Solar Steam Generation Research Articles

Carboxymethylcellulose sodium-derived carbon aerogels for solar-driven water purification

Recycling polluted water via different techniques has become one of the most feasible ways to solve the freshwater crisis. We describe a novel method to prepare reusable and efficient photothermal energy conversion materials for water purification. Using crosslinked xerogels as precursor, the porous and interconnected carboxymethylcellulose sodium-derived carbon aerogels (abbreviated as CCAs) with good hydrophilic performance and strong light absorption capability are firstly fabricated through pyrolysis. Photothermal measurement results show that CCA15 exhibit excellent solar steam generation rate of 2.31 kg m−2 h−1 with high light-to-vapor conversion efficiency of 95.9% under 1 sun illumination. In addition, the feasible application of CCA15 for efficient water purification under 1 sun irradiation using a homemade water treatment device has been demonstrated successfully. The as-prepared CCAs shown in here can be a continuable solution to mitigate the global freshwater crisis.

Phase‐Change Material‐Integrated Hybrid Gels for Solar Steam Generation Under Solar Fluctuations

Solar‐driven steam generation by heat localization has proven to be one of the most promising technologies for broad water‐related applications to relieve global water shortage and pollution due to the excellent interfacial water evaporation ability demonstrated both experimentally and theoretically. However, solar power changes fast in practical, such fluctuations on solar energywould invalidate conventional solar evaporator, leave a challenge on sustaining an efficient thermal evaporation. Herein, a mitigating‐solar‐fluctuation hybrid gel material (MHG) with chemical integrating of phase‐change material to achieve efficient steam generation under solar fluctuations is reported. By storing solar energy when it is surplus and providing thermal energy to sustain evaporation when it is insufficient, the MHGs solar evaporator under solar fluctuations achieves optimized water evaporation rate of 1.7 ± 0.02 kg m−2 h−1 for the high period of 0.8 sun and 1.3 ± 0.06 kg m−2 h−1 for the low period of 0.5 sun. The MHGs also exhibit outstanding solar desalination performance with good stability and demonstrate an effective brine desalination during round‐the‐clock desalination process with an average high evaporation rate of 1.24 kg m−2 h−1 d−1. This new material design provides a feasible strategy for solar evaporator to mitigate damage from solar fluctuations.

Solar Steam Generator with Divergent Microchannels for Highly Efficient and Salt‐Resistant Brine Evaporation

AbstractA novel solar steam generator featuring divergent microchannels (SSG‐DM) is developed via directional freezing of a polypyrrole (PPy)–cellulose nanofiber (CNF) suspension in an inverted frustum mold. Contrary to the conventional 3D SSGs characterized by random micropores (SSG‐RM), SSGs incorporating vertical microchannels (SSG‐VM), fabricated through directional freezing procedure, demonstrate increased evaporation performance due to enhanced water transport to the top surface. However, SSG‐VM manifests a limitation in the form of reduced salt resistance on its side surfaces where water transport is restricted. This issue is addressed by directional freezing of a PPy–CNF suspension in an inverted frustum mold, followed by freeze‐thawing gelation in an AlCl3 solution. The fabricated SSG features divergent microchannels that spanned from the bottom surface to the top and side surfaces, with a gradual increase in diameter. The evaporation rate of SSG‐DM is recorded at 2.42 kg m−2h−1 under 1‐sun illumination; this rate further increases to 15.73 kg m−2h−1 in the presence of a 4 m s−1 wind. Notably, SSG‐DM demonstrates excellent salt resistance in highly saline brine (10 wt%) under windy conditions (4 m s−1), whereas SSG‐RM and SSG‐VM are ineffective under the same conditions.

Robust and multifunctional MXene/rGO composite aerogels toward highly efficient solar-driven interfacial evaporation and wastewater treatment

Given the ever-growing global water resource crisis, exploiting multifunctional materials featuring with high interfacial solar steam generation efficiency and good purification capability to achieving seawater desalination and wastewater treatment simultaneously are highly desired, yet it still remains a huge challenge to date. Herein, robust and multifunctional MXene/rGO (MRGA) and polydopamine & chitosan @ MRGA (CS&PDA@MRGA, CPM) three-dimensional composite aerogels with distinct interconnected cellular architecture were developed via a facile ice template-assisted chemical reduction self-assembly technology and subsequent sequential deposition modification. Due to the favorable graphene oxide-assisted assembly behavior, the resultant aerogels displayed a desirable mechanical robustness along with an excellent lightweight property. Benefiting from the strong electrostatic interaction deriving from aerogel surface moieties and dye molecules, MRGA-12 exhibited a prominent adsorption capability towards various dyes and achieved a superb adsorption capacity of up to 396.05 mg/g for malachite green (MG). Moreover, by virtue of the synergistic effect between the intentionally regulated low reduction degree of rGO and the integration of PDA and CS, CPM-12 achieved a dramatically reduced evaporation enthalpy of water from 2256 to 1617.18 J/g. Accordingly, this distinct feature resulted in an extraordinary solar-driven interfacial evaporation performance with a remarkable evaporation rate of 1.86 kg/m2/h and a high evaporation efficiency of 83.28 % under 1 sun illumination. Therefore, together with the terrific oil/water separation capability, these novel MXene-based aerogels hold a great potential for high-performance solar-driven interfacial evaporation and wastewater treatment.

Cellulose‐Based Aerogels with Photocatalytic Function for Solar Steam Generation

Solar steam generation is considered an efficient, renewable, and environmentally friendly technology for clean freshwater production, offering the potential to alleviate the growing global water scarcity issue. Herein, the commercial cellulose is used as raw material and water transport matrix, and silver phosphate particles are used as difunctional light‐absorbing matters and photocatalyst to prepare cellulose‐based composite material (silver‐plated cellulose aerogel [CAAg]). The resulting CAAg possesses superhydrophilicity, intrinsic network structure, high porosity (89.88%), and low thermal conductivity (0.091 W m−1 K−1). As a result, the CAAg exhibits an evaporation rate of nearly 1.55 kg m−2 h−1 in simulated seawater under a light intensity of 1 kW m−2. Furthermore, due to the excellent photocatalytic properties of silver phosphate particles, the CAAg can simultaneously achieve high degradation rates toward various dye molecules including methylene blue, rhodamine B, and methyl orange in water, making it show tremendous potential applications for clean freshwater production and organic wastewater treatment.

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.

Efficient solar-powered evaporator with multifunctional nanofiber

Interfacial solar steam generation is acknowledged as an extremely effective and environmentally friendly method of producing potable water. Nevertheless, significant challenges persist in the development of an evaporator capable of achieving heightened rates of evaporation, catalytic capabilities, resistance to bacterial proliferation, and effective light absorption across a broad spectrum. This article outlines the fabrication of a solar steam generator utilizing electrospinning technology and membrane evaporators constructed from α-Fe2O3/PAN (polyacrylonitrile) nanofibers. The integration of α-Fe2O3/PAN composite enhances both light absorption and heat generation. In sunlight, the maximum evaporation rate is 2.7 kg m−2 h−1, which is significantly more than the rate of today's cutting-edge solution-electrospun nanofiber-based evaporators. The electrospun mat has high catalytic activity and antibacterial properties, making it an important component in desalination.

Porous carbon@carbon sponge for enhanced solar-driven seawater evaporation and wastewater remediation

Utilizing solar energy for interfacial solar steam generation and wastewater remediation is regarded as one of the sustainable approaches for alleviating clean water shortage. However, it is still a great challenge to comprehend all the requirements of efficient evaporation, salt resistance and wastewater treatment as well as low cost in one evaporator, thus hindering its large-scale practical application. Herein, in this work, an environmentally friendly and low-cost hierarchical porous architecture (APC@TMF) was prepared by assembling potassium citrate activated poplar catkin derived porous carbon (APC) into the porous structure of thermalized melamine formaldehyde resin sponge (TMF) by a simple dipping method. The APC@TMF integrates the advantages of APC and TMF, thus leading to good light absorption, low thermal conductivity, high hydrophilicity and fast water transport. As expected, APC@TMF exhibits a high evaporation flux of 2.28 kg m−2 h−1 with energy conversion efficiency of 96.3 % in seawater, which outperforms TMF, PVA/TMF, PVA/APC and recently reported evaporators. Beyond that, it demonstrates good performance for seawater desalination and wastewater remediation as well as high cost-effectiveness.

Heat-Localized and Salt-Resistant 3D Hierarchical Porous Ceramic Platform for Efficient Solar-Driven Interfacial Evaporation.

Solar-driven interfacial evaporation (SDIE) is a highly promising approach to achieve sustainable desalination and tackle the global freshwater crisis. Despite advancements in this field, achieving balanced thermal localization and salt resistance remains a challenge. Herein, the study presents a 3D hierarchical porous ceramic platform for SDIE applications. The utilized alumina foam ceramics (AFCs) exhibit remarkable corrosion resistance and chemical stability, ensuring a prolonged operational lifespan in seawater or brines. The millimeter-scale air-filled pores in AFCs prevent thermal losses through conduction with bulk water, resulting in heat-localized interfaces. The hydrophilic nature of macroporous AFC skeletons facilitates rapid water replenishment on the evaporating surface for effective salt-resistant desalination. Benefiting from its self-radiation adsorption and side-assisted evaporation capabilities, the AFC-based evaporators exhibit high indoor evaporation rates of 2.99 and 3.54kg m-2 h-1 under one-sided and three-sided illumination under 1.0 sun, respectively. The AFC-based evaporator maintains a high evaporation rate of ≈2.77kg m-2 h-1 throughout the 21-day long-term test. Furthermore, it achieves a daily water productivity of ≈10.44kg m-2 in outdoor operations. This work demonstrates the potential of 3D hierarchical porous ceramics in addressing the trade-off between heat localization and salt resistance, and contributes to the development of durable solar steam generators.

Biomimetic Design of 3D Fe3O4/V-EVOH Fiber-Based Self-Floating Composite Aerogel to Enhance Solar Steam Generation Performance.

An interfacial solar steam generation evaporator for seawater desalination has attracted extensive interest in recent years. Nevertheless, challenges still remain in relatively low evaporation rate, unsatisfactory energy conversion efficiency, and salt accumulation. Herein, we have demonstrated a biomimetic bilayer composite aerogel consisting of bottom hydrophilic and vertically aligned EVOH channels and an upper hydrophobic conical Fe3O4 array. Thanks to the design merits, the 3D Fe3O4/V-EVOH evaporator exhibits a high evaporation rate of ∼2.446 kg m-2 h-1 and an impressive solar energy conversion efficiency of ∼165.5% under 1 sun illumination, which is superior to those of state-of-the-art evaporators reported so far. Moreover, the asymmetrical wettability not only allows the evaporator to self-float on the water but also facilitates the salt ion diffusion in the channels; thus, the evaporator shows no salt crystals on its surface and only a 6% decrease in evaporation performance even after the salt concentration increases from 0 to 10.0 wt %.

Black titania coated glass fiber as a photo absorber in interfacial solar steam generation under harsh condition

Interfacial solar steam generation (ISSG) is one of the promising solutions in the field of water filtration, desalination, and solvent recovery. For the industrial applications of the technology, there is a need for developing highly durable, thermally stable, and inert light absorbers. Therefore, this work addresses this issue by synthesizing black Titania (B–TiO2) via vacuum annealing and depositing it on glass fiber (GF) via vacuum filtration with an ethyl cellulose binder. According to the characterization techniques analyses, the change of colour is attributed to the occurrence of oxygen vacancies in the surface layers of TiO2 nanoparticles during vacuum annealing. The deposition parameters were optimized for achieving a maximum solar-weighted light absorptance of 95.7%. The optimized B–TiO2 GF was applied for the steam generation experiments and achieved the evaporation rate of 1.53 kg m−2 h−1, which corresponds to solar-steam conversion efficiency of 97.7 % under standard measurements condition of AM 1.5 G sun and ambient temperature and relative humidity of 20 °C and 40% respectively. Thanks to the high durability and chemical inertness of B–TiO2 GF it was applied for water filtration in extreme conditions of acidic/alkaline water and high-sun illumination (up to 35-sun). Worth noting that for high-sun experimentation there is a need to use a binder to improve particle attachment to the glass fibers.

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.

The application of cellulosic‐based materials on interfacial solar steam generation for highly efficient wastewater purification: A review

AbstractThe world's population is growing, leading to an increasing demand for freshwater resources for drinking, sanitation, agriculture, and industry. Interfacial solar steam generation (ISSG) can solve many problems, such as mitigating the power crisis, minimizing water pollution, and improving the purification and desalination of seawater, rivers/lakes, and wastewater. Cellulosic materials are a viable and ecologically sound technique for capturing solar energy that is adaptable to a range of applications. This review paper aims to provide an overview of current advancements in the field of cellulose‐based materials ISSG devices, specifically focusing on their applications in water purification and desalination. This paper examines the cellulose‐based materials ISSG system and evaluates the effectiveness of various cellulosic materials, such as cellulose nanofibers derived from different sources, carbonized wood materials, and two‐dimensional (2D) and 3D cellulosic‐based materials from various sources, as well as advanced cellulosic materials, including bacterial cellulose and cellulose membranes obtained from agricultural and industrial cellulose wastes. The focus is on exploring the potential applications of these materials in ISSG devices for water desalination, purification, and treatment. The function, advantages, and disadvantages of cellulosic materials in the performance of ISSG devices were also deliberated throughout our discussion. In addition, the potential and suggested methods for enhancing the utilization of cellulose‐based materials in the field of ISSG systems for water desalination, purification, and treatment were also emphasized.

Magnetic Nanoparticle Cluster-Based 3D Solar Steam Generator with High Recyclability

Magnetic Nanoparticle Cluster-Based 3D Solar Steam Generator with High Recyclability

Synergism of solar-driven interfacial evaporation and photo-Fenton Cr(VI) reduction by sustainable Bi-MOF-based evaporator from waste polyester

The integration of interfacial solar steam generation and photocatalytic degradation technology has provided a promising platform to simultaneously produce freshwater and degrade pollutants. However, constructing low-cost, multi-functional evaporators for treating Cr(VI)-polluted water remains challenging, and the synergistic mechanism on Cr(VI) reduction is fuzzy. Herein, we propose the combined strategy of ball milling and solution mixing for the sustainable production of Bi-MOF microrod from waste poly(ethylene terephthalate), and construct Bi-MOF-based solar evaporators for simultaneous photo-Fenton Cr(VI) reduction and freshwater production. Firstly, the evaporator comprised of Bi-MOF microrod and graphene nanosheet possesses high light absorption, efficient photothermal conversion, and good hydrophilic property. Attributing to the advantages, the hybrid evaporator exhibits the evaporation rate of 2.16 kg m−2 h−1 and evaporation efficiency of 87.5% under 1 kW m−2 of irradiation. When integrating with photo-Fenton reaction, the Cr(VI) reduction efficiency is 91.3%, along with the reaction kinetics of 0.0548 min−1, surpassing many advanced catalysts. In the outdoor freshwater production and Cr(VI) reduction, the daily accumulative water yield is 5.17 kg m−2 h−1, and the Cr(VI) reduction efficiency is 99.9%. Furthermore, we prove that the localization effect derived from the interfacial solar-driven evaporation enhances H2O2 activation for the photo-Fenton reduction of Cr(VI). Based on the result of density functional theory, Bi-MOF microrod provides rich active centers for H2O2 activation to produce active sites such as e− or ·O2−. This study not only proposes a new strategy to construct multi-functional solar evaporators for freshwater production and catalytic reduction of pollutants, but also advances the chemical upcycling of waste polyesters.

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.

Versatile cationic dual-layer hydrogel filtration system for sustainable solar steam generator

Our increasing water demand has been an ongoing critical challenge due to water usages in areas such as industrial, agriculture, and domestic household. Conventional water production faces challenges, such as high investment, energy consumption, and brine discharge that may be unsustainable in the future. Solar steam generation (SSG) has been recently proposed by many researchers due to their sustainable and green water production method. Here we demonstrated the use of simple manufacturing and low-cost dual-layer hydrogel (DLH) system containing a double network of positive charged poly-[2-(acryloyloxy)ethyl] trimethyl ammonium chloride (PAETAC) and polyvinyl alcohol (PVA) bottom layer for fast water transport, as well as a broad light absorbing and heat generating PVA/graphene oxide (GO) top layer for fast water evaporation. As a result, the DLH was able to generate a high 3.12 kg m−2 h−1 water evaporation with 92% efficiency under 1 sun (kW m−2) exposure. Furthermore, this DLH design allows for a safe and passive anti-salt and bacterial property due to PAETAC cationic chain, eliminating 99% salt and bacteria via Donnan repulsion and electrostatic interaction without the need of sunlight exposure.

Highly salt-resistant 3D melamine sponge-polypyrrole composites for efficient solar interfacial evaporation

Solar desalination has received great attention as an environmentally friendly and cost-effective way to desalinate seawater. In this paper, a melamine sponge composite polypyrrole (MSPPy) evaporator was prepared by in-situ polymerization of Pyrrole (Py) on a melamine sponge (MS). PPy has an efficient light absorption ability. The large aperture network structure of MS can realize multiple reflections of light and greatly increase the absorption of light. Their synergistic effect makes the light absorption efficiency of the MSPPy evaporator reach 96.97%. Under one sun, the average evaporation rate of 1.886 kg⋅m−2⋅h−1 and energy conversion efficiency of 96.8% were achieved during 10 h. Moreover, the evaporator has an edge-priority crystallization function, which enables it to work for a long time in a high-salt environment. It works continuously for 12 h in simulated seawater with a salinity of 20% without further accumulation of salt crystals on its surface. More important, it can rapidly diffuse accumulated salt into the bulk water at night. This study provides a new idea for the application of solar steam generation technology in high-salt wastewater treatment.

The Application of Textile Materials in Interfacial Solar Steam Generation for Water Purification and Desalination.

The global increase in population, the phenomenon of climate change, the issue of water pollution and contamination, and the inadequate management of water resources all exert heightened strain on freshwater reserves. The potential utilization of the interfacial solar steam generation (ISSG) system, which utilizes photothermal conversion to generate heat on material surfaces for wastewater purification and desalination purposes, has been successfully demonstrated. Textile-material-based ISSG devices, including (woven, nonwoven, and knitted) fabrics and electrospinning membranes, exhibit distinct properties such as a rough surface texture, high porosity, significant surface area, exceptional flexibility, and robust mechanical strength. These characteristics, combined with their affordability, accessibility, and economic viability for widespread implementation, make them extremely attractive for applications in SSG. In this review, a comprehensive analysis of the emerging concepts, advancements, and applications of textile materials, such as woven, nonwoven, and knitted fabrics and electrospun membranes, in ISSG for wastewater purification and desalination is presented. We also emphasize significant obstacles and potential prospects in both theoretical investigations and real-world implementations, aiming to contribute to future advancements in the domain of textile-material-based interfacial evaporation in wastewater purification and desalination. Furthermore, the drawbacks and the challenges of ISSG systems are also highlighted.

Interfacial Solar Evaporation: From Fundamental Research to Applications.

In the last decade, interfacial solar steam generation (ISSG), powered by natural sunlight garnered significant attention due to its great potential for low-cost and environmentally friendly clean water production in alignment with the global decarbonization efforts. This review aims to share the knowledge and engage with a broader readership about the current progress of ISSG technology and the facing challenges to promote further advancements toward practical applications. The first part of this review assesses the current strategies for enhancing the energy efficiency of ISSG systems, including optimizing light absorption, reducing energy losses, harvesting additional energy, and lowering evaporation enthalpy. Subsequently, the current challenges faced by ISSG technologies, notably salt accumulation and bio-fouling issues in practical applications, are elucidated and contemporary methods are discussed to overcome these challenges. In the end, potential applications of ISSG, ranging from initial seawater desalination and industrial wastewater purification to power generation, sterilization, soil remediation, and innovative concept of solar sea farm, are introduced, highlighting the promising potential of ISSG technology in contributing to sustainable and environmentally conscious practices. Based on the review and in-depth understanding of these aspects, the future research focuses are proposed to address potential issues in both fundamental research and practical applications.