Solar-driven Interfacial Evaporation Research Articles

A stable and efficient hydrogel/sponge solar evaporator with splendid water supply

Solar-driven interfacial evaporation is an effective and realizable way of water purification. However, a short supply of water limits the evaporation performance of evaporator greatly. Here, an integrated photothermal evaporator owning double-layer structure of hydrogel and sponge with strong water transport ability is successfully prepared by cross-linking and dopamine modification. Abundant pores and hydrophilic functional groups in hydrogel and modified sponge benefit to enhance water transport of the whole evaporator and further relieve salt accumulation. Carbon black having the advantages of low cost and full spectrum absorption is dispersed into hydrogel networks to improve the capacity of photothermal conversion. Under the illumination of 1 kW m−2, the evaporator exhibits an excellent evaporation rate of 1.71 kg m-2h−1, corresponding to an evaporation efficiency of 93.8 %. Furthermore, the evaporator shows excellent stability during 8 cycles of solar evaporation. And the evaporator demonstrates superior salt tolerance in 3.5 wt% NaCl solution during the continuous evaporation of 8 h and has an outstanding efficiency of 99.8 % in 4-NP wastewater purification. The outdoor experiment proves that the evaporator of 1 m2 can produce 7.28 L of fresh water per day, which meet the drinking water demand of two adults. The hydrogel/sponge integrated photothermal evaporator has great application potential in seawater desalination and wastewater purification.

Trapping waste metal ions in a hydrogel/coal powder composite for boosting sewage purification via solar-driven interfacial water evaporation with long-term durability

The improper disposal of effluents contaminated with waste metal ions poses significant threats to clean water resources. Recently, solar-driven interfacial water evaporation has gained increasing interests for sustainable water purification, nevertheless, the presence of various hydrated metal ions from industrial effluents makes it challenging for conventional distillers to achieve efficient purification performances. Herein, a waste metal ion trapping strategy based on a novel solar vapor generator (SVG) toward highly efficient solar-driven sewage purification with prolonged durability is reported. This SVG is constructed based on a polyion complex (PIC) hydrogel/coal powder composite (PCC), where the PIC skeleton provides metal ion entrapment capabilities, and the low-cost coal powders act as solar absorbents. PCC enables improved solar-driven sewage purification from two aspects: first, the entrapped multivalent ions help to activate the water molecules inside PCC and lower water evaporation enthalpy, leading to enlarged evaporation rate; second, the strong interactions between the multivalent metal ions and polyelectrolyte chains aid in stabilizing their porous structure and maintaining continuous water transport capabilities. The resultant PCC-based SVG demonstrated high evaporation rate up to 3.6 kg · m−2· h−1 in simulated industrial sewage under one sun illumination, as well as stable and efficient clean water generation in actual coal washery wastewater even for three weeks. We envision that the rational design of SVG with ions trapping capabilities and cost-effective solar absorbers should broaden the practical applications of SVG for harsh wastewater treatment.

A lignin-derived carbon dot-upgraded bacterial cellulose membrane as an all-in-one interfacial evaporator for solar-driven water purification.

Solar-driven interfacial evaporation has emerged as an efficient approach for wastewater treatment and seawater desalination. New trends demand adaptive technology to develop photothermal membranes with multifunctional features. Herein, we report a robust multi-purpose near-infrared (NIR)-active hydrogel composite (c-BC@N-LCD) from broad-spectrum active nitrogen-doped lignin-derived carbon dots (N-LCDs) covalently cross-linked with a bacterial cellulose (BC) matrix. BC provides adequate porosity and hydrophilicity required for easy water transport while managing heat loss. A commendable evaporation rate (ER) of 2.2 kg m-2 h-1 under one sun (1 kW m-2) is achieved by c-BC@N-LCD. The developed hydrogel system is also found to be efficient for desalination (∼2.1 kg m-2 h-1) and for remediating various pollutants (heavy metal ions, dyes, and pharmaceuticals) from feed water. The efficacy of the membrane remains unaltered by different grades of water, and hence can be adoptable for economically stressed communities living in water-polluted regions as well as those residing in coastal areas.

A bioinspired hydrogel with tailored nano-topography and desired mechanical performance for highly efficient solar-driven water purification

Solar-driven interfacial evaporation has emerged as a sustainable and innovative technology for efficient, clean water production.

Efficient solar-driven freshwater generation through an inner hierarchical porous metal-carbon layer bridging synergistic photothermal evaporation and adsorption photodegradation.

Solar-driven interfacial evaporation has emerged as a promising avenue for clean water production, leveraging solar energy to extract water vapor from salty and polluted water sources. However, a critical challenge remains, during the photothermal evaporation process, organic pollutants and small water-soluble molecules can transfer into distilled steam, degrading the purity of the collected water. Herein, we develop a multifunctional clean water generation system that integrates photothermal conversion, adsorptive filtration and subsequent photocatalytic purification within a unified platform. This system features an inner hierarchical porous metal-carbon layer derived from ZIF-67 carbonization, seamlessly bridging a wood carbon scaffold and BiOBr nanosheets (BiOBr@ZCW) to smoothly facilitate synergistic actions between photothermal evaporation and adsorption-photodegradation processes. This BiOBr@ZCW configuration not only minimizes thermal dissipation, facilitating a high evaporation rate of 1.67 kg m-2 h-1 and an efficiency of 85% under standard solar irradiation but also enhances the photocatalytic degradation of the rhodamine B organic pollutant with a remarkable 98.43% degradation rate within just 20 minutes. This integrated system offers a robust solution to the challenges of water purification by ensuring both high efficiency in solar steam generation and effective pollutant degradation.

A dual-crosslinked macroporous aerogel with enhanced mechanical durability for efficient solar-driven desalination of seawater and wastewater

Solar-driven interfacial evaporation for seawater desalination is an effectively green measure to produce clean water and help alleviate freshwater scarcity. However, it is still a challenge to fabricate an interfacial...

Carbon nanotube-based photothermal membrane for efficient cold air heating and removal of particulate matter and airborne bacteria

Indoor heating results in high energy consumption and severe atmospheric pollution. Although the development of solar air heaters provides a sustainable route for indoor thermal comfort, such heaters still face challenges in terms of adequate heat exchange and filtering of atmospheric pollutants. Inspired by solar-driven interfacial evaporation, we propose a multifunctional carbon nanotube-based photothermal membrane for efficient cold air heating and purification via ventilation. Carbon nanotubes endow the membrane with high light absorption and thermal conversion capabilities, thereby sufficiently heating the approaching cold air. With the hierarchical structure formed by phase inversion, the thin upper skin of the composite membrane intercepts micropollutants via the size-sieving effect, whereas the finger-like pores and interpenetrating macrovoids inside the membrane ensure that the heated clear air passes through quickly. A proof-of-principle experiment indicated a cold airflow of 1 L/min across the membrane, yielding a temperature increase of ca. 37 °C as well as a PM 2.5 rejection always higher than 93%. Further antibacterial experiments demonstrated that the membrane effectively removed airborne bacteria. This multifunctional carbon nanotube-based photothermal membrane with specific microstructures not only improves the indoor living quality but also provides a sustainable development scheme to coordinate the relationship among energy utilization, building heating, and air purification.

Vertical porous aerogel based on polypyrrole and bimetallic modified β-cyclodextrin polymer-chitosan for efficient solar evaporation

Solar-driven interfacial evaporation (SDIE) stands out as a prospective technology for freshwater production, playing a significant role in mitigating global water scarcity. Herein, a cyclodextrin polymer/chitosan composite aerogel (PPy-La/Al@CDP-CS) with vertically aligned channels was prepared as a solar evaporator for efficient solar steam generation. The vertically aligned pore structure, achieved through directional freezing assisted by liquid nitrogen, not only improves water transport during evaporation but also enhances light absorption through multiple reflections of sunlight within the pores. The polypyrrole particles sprayed on the surface of the aerogel acted as a light-absorbing layer, resulting in an impressive absorbance of 98.15 % under wetting conditions. The aerogel has an evaporation rate of 1.85 kg m−2 h−1 under 1 kW m−2 irradiation. Notably, the vertical pore structure of the aerogel allows it to exhibit excellent evaporation performance and salt resistance even in highly concentrated salt solutions. Furthermore, this aerogel is an excellent solar-driven interfacial evaporator for purifying seawater and fluoride-containing wastewater. This photothermal aerogel has the advantages of excellent performance, low cost, and environmental friendliness, and thus this work provides a new approach to the design and fabrication of solar photothermal materials for water treatment.

Improved solar-driven water purification using an eco-friendly and cost-effective aerogel-based interfacial evaporator with exceptional photocatalytic capabilities

As a promising solution to address the global challenge of freshwater scarcity, solar-powered interfacial steam generation has undergone notable advancements. This study introduces a novel solar-driven interfacial evaporation membrane (ZnIn2S4@SiO2/ACSA, ZSAS) comprising a ZnIn2S4@SiO2 composite and a black sodium alginate aerogel infused with activated carbon. The ZSAS membrane demonstrates exceptional light absorption and thermal insulation, leading to elevated surface temperatures and reduced heat dissipation into the bulk water. Furthermore, the incorporation of AC reinforces the mechanical properties of the ZSAS membrane and enhances the water purification performance. These collective features result in an impressive evaporation rate of 1.485 kg m−2 h−1 and a high photothermal conversion efficiency of 91.2% under 1 sun irradiation for the optimal ZSAS membrane. Moreover, the optimal ZSAS membrane can effectively remove salts, heavy metal ions, and organic pollutants, benefitting from its superior evaporation separation effect and the photocatalytic properties of the ZnIn2S4@SiO2 composite.

Developing a highly efficient, environmentally friendly and cost-effective copper sulfide semiconductor sponge for nuclear wastewater treatment under one sun

Solar-driven interfacial evaporation technology, as a green and low-energy water treatment method, finds widespread applications in desalination, power generation, and wastewater treatment systems. In this study, a three-dimensional sponge solar evaporator was prepared using hydrophilic compounds (konjac glucomannan, KGM) and a solar absorber (copper sulfide, CuS). In a single instance of solar irradiation, the sponge demonstrated swift evaporation rates at 1.58 kg m−2 h−1, coupled with an impressive interfacial water evaporation efficiency of 94.30%. Due to the characteristics of CuS and KGM, the sponge demonstrated photothermal properties, insulation, and rapid water transport. Even under radiation (1 kW/m2) and a wide range of pH conditions (pH∼2–12), the concentration of elements in radioactive wastewater could be reduced by a million times (from 1 g/L to 0.253 μg/L). Notably, during 20 cycles of testing, the sponge's evaporation efficiency only decreased by 1.13%. Furthermore, over an extended 5-hour evaporation period, it consistently sustained a steady evaporation rate of 1.577 kg m−2 h−1, showcasing its exceptional reproducibility and enduring resilience. Therefore, solar-driven interfacial evaporation technology exhibits significant potential for efficient treatment of radioactive wastewater.

Flexible hierarchical polypyrrole-coated Cu-BTC MOFs photothermal textile for efficiently solar water evaporation and wastewater purification

Solar-driven interfacial water evaporation (SDIWE) endures a significant potential for producing clean water from seawater and wastewater because it requires no additional energy source. Photothermal materials with efficient solar absorption and pollutant removal capabilities are critical for SDIWE. However, an efficient and facile strategy to prepare a high-performance and flexible photothermal material and simultaneously prevent the salt accumulation for efficient and long-term steady evaporation to produce potable water from seawater and wastewater is still a challenge. Herein, based on the MS and ALD processes, two novel flexible photothermal materials are synthesized using the flexible polyester fabric substrate, hierarchical metal–organic framework Cu-BTC MOFs, and polypyrrole (PPy) as a light-absorption layer. In particular, under the synergistic effect of the hierarchical porous Cu-BTC MOFs and PPy with excellent solar absorption, the flexible photothermal material possesses excellent light absorption (92.58 % ∼ 93.98 %), super hydrophilicity, low thermal conductivity, high evaporation rate (1.53 ∼ 1.56 kg m-2h−1 for 15 days), outstanding salt resistance (1.42 kg m-2h−1 at a salinity of 15 wt%), and excellent metal ions and organic pollutants removal capacity after solar evaporation. These multifunctional properties ensure its great application prospect for future freshwater production while also providing a new reference for other applications.

Z-Scheme heterojunction WO3/ZnIn2S4 solar absorber for wastewater remediation

Z-Scheme heterojunction, recognized as one of the optimal methods for the separation of electrons and holes, is extensively applied in the domain of photocatalytic. Leveraging the Z-Scheme heterojunction for photocatalytic and solar interfacial water evaporation presents a promising solution for the purification of dye wastewater and the mitigation of organic pollutant accumulation on traditional solar absorbers. In this study, WO3/ZnIn2S4 heterojunction was synthesized through a two-step solvothermal method, and resulting WO3/ZnIn2S4, which rested on a flexible substrate Ti mesh, possessed the dual functionality of interfacial water evaporation and photocatalytic treatment of dye wastewater, which not only water evaporation rate for WO3/ZnIn2S4 reached 1.26 kgꞏm−2ꞏh−1 but also the Z-Scheme heterojunction WO3/ZnIn2S4 empowered it to effectively degrade dye wastewater, with a degradation rate of Rhodamine B up to 98.6%. The harmonization of these two functionalities effectively circumvented the issue of secondary pollution commonly associated with dye wastewater treatment. This study effectively integrates photocatalysis into a cutting-edge solar-driven interfacial evaporation system, effectively expanding the capabilities of a multifunctional solar absorber and introducing novel applications for zero-discharge dye wastewater treatment.

Wicking-controlled interfacial water content for highly efficient solar desalination

Solar-driven interfacial evaporation offers a potential solution to address global freshwater scarcity. However, the water-thermal-vapor-salt imbalance issue severely affects the operating efficiency of the evaporator. This research examines the correlation among water supply height, spontaneous wicking rate, and interfacial water content. Subsequently, an engineering strategy is proposed to control the water concentration gradient within a two-dimensional solar absorber with vertical water supply channels. The results demonstrate that the hydrophilicity and internal structure of the material exert a crucial influence on the transport of bulk water. Specifically, longitudinal stripes within the water-conducting material promote a faster wicking rate and higher wicking height. This phenomenon occurs due to the combined effects of capillary forces and gravity, leading to a gradual decrease in liquid saturation along the capillary direction within the water-conducting material. By optimizing the water supply height and rate, the evaporation interface achieves a remarkable water evaporation rate of 1.50 kg m−2h−1. Building on this success, a novel configuration for a flow desalination evaporator is proposed, capable of sustaining the same evaporation rate even when operating continuously for 9 h in saltwater with a mass concentration of 20 %. Overall, this study emphasizes the importance of water and heat balance at the evaporative interface, reconciling conflicting requirements of interface flow and evaporation rate. These findings contribute to the development of highly efficient and reliable evaporators for sustainable freshwater generation.

Downward design of solar-driven interfacial evaporators: Beyond the limitation of vertical water delivery in conventional upward evaporators

Solar-driven interfacial evaporation (SIE) represents a promising approach for freshwater production that eliminates the need for fossil fuel inputs. One of the primary objectives of SIE is to achieve a high evaporation rate. To enhance SIE performance, it is advantageous to increase the height of the evaporators, as this expands the evaporating interface. However, many existing evaporators face limitations in water delivery due to the competition between gravity and capillary forces. In this study, we propose a downward design strategy that mitigates this competition, resulting in a larger evaporating interface and higher evaporation rate. Through our experimental setup, we achieved an impressive evaporation rate of 2.01 kg·m−2·h−1 using the downward evaporator, which is 46.7% higher than that of the upward evaporator. When applied to desalination, downward evaporators exhibit excellent anti-salt performance, owing to an ample water supply, thereby enabling prolonged operation without a decline in evaporation rate or observable salt precipitation, even under 2.0-sun illumination. Furthermore, we demonstrate that the downward design strategy allows water bodies, rather than air, to serve as the cold source for condensation, enabling the attainment of a higher temperature gradient and enhanced vapor condensation. We achieved a notable water harvesting rate of 0.76 kg·m−2·h−1 under 1.0-sun irradiation.

Economic and environmental protection high efficiency solar steam generator: Carbonized starch with porous structure

Solar-driven interfacial water evaporation is an emerging water purification technology. However, the high cost and low evaporation efficiency limit the wide application of solar-driven interfacial water evaporation technology. In this work, we use the dough fermented flour and yeast powder production, and then after fermentation of dough to produce high temperature carbonization of carbon materials, the preparation of the sample surface formed a large number of pits, increased specific surface area and the absorbance of the sample, and increased the solar-thermal conversion efficiency of the sample. It is found that the evaporation rate and evaporation efficiency of the sample made in this work is 1.5 kg m−2h−1 and 94.2 % respectively under one solar irradiation intensity. The maximum surface temperature of the sample can reach 43.3℃ during the experimental test, which has good evaporation performance. It provides a new idea for making economical and environmentally friendly materials in the field of solar-driven water evaporation.

Recycling Graphite from Spent Lithium Batteries for Efficient Solar-Driven Interfacial Evaporation to Obtain Clean Water.

Invited for this month's cover, the researchers from Huaqiao University and Jilin Jianzhu University. The Cover image shows the use of spent graphite to prepare hydrogels for photothermal evaporation to produce clean water. The Research Article itself is available at 10.1002/cssc.202300845.

Bioinspired Asymmetric Polypyrrole Membranes with Enhanced Photothermal Conversion for Highly Efficient Solar Evaporation.

Solar-driven interfacial evaporation (SDIE) has attracted great attention by offering a zero-carbon-emission solution for clean water production. The manipulation of the surface structure of the evaporator markedly promotes the enhancement of light capture and the improvement of evaporation performance. Herein, inspired by seedless lotus pod, a flexible pristine polypyrrole (PPy) membrane with macro/micro-bubble and nanotube asymmetric structure is fabricated through template-assisted interfacial polymerization. The macro- and micro-hierarchical structure of the open bubbles enable multiple reflections inner and among the bubble cavities for enhanced light trapping and omnidirectional photothermal conversion. In addition, the multilevel structure (macro/micro/nano) of the asymmetric PPy (PPy-A) membrane induces water evaporation in the form of clusters, leading to a reduction of water evaporation enthalpy. The PPy-A membranes achieve a full-spectrum light absorption of 96.3% and high evaporation rate of 2.03kgm-2 h-1 under 1 sun. Long-term stable desalination is also verified with PPy-A membranes by applying one-way water channel. This study demonstrates the feasibility of pristine PPy membranes in SDIE applications, providing guidelines for modulation of the evaporator topologies toward high-efficient solar evaporation.

Ti3C2TX/carbon aerogels derived from winter melon for high-efficiency photothermal conversion

Solar-driven interfacial evaporation is a promising and cost-effective technique for converting light to heat, especially for seawater desalination to address the scarcity of fresh water resources. Biomass-based carbon aerogels have demonstrated significant potential for photothermal conversion due to their low cost, renewability, and environmental friendliness. However, there is still room for improvement in enhancing the photothermal conversion performance of biomass-derived carbon aerogels. In this study, we present Ti3C2TX/carbon aerogels derived from winter melon, which exhibit exceptional photothermal conversion properties for solar steam generation. The Ti3C2TX/carbon aerogels were prepared using a combined process involving hydrothermal treatment, carbonization, and dip-coating, with winter melon as the raw material. The synergistic effect of MXene and carbon aerogels contributes to the satisfactory photothermal conversion performance of the Ti3C2TX/carbon aerogels, including a high evaporation rate (up to 1.48 kg m−2 h−1 under 1 sun irradiation), a high photothermal conversion efficiency (92.3 %), and excellent cycling stability. Moreover, the photothermal properties of the Ti3C2TX/carbon aerogels improve with an increasing mass of Ti3C2TX loading in the aerogel. In addition to solar steam generation, the Ti3C2TX/carbon aerogels also exhibit great potential in applications such as photothermal therapy, deicing, and oil absorption, owing to their exceptional photothermal properties.

Pyramid-shaped solar evaporator with high-efficient interfacial evaporation and salt harvesting capability

Solar-driven interfacial evaporation shows significant potential for addressing challenges associated with freshwater shortages and environmental pollution. In this study, a series of pyramid-shaped solar evaporators were fabricated to achieve highly efficient solar interfacial evaporation. The optimized triangular pyramid evaporator exhibits exceptional adaptability and stability in seawater desalination and wastewater purification, thanks to its excellent light capture and photothermal conversion capacity, controlled water supply, effective thermal management, and energy input from the environment. It maintains a high evaporation rate and energy efficiency even in highly concentrated saltwater and strongly acidic or alkaline solutions. The 3D conical evaporation structure promotes top-preferential crystallization, directing the crystallization process towards the apex and facilitating efficient spatial salt harvesting. The collected condensate meets the drinking water requirements set by the World Health Organization (WHO) and the US Environmental Protection Agency (EPA). Under outdoor evaporation conditions, the evaporator achieves a daily freshwater production of 24.93 and a salt production of 2.09 kg m−2 d−1, fully satisfying the needs of a typical three-person household. Our microstructure control strategy for enhancing solar interfacial evaporation offers valuable insights and inspiration to researchers aiming to improve the performance of 3D solar evaporators.

Hierarchical nanofibrous and recyclable membrane with unidirectional water-transport effect for efficient solar-driven interfacial evaporation

Solar-driven interfacial evaporation technology has attracted significant attention for water purification. However, design and fabrication of solar-driven evaporator with cost-effective, excellent capability and large-scale production remains challenging. In this study, inspired by plant transpiration, a tri-layered hierarchical nanofibrous photothermal membrane (HNPM) with a unidirectional water transport effect was designed and prepared via electrospinning for efficient solar-driven interfacial evaporation. The synergistic effect of the hierarchical hydrophilic-hydrophobic structure and the self-pumping effect endowed the HNPM with unidirectional water transport properties. The HNPM could unidirectionally drive water from the hydrophobic layer to the hydrophilic layer within 2.5 s and prevent reverse water penetration. With this unique property, the HNPM was coupled with a water supply component and thermal insulator to assemble a self-floating evaporator for water desalination. Under 1 sun illumination, the water evaporation rates of the designed evaporator with HNPM in pure water and dyed wastewater reached 1.44 and 1.78 kg·m−2·h−1, respectively. The evaporator could achieve evaporation of 11.04 kg·m−2 in 10 h under outdoor solar conditions. Moreover, the tri-layered HNPM exhibited outstanding flexibility and recyclability. Our bionic hydrophobic-to-hydrophilic structure endowed the solar-driven evaporator with capillary wicking and transpiration effects, which provides a rational design and optimization for efficient solar-driven applications.