Interfacial Solar Evaporation Research Articles

A dual-functional hydrogel for efficient water purification: Integrating solar interfacial evaporation with fenton reaction

Solar interfacial evaporation is a potential technology to produce clean water due to its simplicity and being driven by renewable clean energy, but it still requires further development to break through the bottleneck of removing volatile organic compounds (VOCs), especially in wastewater treatment. Herein, we proposed a dual-functional hydrogel evaporator that coupled solar interfacial evaporation with Fenton reaction to simultaneously remove VOCs and non-volatile pollutants from water with low energy consumption and high efficiency. The evaporator was composed with β-FeOOH and polydopamine (PDA) on an electrospun nanofibrous hydrogel. Arising from the PDA with excellent photothermal properties, the evaporator revealed a high light absorption characteristics (∼90%) and photothermal efficiency (83.4%), which ensured a favorable evaporation rate of 1.70 kg m-2 h-1 under one solar irradiation. More importantly, benefited from the coupled Fenton reaction, the VOCs removal rate of β-FeOOH@PDA/polyvinyl alcohol nanofibrous hydrogel (β-FeOOH@PPNH) reached 95.8%, which was 6.5 times than that of sole solar interfacial evaporation (14.8%). In addition, the evaporator exhibited an outstanding non-volatile pollutant removal capability and stable removal performance for organic pollutants over a long period of operation. The prepared β-FeOOH@PPNH evaporator provides a promising idea for simultaneous removal of non-volatile pollutants and volatile pollutants performance in long-term water purification.

Plant-inspired multi-environmentally adaptive, flexible, and washable solar steam generation fabric

Interfacial solar water evaporation has been widely fabricated for water treatment owing to its great promise in harvesting fresh water with clean energy in need for carbon neural target. However, developing an evaporator with recyclability under severe contamination and adaptability for various complex aqueous environments, remains challenging. Herein, inspired by mangrove forest growing in salty shoals, an adaptive tree-like evaporator (ATE) was fabricated by rolling cotton threads and punched (pin-holed) carbon nanotube (CNT) film into modified photothermal bundles and further weaving them into root-leaf like structure, enabling uncoated cotton bundles as dense roots for extracting and transporting water and coated part as leaves with open holes for evaporation. Such a facile ATE showed stable water evaporation rate, and an excellent salt-self-cleaning performance. Importantly, the ATE was also available to extract and evaporate wastewater from some severe environments, such as mud, sand, emulsion and dye solution. The ATEs were scalable, and particularly proved to be flexible and robust for washing and reusing, with evaporation performance almost unchanged after 100 cycles. This work has demonstrated a prototype for an efficient, adaptive and scalable fabric evaporator for solar-driven wastewater treatment, opening the possibility to solve provisional freshwater supply in poverty-stricken or polluted areas.

Rationally constructing a 3D bifunctional solar evaporator for high-performance water evaporation coupled with pollutants degradation

In this work, nitrogen-doped carbon nanotubes encapsulated with Co are grown on carbon fibers (Co-NCNT/CF) and utilized as photothermal materials to construct 3D evaporators, which simultaneously realize highly efficient solar evaporation and organic pollutant degradation. The deliberate structure enables the 3D evaporator to take advantage of the spontaneously generated internal convection flow to significantly enhance solar evaporation, achieving a high evaporation rate of 3.85 kg m−2 h−1 under 1.0 sun irradiation. More importantly, the evaporator exhibits excellent performance on peroxymonosulfate (PMS) activation, effectively preventing phenol in water sources from entering the condensed clean water. Density functional theory (DFT) calculation shows that the enhanced van der Waals interaction facilitates PMS adsorption and activation on the confined inner surfaces of Co-NCNT compared to the unconfined system. This solar evaporator successfully combines interfacial solar evaporation and advanced oxidation processes, providing a new strategy for producing clean water from water sources containing organic volatiles.

PC@PPy porous membrane prepared by breath figure method with superior mechanical property for efficient solar interfacial evaporation

Solar interfacial evaporation (SIE) is one of the most prospective solar energy harvesting technologies for solving the scarcity of freshwater resources. Herein, we report a novel photothermal membrane polycarbonate (PC)@polypyrrole (PPy) (PC@PPy) adopting to breath figure method followed by surface chemistry modification, and assemble a double-layer solar interfacial evaporator consisting of PC@PPy photothermal membrane as the upper layer and plant fiber-wrapped expanded polyethylene (EPE) foam as the bottom layer for SIE. Due to the abundant porous structure and strong light absorption of the PC@PPy membrane, excellent insulation of the EPE sponge, the as-prepared PC@PPy-EPE evaporator exhibits a high evaporation of 1.78 kg m-2h−1 and photothermal conversion efficiency of 93.57%, and outstanding evaporation stability and resistance in 16% wt NaCl with an evaporation of 1.58 kg m-2h−1 under 1 sun irradiation. Moreover, the PC@PPy photothermal possess superior flexibility and strong mechanical properties. Coupling with cost-effective, environment-friendly, simple and easily scale-up breath figure preparation method, the PC@PPy-EPE generator has broad application prospects in SIE.

H2O2 treatment with rGO surface coating for interfacial solar evaporation of river sediment drying

Interfacial solar evaporation is a low-energy, low-carbon emission method used to enhance seawater desalination and sewage treatment. In this work, this technology is employed for drying of river sediment. This is an innovative approach to solve the perpetual problem of large volume and high water content river sediment. Reduced graphene oxide (rGO) is coated on to the surface of the mud to enhance photothermal conversion, and H2O2 is used to condition the properties of the sediment so that multitudinous pores are formed inside the mud cake aiding heat convection transfer. These two strategies were implemented simultaneously to promote drying efficiency. Indoor simulated evaporation for 2 h under 1.0 sun illumination of sediment (3 cm thickness) conditioned using 62.5 mL·kgDS-1 H2O2 (H2O2 solution concentration of v/v 30%, DS – dry solids) coated with 97 g m−2 rGO, compared with the original mud without any treatment, resulted in an increase in evaporation rate of 40%. In outdoor experiments (5 h) the evaporation rate was increased by 54%, confirming that H2O2 coupled with rGO can effectively enhance the drying efficiency of interfacial solar evaporation for river sediment. Evaporation tests on different thicknesses of sediment showed that the thinner the mud cake the more favorable it is for drying. The water diffusion coefficient in the mud cake treated with 62.5 mL·kgDS-1 of H2O2 (30% v/v) and 97 g m−2 rGO was 9.73 × 10−8 m2 s−1. The untreated mud cake that had water diffusion coefficient of 3.86 × 10−9 m2 s−1. The logarithmic thin layer model was found to describe the sediment drying process well.

Scalable Core–Sheath Yarn for Boosting Solar Interfacial Desalination Through Engineering Controllable Water Supply

Tailoring water supply to achieve confined heating has proven to be an effective strategy for boosting solar interfacial evaporation rates. However, because of salt clogging during desalination, a critical point of constriction occurs when controlling the water rate for confined heating. In this study, we demonstrate a facile and scalable weaving technique for fabricating core–sheath photothermal yarns that facilitate controlled water supply for stable and efficient interfacial solar desalination. The core–sheath yarn comprises modal fibers as the core and carbon fibers as the sheaths. Because of the core–sheath design, remarkable liquid pumping can be enabled in the carbon fiber bundle of the dispersed super-hydrophilic modal fibers. Our woven fabrics absorb a high proportion (92%) of the electromagnetic radiation in the solar spectrum because of the weaving structure and the carbon fiber sheath. Under one-sun (1 kW·m−2) illumination, our woven fabric device can achieve the highest evaporation rate (of 2.12 kg·m−2·h−1 with energy conversion efficiency: 93.7%) by regulating the number of core–sheath yarns. Practical application tests demonstrate that our device can maintain high and stable desalination performance in a 5 wt% NaCl solution.

Recent strategies for constructing efficient interfacial solar evaporation systems

Interfacial solar evaporation (ISE) is a promising technology to relieve worldwide freshwater shortages owing to its high energy conversion efficiency and environmentally sustainable potential. So far, many innovative materials and evaporators have been proposed and applied in ISE to enable highly controllable and efficient solar-to-thermal energy conversion. With rational design, solar evaporators can achieve excellent energy management for lowering energy loss, harvesting extra energy, and efficiently utilizing energy in the system to improve freshwater production. Beyond that, a strategy of reducing water vaporization enthalpy by introducing molecular engineering for water-state regulation has also been demonstrated as an effective approach to boost ISE. Based on these, this article discusses the energy nexus in two-dimensional (2D) and three-dimensional (3D) evaporators separately and reviews the strategies for design and fabrication of highly efficient ISE systems. The summarized work offers significant perspectives for guiding the future design of ISE systems with efficient energy management, which pave pathways for practical applications.

Ion‐Transfer Engineering via Janus Hydrogels Enables Ultrahigh Performance and Salt‐Resistant Solar Desalination (Adv. Mater. 24/2023)

Solar Desalination In article number 2300189, Lin Li and co-workers present a Janus ion-selective hydrogel interfacial evaporator, which enables ion-electromigration salt removal. The from-scratch salt-removal route breaks the limitations of the conventional water-convection enhanced routes, and significantly lowers heat loss, achieving a record-high evaporation rate and holding great promise for future solar interfacial evaporation applying desalination.

Going beyond efficiency for solar evaporation

Interfacial solar evaporation, which captures solar energy and localizes the generated heat for evaporating water molecules, is regarded as an important emerging strategy for solar energy conversion. In the past decade, global collective efforts have propelled fast and exciting advancements, with solar-to-vapour efficiencies approaching the thermodynamic limit. This has also spurred significant interest in many applications. However, improving the energy efficiency alone cannot move the field towards the practical development of these applications. A matrix of different factors and fundamental challenges should therefore be taken into consideration in addition to the solar-to-vapour efficiency or evaporation flux. In this Perspective we first discuss several promising applications of solar evaporation, and the corresponding figures of merit, for clean water production, wastewater and brine management, resource recovery, sterilization and power generation. We then discuss the fundamental aspects of solar evaporation that need to be determined, such as microscopic thermal transfer and water molecule bonding, which are closely related to evaporative performance. Finally, energy sources beyond solar energy will be discussed to further boost the evaporative performance. Efficiency is only one of the parameters involved in solar evaporation that should be improved to make it practical. Depending on the application, various factors of merit should be taken into consideration, as discussed in this Perspective.

Laser-Induced Transfer of Functional Materials

Patterning is crucial for the large-scale application of functional materials. Laser-induced transfer is an emerging patterning method for additively depositing functional materials to the target acceptor. With the rapid development of laser technologies, this laser printing method emerges as a versatile method to deposit functional materials in either liquid or solid format. The emerging applications such as solar interfacial evaporation, solar cells, light-emitting diodes, sensors, high-output synthesis, and other fields are rising fields benefiting from laser-induced transfer. Following a brief introduction to the principles of laser-induced transfer, this review will comprehensively deliberate this novel additive manufacturing method, including preparing the donor layer and the applications, advantages, and limitations of this technique. Finally, perspectives for handling current and future functional materials using laser-induced transfer will also be discussed. Non-experts in laser technologies can also gain insights into this prevailing laser-induced transfer process, which may inspire their future research.

Cellulose‐based Interfacial Solar Evaporators: Structural Regulation and Performance Manipulation

AbstractThe shortage of freshwater resources has become a major obstacle threatening human development, and directly utilizing solar energy by solar evaporators is emerging as a promising method to produce freshwater from the seawater. Compared to many synthetic polymer‐based evaporators, cellulose‐based evaporators are expected to offer more interesting features benefiting from the renewable feature and abundant reserves of cellulose‐contained naturally occurring materials. First, according to the different fabrication methods, cellulose‐based solar evaporators can be divided into two types, i.e., top‐down utilization (wood‐based) and bottom‐up assembled (cellulose composite‐based), respectively. The different fabrication schemes also bring their own unique advantages, such as the bimodal porous structure of wood‐based evaporators and the artificial interconnection microporous network of cellulose composite‐based evaporators. Subsequently, this review further summarizes the most recent advances and highlights of those cellulose‐based solar evaporators, by focusing on their structural regulation strategies (e.g., drilled channel array, asymmetric wettability structure, delignification, 2D waterway, etc.) and evaporation performance improvements (e.g., salt resistance, high evaporation rate, etc.). Finally, the challenges in this field and potential solutions are also discussed, which are anticipated to provide new opportunities toward the future development of cellulose and other kinds of biomass‐based evaporators.

Solar-powered and antibacterial water purification via Cu-BTC-embedded reduced graphene oxide nanocomposite aerogels

Advancements in the design of porous active materials for interfacial solar evaporation have shown promise in the development of next-generation solar evaporation active materials that can present a wide range of water-purification properties. In this study, a new class of metal–organic nanoparticles-embedded reduced graphene oxide (rGO) nanocomposite aerogels is developed, with both solar steam generation behavior and antibacterial properties. The self-assembly process is used to introduce Cu-BTC nanoparticles (Cu-BTC NPs) into the structure of rGO aerogels to fabricate Cu-BTC/rGO nanocomposite aerogels. By varying the content of Cu-BTC NPs in the self-assembly precursor solution, the surface area, pore texture, and evaporation rate of samples are altered to reach both high energy conversion efficiency and antibacterial properties. An evaporation rate of 1.13 kg/m2h and an efficiency of 81.8% are achieved when the highest content of Cu-BTC NPs (1 mg/ml) is introduced to the precursor solution. This evaporation efficiency is 32% and 59% higher than that of the rGO aerogel and pure water, respectively. This behavior is related to the surface area and pore size of the nanocomposite aerogels, which increase and decrease with the content of Cu-BTC NPs, respectively. Additionally, the Cu-BTC/rGO aerogel presents antibacterial activity against S. aureus and E. coli. As a result, Cu-BTC/rGO nanocomposite aerogels have great potential as active materials for the design of next-generation solar steam generation systems for the treatment of wastewater contaminated with pathogenic bacteria.

A multi-function bamboo-based solar interface evaporator for efficient solar evaporation and sewage treatment

Bamboo-based interfacial solar evaporation (B-BISE) is leading a new generation of biomass-based materials for solar-driven water purification. Compared with the popular wood, the variety, growth rate and unique channel structure of bamboo make it a research hotspot. Herein, inspired by bamboo transpiration, we manufactured an easily obtained solar evaporator. The TA/Fe3+ particles were successfully loaded onto the surface of bamboo by dipping it in tannic acid (TA) and Fe (III) solution. The acquired evaporator (TA/Fe3+-bamboo) has a unique structure that allows it to transport water horizontally and vertically, simultaneously low heat loss and outstanding light absorption can improve its evaporation performance. The evaporator exhibited evaporation performance with the rate of 1.152 kg m−2 h−1 and efficiency of 78.86 % at 1 kW m−2. Moreover, the device also exerted excellent decontamination function in sewage treatment, which was expected to obtain freshwater in sewage for human daily use. This research offers a new approach for effectively utilizing bamboo resources and provides a new direction for seawater desalination by using clean energy and biomass materials.

Orderly-assembled photothermal photonic crystals with multiple structural colors for high-performance interfacial solar desalination

The microstructure of photothermal materials plays a central role in interfacial solar evaporation, which is vital to solar absorption, thermal management, water and vapor transportation. Ordered structures constructed on cross-scale in a controllable fashion are potentially important for high-performance photothermic vaporization, and may provide fundamental insight into the correlation between microstructure and evaporation efficiency. Herein, the ordered photothermal materials featuring brilliant structural colors and spectral and thermal management are cross-scale assembled using unique colloidal photonic crystals (PCs) as the building block. Multidimensional ordered PC photothermal materials including PC layered nanofilms, microbeads and three-dimensional (3D) scaffolds are facially constructed by Langmuir-Blodgett, microfluidics and 3D printing techniques, respectively, exhibiting excellent internal light reflection and water wettability. As a result, the corresponding solar vaporization rates of 2.23, 2.14 and 2.0 kg m-2h−1 are achieved under 1 sun, greatly surpassing that in disordered PC films. Notably, the structural color originated from periodic-arranged PC structure shows a regulable and colorful appearance, in contrast to the monotonous black color in conventional broadband photothermal materials. The controllable methodology for ordered architecture construction inspires more novel nanostructured and multifunctional photothermal materials for solar evaporation materials.

Highly Salt-Resistant interfacial solar evaporators based on Melamine@Silicone nanoparticles for stable Long-Term desalination and water harvesting

Interfacial solar-driven evaporation (ISE) is one of the most promising solutions for collecting fresh water, however, poor salt-resistance severely limits the long-term stability of solar evaporators. Here, highly salt-resistant solar evaporators for stable long-term desalination and water harvesting were fabricated by depositing silicone nanoparticles onto melamine sponge, and then modifying the hybrid sponge sequentially with polypyrrole and Au nanoparticles. The solar evaporators have a superhydrophilic hull for water transport and solar desalination, and a superhydrophobic nucleus for reducing heat loss. Spontaneous rapid salt exchange and reduction in salt concentration gradient were achieved due to ultrafast water transport and replenishment in the superhydrophilic hull with a hierachical micro-/nanostructure, which effectively prevents salt deposition during ISE. Consequently, the solar evaporators have long-term stable evaporation performance of 1.65 kg m-2h−1 for 3.5 wt% NaCl solution under 1 sun illumination. Moreover, 12.87 kg m−2 fresh water was collected during consecutive 10 h ISE of 20 wt% brine under 1 sun without any salt precipitation. We believe that this strategy will shed a new light on the design of long-term stable solar evaporators for fresh water harvesting.

Solar Interfacial Evaporation at the Water–Energy Nexus: Bottlenecks, Approaches, and Opportunities

Solar Interfacial Evaporation Water-energy nexus is a crucial factor affecting economic and social development of nations. In article number 2201098, Haibing Cong, Bing Xu, and co-workers review solar interfacial evaporation (SIE) having merged as an eco-friendly and sustainable technology that utilizes available solar energy to produce fresh water. With the booming of SIE technology in recent years, realizing the concurrent clean water production and energy exploitation effectively.

Cryptomelane Modified Biomass Wastes for Solar Interfacial Evaporation and Stabilization of Cadmium

In this work, after carbonization of two biomass wastes, rice husk and coconut husk, they were modified by hydrothermally synthesized cryptomelane manganese and prepared into a solar interfacial evaporation system to explore their evaporation performance and stabilization performance of cadmium. The results demonstrate that the cryptomelane-modified biochar can obtain an evaporation rate of 1.247 kg m−2 h−1 and a photothermal conversion efficiency of 89.36% under one sun (1 kW m−2). In an outdoor experiment with an average solar power density of only 465.22W m−2, the evaporation capacity reached 4.7 kg m−2 and the evaporation rate reached 0.78 kg m−2 h−1 within 6 h. The cadmium adsorption capacity of biomass waste modified by manganese potassium ore increased by 50.94%, which could be well used for long-term stabilization and recycling of Cd. It could be verified that the cryptomelane-modified biochar material is a low-cost, scalable, and efficient material for interfacial evaporation and reduce wastewater pollution. The evaporation system designed in this work is a feasible way to obtain clean water and solve wastewater problems in the future.

Facile fabrication of compressive aerogels with novel core/shell fibrous skeleton for oil sorption and thermal evaporation

Due to the great size difference and poor interfacial compatibility, the traditional fiber reinforced aerogel composites mainly exist in form of particles deposited on the filled fibers with insufficient mechanical property. In this work, A novel compressive silica aerogel (SNAG) with electrospun SiO2 nanofibers (SNFs) as reinforcement was facilely established via a simple acid/base catalyzed two-step method under ambient pressure drying. The obtained SNAG is organized with unique fibrous core/shell skeletons to acquire excellent properties of low density, hydrophobicity, strong mechanical and effective insulation. The SNAG has a sorption capacity of 10.3 g g−1 for CH2Cl2 and can be repeatedly used through rapid compression and springback with a compressive ratio of 65%. The mechanical strength of the SNAG with 0.6 wt% SNFs can reach up to 0.23 MPa, which is 4.9 times higher than that of pure silica aerogel without addition of SNFs. Moreover, SNAG has been successfully employed as insulator for interfacial solar thermal evaporation with an evaporation rate of 1.31 kg m−2 h−1 to produce fresh water. It is believed that the obtained SNAG would be a prospective elastic aerogel for various applications and bring new insights into designing high-strengthen aerogels.

A Lotus‐Petiole‐Inspired Hierarchical Design with Hydrophilic/Hydrophobic Management for Enhanced Solar Water Purification

AbstractSolar‐driven vapor generation offers an affordable and sustainable approach to solve global freshwater scarcity. Creating interfacial solar evaporators capable of increasing water production rates matching human water requirements is highly desirable but challenging due to the slow water transportation dynamics and unavoidable oil‐fouling. Herein, a bio‐inspired lotus‐petiole‐mimetic microstructured graphene/poly(N‐acryloyl glycinamide) solar evaporator with integrated hydrophilic and hydrophobic microregions is developed. Through accurate control of the supramolecular interactions, the optimized solar evaporator incorporating unique structural features and wettability shows high light harvesting, enhanced water activation, and reduced energy demand for water vaporization, enabling a groundbreaking comprehensive performance along evaporation rate up to 3.4 kg m−2 h−1 and energy conversion efficiency of ≈93% under one sun irradiation (1 kW m−2). Molecular dynamics simulations reveal that the abundant hydrogen bonding sites of the polymeric networks can thermodynamically modulate the escape behavior of water molecules. Notably, neither decrease in evaporation rate nor fouling on solar evaporators is observed during the prolonged purification process toward nano/submicrometer emulsions, oily brines, actual seawater, and domestic wastewater. This study provides distinctive insights into water evaporation behaviors at a molecular level and pioneers a rational strategy to design high‐yield freshwater‐generation systems for wastewater containing complex contaminants.

Scalable and flexible biomass-based porous Juncus effusus fabric for high-efficient solar interfacial evaporation

Biomass porous materials have special structural properties that serve as solar interfacial evaporators. However, the integrated flexible design of porous materials for vapor generation is a problem. In this study, a novel textile weaving craft was proposed to fabricate a scalable, flexible, and stable solar vapor generator using a natural biomass porous plant (Juncus effusus, JE fibers). The high porosity, reflection, and refraction paths of light in the pore structure of JE fibers help improve water vapor escape and light absorption. Additionally, the designed bridge-like porous Juncus effusus-cotton yarn fabric (JECYF)-based solar vapor generator can achieve efficient thermal management, which can enhance the photothermal conversion efficiency of evaporation. After acquiring a light absorption modification treatment, the JECYF-based solar vapor generator obtained a significant photothermal performance of 2.42 kg m−2h−1 under 1 sun irradiation. Thus, textile weaving technology’s unique properties make large-scale preparation and practical application of porous materials in solar vapor evaporator devices possible.