Solar-driven Seawater Desalination Research Articles

Construction of magnetic and photothermal wood membrane with asymmetric wettabilities and wind drift resistance for solar-driven seawater desalination and purification

To generate clean freshwater controllably and efficiently, Fe3O4/CNT nanomaterials and hydrophobic PVDF were introduced to delignified wood with man-made-cutting structure (D-Wood) in simple brushing method for constructing the magnetic and photothermal wood evaporator with asymmetric wettabilities and wind drift resistance. Such method could endow wood with various shapes design, outstanding magnetically sensitivity, remarkable photothermal conversion efficiency (129.08 %), high evaporation rate (1.92 kg·m−2·h−1), good dye degradability (97.23 %), and excellent wind resistance (6.6 m/s). The superhydrophilic and underwater superoleophobic bottom of Fe3O4/CNT/PVDF@D-Wood evaporator accelerated the bulk seawater transport during its evaporation procedure, but prevented the oil pollutants blocking the microchannels of evaporator during the long periods of flotation at sea. Meantime, its hydrophobic top could effectively reduce the downward diffusion of heat, and improve the salt tolerance. After 10 cycles of acid-base, ultrasound treatments and evaporating experiments, Fe3O4/CNT/PVDF@D-Wood evaporator still exhibited excellent evaporation rate and conversion efficiency, displaying remarkable repeatability and long-term durability. In weak magnetic field (3 V), its furthest response displacement and time were 5 cm and 41 s, respectively. After prolonged evaporation procedure, the magnetic responsivity of Fe3O4/CNT/PVDF@D-Wood evaporator could be in almost constant level, which offers a promising biomass product for seawater desalination and polluted-water purification.

A multi-layer fabric for high-efficiency solar-driven seawater desalination

Fiber-based photothermal materials for seawater desalination usage have garnered significant attention owing to their outstanding properties. However, traditional monolayer fabrics are prone to possess inherent inefficiencies such as high thermal dissipation and salt crystallization within the evaporation zone, especially reducing the evaporation efficiency during the long-term seawater desalination. Herein, a novel three-layered three-dimensional (3D) spacer carbon/polyester cotton spacer woven fabric (SWF) evaporator is designed. This SWF material was delineated into three distinct layers: an upper evaporate layer, a foundational water absorption layer, and a central water dedicated to water transition, thermal insulation, and salt crystallization. The rational three-layered 3D architecture guarantees the swift aqueous transition within SWF evaporator, simultaneously curtailing thermal losses from the top layer. The evaporation rate of 3D SWF, with 6 mm interval space, registered at 1.6721 kg · m−2·h−1 under a solar intensity of 1 kW · m−2. Furthermore, under conditions with a solar power of 1 kW · m−2 and a wind velocity of 2 m · s−1, the evaporation efficiency of liquid water from SWF, with a central layer height of 12 mm, culminated at 3.9742 kg · m−2·h−1, which validated its adeptness for the seawater desalination applications. The results of our research are helping to provide for efficient and stable methods of wastewater treatment, desalination, and drinking water collection.

A coal-based multifunctional membrane for solar-driven seawater desalination and power generation

Water evaporation systems driven by solar energy delivers great potential for seawater desalination and sustainable energy generation, which is of great significance to relieve the worldwide shortage of fresh-water and energy. However, the achievement of well-designed materials and configuration for water evaporation systems remains a great challenge, hindering the realization of high evaporation rates and stable energy output. Herein, conductive coal-based nanocarbon material was creatively fabricated to assemble a novel multifunctional membrane based evaporation system for simultaneous solar thermal desalination of seawater and power generation. The coal-based multifunctional membrane (CBMM) possesses a permanently asymmetric wetting structure, which can ensure high photothermal evaporation efficiency and stable energy output. The constructed device unit demonstrate a long and stable operation in seawater under one sun irradiance for 100 h, achieving a high evaporation rate of 1.81 kg m−2 h−1 and a large voltage output of 410 mV. Especially, multiple units of the devices can be easily connected in series or parallel to power small electronic devices. This work provides a cost-effective and large scale method for the fabrication of coal-based nanomaterials and the creative application in high-perforamnce water evaporation systems for seawater desalination and sustainable energy generation.

Waste Tea-Derived Theabrownins for Solar-Driven Steam Generation.

Solar-driven seawater desalination has been considered an effective and sustainable solution to mitigate the global freshwater crisis. However, the substantial cost associated with photothermal materials for evaporator fabrication still hinders large-scale manufacturing for practical applications. Herein, we successfully obtained high yields of theabrownins (TB), which were oxidation polymerization products of polyphenols from waste and inferior tea leaves using a liquid-state fermentation strategy. Subsequently, a series of photothermal complexes were prepared based on the metal-phenolic networks assembled from TB and metal ions (Fe(III), Cu(II), Ni(II), and Zn(II)). Also, the screened TB@Fe(III) complexes were directly coated on a hydrophilic poly(vinylidene fluoride) (PVDF) membrane to construct the solar evaporation device (TB@Fe(III)@PVDF), which not only demonstrated superior light absorption property and notable hydrophilicity but also achieved a high water evaporation rate of 1.59 kg m-2 h-1 and a steam generation efficiency of 90% under 1 sun irradiation. More importantly, its long-term stability and exceptionally low production cost enabled an important step toward the possibility of large-scale practical applications. We believe that this study holds the potential to pave the way for the development of sustainable and cost-effective photothermal materials, offering new avenues for utilization of agriculture resource waste and solar-driven water remediation.

Intensifying heat using AgCu core-shell-based black titania with highly efficient photothermal conversion performance for solar-driven seawater desalination

A novel photoreceiver composed of black titania (BT) matrix with biochar for efficient steam production was investigated to measure the desalination efficiency under the illumination of one sun (1 kW m−2). The density of localized hotspots on the surface of the photothermal system is enhanced by the incorporation of AgCu core-shell that promotes photothermal activity and improves the degradation of methyl orange (MO) dye. Assemblages of AgCu nanoparticles on the surface of BT generated a strong stochastic plasmonic coupling and therefore broad-band absorption for much better solar energy consumption. The nanocomposite exhibited an excellent vaporization flux of 1.4 kg m−2 h−1 with high efficiency reaching 95.7 % under the illumination of one sun. AgCu@BT/BC exhibited an excellent surface temperature of 41 °C after only 5 min compared to other prepared photothermal systems. Furthermore, the prepared composites revealed superb degradation of MO dye under UV–vis light with a percentage of 96 %. The band gap energy of white titania decreased from 3.2 eV to 1.86 eV in the case of AgCu@BT/BC nanocomposite. Moreover, the crystalline AgCu@BT/BC demonstrates outstanding photocatalytic performance because of boosted charge migration, reduced electron-hole pair recombination rate, and identifiable shift to the red region.

Double-layered hydrogels based on phase change material and pen ink for continuous and efficient solar-driven seawater desalination

A novel double-layered hydrogel based on the polyacrylamide matrix, pen ink, and phase-change microcapsules was developed to construct a hydrogel-based evaporator for efficient and continuous seawater desalination. The n-eicosane (core)@crystalline TiO2 (shell) phase-change microcapsules were fabricated through interfacial polycondensation, and the resulting phase-change microcapsules obtained a considerably high latent-heat capacity of 187 J·g−1. The upper layer of the hydrogel exhibits a high solar absorptivity of over 90 % due to the introduction of pen ink as a solar absorber, which helps the hydrogel-based evaporator to gain an excellent photothermal energy conversion capability. A high evaporation efficiency of 93.89 % was obtained for the developed hydrogel-based evaporator along with a high evaporation rate of 1.85 kg·m−2·h−1 under one-sun illumination. The phase-change microcapsules dispersed in the lower layer of the hydrogel can act as a latent heat-storage unit to store a great quantity of photothermal energy through melting phase change by the phase change material core. This imparts a consecutive evaporation capability to the developed hydrogel-based evaporator. As a result, its water production was increased by 11 % under 50-min one-sun illumination and 50-min non-illumination.

Super-hydrophilic LaCoO3/g-C3N4 nanocomposite coated beauty sponge for solar-driven seawater desalination with simultaneous volatile organic compound removal.

Interfacial solar steam generation (ISSG) is emerging as a promising, environment-friendly solution for fulfilling freshwater and energy demands. However, a critical challenge for ISSG lies in the presence of harmful volatile organic compounds (VOCs) in the feedwater which are co-evaporated with water, leading to more enriched concentration in condensed water. Herein, lanthanum cobaltate-graphitic carbon nitride (LaCoO3/g-C3N4, LCO/g-CN) nanocomposite decorated beauty sponge (LCO/g-CN@BS) is proposed as an efficient photothermal/photocatalytic material for solar-driven seawater desalination and simultaneous VOC degradation. The hydrophobic surface of the beauty sponge after LCO/g-CN coating becomes super-hydrophilic, ensuring sufficient water supply and our LCO/g-CN@BS delivers an evaporation rate of 1.94 kg m-2 h-1 under 1 sun irradiation. This LCO/g-CN@BS shows excellent seawater desalination capacity with a self-cleaning ability when employed for saltwater purification for a salt (NaCl) concentration as high as 15 wt%. Moreover, fast photocarrier transfer between LCO and g-CN leads to enhanced photocatalytic degradation of over 90% of phenol simultaneously, which is about 60% for only an LCO-based beauty sponge. This work presents a promising approach to combining novel nanocomposites with microporous structures for efficient solar desalination, offering simultaneous VOC degradation.

Research Advances in Wood Composites in Applications of Industrial Wastewater Purification and Solar-Driven Seawater Desalination.

In recent years, the ecosystem has been seriously affected by sewage discharge and oil spill accidents. A series of issues (such as the continuous pollution of the ecological environment and the imminent exhaustion of freshwater resources) are becoming more and more unmanageable, resulting in a crisis of water quality and quantity. Therefore, studies on industrial wastewater purification and solar-driven seawater desalination based on wood composites have been widely considered as an important development direction. This paper comprehensively analyzes and summarizes the applications of wood composites in the fields of solar-driven seawater desalination and polluted water purification. In particular, the present situation of industrial wastewater containing heavy metal ions, microorganisms, aromatic dyes and oil stains and related problems of solar-driven seawater desalination are comprehensively analyzed and summarized. Generally, functional nanomaterials are loaded into the wood cell wall, from which lignin and hemicellulose are selectively removed. Alternatively, functional groups are modified on the basis of the molecular structure of the wood microchannels. Due to its three-dimensional (3D) pore structure and low thermal conductivity, wood is an ideal substrate material for industrial wastewater purification and solar-driven seawater desalination. Based on the study of objective conditions such as the preparation process, modification method and selection of photothermal conversion materials, the performances of the wood composites in filtration, adsorption and seawater desalination are analyzed in detail. In addition, this work points out the problems and possible solutions in applying wood composites to industrial wastewater purification and solar-driven seawater desalination.

Carbon nanotubes@polydopamine/nickel foam with a wavy shape applied for efficient solar-driven seawater desalination

Solar-powered water evaporation has been recognized as a potential water purification regeneration technology to alleviate the issue of global water shortage. Interfacial solar steam generation (ISSG) with a high rate of evaporation and high photo-thermal conversion efficiency is very desirable. Herein, a scalable, high-efficiency and surface tunable ISSG was developed by carbon nanotubes (CNTs) loaded on polydopamine (PDA) modified nickel foam (NF) with a honeycomb three-dimensional (3D) network structure. The surface of CNTs@PDA/NF (CPNF) solar evaporator was designed as the 3D wave-like for further improved water evaporation. The as-prepared solar steam generator has an evaporation rate of 1.61 kg m−2 h−1, and photo-thermal conversion efficiency of 91.0 % at 1.0 solar irradiance. Moreover, it displays efficient purification ability for heavy metal ions in seawater and lake water, and the concentration of Na+, Mg2+, K+ and Ca2+ in the desalinated condensate is in line with the World Health Organization's drinking water standards. Additionally, the dye-contaminated wastewater can also be purified and treated to be drinking water. Furthermore, it has a good salt self-melting function. In sum, this work provides some new insights for designing innovative solar evaporators with outstanding photothermal conversion capability.

Fully waste-based solar evaporator in interfacial solar-driven seawater desalination

The scarcity of freshwater resources and the increasing demand for sustainable water treatment technologies have prompted the development of interfacial solar-driven seawater desalination (ISSD). However, designing stable solar evaporators to alleviate freshwater scarcity and reduce environmental stress remains a significant challenge. This study presents a solar evaporator from waste materials to address these challenges. The device comprises a photothermal membrane (CLPM) made from cattail leaf-based fibers (CLF) and cattail leaf-based carbon (CLC) with a simple crosslinking method using sodium alginate and CaCl2, a waste humidifier filter (WHF), and discarded packaging foam. The CLPM exhibits approximately 96 % solar absorption, achieving an evaporation rate of 1.38 kg m–2 h–1 when treating groundwater and 1.22 kg m–2 h–1 when desalinating a 3.5 wt % NaCl solution. The desalination performance of CLPM can be stable for 6 h due to the sufficient water provided by the WHF with vertical water conductivity channels. The desalination performance of CLPM can be restored by washing off the accumulated salts in a 3.5 wt % NaCl solution or by self-cleaning overnight, as verified by indoor and outdoor cycling experiments. 1 m2 of CLPM can produce approximately 5.3 kg of freshwater during the daytime, sufficient to meet two adults' daily water consumption needs. This waste-derived solar evaporator promotes the efficient utilization of waste materials and offers a sustainable solution to address freshwater scarcity while reducing environmental impact.

The solar-driven redox seawater desalination based on the stable and environmentally friendly WO3/BiVO4 photoanode

Nowadays, stable photoelectrochemical seawater desalination is a challenge. In this work, an environmentally friendly WO3/BiVO4 photoanode is reported to achieve stable solar-driven redox desalination. The WO3/BiVO4 photoanode was prepared by the hydrothermal method and drop-casting and the cathode is the activated carbon coated on graphite paper. Within the desalination system, the I−/I3− redox species are recycled between anode/cathode chambers. In the short-circuit state, with illumination as the driving force, the salt removal rate of 65.03 μg/(cm2·min) is obtained without the electric consumption. During the desalination process, the energy output process can be implemented with a salt removal rate of 29.8 μg/(cm2·min) with constant current discharge. Importantly, the solar desalination system based on WO3/BiVO4 photoanode is quite stable. Within the five cycles, the variation of the salt removal rate is within 3.32 μg/(cm2·min). As the practical application, the seawater is desalted to the freshwater standard using the current system, in which the conductivity decreases to 0.96 mS/cm from 53 mS/cm. This work provides a feasible approach to developing stable and efficient solar-driven seawater desalination for long-term usage.

Salt-resistance holocellulose-based solar steam evaporator for desalination brine water

Interfacial solar-powered water evaporation is a cost-effective and sustainable approach using solar energy for seawater desalination. Nevertheless, salt accumulation during solar desalination generally restricts the widespread application of solar vapor generation. Herein, taking merits of the excellent hydrophilicity and inherent porosity of holocellulose (HC), An excellent salt-resistant solar steam evaporator for long-term interfacial solar water desalination was fabricated by decorating polypyrrole (PPy) on the surface of HC. Due to the broadband light absorbance of PPy and the superhydrophilic HC substrate, the PPy-HC evaporator exhibited a high evaporation rate of 1.45 kg m−2 h−1 and conversion efficiency of 93.4 % in a 5 wt% NaCl solution under one sun illumination. Importantly, the evaporator presented superior salt-resistance and stability during long-term cycling test in high salinity brine. This work reveals the key role of superhydrophilicity and water transportation capability in high salt solution solar-driven desalination. Thus, this work provides an effective approach to address the issue of salt accumulation of the traditional evaporator, demonstrating its great potential for real-world solar-driven seawater desalination.

A solar-driven seawater desalination and electricity generation integrating system based on carbon black-decorated magnetic phase-change composites

We have developed a novel type of solar-driven interfacial evaporation and electricity generation integrating system based on the modified carbon black (MCB)-decorated magnetic phase-change composites (MCB-MPCC) for continuous seawater desalination and clean electric power generation under intermittent solar illumination. In this system, MCB-MPCC acts as not only a solar absorber but also a hydrovoltaic functional coating. MCB-MPCC was fabricated through encapsulating n-docosane as a phase change material (PCM) in a SiO2/Fe3O4 composite shell through emulsion-templated interfacial polycondensation, followed by coating a polydopamine layer and surface-depositing MCB nanoparticles. Owing to the introduction of a PCM core, the resultant MCB-MPCC obtained a high latent heat capacity of over 145 J g−1 for consecutive seawater evaporation under intermittent solar illumination. Moreover, the surface-decorated MCB nanoparticles contribute to superior sunlight absorptivity and good wettability of MCB-MPCC, promoting a high evaporation rate of 2.67 kg m−2 h−1 for the MCB-MPCC-based evaporator under one-sun illumination along with excellent salt resistance. Meanwhile, the developed system achieved a stable output voltage of 0.43 V and output current of 10.05 μA under one-sun illumination, and the generated electric power could be stored by a commercial capacitor to provide a power supply for lightening an LED lamp.

Multi-bioinspired hierarchical integrated hydrogel for passive fog harvesting and solar-driven seawater desalination

In recent years, with the outbreak and epidemic of the novel coronavirus in the world, how to obtain clean water from the limited resources has become an urgent issue of concern to all mankind. Atmospheric water harvesting technology and solar-driven interfacial evaporation technology have shown great potential in seeking clean and sustainable water resources. Here, inspired by a variety of organisms in nature, a multi-functional hydrogel matrix composed of polyvinyl alcohol (PVA), sodium alginate (SA) cross-linked by borax as well as doped with zeolitic imidazolate framework material 67 (ZIF-67) and graphene owning macro/micro/nano hierarchical structure has successfully fabricated for producing clean water. The hydrogel not only can reach the average water harvesting ratio up to 22.44 g g−1 under the condition of fog flow after 5 h, but also be capable of desorbing the harvested water with water release efficiency of 1.67 kg m−2 h−1 under 1 sun. In addition to excellent performance in passive fog harvesting, the evaporation rate over 1.89 kg m−2h−1is attained under 1 sun on natural seawater during long-term. This hydrogel indicates its potential in producing clean water resources in multiple scenarios in different dry or wet states, and which holds great promise for flexible electronic materials and sustainable sewage or wastewater treatment applications.

CNT-based gel-coated cotton fabrics for constructing symmetrical evaporator with up/down inversion property for efficient continuous solar desalination

Solar-driven seawater desalination has drawn much attention, while the practical application has been limited by the unsatisfactory photoabsorption as well as solid-salt crystallization. To address the issues, hereby we have constructed a symmetrical evaporator with up/down inversion property by using carbon nanotubes (CNTs)-based gel-coated cotton fabrics. Such CNT-cotton fabrics have porous structure and strong photoabsorption in 280–2500 nm range. Subsequently, two CNT-cotton fabrics are coated on cotton-embedded polystyrene for constructing symmetrical evaporator. Such symmetrical evaporator is placed in NaCl solution (3.5 wt%), it exhibits an excellent evaporation rate of 1.62 kg m−2 h−1 under 1 sun irradiation. To investigate the effects of solid-salt crystallization, a higher concentration of NaCl solution (21 wt%) can be used for evaporation. As expected, the evaporation rate decreases from 1.62 to 0.75 kg m−2 h−1 in 8 h because of solid-salt crystallization on the upper-surface. Importantly, the symmetrical evaporator can eliminate adverse effect of solid-salt crystallization by using an inverse strategy (twice an hour), remaining a stable evaporation rate (1.49–1.62 kg m−2 h−1) during long-time test. Therefore, the present design of CNT-cotton fabrics and symmetrical evaporator may provide some new insights for efficient continuous desalination under sunlight irradiation.

A super-hydrophilic honeycomb activated carbon evaporator for simultaneous salt rejection and VOCs removal during solar-driven seawater desalination

Salt accumulation and volatile organic compounds (VOCs) entering condensed freshwater are two main drawbacks in the new approach of solar-driven seawater desalination. In this work, a super-hydrophilic honeycomb activated carbon (SHHAC) evaporator was fabricated for simultaneous salt rejection and VOCs removal. The optimal water evaporation rate of the SHHAC evaporator was as high as 1.50 kg·m−2·h−1 under one sun illumination with the corresponding photothermal conversion efficiency of 99.4 %. Due to the super-hydrophilic properties, high water absorption capacity, fast water absorption rate and unique honeycomb structure of SHHAC, the salt-rejection property of the SHHAC evaporator was achieved by flowing back the concentrated brine to the underneath seawater. Simultaneously, the distillation concentration ratio (RD) of phenol was reduced from 75 % to 0 % by the SHHAC evaporator resulting in zero phenol entering condensed freshwater. Finally, the potential application of the SHHAC evaporator was demonstrated by an expanded outdoor experiment using the real seawater as the feedwater.

Development of MXene-decorated sodium alginate/SiO2@n-docosane hierarchical phase-change microcapsules for solar-driven sustainable seawater desalination

A novel type of MXene-decorated and sodium alginate (SA)-coated phase-change microcapsules (hereafter named “MXene/SA/SiO2-MEPCM”) was designed as a bifunctional solar absorber for the interfacial evaporator to realize sustainable seawater desalination. The MXene/SA/SiO2-MEPCM was fabricated by encapsulating n-docosane as a phase change material (PCM) in the SiO2 shell, followed by depositing a SA layer and decorating MXene nanosheets. An innovative integration of SA and MXene nanosheets enables the microcapsules to achieve a high light absorption capability of over 97 % together with good wettability, promoting a high evaporation rate of 2.11 kg·m−2·h−1 under one-sun illumination. The MXene/SA/SiO2-MEPCM exhibits a high latent heat capacity of over 150 J·g−1 for consecutive and high-efficient evaporation under intermittent solar illumination. Compared to the evaporator without a PCM core, the MXene/SA/SiO2-MEPCM-based evaporator achieved an increase in evaporation mass by 1.4 kg·m−2 through 5-cycle consecutive evaporation processes under solar illumination and natural cooling. Furthermore, its total water production was increased by 1.01 kg·m−2 under natural solar illumination for 7.5 h on a semi-cloudy day. The MXene/SA/SiO2-MEPCM also exhibits good recyclability for long-term use in solar-driven seawater desalination thanks to the good structural stability of its shell and highly stable reversible phase transitions of its PCM core.

Biomass-derived photothermal carbon aerogel for efficient solar-driven seawater desalination

Solar-driven interface evaporation is an effective method to produce fresh water to alleviate the shortage of water resources. However, there are still challenges in preparing photothermal conversion materials with high evaporation rate, high photothermal conversion efficiency and low cost. Herein, a 3D carbon aerogel with excellent photothermal conversion performance was prepared by using environmental-friendly biomass materials as the matrix. The hydrophilic 3D photothermal carbon aerogel with low thermal conductivity was prepared by depositing polydopamine and loading Cu nanoparticles (CuNPs) on the surface of bacterial cellulose nanofibers. The deposition of PDA improved the mechanical properties and hydrophilicity of carbon aerogel, and the introduction of CuNPs further enhanced the photothermal conversion performance of carbon aerogel. Interestingly, the side temperature of 3D carbon aerogel was lower than the ambient temperature in the evaporation process, which could absorb energy from the environment and significantly improve the photothermal conversion efficiency, giving rise to the impressive water evaporation rate (2.07 kg·m−2·h−1) and photothermal conversion efficiency (115.36%) of 3D carbon aerogel under 1 sun. Moreover, the prepared 3D carbon aerogel had excellent purification effect on seawater, strong acid/alkali and dye solution, demonstrating its broad application prospect in the field of solar-driven seawater desalination.

Fully Superhydrophilic, Self-Floatable, and Multi-Contamination-Resistant Solar Steam Generator Inspired by Seaweed

• Independent floatability guarantees stable interfacial steam generation. • Complete hydration ensures superhydrophilicity and continuous water pumping. • High water affinity endows the floater with long-term multi-contamination resistance against oil spill, microbial corrosion, salt crystallization, protein adsorption, etc. • These merits allow the floater to perform stable solar evaporation from seawater or even wastewater. Highly hydrophilic materials enable rapid water delivery and salt redissolution in solar-driven seawater desalination. However, the lack of independent floatability inhibits heat localization at the air/water interface. In nature, seaweeds with internal gas microvesicles can float near the sea surface to ensure photosynthesis. Here, we have developed a seaweed-inspired, independently floatable, but superhydrophilic (SIFS) solar evaporator. It needs no extra floatation support and can simultaneously achieve continuous water pumping and heat concentration. The evaporator resists salt accumulation, oil pollution, microbial corrosion, and protein adsorption. Densely packed hollow glass microbeads promote intrinsic floatability and heat insulation. Superhydrophilic zwitterionic sulfobetaine hydrogel provides a continuous water supply, redissolves the deposited salt, and endows the SIFS evaporator with excellent anti-fouling properties. With its unprecedented anti-contamination ability, this SIFS evaporator is expected to open a new avenue for designing floatable superhydrophilic materials and solving real-world issues of solar steam generation in complex environmental conditions.

A highly efficient and sustainable photoabsorber in solar-driven seawater desalination and wastewater purification.

Producing freshwater from seawater and wastewater is of great importance through interfacial solar steam generation (ISSG). Herein, the three-dimensional (3D) carbonized pine cone, CPC1, was fabricated via a one-step carbonization process as a low-cost, robust, efficient, and scalable photoabsorber for the ISSG of seawater as well as a sorbent/photocatalyst for use in wastewater purification. Taking advantage of the large solar-light-harvesting ability of CPC1 due to the presence of carbon black layers on the 3D structure, its inherent porosity, rapid water transportation, large water/air interface, and low thermal conductivity, a conversion efficiency of 99.8% and evaporation flux of 1.65 kg m-2 h-1 under 1 sun (kW m-2) illumination were achieved. After carbonization of the pine cone, its surface becomes black and rough, which leads to an increase in its light absorption in the UV-Vis-NIR region. The photothermal conversion efficiency and evaporation flux of CPC1 did not change significantly during 10 evaporation-condensation cycles. CPC1 exhibited good stability under corrosive conditions without significant change in its evaporation flux. More importantly, CPC1 can be used to purify seawater or wastewater by the removal of organic dyes as well as by the reduction of polluting ions, like nitrate ions in sewage.