High-efficiency Solar Steam Generation Research Articles

Black Silver-Decorated liquid metal nanofillers coupled with Glycerol-Modified hydrogel composites for high efficiency solar steam generation and thermoelectric conversion

Solar-driven interfacial evaporation (SDIE) holds great potential in alleviating global freshwater scarcity, which requires the design of efficient energy conversion devices. Herein, a quadruply engineered hydrogel-based evaporator is developed based on multipath regulation of the four key processes involved in SDIE, i.e., heat generation, energy utilization, water transportation, and evaporation. Surface-tailored liquid metal nanoparticles (EGaIn@Ag NPs) with a high photothermal conversion efficiency (PCE) of 30.4 % serve as the nanofiller to produce heat efficiently. Vertically aligned microchannels are constructed in the poly(vinyl alcohol) (PVA) hydrogel through directional freezing to accelerate water transportation. Glycerol is introduced to the PVA matrix to synergistically a) prevent heat loss from the interface to bulk water, and b) modulate the bonding state of water in the hydrogel to reduce the vaporization enthalpy. Such an elaborate design achieves a rather high evaporation rate of 3.26 kg m−2h−1 under 1 sun illumination. The hydrogel evaporator (EGaIn@Ag/PVAG) is applicable in treating real seawater and dye-contaminated sewages, showing favorable desalination durability and self-cleaning property. The synergistic design also imparts the hydrogel with thermoelectric power generation capabilities. This work offers a new insight into the synergistic design of SDIE devices, which is expected to inspire innovations in solar energy conversion and utilization.

Boosted light absorption by WO3-x/Ag/PbS heterostructure for high-efficiency interfacial solar steam generation

Interfacial solar steam generation is considered a promising approach to address energy and drinking water shortages. However, designing efficient light-absorbing and photothermal-converting materials remains challenging. In this study, we describe a detailed method for synthesising a three-dimensional (3D) hierarchical oxygen defect-rich WO3/Ag/PbS/Ni foam (termed WO3-x/Ag/PbS/NF) composite to realise efficient exciton separation and enhanced photothermal conversion. The 3D heterogeneous ternary photothermal material combines the individual benefits of WO3-x, Ag and PbS, improving charge transfer and promoting photogenerated electron-hole pairs. This enhances light absorption and energy conversion. Theoretical calculations indicate that the increased photothermal conversion efficiency primarily results from the heterojunction between Ag, WO3-x and PbS, facilitating exciton separation and electron transfer. Consequently, the WO3-x/Ag/PbS/NF solar evaporator exhibits exceptional light absorption (98% within the sunlight spectrum), a high evaporation rate of 1.90 kg m−2h−1 under 1 sun and a light-to-heat conversion efficiency of 94%. The WO3-x/Ag/PbS/NF evaporator also exhibits excellent capabilities in seawater desalination and wastewater treatment. This approach introduces a synergistic concept for creating novel multifunctional light-absorbing materials suitable for various energy-related applications.

Superhydrophilic carbon@halloysite nanotube decorated sponge composites for high efficiency solar steam generation and cleanup of crude oil

Three dimensional composite evaporators have now widely been used for solar driven steam generation. However, some issues such as weak interfacial interaction, moderate water transport ability and salt precipitation should be addressed for high efficiency solar driven interface evaporation. Here, carbon modified halloysite nanotubes (CHTs) are firmly anchored onto the skeleton of Polyvinyl alcohol (PVA) sponges for preparation of compressible and superhydrophilic CHTs/PVA evaporators (CPEs). CHTs endow the evaporator with outstanding light absorption and photothermal conversion performance. In addition, the hierarchically porous and hollow structures inside CPEs ensure the evaporator powerful water transport capability and hence excellent salt rejection behavior. Benefiting from the strong interfacial interaction between CHTs and the PVA sponge, CPEs possess superior surface stability and durability. The synergy of the solar driven interface evaporation and natural evaporation from the side walls contributes to a high evaporation rate (up to 3.49 kg m−2 h−1). The evaporation rate is maintained when CPE is mechanically compressed. Also, the sponge composite can be used for cleanup of crude oil, based on the photothermally induced decrease of oil viscosity. This study can provide inspiration to develop solar evaporators for high performance desalination and water purification.

Interface engineering of Co3O4 nanoparticle for high-efficiency interfacial solar steam generation

Solar steam generation has been proven to be an innovative and sustainable technology to mitigate the issue of clean water shortage. But, to-date, optimizing a suitable candidate material system to improve the evaporation efficiency is an urgent need, especially the interface engineering tailored heat transfer of materials has not yet made a breakthrough. Herein, we successfully designed a Co3O4 nanoparticle that can promote the optimization of the heat transfer performance using interface engineering. The optimized Co3O4 nanoparticles creates a close contact with the cotton sheet, creating an efficient channel for heat transfer and achieving high photothermal steam generation efficiency. The interfacial solar steam generation has been found to achieve a high evaporation rate of 2.72 kg/m2·h, which is higher than that of traditional bulk phase heating. Our findings not only showcase the efficacy of interface engineering in the design of solar steam generation, but also present a cost-effective and straightforward methodology that can be applied for water purification purposes.

Surface hydrophobicity-hydrophilicity switching induced interface heat and water transfer enhancement for high-efficiency solar steam generation

Beyond photothermal conversion, the surface wettability of light-absorbing materials should be also determinative to the efficiency of solar-driven interfacial steam generation (SISG). Herein, by modifying hydrophobic Cu nanoparticles (NPs) with a hydrophilic carbon (C) shell, hydrophilic Cu@C core–shell NPs were successfully fabricated and used for constructing evaporation films for SISG. In comparison to the film constructed with Cu NPs, the evaporation films constructed with Cu@C core–shell NPs exhibit much increased SISG efficiency, reaching 94.6% as high. Except for the localized surface plasmon resonance (LSPR) effect of Cu NPs ensuring the excellent photothermal conversion, it is experimentally and theoretically revealed that the surface wettability switching from hydrophobicity to hydrophilicity, as induced by C coating, is beneficial to heat transfer at the solid/liquid interface and water transport at the evaporative surface, thus improving the thermal-evaporation conversion performance for efficient SISG. However, the further thickened C shells would weaken the LSPR effect and hinder the interface heat and water transfer, leading to the decreased photothermal and thermal-evaporation conversion efficiencies, and thus the lowered SISG performances. This demonstration gives an alternative and promising access to the rational design of photothermal materials featured with switchable surface wettability ensuring interface heat and water transfer enhancement for efficient SISG.

Optimization of bamboo-based photothermal interfacial solar evaporator for enhancing water purification.

Although solar desalination is a promising approach for obtaining freshwater, its practical application encounters challenges in achieving efficient photothermal evaporation. Recent research has focused on novel configurations of solar absorbers with unique structural features that can minimize heat loss. High-efficiency interfacial solar steam generation (SSG) can be achieved by optimizing the design of the absorber to harness incident heat energy on the top interfacial surface and ensuring a continuous water supply through microchannels. Artificially nanostructured absorbers might have high solar absorptivity and thermal stability. However, the manufacturing of absorbers is expensive, and the constituting materials are typically non-biodegradable. The unique structural configuration of natural plant-based solar absorbers provides a major breakthrough in SSG. Bamboo, as a natural biomass, possesses exceptional mechanical strength and excellent water transport through vertically oriented microchannels. This study aimed to enhance the performance of SSG with a carbonized bamboo-based solar absorber (CBSA). To achieve this goal, we optimized the carbonization thickness of the absorber by varying the carbonization time. Furthermore, the height of the CBSA was varied from 5 to 45mm to determine the optimal height for effective solar evaporation. Accordingly, the highest evaporation rate of 3.09kgm-2h-1 was achieved for the CBSA height of 10mm and top-layer carbonization thickness of 5mm. The cost-effectiveness, simple fabrication, and superior desalination performance of the CBSA demonstrate a strong potential for practical applications.

Interface engineering of amorphous boron for high-efficiency interfacial solar steam generation

We investigate interface regulation of amorphous boron and cotton pads to experimentally verify their performance in solar steam generation. Thanks to the superabsorbent cotton pads and the construction design, unobstructed water flow is achieved.

Extremely high-efficiency solar steam generation, robust and scalable photothermal evaporator based on ZIF-67@MXene/rGO decorated rock wool

For the first-time, recycled RW waste is decorated with a ZIF-67, MXene and reduced graphene oxide as the photothermal evaporator. Solar-thermal conversion efficiency of 153.7% was achieved under 1 sun illumination.

Three dimensional hydrogel evaporator made of nano level antireflection particles for high-efficiency solar steam generation

Solar-driven interface evaporation technology provides a sustainable green method for the acquisition of freshwater resources. In this article, a hydrogel of a three-dimensional porous structure has been synthesized for solar steam generation. Ag nanoparticles are used as a photothermal material. Given the long-term utilization of Ag nanoparticles, they have been coated with a SiO2 layer. Moreover, SiO2 can act as a “reduced reflection” layer that can minimize light reflection on a single Ag nanoparticle, and enhance the nanoparticles’ absorbing ability of optical waves. Furthermore, the performance of the evaporator is significantly improved by the addition of cuttlefish powder material in the hydrogel. Specifically, under 1 KW m−2, the surface temperature of the evaporator reached 41 ℃, the steam generation rate was 1.78 (kg m−2h−1), and the solar thermal conversion efficiency is 94 %. Moreover, when the evaporator is used in heavy metal sorption, the resulting evaporated water meets international drinking water criteria. After photothermal evaporation, the ion concentrations of Cu, Mn and Cd decreased from 1000, 100 and 20 mg L−1 to 0.021, 0.017 and 0.04 mg L−1 respectively. This study provides a feasible idea for the practical application of photothermal evaporator.

Laser-treated wood for high-efficiency solar thermal steam generation.

Solar-driven water vaporization is considered one of the most sustainable ways to solve water scarcity. The design of highly efficient solar absorber systems has received extensive attention. Here, we report a novel light absorption material for water evaporation using laser-treated wood. The obtained laser-treated wood possesses interconnected 3D porous networks formed by the random construction of carbon arrays and a hydrophilic surface due to the oxygen implantation by laser treatment. When under 1 sun solar-simulated light irradiation (1 kW m−2), the surface temperatures of dry and water-saturated wood reach 59.5 °C and 40.4 °C, respectively, indicating good heat localization. As a result, the laser-treated wood under 1 sun illumination shows high solar to vapor efficiencies of 93.1% and 92.6% for pure water and seawater, respectively, which are higher than that of most wood-based reported photo-thermal conversion materials. Therefore, the fabricated laser-treated wood may pave the way for harvesting solar energy to produce clean water at low cost.

Hydrophobic and porous carbon nanofiber membrane for high performance solar-driven interfacial evaporation with excellent salt resistance

Interfacial evaporation has recently received great interest from both academia and industry to harvest fresh water from seawater, due to its low cost, sustainability and high efficiency. However, state-of-the-art solar absorbers usually face several issues such as weak corrosion resistance, salt accumulation and hence poor long-term evaporation stability. Herein, a hydrophobic and porous carbon nanofiber (HPCNF) is prepared by combination of the porogen sublimation and fluorination. The HPCNF possessing a macro/meso porous structure exhibits large contact angles (as high as 145°), strong light absorption and outstanding photo-thermal conversion performance. When the HPCNF is used as the solar absorber, the evaporation rate and efficiency can reach up to 1.43 kg m−2h−1 and 87.5% under one sunlight irradiation, respectively. More importantly, the outstanding water proof endows the absorber with superior corrosion resistance and salt rejection performance, and hence the interfacial evaporation can maintain a long-term stability and proceed in a variety of complex conditions. The HPCNFs based interfacial evaporation provides a new avenue to the high efficiency solar steam generation.

Highly efficient solar vapour generation via self-floating three-dimensional Ti2O3-based aerogels

To reduce the shortage of water resources, solar-driven water evaporation is considered as a sustainable solution. High efficiency solar steam generation (SSG) with the good light absorption, sufficient water transmission, high thermal management and freely floating photothermal materials is highly desirable. Herein, a simple solar desalination strategy was proposed and a new type three-dimensional Ti2O3-based aerogel with high porosity and low thermal conductivity was prepared. In short, polydopamine (PDA)-modified Ti2O3 nanoparticles were uniformly dispersed in chitosan (CS) solution and a porous Ti2O3-based aerogel was formed after freeze-drying. The evaporation rate of this solar steam generator is as high as 1.31 kg m−2 h−1 at 1.0 solar irradiance (1.0 kW m−2), and the photothermal conversion efficiency is about 81.7%. The optical absorption at 250–2500 nm was 94.49%. In addition, the aerogel has a porosity of 97.50% and a density of 0.025 g cm−3, making it freely float on the surface of water. Besides, its thermal conductivity is 0.037 W m−1 K−1, indicating it has excellent thermal insulation performance. The porous Ti2O3-based aerogel can maintain stable evaporation rate and high evaporation efficiency after 10 repeated evaporation cycles. Additionally, the seawater after desalination was tested and the removal rates of ions and carbon-containing organic matter reached 99.80% and 75.45%, respectively. Therefore, the interfacial water evaporator prepared in this work has excellent photothermal conversion ability and is expected to be a candidate material for solar seawater desalination.

The Biochar Derived from Carp for High-Efficiency Solar Steam Generation and Water Purification.

Efficient utilization of solar energy to generate steam is a green and promising technology because of its great potential applications in seawater desalination and industrial wastewater purification. However, the practical application of high‐efficiency solar steam generation devices is largely overshadowed due to their complex process, high cost, low life‐span, and poor thermal performance. Here, novel meat and bonemeal biochar (MBB) with high solar steam generation efficiency is produced by pyrolyzing dead carp at 300, 400, and 500 °C under anoxic conditions. Attributed to its typical hydrophilic pore structure, the photon trapping ability of MBB500 is up to 97% and 84.1% in the ultraviolet and visible regions and near‐infrared light regions, respectively. Meanwhile, hydrophilic pore structural provides a strong capillary force for the rapid transmission of water. As a result, under 1 sun illumination (1 kW m−2), the water evaporation rate and the apparent energy conversion efficiency of MBB500 reach 1.48 kg m−2 h−1 and 131.2%, respectively. In addition, MBB500 also exhibits excellent seawater and heavy metal wastewater evaporation effects, providing a new manufacturing strategy for photo‐thermal materials, which greatly benefit their practical application in pure water regeneration.

Combining carbonized sawdust beds with preheating water design for efficient solar steam generation

• Preheating and insulation chamber couldlargely increase evaporation efficiency. • Maximum efficiency of 91.5% was achieved at thesecond-layer porosity of 76%. • It is meaningful to reduce conductive heat losses only under a good water supply. • Evaporation efficiency and temperature arecoordinated by tuningwater-supply area. • Efficiency of 33.8% and steam temperature of 115.8 °C aresimultaneously achieved. Solar steam generation has become one of the most promising techniques to realize water purification and desalination owing to the abundance and cleanness of solar energy. Here, we proposed a preheating chamber structure for high-efficiency solar steam generation with carbonized sawdust beds as the solar absorber. Effects of bed porosity on the water transportation, heat transfer and evaporation performance were studied. Experimental results turn out that with the increase of the bed porosity, the heat conductive loss will be increased while water transportation is promoted. When the positive effect of the increased water transportation and the negative effect of the increased heat losses on the evaporation are balanced, the evaporation efficiency reaches the maximum of about 91.5% at the porosity of 76% under one sun illumination in this work. In addition, the influence of water supply on the steam temperature under 3-sun irradiation was also investigated. It turns out that the evaporation efficiency and temperature can be coordinated by adjusting the water-supply area. When the ratio of water-supply area to the evaporation area reaches 58.8%, a proper balance between efficiency (33.8%) and steam temperature (115.8 °C) can be achieved. This work is expected to supply a method to obtain high temperature and also efficiency steam generation.

Bilayer fiber membrane electrospun from MOF derived Co3S4 and PAN for solar steam generation induced sea water desalination

Solar steam generation system has attracted great attention because of high efficiency and low energy consumption in sea water desalination. Bilayer membrane is an important part in high efficiency solar steam generation system, which is built by thermal conversion and water transportation layers. With two-dimensional Co based Metal-Organic Framework (MOF) as precursor, Co3S4 hollow nanoparticle is synthesized, which exhibits excellent photothermal effect. With electrospinning technology, Co3S4 hollow nanoparticle and polyacrylonitrile (PAN) are weaved together and generates a bilayer membrane. Under one sun (1 ​kW ​m−2) irradiation, its evaporation rate reaches 1.26 ​kg ​m−2 ​h−1 with efficiency 86.5%. After 15 cycle continuous test, the performance of bilayer membrane is still well kept. The concentrations of Na+, K+, Ca2+ and Mg2+ in obtained water meet drinking standard. Co3S4 hollow nanoparticle can also be used as an activator to peroxymonosulfate (PMS) for tetracycline degradation with advanced oxidation processes (AOPs). Under catalysis of Co3S4 hollow nanoparticle, degradation rate of tetracycline (20 ​mg ​L−1, 30 ​mL) achieves 93.7% in 20 ​min. This donates potential application of this bilayer membrane in PMS involved tetracycline degradation. We can expect the promising prospect of bilayer membrane in sea water desalination and organic pollutants such as antibiotics removal.

Nanofiber based origami evaporator for multifunctional and omnidirectional solar steam generation

Interfacial solar steam generation is considered as an effective and environment-friendly technology for clean water production. However, the preparation of an evaporator with omnidirectional light harvesting, high evaporation rate, catalytic and antibacterial properties simultaneously remains a great challenge. Herein, we report the Ag nanoparticles decorated MXene nanosheets/polyacrylonitrile (Ag@MXene/PAN) nanofiber based evaporators for high-efficiency, multifunctional and omnidirectional solar steam generation by solution electrospinning technology. The conjunction of Ag nanoparticles and MXene nanosheets not only enhances the broadband light absorption and heat production, but also contributes to the good catalytic and antibacterial performance. Furthermore, the flexibility and foldability of Ag@MXene/PAN nanofiber membranes enable the design of 3D fine-structure evaporator with increased evaporation surface area and optimized light absorption. As a proof of concept, Ag@MXene/PAN nanofiber based origami evaporator is constructed, which demonstrates relatively stable evaporation rates during a wide range of incident angle from 30° to 150°. The maximum evaporation rate reaches 2.08 kg m−2 h−1 under 1 sun illumination, far superior to the state-of-the-art solution-electrospun nanofiber based evaporators. Integration of structure flexibility, high performance and multi-functionality makes the designed nanofiber based evaporator promising for practical clean water production.

Facile Preparation of MnO2-Deposited Wood for High-Efficiency Solar Steam Generation

Wood, a natural renewable material, has drawn great attention in solar steam generation in recent years due to its intrinsic properties such as high hydrophilicity and low thermal conductivity. Unt...

Poly(p-phenylene benzobisoxazole) nanofiber/reduced graphene oxide composite aerogels toward high-efficiency solar steam generation

Interfacial solar steam generation is emerging as a promising high-efficiency strategy to produce clean water by harvesting and converting clean solar energy to the localized heat. It is highly desirable to introduce robust materials that are able to bear the extreme conditions for advanced applications of solar steam generation. Here, we demonstrate an all-in-one interfacial solar evaporator made from poly(p-phenylene benzobisoxazole) nanofiber (PBONF)/graphene oxide (GO) and PBONF/reduced graphene oxide (RGO) composite aerogels with high porosity, robust mechanical properties, and excellent thermal insulation performance. The evaporators of PBONF/RGO composite aerogel show fast and durable solar-vapor conversion with a high efficiency of 98.4 % under unconcentrated one sun irradiation. The PBONFs not only reinforce the mechanical properties of composite aerogels, but also affords them great potential applications in wastewater purification in some extreme environment, for instance, aerospace.

A high efficiency solar steam generation system with using residual heat to enhance steam escape

Solar steam generation has become the most promising solar-thermal applications in recent years. Scientists often focus on the search for superior materials, efficient structures, while ignoring the use of residual heat from the water at the bottom. In this paper, a membrane distillation system that utilizes residual heat was added in a new solar house of a domestic hot water and drinking water supply system in the first place. The pDA-rGO-PTFE membrane as an excellent evaporator was characterized in solar steam generation system, which possesses good hydrophilicity capacity and high intrinsic absorption properties. And at the optimal concentration of 20mg/mL, the evaporation rate and efficiency of pDA-rGO-PTFE membrane could reach up 1.45kg·m−2·h−1 and 93.8% respectively in one sun (one sun=1kw·m−2). The PTFE membrane as a separator was applied in a membrane distillation system. Under average 0.66 sun in the natural environment, the average evaporation rate of a new solar house could reach about 1.10kg·m−2·h−1, and there is an additional 0.71kg·m−2·h−1 membrane permeation flux by the residual heat. In addition, the new solar house showed an excellent durability and desalination ability, the ions rejection rations of the collected condensate water were close to 99.8%. Hence, we conclude that further ideas of a new solar house were provided for solving water scarcity, domestic water consumption and the application of solar steam generation in the future.

Hierarchical Porous Aluminophosphate-Treated Wood for High-Efficiency Solar Steam Generation.

Solar steam generation as a promising solar energy conversion technology has attracted considerable interest in achieving seawater desalination and water purification. Although wood with fast water transportation and excellent heat localization has drawn particular interest in regard to its application for solar steam generation, challenges still remain in terms of its complicated processing techniques and relatively low efficiency. Here, we propose a facile, cost-efficient, and scalable brushing method to prepare an aluminophosphate-treated wood (Wood@AlP) solar steam generation device. The aluminophosphate compound deposited on the wood surface can not only be considered as the Lewis acid catalyst capable of accelerating the formation of the carbon layer but also provide an aluminophosphate layer with a hierarchical porous structure, which is beneficial for broad solar absorption and vapor escape. On the other hand, benefiting from the natural hydrophilicity, low thermal conductivity, and excellent water transportation of wood, the obtained Wood@AlP device can float on seawater and exhibit a high solar thermal efficiency of 90.8% with a net evaporation rate of 1.423 kg m-2 h-1 under 1 sun illumination.