Solar Steam Generation Device Research Articles

Biomimic Design of Solar Steam Generation Devices Enabled by the Tannin-Iron Complex.

Solar-powered steam generation equipment has experienced considerable advancement in recent years as it offers a cleaner and greener method for freshwater production. However, the devices always suffer from a complicated process, high cost, and salt accumulation, which hinder their further application. Here, inspired by the water lily, a highly efficient and antisalt accumulation interfacial solar-driven steam generation device was designed by using the tannic acid-Fe3+ complex as photothermal material. The designed evaporator could be quickly unfolded within 24 s after being irradiated with light and then produce fresh water. It folded within 10 s and then sank into water for removing the accumulated salt after removing the irradiation sources. In addition, the tannic acid-Fe3+ complex on the evaporator surface and the angle of the evaporator allowed light to be reflected several times within the evaporator, effectively increasing the solar energy conversion efficient (2.22 kg/(m2·h)), and apparently, the overall evaporation efficiency of 139.18% was achieved under 1 sun illumination. Moreover, it exhibited an extraordinary antisalt accumulation capacity (by working continuously for 7 days in 10 wt % saline water and 80% reduction in salt accumulation) as well as a low price ($ 1.11/m2). This design would provide a strategy to prepare an antisalt accumulation solar steam devices.

3D Cellulose‐Based Solar Evaporator with Tunable Porous Structures for High Steam Generation

AbstractSolar vapor evaporation have emerged as a promising green technology to harvest fresh water. Achieving high evaporation rates while employing accessible and renewable materials is key focus in this field. Here, a 3D cylindrical‐shaped solar evaporator composed of natural cellulose is fabricated through ice‐templating freezing combined with crosslinking gelation. It demonstrates an evaporation rate of 4.2 kg m−2 h−1 under 1 sun irradiation, and reaches an energy efficiency of 173%, surpassing most reported cellulose/wood‐based evaporators. This enhanced performance is facilitated by absorbing energy from surrounding, possessing connected pores, and reducing the evaporation enthalpy. Moreover, a systematic exploration of the correlation between pore size and evaporation performance reveals that the reduced pore size (several micrometers) does not necessarily result in a higher evaporation rate, despite improving the fluid transportation. The interaction between water and cellulose induces the formation of intermediate water and reduces the evaporation enthalpy by more than 35%. Thus, the final evaporation performance is determined by a synergistic effect involving water transport, hydrophilicity, and vaporization enthalpy. Giving the high evaporation rate achieved, this 3D cellulose‐based solar evaporator presents a promising candidate toward a high‐throughput, eco‐friendly solar steam generation devices, aligning well with the criteria of green and sustainable development.

Joule-heating assisted heliotropic solar steam generator for all-day, all-weather solar desalination

Recently, interfacial solar based desalination has gained large interest as a sustainable solution for global water scarcity. However, the poor water collection rate due to unfavorable weather conditions and unpredictable solar intensity makes it impractical in real operations. In this report, we proposed a novel joule-heating assisted heliotropic solar steam generator for all-day, all-weather solar desalination. For this, hydrophobic carbon fabric (CF) was first functionalized using thiol functionalization (t-CF) and then combined with melamine sponge to obtain t-CF-melamine solar steam generator (SSG). The heating properties of t-CF-melamine are examined, and the surface temperature reaches as high as 155°C in <5 min at an input voltage of 3 V. Under 1 sun irradiation condition, the evaporation rate of the t-CF-melamine SSG is increased dramatically to 11.2 kg m−2 h−1 at 3 V input voltage. This is attributed to the synergetic effect of photothermal and electrothermal effects of t-CF. Through desalination experiments, the heliotropic design was able to reject salt effectively while maintaining a stable evaporation rate of 11.57 kg m−2 h−1. In addition, t-CF also performed extremely well at low voltage (1–3 V) conditions demonstrating the capability of all-day, all-weather solar desalination. The present results of this work would inspire further research on electrically conductive materials for joule-heating assisted solar steam generation (SSG) devices for practical all-day, all-weather solar desalination.

Hydrothermally Modified 3D Porous Loofah Sponges with MoS2 Sheets and Carbon Particles for Efficient Solar Steam Generation and Seawater Desalination.

Although the emerging interfacial solar steam generation technology is sustainable and eco-friendly for generating clean water by desalinating seawater and purifying wastewaters, salt deposition on the evaporation surface during solar-driven evaporation severely degrades the purification performances and adversely affect the long-term performance stability of solar steam generation devices. Herein, to construct solar steam generators for efficient solar steam generation and seawater desalination, three-dimensional (3D) natural loofah sponges with both macropores of the sponge and microchannels of the loofah fibers are hydrothermally decorated with molybdenum disulfide (MoS2) sheets and carbon particles. Benefiting from fast upward transport of water, rapid steam extraction, and effective salt-resistant capacity, the 3D hydrothermally decorated loofah sponge with MoS2 sheets and carbon particles (HLMC) with an exposed height of 4 cm can not only obtain heat by its top surface under the downward solar light irradiation based on the solar-thermal energy conversion but also gain environmental energy by its porous sidewall surface, achieving a competitive water evaporation rate of 3.45 kg m-2 h-1 under 1 sun irradiation. Additionally, the 3D HLMC evaporator exhibits long-term desalination stability during the solar-driven desalination of an aqueous salt solution with 3.5 wt % NaCl for 120 h without apparent salt deposition because of its dual type of pores and uneven structure distribution.

3D wood-based evaporator for highly efficient solar steam generation

Abstract Interfacial solar-driven steam generation is one of the most promising techniques used to produce clean water. However, achieving rapid water evaporation using solar steam generation devices is challenging because of their two-dimensional (2D) planar structures and confined evaporation areas. The three-dimensional (3D) structural design of evaporation devices improves water evaporation rates, thereby enhancing solar-driven steam generation. This study developed a 3D wood-based evaporator through 3D structure shaping and the flexible treatment of wood that involved coating photothermal materials with tannic acid. Because of the ampliative evaporation area and outstanding absorption, the water evaporation rate of the prepared 3D wood-based evaporator was as high as 2.5 kg m −2 h −1 , and the efficiency of energy transformation was up to 101 % under simulated 1-sun irradiation; the evaporation rate and efficiency of energy transformation were considerably higher than those of 2D planar wood evaporators. Furthermore, the effective seawater desalination performance and good durability of the 3D wood-based evaporator were demonstrated. This study provides different insights into the fabrication of high-efficiency wood-based solar steam generators with high prospects for application in seawater desalination.

Three-dimensional multimodal porous graphene-carbonized wood for highly efficient solar steam generation

Recently, solar steam generation systems have become a promising solar energy technology that can alleviate the energy crisis and reduce water pollution. However, because of weak solar radiation energy, rapid heat loss, and negative environmental impacts, there are still numerous challenges that must be overcome before solar steam generation systems can be used for practical energy utilization. Inspired by natural tree transpiration, this paper reports a 3D carbonized wood (hydrophilic)-based photothermal system coated with 2D porous reduced graphene oxide (hydrophobic) to promote solar steam generation. Wood with vertically aligned microchannels and high hydrophilicity is used to efficiently pump water, which is then spread to a 2D porous reduced graphene oxide layer with a sufficient evaporation surface. The unique 3D micro-sized water reservoirs formed between the wood and reduced graphene oxide maximize the thermal energy use of the graphene layer by preventing heat loss from its transference to the water and reducing light reflection. The evaporation rate and solar energy conversion efficiency were 1.492 kg⋅m−2⋅h−1 and 94.7% under 1 sun illumination, respectively. Moreover, our solar steam evaporator maintained its original evaporation rate after 20 h. This work provides new insights into the structural design for highly efficient solar steam generation devices.

MoS2 Nanosheets Decorated with Fe3O4 Nanoparticles for Highly Efficient Solar Steam Generation and Water Treatment.

The shortage of water resources has always been one of the most difficult problems that perplexes humanity. Solar steam generation (SSG) has been a new non-polluting and low-cost water purification method in recent years. However, the high cost of traditional photothermal conversion materials and the low efficiency of photothermal conversion has restricted the large-scale application of SSG technology. In this work, composite materials with Fe3O4 nanospheres attached to MoS2 nanosheets were synthesized, which increased the absorbance and specific surface area of the composite materials, reduced the sunlight reflection, and increased the photothermal conversion efficiency. During the experiment, the composite material was evenly coated on cotton. The strong water absorption of cotton ensured that the water could be transported sufficiently to the surface for evaporation. Under one sun irradiation intensity, the evaporation rate of the sample synthesized in this work reached 1.42 kg m-2 h-1; the evaporation efficiency is 89.18%. In addition, the surface temperature of the sample can reach 41.6 °C, which has far exceeded most photothermal conversion materials. Furthermore, the use of this composite material as an SSG device for seawater desalination and sewage purification can remove more than 98% of salt ions in seawater, and the removal rate of heavy metal ions in sewage is close to 100%, with a good seawater desalination capacity and sewage purification capacity. This work provides a new idea for the application of composite materials in the field of seawater desalination and sewage purification.

Multifunctional Photoabsorber for Highly Efficient Interfacial Solar Steam Generation and Wastewater Treatment

AbstractInterfacial solar steam generation (ISSG) is a sustainable and environmental‐friendly technology for seawater desalination and wastewater purification using green and sustainable solar energy. Herein, a robust and efficient interfacial solar steam generation device or photoabsorber for ISSG of seawater and wastewater treatment was designed by coating wood with trace amount of Pd nanoparticles (NPs) and reduced graphene oxide (RGO). High evaporation flux of 5.25 kg m−2 h−1 was achieved by Pd20/RGO80/wood (a piece of wood was coated with 80 and 20 mg L−1 of Pd NPs and RGO as a top and bottom layer, respectively) under 3 kW m−2. The value of electrical conductivity of seawater decreased from 6000.0 to 5.8 μS cm−1 after desalination. The durability test showed the photoabsorber was stable for 30 cycles. The total cost to evaporation rate of the device was calculated as 0.29 0.003 USD/(cm3 h−1). The photoabsorber also showed excellent performance in wastewater treatment in removal of dyes of methylene blue and Reactive blue 5. Also, the concentration of heavy metals of Zn2+, Cd2+, Pb2+, Fe2+, Ni2+, and Cr6+ reduced from 1000 ppm to near zero in the presence of photoabsorber.

Omnidirectionally irradiated three-dimensional molybdenum disulfide decorated hydrothermal pinecone evaporator for solar-thermal evaporation and photocatalytic degradation of wastewaters

Although most solar steam generation devices are effective in desalinating seawater and purifying wastewaters with heavy metal ions, they are ineffective in degrading organic pollutants from wastewaters. Herein, we design novel solar-driven water purification devices by decoration of three-dimensional pinecones with MoS2 nanoflowers via a one-step hydrothermal synthesis for generating clean water. The vertically arrayed channels in the central rachis and the unique helically arranged scales of the hydrothermal pinecone can not only transfer bulk water upward to the evaporation surface, but also absorb more solar light from different incident angles for solar-thermal evaporation and photodegradation of wastewaters under omnidirectional irradiations. The decorated MoS2 nanoflowers can not only enhance the solar-thermal energy conversion efficiency, but also decompose organic pollutants in the bulk water by their photocatalytic degradation effects. The resultant hydrothermal pinecone with in situ decorated MoS2 (HPM) evaporator exhibits a high evaporation rate of 1.85 kg m−2 h−1 under 1-sun irradiation with a high energy efficiency of 96 %. During the solar-driven water purification processes, the powdery HPM can also photodegrade organic pollutants of methylene blue and rhodamine B with high removal efficiencies of 96 % and 95 %, respectively. For practical demonstration, by floating in the methylene blue solution under 1-sun irradiation, the bulky HPM can generate clean water by simultaneous solar-thermal evaporation and photocatalytic degradation. The integration of solar steam generation and photocatalytic degradation mechanisms makes the HPM evaporator highly promising for practical high-yield purification of wastewaters.

Engineering Materials to Enhance Light-to-Heat Conversion for Efficient Solar Water Purification

Water scarcity has become one of the most prevalent problems afflicting people throughout the world and is expected to grow worse in the future due limited resources and increasing demand. This problem calls out for an urgent need to develop inexpensive, stand-alone desalination and water purification technologies that can adopt water resource distribution, water quality conditions, economic status, and developing levels of communities. Solar energy is abundantly available and has become one of the most promising emerging strategies in sustainable water treatment technologies. In this review paper, we highlight the recent progress of solar-driven desalination and water purification technologies for clean water production. We begin by introducing the fundamental concepts of solar radiation, solar thermal conversion, and heat localization. Then, we review the key components of solar steam generation including solar-thermal conversion materials, water pathways, and heat insulators and the strategies to promote efficient solar-to-vapor conversion in terms of chemical regulation, structural engineering, and heat management to maximize solar absorption and to minimize heat loss. Next, we discuss an efficient design of a solar steam generation device using an integrated approach that accounts for the performance of photothermal materials, heat losses, and water supply with respect to the hot evaporation region. Last, existing challenges and future opportunities in both fundamental studies and practical implementations of solar steam generation for water purification are discussed.

Interfacial solar steam generation by wood-based devices to produce drinking water: a review

Freshwater supply is declining in the context of climate change, pollution, and soil salinization, calling for sustainable methods to produce drinking water. For instance, salt water can be converted into pure water by steam generation. Interfacial solar steam generation involves photoabsorbers consisting of a photothermal material with broad solar absorption and a porous substrate with a thermal insulating character. Nonetheless, scaling up of classical devices for interfacial solar steam generation is actually limited by cost, biofilm formation, salt fouling, complicated fabrication processes, and toxicity. Alternatively, wood-based devices are cheap, biodegradable, abundant, and display high fluxes of evaporation compared with other nonbiodegradable photoabsorbers. Here we review the design and applications of wood-based solar steam generation devices, with focus on wood structure and properties, different types of devices, and factors controlling the evaporative performance.

Fe3O4/Diatomite-Decorated Cotton Evaporator for Continuous Solar Steam Generation and Water Treatment.

Improving the evaporation rate of solar steam generation (SSG) has always been a research hotspot to solve the shortage of water resources. Using cotton, Fe3O4, polyvinyl alcohol (PVA) and diatomite (DM) as raw materials, DM/PVA/Fe3O4@cotton composites with both firmness and hydrophilicity were prepared. Fe3O4 has a wide range of light absorption characteristics and good photothermal conversion performance, and is an ideal photothermal conversion material. PVA enhances the adhesion between Fe3O4, cotton and DM and enhances the hardness of the sample and the internal porous structure. The existence of DM greatly improves the hydrophilicity of the sample, ensuring that the water in the lower layer can be continuously transported to the surface of the sample, and DM makes the surface of the sample rough, which reduces the reflection of sunlight and improves the efficiency of light heat conversion. Under one-sun irradiation, the temperature of the sample surface increases by 52.6 °C, the evaporation rate can reach 1.32 kg m−2 h−1 and the evaporation efficiency is 82.9%. Using this sample as the photothermal conversion layer of the SSG device, the removal rate of salt ions in seawater is more than 98% and the removal rate of heavy metal ions in sewage is close to 100%. This work provides a new idea and design method for SSG in the field of seawater desalination and sewage treatment.

Watermelon Pulp Templated Polypyrrole for Solar Steam Generation with High Photothermal Conversion Efficiency

AbstractEfficient utilization of solar energy for solar steam generation is an effective way to tackle the shortage of fresh water resources. However, the utilization of solar steam evaporators often suffers from a series of problems, such as high cost, complex processes, and low conversion rate, which seriously hinders the development of solar steam devices. Here, a polypyrrole/watermelon pulp (WPPY) evaporator, which is based on soaking freeze‐dried lumpy watermelon pulp (WP) in pyrrole solution, initiating polymerization in the ice bath, followed by heat‐treatment to achieve an efficient solar steam generation (SSG) device, is designed and produced. The WPPY with a pyrrole to WP mass ratio of 1:2 (WPPY‐3) exhibits a developed porous structure, superior hydrophilicity, relatively small thermal conductivity (0.0375 W m−1 K−1, a simple one‐step fabrication process, and superior light absorption (94.7%). Its evaporation rate reaches 1.64 kg m−2 h−1 without additional insulation, while the light‐to‐heat conversion efficiency reaches 96.1% under one solar irradiation (1 kW m−2) at the same time. Additionally, it also shows good durability. This environmentally friendly and stable photothermal conversion composite material that shows good cycle stability has great potential for applications in seawater desalination via SSG.

Simultaneous engineering on absorption window and transportation geometry of graphene-based foams toward high-performance solar steam generator

Graphene-based materials are frequently highlighted as the candidate for solar steam generation (SSG) because of their advantages such as high solar absorption, tunable structure and low cost. However, graphene itself is not a “perfect” absorber for full solar spectrum and cannot efficiently transport water on its surface due to its intrinsic physicochemical characteristics. Here we designed and synthesized a graphene foam in a three-dimensional (3D) interconnected porous structure with silicon carbide nanoparticles anchored on graphene surfaces. The systematical characterizations confirm that the hybrid structure extends the solar absorption window of graphene in full solar spectrum; and moreover, the in situ environmental scanning electron microscopy (ESEM) experiments suggest the incorporation of SiC nanoparticles on two-dimensional graphene surface improves the condensation and transportation kinetics of water in the foam. As a result, the SSG device based on the graphene-SiC composite demonstrates an improved energy conversion efficiency up to 95% under one sun illumination compared with those of previous reported graphene-based materials. The findings may shed new light on the technologies for solar-energy-water nexus.

Au-Ag Alloy Nanocorals with Optimal Broadband Absorption for Sunlight-Driven Thermoplasmonic Applications.

Noble metal nanoparticles are efficient converters of light into heat but typically cover a limited spectral range or have intense light scattering, resulting in unsuited for broadband thermoplasmonic applications and sunlight-driven heat generation. Here, Au–Ag alloy nanoparticles were deliberately molded with an irregular nanocoral (NC) shape to obtain broadband plasmon absorption from the visible to the near-infrared yet at a lower cost compared to pure Au nanostructures. The Au–Ag NCs are produced through a green and scalable methodology that relies on pulsed laser fragmentation in a liquid, without chemicals or capping molecules, leaving the particles surface free for conjugation with thiolated molecules and enabling full processability and easy inclusion in various matrixes. Numerical calculations showed that panchromism, i.e., the occurrence of a broadband absorption from the visible to the near-infrared region, is due to the special morphology of Au–Ag alloy NCs and consists of a purely absorptive behavior superior to monometallic Au or Ag NCs. The thermoplasmonic properties were assessed by multiwavelength light-to-heat conversion experiments and exploited for the realization of a cellulose-based solar-steam generation device with low-cost, simple design but competitive performances. Overall, here it is shown how laser light can be used to harvest solar light. Besides, the optimized broadband plasmon absorption, the green synthetic procedure, and the other set of positive features for thermoplasmonic applications of Au–Ag NCs will contribute to the development of environmentally friendly devices of practical utility in a sustainable world.

Wood‐Derived Monolithic Carbon Materials and Their Functional Applications

AbstractWood‐derived monolithic carbon materials have attracted increasing attention because of the unique porous structure, renewability, and easy processing. They are frequently used as a structural functional material in energy, environment, catalysis, and other applications recently. Wood‐derived monolithic carbon materials still exhibit the interconnected capillary array structure of wood which is in favor of mass transfer and energy storage/conversion offering application performance and prospect. Herein, wood‐derived monolithic carbon materials, from preparation to function application, are summarized. Various wood raw materials and carbonization methods are described in this work, as well as their impressive application performance in different fields. The aim is to provide an overview of the different monolithic carbon materials obtained from bulk wood which are employed for various functional applications, including energy storage/conversion, environmental conservation, solar steam generation devices, catalysis, and microwave absorption. This review will deepen the understanding of wood‐derived monolithic carbon utilization and inspire new ideas in the area of designing advanced wood‐based materials.

Low cost, robust, environmentally friendly, wood supported 3D-hierarchical Cu3SnS4 for efficient solar powered steam generation

Solar steam generation has great potential in alleviating freshwater crises, particularly in regions with accessible seawater and abundant insolation. Inexpensive, efficient, and eco-friendly photothermal materials are desired to fabricate sunlight-driven evaporation devices. Here, we have designed an economical strategy to fabricate a high-performance wood-based solar steam generation device. In current study, 3D-hierarchical Cu3SnS4 has been loaded on wood substrates of variable sizes via an in-situ solvothermal method. Considering the water transportation capacity and thermal insulation property of wood, an enhanced light absorption was achieved by a uniform coating of Cu3SnS4 on the inside and outside of the 3D porous structure of the wood. Thanks for the synergistic effect of Cu3SnS4 and wood substrate, the obtained composite endorsed high-performance solar steam generation with a steam generation efficiency of 90% and an evaporation rate as high as 1.35 kg m-2h−1 under one sun.

Recent Advances in Simple Preparation of 3D Graphene Aerogels Based on 2D Graphene Materials.

Recently, 3D graphene aerogels (3GAs) with high electrical conductivity, excellent mechanical properties, and fast mass and electron transport have attracted increasing attention and shown wide applications (such as flexible electronics devices, sensors, absorbents, catalysis, energy storage devices, solar steam generation devices, and so on). The drying process becomes an important factor limiting the large-scale preparation of 3GAs. Therefore, how to simplify the preparation process plays an important role in the large-scale application of 3GAs. In this study, we summarize the recent progresses of 3GAs by different drying methods and focus on the effect of robust graphene network on the simple preparation of 3GAs. Besides, the design and synthesis strategies of 3GAs with robust graphene network structures have been systematically discussed. Finally, the emerging challenges and prospective for developing simple preparation and functionalization of 3GAs were outlined. It is expected that our study will lay a foundation for large-scale preparation and application of 3GAs and inspire more new ideas in this field.

Coffee Grounds-Doped Alginate Porous Materials for Efficient Solar Steam Generation.

Solar steam generation (SSG) devices have emerged as one of the promising technologies for seawater desalination to meet the worldwide demand for clean water. Herein, we fabricated a new monolithic SSG system derived from waste coffee grounds (CG) through a simple carbonization followed by a freeze-drying process (named as CCGA). The as-prepared CCGA possesses a porous structure with superhydrophilic, abundant porosity (81.7%); low thermal conductivity (0.129 W m-1 K-1) in a wet state; low apparent density (25 mg cm-3); and broad sunlight absorption in a wet state (ca. 93%). The combination of its carbon nature and abundant porous structure endowed barrier-free water transmission channels, a self-floating property, and a superb photothermal conversion performance to the SSG. The temperature of the CCGA's upper surface can reach up to 42.6 °C under 1 sun irradiation, and for pure water, the evaporation rate of CCGA can be up to 1.486 kg m-2 h-1, corresponding to a good photothermal conversion efficiency of 86.96%. It also exhibits an excellent desalination capability; e.g., the photothermal conversion efficiency of CCGA in NaCl (20 wt %) brine is measured to be 75.77% under 1 sun irradiation, and the fresh water obtained from artificial seawater can achieve the WHO's standard for domestic water. With the advantages of low cost and a simple preparation process, such biomass-based CCGA materials may have great potential as an efficient SSG device for seawater desalination.

Solar‐Driven Airflow‐Enhanced All‐Daytime Solar Steam Generation Based on Inverse‐Bowl‐Shaped Graphene Aerogels

Solar steam generation (SSG) is a promising approach to solve the shortage of fresh water resources. Despite intensive research on photothermal materials, the SSG performance is still unsatisfactory for practical applications. Moreover, the actual solar trajectory is a semicircular arc, resulting in a continuous change of the incident angle, which is often ignored in previous reports. Herein, an inverse‐bowl‐shaped graphene aerogel (IBGA) is synthesized as the photothermal component for the SSG, which can always maintain a high water evaporation rate with the change of the incident angles. Furthermore, a solar‐driven airflow is introduced based on a modified Stirling engine to enhance the SSG performance. The SSG device based on IBGA with solar‐driven airflow exhibits a high evaporation rate of 2.46 kg m−2 h−1 under 1 sun irradiation. The outdoor experiments demonstrate that an SSG device with 1 m2 of IBGA can collect 15 kg freshwater on a sunny day, showing great potential for seawater desalination and wastewater treatments in practical applications.