Efficient Solar-Driven Interfacial Water Evaporator using Hydrogel Modified Carbon-Based Biomass with Abundant Microchannels.

The conventional sea water desalination technologies are not yet adopted worldwide, especially in the third world countries due to their high capital cost as well as large energy requirement. To solve this issue in a sustainable way an interfacial solar water evaporation device is designed and proposed in this article using the branches of Prunus serrulata (PB). The PB has abundant microchannels and shows excellent photothermal conversion capability after carbonization. Moreover, the easy access to raw materials and the facile fabrication process makes the solar water evaporating device very cost effective for seawater desalination application. Experiments show that in the presence of the fabricated evaporator the evaporation rate of water can reach 3.5 kg m-2  h-1 under 1 sun, which is superior to many similar experimental devices. In addition, its advantages, such as effective sewage purification capability, low cost, and environmental friendliness, make this evaporator highly competitive in the extensive promotion of this technology and can be considered as a new sustainable solution for seawater desalination with great application potential and prospects.

Constructing Thermal Convection Film for Low Heat Loss and High Salt Resistance in Wood-Based Solar Evaporators.

Unique suspension solar evaporator is one of the effective measures to address the major bottleneck of the emerging interfacial evaporators, i.e., the accumulation of salts on the surface. Yet, it remains a considerable challenge to avoid substantial heat loss underwater. Herein, a suspension wood-based evaporator is proposed with a thermal convection structure that effectively balances the contradiction between salt-resistance ability and heat loss. Benefitting from the heat centralization due to thermal convection, such suspension evaporator exhibits an excellent steam generation rate, which increases from 1.23 to 1.63 kg m-2 h-1 compared to the conventional suspension evaporator. Simultaneously, the steam generation rate retention improves from 64.9% over 20 test cycles to nearly 100% compared to the interfacial evaporator. This work provides an effective pathway for exploring efficient and stable suspension evaporators, offering essential directions for the future development and application of solar-driven evaporation technologies.

Tortuosity Engineering of Water Channels to Customized Water Supply for Enhancing Hydrogel Solar Evaporation.

Hydrogel as a solar evaporator shows great potential in freshwater production. However, hydrogels often lead to an imbalance between solar energy input and water supply management due to their excessively high saturated water content. Thus, achieving a stable water-energy-balance in hydrogel evaporators remains challenging. Here, by tortuosity engineering designed water transport channels, a seamless high-tortuosity/low-tortuosity/high-tortuosity structured hydrogel (SHLH structure hydrogel) evaporator is developed, which enables the hydrogel with customized water transport rate, leading to the controlled water supply at the evaporator interface. An excellent equilibrium between the photothermal conversion and water supply is established, and the maximum utilization of solar energy is realized, thereby achieving an excellent evaporation rate of 3.64 kg m-2 h-1 under one solar illumination. This tortuosity engineering controlled SHLH structured evaporator provides a novel strategy to attain water-energy-balance and expands new approaches for constructing hydrogel-based evaporators with tailored water transportation capacity.

Harnessing Natural Evaporation for Electricity Generation using MOF-Based Nanochannels.

Functionalized nanochannels can convert environmental thermal energy into electrical energy by driving water evaporation. This process involves the interaction between the solid-liquid interface and the natural water evaporation. The evaporation-driven water potential effect is a novel green environmental energy capture technology that has a wide range of applications and does not depend on geographical location or environmental conditions, it can generate power as long as there is water, light, and heat. However, suitable materials and structures are needed to harness this natural process for power generation. MOF materials are an emerging field for water evaporation power generation, but there are still many challenges to overcome. This work uses MOF-801, which has high porosity, charged surface, and hydrophilicity, to enhance the output performance of evaporation-driven power generation. It can produce an open circuit voltage of ≈2.2 V and a short circuit current of ≈1.9 µA. This work has a simple structure, easy preparation, low-cost and readily available materials, and good stability. It can operate stably in natural environments with high practical value.

An Azulene-Based Crystalline Porous Covalent Organic Framework for Efficient Photothermal Conversion.

The designed synthesis of a crystalline azulene-based covalent organic framework (COF-Azu-TP) is presented and its photothermal property is investigated. Azulene, a distinctive 5-7 fused ring non-benzenoid aromatic compound with a large intramolecular dipole moment and unique photophysical characteristics, is introduced as the key feature in COF-Azu-TP. The incorporation of azulene moiety imparts COF-Azu-TP with broad-spectrum light absorption capability and interlayer dipole interactions, which makes COF-Azu-TP a highly efficient photothermal conversion material. Its polyurethane (PU) composite exhibits a solar-to-vapor conversion efficiency (97.2%) and displays a water evaporation rate (1.43 kg m-2 h-1) under one sun irradiation, even at a very low dosage of COF-Azu-TP (2.2 wt%). Furthermore, COF-Azu-TP is utilized as a filler in a polylactic acid (PLA)/polycaprolactone (PCL) composited shape memory material, enabling rapid shape recovery under laser stimulation. A comparison study with a naphthalene-based COF isomer further emphasizes the crucial role of azulene in enhancing photothermal conversion efficiency. This study demonstrates the significance of incorporating specific building blocks into COFs for the development of functional porous materials with enhanced properties, paving the way for future applications in diverse fields.

Copper-Nanoparticle-Decorated Hydrothermal Carbonaceous Carbon-Polydimethylsiloxane Nanocomposites: Unveiling Potential in Simultaneous Light-Driven Interfacial Water Evaporation and Power Generation.

This study introduces a hydrothermal synthesis method that uses glucose and Cu2+ ions to create a Cu-nanoparticle (NP)-decorated hydrothermal carbonaceous carbon hybrid material (Cu-HTCC). Glucose serves both as a reducing agent, efficiently transforming Cu2+ ions into elemental Cu nanostructures, and as a precursor for HTCC microstructures. An enhanced plasmon-induced electric field resulting from Cu NPs supported on microstructure matrices, coupled with a distinctive localized π-electronic configuration in the hybrid material, as confirmed by X-ray photoelectron spectroscopic analysis, lead to the heightened optical absorption in the visible-near-infrared range. Consequently, flexible nanocomposites of Cu-HTCC/PDMS and Cu-HTCC@PDMS (PDMS = polydimethylsiloxane) are designed as 2 and 3D structures, respectively, that exhibit broad-spectrum solar absorption. These composites promise efficient photo-assisted thermoelectric power generation and water evaporation, demonstrating commendable mechanical stability and flexibility. Notably, the Cu-HTCC@PDMS composite sponge simultaneously exhibits commendable efficiency in both water evaporation (1.47 kg m-2 h-1) and power generation (32.1 mV) under 1 sunlight illumination. These findings unveil new possibilities for innovative photothermal functional materials in diverse solar-driven applications.

Pollutant Photodegradation Affected by Evaporative Water Concentration in a Climate Change Scenario.

Evaporative water concentration takes place in arid or semi-arid environments when stationary water bodies, such as lakes or ponds, prevalently lose water by evaporation, which prevails over outflow or seepage into aquifers. Absence or near-absence of precipitation and elevated temperatures are important prerequisites for the process, which has the potential to deeply affect the photochemical attenuation of pollutants, including contaminants of emerging concern (CECs). Here we show that water evaporation would enhance the phototransformation of many CECs, especially those undergoing degradation mainly through direct photolysis and triplet-sensitized reactions. In contrast, processes induced by hydroxyl and carbonate radicals would be inhibited. Our model results suggest that the photochemical impact of water evaporation might increase in the future in several regions of the world, with no continent likely being unaffected, due to the effects of local precipitation decrease combined with an increase in temperature that facilitates evaporation.

Manipulation of the Self-Assembly Morphology by Side-Chain Engineering of Quinoxaline-Substituted Organic Photothermal Molecules for Highly Efficient Solar-Thermal Conversion and Applications.

Organic photothermal materials have attracted increasing attention because of their structural diversity, flexibility, and compatibility. However, their energy conversion efficiency is limited owing to the narrow absorption spectrum, strong reflection/transmittance, and insufficient nonradiative decay. In this study, two quinoxaline-based D-A-D-A-D-type molecules with ethyl (BQE) or carboxylate (BQC) substituents were synthesized. Strong intramolecular charge transfer provided both molecules with a broad absorption range of 350-1000 nm. In addition, the high reorganization energy and weak molecular packing of BQE resulted in efficient nonradiative decay. More importantly, the self-assembly of BQE leads to a textured surface and enhances the light-trapping efficiency with significantly reduced light reflection/transmittance. Consequently, BQE achieved an impressive solar-thermal conversion efficiency of 18.16 % under 1.0 kW m-2 irradiation with good photobleaching resistance. Based on this knowledge, the water evaporation rate of 1.2 kg m-2 h-1 was attained for the BQE-based interfacial evaporation device with an efficiency of 83 % under 1.0 kW m-2 simulated sunlight. Finally, the synergetic integration of solar-steam and thermoelectric co-generation devices based on BQE was realized without significantly sacrificing solar-steam efficiency. This underscores the practical applications of BQE-based technology in effectively harnessing photothermal energy. This study provides new insights into the molecular design for enhancing light-trapping management by molecular self-assembly, paving the way for photothermal-driven applications of organic photothermal materials.

Bioinspired Aerogel with Vertically Ordered Channels and Low Water Evaporation Enthalpy for High-Efficiency Salt-Rejecting Solar Seawater Desalination and Wastewater Purification.

Solar energy-driven water evaporation is a promising sustainable strategy to purify seawater and contaminated water. However, developing solar evaporators with high water evaporation rates and excellent salt resistance still faces a great challenge. Herein, inspired by the long-range ordered structure and water transportation capability of lotus stem, a biomimetic aerogel with vertically ordered channels and low water evaporation enthalpy for high-efficiency solar energy-driven salt-resistant seawater desalination and wastewater purification is developed. The biomimetic aerogel consists of ultralong hydroxyapatite nanowires as heat-insulating skeletons, polydopamine-modified MXene as a photothermal material with broadband sunlight absorption and high photothermal conversion efficiency, polyacrylamide, and polyvinyl alcohol as reagents to lower the water evaporation enthalpy and as glues to enhance the mechanical performance. The honeycomb porous structure, unidirectionally aligned microchannels, and nanowire/nanosheet/polymer pore wall endow the biomimetic aerogel with excellent mechanical properties, rapid water transportation, and excellent solar water evaporation performance. The biomimetic aerogel exhibits a high water evaporation rate (2.62 kg m-2  h-1 ) and energy efficiency (93.6%) under one sun irradiation. The superior salt-rejecting ability of the designed water evaporator enables stable and continuous seawater desalination, which is promising for application in water purification to mitigate the global water crisis.

PDI-Based Organic Small Molecule Regulated by Inter/Intramolecular Interactions for Efficient Solar Vapor Generation.

Organic small molecules with processing feasibility, structural diversity, and fine-tuned properties have the potential applications in solar vapor generation. However, the common defects of narrow solar absorption, low photothermal conversion efficiency, and photobleaching result in limited materials available and unsatisfactory evaporation performance. Herein, the perylene diimide (PDI) derivatives are exploited as stable sunlight absorbers for solar vapor generation. Particularly, the N,N'-bis(3,4,5-trimethoxyphenyl)-3,4,9,10-perylenetetracarboxylic diimide (PDI-DTMA) is well-designed with donor-acceptor-donor configuration based on plane rigid PDI core. The efficient photothermal conversion is enabled through strong intermolecular π-π stacking and intramolecular charge transfer, as revealed by experimental demonstration and theoretical calculation. The PDI-DTMA with a narrow band gap of 1.17 eV exhibits expanded absorption spectrum and enhanced nonradiative transition capability. The 3D hybrid hydrogels (PPHs) combining PDI-DTMA and polyvinyl alcohol are constructed. With the synergistic effect of solar-to-heat conversion, thermal localization management, water activation, and unobstructed water transmission of PPHs, the high water evaporation rates can reach 3.61-10.07 kg m-2 h-1 under one sun. The hydrogels also possess great potential in seawater desalination and sewage treatment. Overall, this work provides valuable insights into the design of photothermal organic small molecules and demonstrates their potentials in solar water evaporation.

Microfluidic-Assisted Self-Assembly of 2D Nanosheets toward in situ Generation of Robust Nanofiber Film.

Methods allow the enhancement of nanofibers via self-assembly are potentially important for new disciplines with many advantages, including multi-anchor interaction, intrinsic mechanical properties and versatility. Herein, a microfluidic-assisted self-assembly process to construct hydroxyl functionalized boron nitride nanosheets (OH-BNNS)/graphene oxide (GO)/thermoplastic polyurethane (TPU) composite nanofiber film, in which stable and precisely controlled self-assembly is fulfilled by the confined ultra-small-volume chip is demonstrated. Multiple fine structural analyses alongside with the density-functional theory (DFT) calculations are implemented to confirm the synergistic effect of noncovalent interactions (hydrogen bonding interaction, π - π stacking interaction, and van der Waals attraction) plays a critical role in the robust micro-structure and a massive 700% enhancement of mechanical strength via adding only 0.3 wt% OH-BNNS and GO. Importantly, profiled from broadband optical absorption ability, robust mechanical properties and outstanding flexibility, the self-assembled 3D OH-BNNS/GO/TPU nanofiber film reveals an adorable evaporation rate of 4.04 kg m-2  h-1 under one sun illumination with stable energy transfer efficiency (93.2%) by accompanying hydrogen bonding interaction. This microfluidic-assisted self-assembly strategy will provide a constructive entry point for the rational design of nanofibers and beyond.

Modulating photothermal properties by integration of fined Fe-Co in confined carbon layer of SiO2 nanosphere for pollutant degradation and solar water evaporation.

Environmental governance by photothermal materials especially for the separation of organic pollutants and regeneration of freshwater afford growing attention owing to their special solar-to-heat properties. Here, we construct a special functional nanosphere composed of an internal silica core coated by a thin carbon layer encapsulated plasmonic bimetallic FeCo2O4 spinel (SiO2@CoFe/C) by a facile self-assembled approach and tuned calcination. Through combining the advantage of bimetallic Fe-Co and carbon layer, this obtained nanosphere affords improved multiple environmental governing functions including peroxymonosulfate (PMS) activation to degrade pollutants and photothermal interfacial solar water evaporation. Impressively, fined bimetal (FeCo) species (20 nm) acted as main catalytic substance were distributed on the N-doping carbon thin layer, which favors electron transfer and reactive accessibility of active metals. The increasing treatment temperature of catalysts caused the optimization of the surface active metal species and tuning catalytic properties in the AOPs. Besides, the incorporation of Co in the SiO2@CoFe/C-700 could enable the improved PMS activation efficiency compared to SiO2@Fe/C-700 and the mixed SiO2@Co/C-700 and SiO2@Fe/C-700, hinting a synergetic promotion effect. The bimetal coupled catalyst SiO2@CoFe/C-700 affords enhanced photothermal properties compared to SiO2@Co/C-700. Furthermore, photothermal catalytic PMS activation using optimal SiO2@CoFe/C-700 was further explored in addressing stubborn pollutants including oxytetracycline, sulfamethoxazole, 2, 4-dichlorophenol, and phenol. The free radical quenching control suggests that both the sulfate radical, hydroxyl radical, superoxide radical, and singlet oxygen species are involved in the degradation, while the hydroxyl radical and singlet oxygen play a dominant role. Furthermore, the implementation of a solar-driven interfacial water evaporation model using SiO2@CoFe/C-700 was further studied to obtain freshwater regeneration (1.26 kg m-2 h-1, 76.81% efficiency), indicating the comprehensive ability of the constructed nanocomposites for treating complicated environmental pollution including organics removal and freshwater regeneration.

Quantitative evaluation of skin barrier function using water evaporation time related to transepidermal water loss.

BACKGROUND: Transepidermal water loss (TEWL) is often used as an index for skin barrier function. The skin barrier tester, SBT-100 (Rousette Strategy Inc), measures the TEWL, water evaporation time, and time constant by contacting the skin and diffusing water into the closing measurement chamber. However, the relationship between the TEWL and time constant has not been sufficiently investigated. This study involved analyzing the underlying measurement principle and obtaining data through two experiments. MATERIALS AND METHODS: The TEWL and time constant were measured using SBT-100. Experiment 1 produced a simple simulation model for continuous water evaporation from the skin using a moisture-permeable film. In experiment 2, four skin sites of 43 healthy volunteers were examined from May to September 2018. RESULTS: In experiment 1, the TEWL increased and time constant decreased, following an increase in humidity in the external environment. Both parameters demonstrated significant negative correlation (drying: ρ = -0.832, p < 0.001). For the 43 healthy volunteers who participated in experiment 2, their TEWL increased and time constant decreased in summer. For all skin measurement sites, both data demonstrated significant negative correlation (forehead: ρ = -0.909, p < 0.001; back of the left hand: ρ = -0.829, p < 0.001; left lateral elbow: ρ = -0.896, p < 0.001; left lateral malleolus: ρ = -0.865, p < 0.001). CONCLUSION: Results indicated that the time constant is significantly correlated with TEWL. Furthermore, the time constant can be used as a parameter for evaluating skin barrier function.

Resistance matching materials nanoarchitectonics for better performances in water evaporation-driven generators.

The improvement of electricity production for water evaporation-driven generators (WEGs) remains a challenge. Herein, two types of WEGs were designed to study the resistance matching for improving the electricity production using the method of nanoarchitectonics. One type of reduced graphene oxide/carbon nanotube (RGO/CNT) WEG was constructed using RGO with adjustable resistances as working material and CNTs with fixed resistance as electrode material. The other type of graphene oxide (GO)/RGO WEG was constructed using RGO with adjustable resistance as electrode material and GO with fixed resistance was used as working material. The open circuit voltage of RGO/CNT increased from 15 to 56 mV and then decreased to 22 mV with increasing RGO resistance. The short circuit current of RGO/CNT also first increased and then decreased. The performance of GO/RGO was similar with that of RGO/CNT. Typically, the RGO/CNT and GO/RGO WEG showed the highest performance when the working material to electrode material resistance ratio was 2272 and 2365, respectively. It showed that the best resistance ratio of working material to electrode material was in the range of 2000-2500, which helped to improve about 2-5 times of electricity efficiency in the WEG. The present work provides a new direction for optimizing performance of WEGs.

Flower-Shaped Carbon Nanomaterials for Highly Efficient Solar-Driven Water Evaporation.

Solar-driven interface water evaporation is an energy-saving, environmentally friendly, and efficient seawater desalination and wastewater treatment technology. However, some challenges still restrict its further industrial development, such as its complex preparation, heavy metal pollution, and insufficient energy utilization. In this study, a photothermal layer based on flower-shaped carbon nanoparticles is presented for highly efficient solar-driven interface evaporation for water treatment applications. The results show that the surface of the prepared carbon nanomaterials presents a flower-shaped structure with an excellent light absorption capacity and a large specific surface area. Moreover, the C-5.4 (Carbon-5.4) sample has an evaporation rate of 1.87 kg/m2/h and an evaporation efficiency of 87%-far higher than most photothermal materials. In addition, carbon nanomaterials have an excellent ion scavenging capacity, dye purification capacity, and outdoor practical performance. This study provides a new solution for the application of carbon nanomaterials in the field of water purification.

Charge-Transfer Cocrystal via a Persistent Radical Cation Acceptor for Efficient Solar-Thermal Conversion.

Designing organic charge-transfer (CT) cocrystals for efficient solar-thermal conversion is a long-sought goal but remains challenging. Here we construct a unique CT cocrystal by using a persistent 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS+. ) as the electron acceptor. The strong persistency and electron affinity of ABTS+. endow a high degree of electron delocalization between ABTS+. and the 3,3',5,5'-tetramethylbenzidine donor. Together with the intrinsic long-wavelength absorption of ABTS+. , the synthesized cocrystal can effectively capture the full solar spectrum and show distinguished photothermal efficiency. Such a cocrystal is further used for solar-driven interfacial evaporation, and a high evaporation rate of 1.407 kg m-2 h-1 and a remarkable solar-to-vapor efficiency of 97.0 % have been achieved upon 1 sun irradiation. This work indicates the enormous prospects for charge transfer-based functional materials through rational radical cation engineering.

Carbon Materials for Solar Water Evaporation and Desalination.

Seawater desalination is viewed as a promising solution to world freshwater scarcity. Solar assisted desalination is proposed to overcome the high energy consumption in current desalination technologies, as it uses abundant and sustainable solar energy as the only energy input. Interfacial solar vapor generation (SVG) has attracted considerable research interest due to its high energy conversion efficiency, simple implementation, and cost-effectiveness. Among all the candidate materials for solar evaporators, carbon-based materials stand out due to their intrinsic high solar absorption, highly tunable structure, easy preparation, low cost, and earth-abundancy. In this review, the recent progress on carbon-based materials for the development of interfacial SVG is summarized. First, a brief introduction to the basic design principles of the interfacial SVG system is presented. Then, recent efforts in carbon-based solar evaporators, from artificial structures to bioinspired configurations, focusing on their structure-function relationship are highlighted. Strategies for designing antisalt-fouling desalination systems are also summarized. Last, the challenges and opportunities of carbon-based materials for solar evaporation technology are elaborated.

Design of Persistent and Stable Porous Radical Polymers by Electronic Isolation Strategy.

Conjugated organic radical polymers with stable radical features are difficult to design because the π conjugation in the polymer backbones makes the radicals readily delocalize and tend to undergo covalent bonding processes. In this work, we report an electronic isolation strategy to design stable porous radical polymers by homocoupling reaction from a meta-position active monomer. The meta linkage ensures less conjugation in the polymer skeletons, localizes the resonant radicals, and prevents them from recombination. The resulting porous radical polymer exhibits exceptional radical characters with ultralow band gap of 0.68 eV, strong yet extended UV/Vis-NIR absorption up to 1800 nm, and high spin density. The above features make the polymer very promising in the photothermal conversion with record-high photothermal temperature increment of ≈∼240 °C and striking solar-driven water evaporation efficiency of 96.8 %. Our results demonstrate the feasibility of electronic isolation of radicals for producing outstanding photothermal materials.

High-Entropy-Alloy Nanoparticles with Enhanced Interband Transitions for Efficient Photothermal Conversion.

Photothermal materials with broadband optical absorption and high conversion efficiency are intensively pursued to date. Here, proposing by the d-d interband transitions, we report an unprecedented high-entropy alloy FeCoNiTiVCrCu nanoparticles that the energy regions below and above the Fermi level (±4 eV) have been fully filled by the 3d transition metals, which realizes an average absorbance greater than 96 % in the entire solar spectrum (wavelength of 250 to 2500 nm). Furthermore, we also calculated the photothermal conversion efficiency and the evaporation rate towards the steam generation. Due to its pronounced full light capture and ultrafast local heating, our high-entropy-alloy nanoparticle-based solar steam generator has over 98 % efficiency under one sun irradiation, meanwhile enabling a high evaporation rate of 2.26 kg m-2 h-1 .

Laser-Ignited Relay-Domino-Like Reactions in Graphene Oxide/CL-20 Films for High-Temperature Pulse Preparation of Bi-Layered Photothermal Membranes.

Light-ignited combustions have been proposed for a variety of industrial and scientific applications. They suffer, however, from ultrahigh light ignition thresholds and poor self-propagating combustion of typical high-energy density materials, e.g., 2,4,6,8,10,12-(hexanitrohexaaza)cyclododecane (CL-20). Here, reported is that both light ignition and combustion performance of CL-20 are greatly enhanced by embedding ε-CL-20 particles in a graphene oxide (GO) matrix. The GO matrix yields a drastic temperature rise that is sufficient to trigger the combustion of GO/CL-20 under low laser irradiation (35.6 mJ) with only 6 wt% of GO. The domino-like reduction-combustion of the GO matrix can serve as a relay and deliver the decomposition-combustion of CL-20 to its neighbor sites, forming a relay-domino-like reaction. In particular, a synergistic reaction between GO and CL-20 occurrs, facilitating more energy release of the GO/CL-20 composite. The novel relay-domino-like reaction coupled with the synergistic reaction of CL-20 and GO results in a deflagration of the material, which generates a high-temperature pulse (HTP) that can be guided to produce advanced functional materials. As a proof of concept, a bi-layered photothermal membrane is prepared by HTP treatment in an extremely simple and fast way, which can serve as a model architecture for efficient interfacial water evaporation.