Bioinspired design of integral molded Janus silk fibroin-MXene evaporator for efficient solar vapor generation

Solar vapor generation is a promising sustainable technology that uses solar distillation to produce fresh water from seawater and wastewater,helping relieve global water resource shortage.Here,inspired by naturally grown integrally molded mulberry leaves with a Janus hydrophilic and hydrophobic structure,a novel,simple,and efficient integrated molding method is proposed to break through the limitations of the traditional split manufacturing strategy and realizes the integrated formation of Janus evaporator.Based on the spontaneous sedimentation characteristics of MXene in silk fibroin solution and its regulation of mesoscopic structure and hydrophilicity of silk fibroin,layered structures with different compositions and hydrophilicities were obtained in one step.Meanwhile,ethanol and glutaraldehyde were added to construct a physical crystallization-chemical crosslinking dual stabilization structure in silk fibroin.Our evaporator has the evaporation rate of 3.07 kg·m^(-2)·h^(-1) and the efficiency of 86.8%under 1 sun and maintains high evaporation performance under various extreme test conditions including vigorous washing,repeated compression,and high-intensity ultraviolet(UV)irradiation.Additionally,the evaporator performs well in practical application scenarios,its evaporation rate in the simulated Dead Sea seawater exceeds 2.13 kg·m^(-2)·h^(-1),and more than 99.9%of the salt,heavy metal ions,oil pollution,and dyes are purified.

Polyoxometalates-Modulated Hydrophilic-Hydrophobic Composite Interfacial Material for Efficient Solar Water Evaporation and Salt Harvesting in High-Salinity Brine

Solar vapor generation(SVC)represents a promising technique for seawater desalination to alleviate the global water crisis and energy shortage.One of its main bottleneck problems is that the evaporation efficiency and stability are limited by salt crystallization under high-salinity brines.Herein,we demonstrate that the 3D porous melamine-foam(MF)wrapped by a type of self-assembling composite materials based on reduced polyoxometalates(i.e.heteropoly blue,HPB),oleic acid(OA),and polypyrrole(PPy)(labeled with MF@HPB-PPy_(n)-OA)can serve as efficient and stable SVC material at high salinity.Structural characterizations of MF@HPB-PPy_(n)-OA indicate that both hydrophilic region of HPBs and hydrophobic region of OA co-exist on the surface of composite materials,optimizing the hydrophilic and hydrophobic interfaces of the SVC materials,and fully exerting its functionality for ultrahigh water-evaporation and anti-salt fouling.The optimal MF@HPB-PPy_(10)-OA operates continuously and stably for over 100 h in 10wt%brine.Furthermore,MF@HPB-PPy_(10)-OA accomplishes complete salt-water separation of 10wt%brine with 3.3kgm^(-2)h^(-1)under 1-sun irradiation,yielding salt harvesting efficiency of 96.5%,which belongs to the record high of high-salinity systems reported so far and is close to achieving zero liquid discharge.Moreover,the low cost of MF@HPB-PPy_(10)-OA(2.56$m^(-2))suggests its potential application in the practical SVC technique.

Fibrous Aerogels with Tunable Superwettability for High-Performance Solar-Driven Interfacial Evaporation

Solar-driven interfacial evaporation is an emerging technology for water desalination.Generally,double-layered structure with separate surface wettability properties is usually employed for evaporator construction.However,creating materials with tunable properties is a great challenge because the wettability of existing materials is usually monotonous.Herein,we report vinyltrimethoxysilane as a single molecular unit to hybrid with bacterial cellulose(BC)fibrous network,which can be built into robust aerogel with entirely distinct wettability through controlling assembly pathways.Siloxane groups or carbon atoms are exposed on the surface of BC nanofibers,resulting in either superhydrophilic or superhydrophobic aerogels.With this special property,single component-modified aerogels could be integrated into a double-layered evaporator for water desalination.Under 1 sun,our evaporator achieves high water evaporation rates of 1.91 and 4.20 kg m^(-2)h^(-1)under laboratory and outdoor solar conditions,respectively.Moreover,this aerogel evaporator shows unprecedented lightweight,structural robustness,long-term stability under extreme conditions,and excellent salt-resistance,highlighting the advantages in synthesis of aerogel materials from the single molecular unit.

Polysulfide nanoparticles-reduced graphene oxide composite aerogel for efficient solar-driven water purification

Along with the environmental pollution, the scarcity of clean water seriously threatens the sustainable development of human society.Recently, the rapid development of solar evaporators has injected new vitality into the field of water purification. However, the industry faces a considerable challenge of achieving comprehensive purification of ions, especially the efficient removal of mercury ions. In this work, we introduce an ideal mercury-removal platform based on facilely and cost-effectively synthesized polysulfide nanoparticles(PSNs). Further development of PSN-functionalized reduced graphene oxide(PSN-rGO) aerogel evaporator results in achieving a high evaporation rate of 1.55 kg m^(-2)h^(-1)with energy efficiency of 90.8% under 1 sun. With the merits of interconnected porous structure and adsorption ability, the photothermal aerogel presents overall purification of heavy metal ions from wastewater. During solar desalination, salt ions can be rejected with long-term stability. Compared with traditional water purification technologies, this highly efficient solar evaporator provides a new practical method to utilize clean energy for clean water production.

Novel advances in metal-based solar absorber for photothermal vapor generation

Access to safe drinking water has become an extremely urgent research topic wo rldwide.In recent years,the technology of solar vapor generation has been extensively explored as a potential and effective strategy of transforming elements content in seawater.In this review,the basic concepts and theories of metal-based photothermal vapor generation device(PVGD) with excellent optical and thermal regulatory are introduced.In the view of optical regulation,how to achieve high-efficiency localized evaporation in different evaporation system(i.e.,volumetric solar heating and interface solar heating) is discussed;from the aspect of thermal regulation,the importance of selective absorption surface for interfacial PVGD is analyzed.Based on the above discussion and analysis,we summarize the challenges of metal-based desalination device.

Macroporous 3D MXene architecture for solar-driven interfacial water evaporation

Interfacial water evaporation through solar heating with photothermal materials is a promising strategy for seawater desalination and wastewater purification.Tightly packed 2D membranes with high reflection losses and limited vapor escape channels result in a low evaporation rate.In this work,3D MXene architecture was fabricated by dropping the delaminated Ti_(3)C_(2)(d-Ti_(3)C_(2))nanosheets onto the carbonized melamine foam(CMF)framework.Owing to the macroporous 3D architecture,more effective broadband solar absorption and vapor escaping were achieved.As a result,the 3D CMF@d-Ti_(3)C_(2)-based evaporator delivers a water evaporation rate of 1.60 kg/m2·h with a solar-to-vapor conversion efficiency of up to 84.6%.

Facile strategy for carbon foam fabrication with lignin as sole feedstock and its applications

This research is a follow-up to our recent discovery of a facile strategy for directly converting lignin powder into carbon foam.In this work,we report that the thermal pretreatment parameters in air can remarkably influence the formation and properties of the derived carbon foam.Thermal pretreatment parameters(heating rate,temperature,and residence time)were systematically investigated and a conversion mechanism into carbon foam was proposed.During the thermal pretreatment,relatively low temperatures,low heating rates,and short residence time hindered the formation of smooth and well-connected structures in the carbon foam.The overall product yields were similar regardless of the thermal pretreatment conditions.The densities of the different carbon foams ranged 0.27–0.83 g∙cm^(−3).The carbon foams with the highest compressive strengths(>10 MPa)were KLPC280-2-5,KLPC300-0-5,and KLPC300-2-2.5.KLPC280-2-5 exhibited a high iodine sorption value(182 mg∙g^(−1)).KLPC300-2-5 exhibited a specific capacitance of 158 F∙g^(−1) at a current density of 0.05 A∙g^(−1).The maximum evaporation rates in the solar vapor generation experiments were 1.05 and 1.38 kg∙m^(−2)∙h^(−1) under 100 and 150 mW∙cm^(−2) irradiation,respectively.The good performances are attributed to the robust,porous,and continuous structure.