, the evaporator of Janus structure effectively avoids the format and deposition of salt at photothermal layer, exhibiting positive salt-rejecting and purification in various wastewater for long-term evaporation. What is more, the performance and appearance of self-healing hydrogel-based ISE can be easily restored. An encouraging and cheering Janus evaporator was proved via integrating self-healing and damage-tolerant hydrogels for solar desalination and water purification, which exhibits exciting durability and lifetime.