Efficient Solar Steam Generation Research Articles

Self‑supporting magnetic nanoporous silver-nickel films with broadband light absorption for efficient interfacial solar steam generation

Interfacial solar steam generation (SSG) is a promising eco-friendly strategy for freshwater production to address the global water crisis, which depends upon high-efficiency and low-cost photothermal materials. Herein, a series of self-supporting magnetic nanoporous silver-nickel (NP-AgNi) films were fabricated by one-step dealloying of specially designed Al99AgxNi1-x (x = 0.3, 0.5, 0.7) precursors. Both in-situ and ex-situ characterizations were performed to unveil the phase/structure evolution during dealloying of AlAgNi. Specially, the obtained NP-AgNi films with high porosity (>89 %) and tunable magnetic properties exhibit a unique three-dimensional bicontinuous ligament-channel Ag network with embedded Ni microparticles, as well as good hydrophilicity. Combined with the synergistic light absorption of the bimetal Ag and Ni, the NP-AgNi films exhibit good broadband absorption over the 200–2500 nm wavelength. More importantly, the NP-AgNi films show excellent SSG performance (evaporation efficiency over 89 %, evaporation rate ≥ 1.42 kg·m−2·h−1 and good cycling stability) under one sun irradiation. Additionally, the NP-AgNi films show outstanding seawater desalination and dye wastewater purification capability. This work provides an inspiration for the design and fabrication of multi-functional metal-based photothermal films in solar water treatment.

Bifunctional Photothermal Evaporator Based on an MXene/Fe-MOF Collaborative Effect toward Efficient Solar Steam Generation and Simultaneous VOC Removal.

Solar-driven interfacial water evaporation has become one of the most promising approaches to effectively harvesting freshwater, yet the fabrication of high-performance and multifunctional solar interfacial evaporators (SIEs) still remains a huge challenge to date. In this study, a multifunctional MXene and Fe-MOF@cellulose acetate/polyvinylpyrrolidone (MXM@CP) SIE was prepared via a facile "electrospinning and suction filtration deposition" coupling strategy. Thanks to the incorporation of MXene, MXM@CP displayed excellent photothermal conversion performance. Together with the fast water transport channel provided by the porous cellulose acetate electrospinning substrate, a remarkable solar-driven water evaporation property was achieved for MXM@CP, showing a higher water evaporation rate of 1.1 kg m-2 h-1 under one sun irradiation. Moreover, the resultant composite film also exhibited excellent Fenton catalytic activity to effectively degrade volatile organic compounds (VOCs) due to the synergistic effect of the MXene and Fe-based MOF (Fe-MOF). Particularly, a relatively higher degradation rate of 82.8% was acquired for the resulting evaporator toward the benzene contaminant. These results provide new insights into the construction of high-performance and multifunctional SIEs toward clean freshwater collection from the VOC-contaminated water system.

When cellulose nanocrystals meet graphene oxide: Structurally enhanced aerogels for efficient solar steam generation and water purification

Pollution, population growth, and climate change are intensifying global freshwater shortages. Traditional methods of collecting freshwater, such as rainwater harvesting and sewage treatment, have high energy consumption, limiting their implementation in underdeveloped regions. On the other hand, solar-driven seawater evaporation offers a promising solution, purifying water using naturally abundant solar energy. Reduced graphene oxide (rGO) is considered as a strong candidate for this purpose due to its broad spectral absorption. However, its hydrophobicity hinders its direct use in solar steam generators. Here, we report the preparation of a series of cellulose nanocrystal (CNC)-rGO aerogels (CGAs) through a one-pot hydrothermal gelation process, followed by unidirectional freeze-drying. The introduction of CNCs enhances the hydrophilicity and structural stability of the resulting CGAs. The CGAs also feature uniform and unidirectional channels that promote efficient water transport, as confirmed by scanning electron microscopy (SEM) and X-ray microtomography (XMT). The CGAs have an optimized water evaporation rate of 1.80 kg m−2 h−1 under 1 sun irradiation, with 90 % solar-to-vapor energy efficiency. Moreover, durability and seawater desalination tests provide additional evidence for the practicality of CGAs in water purification. It is anticipated the implementation of CGAs will expedite the application of solar steam generators in practical scenarios.

MXene-Coated Porous Films Prepared by Breathing Figure Method for Efficient Solar Steam Generation.

The interfacial solar steam generation for seawater desalination has attracted attention because of its excellent photothermal performance and efficiency. However, the process of preparing evaporators is often complex and costly, which limits their further practicality. Here, we report an integrated solar evaporator that is easy to prepare and has good salt resistance. The porous structure of poly(methyl methacrylate) and polycarbonate (PMMA-PC) films prepared by the breathing figure (BF) method was used as the upper layer, while MXene was deposited on the as-resulted PMMA-PC film and served as a light absorption layer. Meanwhile, the hydrophilicity of the lower layer of expanded polyethylene (EPE) foam can promote the upward transfer of water and inhibit heat loss. Under one solar irradiation, the water evaporation rate of the composite film was found to be 1.79 kg m-2 h-1 in distilled water and 1.67 kg m-2 h-1 in a 15 wt % NaCl solution, exhibiting excellent evaporation performance and salt resistance. In addition, the PMMA-PC/MXene films exhibit excellent mechanical properties. Based on these merits of the PMMA-PC/MXene solar generator, it may find useful applications in practical solar interfacial evaporation. Moreover, the findings of this investigation may provide a new opportunity for the rational design of large-aperture photothermal conversion materials via a simple breathing figure method.

Construction of bilayer cellulose-based aerogel with salt-resistant design for efficient solar desalination and wastewater purification

Solar-driven interfacial evaporation (SDIE) technology, which utilizes green and renewable solar energy to produce clean water, has shown great potential in alleviating global water scarcity. However, practical applications still face numerous challenges, including salt crystallization precipitation and accumulation, low energy utilization, and complex preparation processes. Hence, We designed a vertically ordered porous bilayer aerogel based on nanofibrillated cellulose (NFC)/polyethyleneimine (PEI) with excellent salt resistance, light absorption and local thermal effects to achieve efficient solar steam generation. Specifically, the photothermal conversion layer (PCL) at the top had excellent light absorption and photothermal conversion efficiency by introducing graphene oxide (GO) as a highly efficient photothermal material. The water transport layer (WTL) at the bottom ensured a stable water supply to the evaporation layer by virtue of the vertical water transfer path and inherent hydrophilicity, and effectively prevented formation of salts in the evaporation area. In addition, the designed aerogel had a low thermal conductivity, which achieved effective thermal insulation and further enhanced the localized heating effect. This superhydrophilic bilayer aerogel achieved a high evaporation rate of 1.9596 kg m−2 h−1 and an energy conversion efficiency of 92.28% under one solar irradiation. It is noteworthy that evaporation process exhibited excellent stability during 8 h of continuous evaporation in 20 wt% brine and no salt accumulation was observed on the evaporated surface. In addition, the bilayer aerogel demonstrated excellent long-term stability and self-cleaning. Meanwhile, its excellent anti-contamination and wastewater treatment capabilities give SDIE technology a stable and continuous operation in practical applications, thus demonstrating significant application potential.

Efficient Solar Steam Generation by Multiscale Photothermal Structures Derived from Cactus Stems.

Solar steam generation (SSG) is a promising technique that may find applications in seawater desalination, sewage treatment, etc. The core component for SSG devices is photothermal materials, among which biomass-derived carbon materials have been extensively attempted due to their low cost, wide availability, and diversified microstructures. However, the practical performance of these materials is not satisfactory because of the multifaceted structural requirements for photothermal materials in SSG scenarios. In this work, cactus stems, which possess abundant and multiscaled pores for simultaneous sunlight gathering and water evaporation, are applied as the photothermal structure for SSG devices after mild heat treatment. Consequently, the SSG device based on the carbonized cactus stems delivers high performance (an absorption rate of 93.7% of the solar spectrum, an evaporation rate of 2.02 kg m-2 h-1, and an efficiency of 91.4% under one solar irradiation). We anticipate that the material can be a potential candidate for efficient SSG devices and may shed light on the sustainable supply of water.

Sustainable lignocellulosic-based sponge with Janus salt-tolerant structure for efficient solar steam generation

Sustainable lignocellulosic-based sponge with Janus salt-tolerant structure for efficient solar steam generation

MXene Sediment-Based Poly(vinyl alcohol)/Sodium Alginate Aerogel Evaporator with Vertically Aligned Channels for Highly Efficient Solar Steam Generation

HighlightsMXene sediments is innovatively used as photothermal material for seawater desalination.Inspired by the natural wood transpiration process, a 3D MXene sediment-based aerogel with vertically aligned channels is innovatively prepared as solar evaporator.With unique structure and composition, excellent photothermal conversion efficiency, evaporation rate, salt resistance, and resistance to biological/oil/special environments are achieved in practical desalination.

Laser‐Induced Porous Graphene/CuO Composite for Efficient Interfacial Solar Steam Generation

AbstractInterfacial solar steam generation can produce clean water in an environmentally friendly and efficient way. The evaporator employing graphene as a photothermal conversion material represents an excellent paradigm within the realm of interfacial evaporators. However, existing graphene materials exhibit a certain degree of hydrophobicity and are associated with intricate manufacturing processes. Hence, the study proposes a hydrophilic composite graphene‐based material incorporating CuO, which is fabricated through a straightforward laser‐induced graphene synthesis method directly onto a polyimide film coated with CuCl2. Due to the fast capillary performance endowed by the enhanced hydrophilicity and hierarchical structural morphology, the assembled laser‐induced‐graphene evaporator achieves an evaporation rate of 2.54 kg m−2 h−1 under 1 sun irradiation with an evaporation efficiency of 91.1%, while also demonstrating excellent desalination capabilities. The as‐prepared graphene‐based evaporator has significant potential for desalination and wastewater treatment applications, offering an effective solution to address clean water challenges in remote areas.

Synergistic effects of hydrophilic function group and micropores on water evaporation in a novel carbon hydrogels for efficient solar steam generation

Solar steam generation (SSG) using hydrogels is emerging as a promising technology for clean water production. Herein, a novel oxygen-doped microporous carbon hydrogel (OPCH), rich in hydrophilic groups and micropores, has been synthesized from microalgae to optimize SSG. OPCH outperforms hydrogels with hydrophobic porous carbon or nonporous hydrophilic biochar, significantly reducing water's evaporation enthalpy from 2216.06 to 1107.88 J g−1 and activating 42.3 g of water per 100 g for evaporation, resulting in an impressive evaporation rate of 2.44 kg m−2 h−1 under one sun. A detailed investigation into the synergistic effects of hydrophilic groups and micropores on evaporation via a second derivative thermogravimetry method revealed two types of bonded water contributing to enthalpy reduction. Molecular dynamics simulations provided further insights, revealing that the hydrophilic micropores considerably decrease both the number and the lifetime of hydrogen bonds among water molecules. This dual effect not only reduces the energy barrier for evaporation but also enhances the kinetic energy needed for the phase transition, significantly boosting the water evaporation process. The sustained high evaporation rates of OPCH, observed across multiple cycles and under varying salinity conditions, underscore its potential as a highly efficient and sustainable solution for SSG applications.

Combined effect of grooves and nanoflower structured Co3O4 coating on bamboo wood for highly efficient solar steam generation at indoor and outdoor conditions.

Currently, interfacial solar steam generation (ISSG) in desalinating water has become very popular for obtaining purified water from polluted water. However, finding an efficient evaporator with low cost is a challenging task for researchers. In this work, we introduce natural bamboo wood (BW) that acts as an interfacial evaporator for obtaining purified water. Four different wood evaporators namely, flat wood (BW-FW), two-cut grooved wood (BW-2G), four-cut grooved wood (BW-4G), and four-cut grooved with Co3O4-coated wood (BW-4G/Co3O4) are used to study the mass loss (ML), evaporation rate (ER), and evaporation efficiency (EY). From the observations, BW-4G/Co3O4 gives an admirable ML, ER, and EY of 4.4 g, 3.366 kg m-2 h-1, and 91.34% under 1 sun illumination for 60 min. Also, the BW-4G/Co3O4 evaporator is kept under natural sun illumination. It achieves 17.8 g of ML, 1.92 kg m-2 h-1 of ER, and 76% of EY respectively under 604.762 W/m2 solar illumination for 8 h. The reasons for the observed results are as follows: (i) the presence of grooves increases the exposing area for solar illuminations, (ii) super hydrophilicity nature of wood gives continuous replenishment of water from the bottom to the evaporative surface, (iii) the excellent salt rejection property of wood aids in continuous water transportation without salt accumulations. As a result of the condensed seawater samples, the ion concentrations (zinc, magnesium, cadmium, lead, copper, and sodium) come under WHO standards. Consequently, it gives better dye water separation from polluted water.

Photothermal graphite phase carbon nitride membrane intercalated with polyoxovanadate for efficient solar steam generation

Graphite phase carbon nitride (GCN) has shown promising prospects in diverse fields due to its exfoliating two-dimensional (2D) layered structure, adjustable electronic properties, wide absorption of visible light, and excellent chemical stability. It is crucial to accurately regulate and functionalize the intercalation space of 2D membrane materials for specific functions. Herein, we demonstrate the first GCN-based photothermal membrane for efficient solar steam generation. The polyoxovanadate anion was intercalated in between protonated GCN layers via an electrostatic interaction strategy, which enlarged the layer spacing up to ∼12.4 Å and increased the water and salt ions transport capability. Owing to the excellent photothermal conversion efficiency of polyoxovanadate, the polyoxovanadate-intercalated GCN membrane fabricated by suction filtration exhibited effective absorbance in full solar spectrum (>95.5 %) and achieved efficient solar steam generation (2.62 kg m−2 h−1 under 1 sun) when floating on water. The long-term durability test showed that the evaporation performance is stable and no salt precipitation observed. These findings not only expand the functional applications of carbon nitride materials, but also provide a new strategy for solar desalination.

Enhanced near-infrared absorption of Cs0.32WO3 nanoparticles for efficient interfacial solar steam generation

Solar steam generation has gained significant attention as a promising method for clean and sustainable water purification and desalination. The spectral absorption performance of the photothermal conversion material directly affects its thermal conversion efficiency. This research investigates the enhanced near-infrared absorption of Cs0.32WO3 nanoparticles for efficient interfacial solar steam generation. In this study, Cs0.32WO3 nanoparticles were synthesized using a simple co-precipitation and heat treatment method. The synthetic nanoparticles were then incorporated into a porous membrane to create a photothermal conversion material for solar steam generation and their near-infrared absorption properties were characterized. The experimental results demonstrated that the Cs0.32WO3 nanoparticles effectively converted solar energy into heat, resulting in efficient interfacial steam generation. The membrane showed a high evaporation rate of of ∼ 3.15 kg·m−2·h−1 under one sun illumination. The findings of this study provide valuable insights into the design and development of efficient solar steam generation systems using near-infrared absorption nanomaterials.

A bioinspired hollow fiber-based evaporator with hybrid photothermal enhancement for efficient solar steam generation

Harvesting sustainable solar energy for interface steam generation is an appealing technological approach to address current water shortages. However, practical implementation has been hindered by suboptimal steam generation rates and significant heat losses. This study proposed a pioneering approach by designing and validating a cost-effective and scalable carbonized kapok fiber-based aerogel (Ni-NCNTs/KF), drawing inspiration from the structural characteristics of penguin feathers. The vertically-aligned Ni-NCNTs array on the surface of the hollow KF achieves exceptional sunlight absorption exceeding 96 %, attributed to a hybrid enhancement mechanism and effective light trapping. Furthermore, the distinctive core–shell architecture of Ni-NCNTs facilitates surface plasmon resonance and fosters efficient electron transfer at the interfaces, resulting in heightened light-to-heat conversion efficiency. The strategic configuration comprising a hydrophobic KF and a hydrophilic Ni-NCNTs effectively regulates water evaporation by spontaneously restricting water transport. Notably, the inherent macroporous nature of kapok fibers (KF) significantly mitigates thermal conductivity, thereby minimizing heat conduction losses. Consequently, Ni-NCNTs/KF exhibits a remarkable water evaporation rate of 3.22 kg m−2h−1 in seawater and an efficiency of 90.5 % under 1 sun. This innovative research not only furnishes a robust design paradigm for the advancement of efficacious photothermal materials but also presents a promising solution for desalination.

Thermoresponsive Janus hybrid hydrogel for efficient solar steam generation

Solar-driven interfacial evaporation technology stands out as a promising solution for sustainable freshwater production. To achieve sustained and efficient water evaporation, it is crucial to carefully modulate the distribution of water content within the solar evaporator. In this study, a novel light-temperature responsive composite hydrogel-based solar evaporator was successful constructed. This involved the incorporation of a hydrophilic backbone (polyacrylamide) and a highly efficient solar absorber (multi-walled carbon nanotubes) into a temperature-sensitive hydrogel polymer backbone (poly (N, N-diethylacrylamide)). Due to its low critical solution temperature, the evaporator can undergo a hydrophilic/hydrophobic phase transition alternating day and night conditions. In natural sunlight, the upper hydrogel evaporation region is rendered hydrophobic, minimizing heat loss and preventing salt crystallization. Simultaneously, the bottom water delivery region is hydrophilic to ensure sufficient water supply. At night, the evaporator absorbs water and dissolves, thereby facilitating the rapid return of highly concentrated brine. Leveraging the spontaneously formed Janus structure, the photo-hydrothermal hydrogel achieves an impressive evaporation rate of 2.74 kg m−2 h−1 and exhibits excellent salt resistance. The notable water evaporation performance and robust salt resistance provide exciting possibilities for achieving ultrafast solar water purification.

Bacterial cellulose-based porous Janus aerogels for efficient interfacial solar steam generation

Interfacial solar steam generation (ISSG) is considered a green and inexpensive technology to solve water scarcity problems. Currently, it still needs to pursue a fast evaporation rate, high-quality fresh water production, and excellent mechanical properties. Herein, Janus aerogels with hydrophilic and hydrophobic structures were prepared by effective spraying of polydimethylsiloxane (PD on the upper surface of bacterial cellulose (BC) /carbon black (CB) /agar powder composites (named JBCA). After a series of experiments, the results showed that the obtained JBCA evaporator had a water evaporation rate of 1.83 kg m−2 h−1 under 1000 W m−2 solar radiation. Meanwhile, the same high evaporation rate (1.63 kg m−2 h−1) was obtained in high salinity (20 wt%) solution. More importantly, the ion removal rate for real seawater was more than 99 %. The results of outdoor evaporation experiments and sustainability analyses indicated that this low-cost material with Janus structure had great potential for practical applications.

Biomass-Based Antibacterial Hybrid Engineering Hydrogel for Efficient Solar Steam Generation

Biomass-Based Antibacterial Hybrid Engineering Hydrogel for Efficient Solar Steam Generation

Ultralight anisotropic Ti3C2Tx MXene/Carbon nanotube hybrid aerogel for highly efficient solar steam generation

Solar steam generation (SSG) has been considered as a promising method to produce fresh water from seawater. Due to high light absorption and excellent chemical stability, carbon nanotube (CNT) has been widely used for SSG. However, it is still challenge to simultaneously realize high water evaporation rate and energy efficiency for CNT based solar steam generator. Herein, ultralight anisotropic Ti3C2Tx MXene/carbon nanotube (A-Ti3C2Tx/CNT) aerogels are designed and fabricated for highly efficient SSG. The combination of CNT and Ti3C2Tx MXene endows the hybrid aerogel with high light absorption and effective localized surface plasmon resonance (LSPR), resuting in enhanced light-to-heat conversion efficiency. The porous structure of aerogel leads to multiple scattering and absorption, further contributing to the photothermal conversion process. Moreover, the low thermal conductivity of aerogel structure effectively reduces the heat loss to environment. Through tailoring the anisotropic channel, the A-Ti3C2Tx/CNT hybrid aerogel with average channel size of 80 μm possesses most efficient water transport due to the capillary effect and formation of intermediate water. Therefore, the A-Ti3C2Tx/CNT hybrid aerogel exhibits high average light absorption of 95.68% in the wavelength range of 200–2500 nm, excellent water evaporation rate of 2.10 kg m−2 h−1 under 1 sun irradiation (1 kW m−2) with a high energy efficiency of 93.4%, and remarkable durability with 7 days continuous water evaporation. The A-Ti3C2Tx/CNT hybrid aerogel also shows high resistance to salt crystallization due to its high salt transport flux of 1.90 kg m−2 h−1. This work offers a prospective strategy for constructing highly efficient solar steam generator with stable performance for practical application in seawater desalination.

Cost-Effective and Scalable Solar Interface Evaporators Derived from Industry Waste for Efficient Solar Steam Generation.

Interfacial solar steam generation for sustainable and eco-friendly desalination and wastewater treatment has attracted much attention. However, costly raw materials and complex preparation processes pose constant challenges to its wide promotion. Herein, a novel, cost-effective, and scalable strategy is presented for preparing solar interface evaporators using industrial waste as a raw material. Modified polyethylene foam evaporators (M-EPEs) are simply prepared by drilling and then hydrophilic modification of industrial waste (EPE-1). M-EPEs not only retain the strong mechanical properties and thermal insulating properties (0.047 W·m-1·K-1) of EPE-1 but also exhibit superhydrophilicity and strong light absorption (over 90%). M-EPEs achieve a high evaporation rate of 1.497 kg·m-2·h-1 and photothermal efficiency of up to 93.8% under 1 kW·m-2 solar illumination. Moreover, it has excellent stability and salt tolerance. Our work addresses the environmental issues of recycling polyethylene waste and provides a facile and efficient strategy for designing low-cost, large-scale solar interface evaporators for desalination.

Unique photothermal material: Copper phosphate (Cu3P2O8) with broadband visible-to-near-infrared absorption properties for efficient solar steam generation

Effective harnessing of renewable solar energy in interfacial solar steam generation (ISSG) is a promising solution for addressing freshwater scarcity worldwide. Therefore, the development of photothermal materials plays a pivotal role in achieving efficient ISSG performance. This paper reports on an innovative photothermal material, copper phosphate (Cu3P2O8; CuPO), with broadband visible-to-near-infrared (Vis-to-NIR) absorption for ISSG. CuPO exhibited favorable characteristics, including extensive light absorption across the Vis to NIR spectrum (500–2200 nm), low thermal conductivity (0.64 W/m·K), high photon-to-heat conversion efficiency (87.9 %), and inherent hydrophilicity. When subjected to simulated sunlight (AM1.5G, 100 mW/cm2), the CuPO-coated polyurethane membrane demonstrated remarkable water evaporation performance (2.05 kg/m2·h) and ISSG efficiency (95.0 %). Notably, employing an ultraviolet cutoff filter (< 450 nm) revealed a substantial NIR absorption contribution of CuPO, surpassing 80 % of its overall performance. Moreover, the CuPO photothermal membrane exhibited durable ISSG performance over 25 cycles, underscoring the structural robustness and resilience of CuPO. Our findings offer a promising foundation for designing cost-effective, high-performance ISSG systems utilizing copper-based complex oxides.