3D Janus structure MXene/cellulose nanofibers/luffa aerogels with superb mechanical strength and high-efficiency desalination for solar-driven interfacial evaporation

Lightweight and Mechanically Robust Ambient-Electrospun Nanofibrous Sponges Combined with Solar-Driven Active Heating and Low-Temperature Superinsulation

Traditional fibrous warmth retention materials suffer from limited performance improvement due to their micrometer-scale diameter and fail to meet the requirements of lightweight yet high-efficiency cold protection in extreme environments. Herein, we present a novel, facile, and ecofriendly strategy to fabricate a lightweight, mechanically robust nanofibrous sponge with integrated solar-driven active heating and low-temperature superinsulation. The high-porosity structure is achieved through urea-induced phase separation during ambient electrospinning, which overcomes the energy-intensive and unsafe high-humidity processing challenges. Simultaneous in situ incorporation of silicon carbide nanoparticles with photothermal properties enables solar-activated heat generation. This nanofibrous sponge realizes dual functionalities: ultralow thermal conductivity (27.31 mW m-1 K-1) for low-temperature superinsulation and rapid solar heating (50.1 °C temperature rise within 10 min under simulated sunlight), combined with exceptional attributes including lightweight property (volume density of 3.8 mg cm-3), hydrophobicity (water contact angle = 128°), antifouling behavior, and stable mechanical performance. Its superior performance in extreme environments (e.g., high-altitude and polar regions) and medical applications establishes a new paradigm for advanced warmth retention materials with integrated passive/active thermal management functionalities.

Biomass-Derived Gradient and Aligned Structured Aerogel for Sustainable Agricultural Irrigation

Interface evaporation-driven hydroelectric systems integrating water purification and energy collection offer the potential for sustainable agricultural irrigation. However, achieving high evaporation rates and efficient energy harvesting poses challenges, particularly in optimizing evaporation and water transport. This study develops a gradient-aligned structured aerogel (GA aerogel), composed of biomass materials such as cellulose and chitosan, which utilizes efficient water transport through aligned cellulose channels, unique ion management in nanoscale channels, and chitosan's ability to reduce evaporation energy consumption, thereby enhancing water and energy harvesting performance. The GA aerogel achieves a solar absorption rate of 91.4%, an evaporation rate of 2.5 kg m-2 h-1, an output power of 680 nW cm-2, and stable operation for over 120 h. Furthermore, by integrating a series array with capacitive energy storage, the system utilizes harvested electrical energy to irrigate plants with purified water, promoting sustainable agriculture and providing insights for designing biomass-based solar evaporators.

3D Molecular-Reconstructed Disordered Precursor Toward Highly Stable Porous Ramie Carbon

Biomass porous carbon possesses broad application prospects in the field of energy storage. However, soft biomass materials with high cellulose content and orders structure usually represent low mechanical strength, which leads to unstable pore structure of prepared porous carbon and even prone to collapse, thus reducing the quality and stability of carbon. Herein, a simple molecular reconstruction method is proposed to effectively re-construct 3D disordered ramie precursors (DRPs) by regulating the chemical interaction of hydrogen bonds. Benefiting from high mechanical strength and high density of DRPs, the highly stable porous ramie carbon (PRC) can display a higher specific surface area of 2404.36 m2 g-1 than that of ordinary ramie carbon (2142.25 m2 g-1). Moreover, this PRC-based supercapacitor delivers a high specific capacitance of 39.35 F g-1 at 1 A g-1 and an excellent capacity retention rate of 89.5% at 40 A g-1 in 1 M Et4NBF4/AN. Attractively, the evolution process of ion adsorption during the charge-discharge process has been uncovered by using in situ electrochemical infrared spectroscopy, confirming the excellent structural stability of PRC. This work provides new insights into preparing biomass precursors with high strength derived from soft biomass materials, greatly promoting the application of soft biomass materials in commercial activated carbon.

MIL-100-Fe self-assembled cellulose nanofibers sponge for Diclofenac cascade encapsulation

The conventional hydrothermal synthesis and inherent hysteresis behavior limited the application of MOFs owing to the low kinetic efficiency in dynamic molecular adsorption. Herein, we developed an in-situ nucleation strategy for the preparation of MIL-100-Fe and immobilized it with hierarchy porous scaffold of TEMPO oxidized cellulose nanofiber (TCNF) sponge in the absence of additional organic solvent during fabrication under ambient conditions. The newly recognized mechanisms of gradient molecular transfer were proposed to illustrate the comprehensive DCF adsorption process from solution to micropores of MIL-100-Fe at molecule level triggered by the stray capacitance, varied Laplace pressure, size exclusion and cellulosic labyrinth. Additionally, the superior biocompatibility and natural degradability (in 24 h) of MIL@TCNF sponge were demonstrated. The used material could be converted rapidly to zero-valent iron (ZVI) sponge via simple reduction process, achieving both dehalogenation of Diclofenac (DCF) and material regeneration. These findings uncover the propagable mechanisms of molecular-diffusion driven adsorption cascade and provide a novel fabrication strategy of 3-D environmental functional sponge with reusability and biodegradability for water pollution control.

Multifunctional Janus-Coated Metafabric for Personal Thermal Comfort and Energy Efficient Buildings

Space cooling and heating consume huge energy resources globally, while existing cooling/heating equipment can only address indoor temperature control. In this work, we report a multifunctional layered Janus-coated fabric (JCF) with radiative cooling/solar heating/Joule heating, which can utilize space and the sun as a source of cooling and heating. By adjusting the reflectivity, emissivity, and absorptivity of the coating, the fabric performs a thermal management function in a complex and changeable environment without consuming energy. In cooling mode, the cooling layer achieves a high solar reflectivity of 96% and an infrared emissivity of 96%, resulting in a 3.1 °C reduction in ambient temperature without any convective shielding. In addition, it reduces temperatures by 1.6 °C on human arms and by 5.1 °C inside houses, respectively. In the heating mode, the heating layer demonstrates excellent light-to-heat conversion efficiency under direct sunlight, achieving a 13.3 °C radiation warming ability, 16 °C heating effect on the surface of the arm, and a 12.8 °C temperature increase in the house. Furthermore, when switched to active heating for temperature regulation, JCF exhibits fast electrical response, high-efficiency electrical heat conversion capability, and stable electrical heat circulation capability. Building energy simulations indicate that widespread deployment of JCF across China could lead to a reduction in cooling and heating energy consumption by more than 25 MJ/m2 in 80% of cities. This multifunctional Janus-coated fabric not only provides a viable engineering path for the practical application of radiative heat management technology but also demonstrates its potential applications in human thermal comfort, smart wearable and building energy efficiency.

Multifunctional Janus-Structured Polytetrafluoroethylene-Carbon Nanotube-Fe3O4/MXene Membranes for Enhanced EMI Shielding and Thermal Management

Herein, a novel Janus-structured multifunctional membrane with integrated electromagnetic interference (EMI) shielding and personalized thermal management is fabricated using shear-induced in situ fibrillation and vacuum-assisted filtration. Interestingly, within the polytetrafluoroethylene (PTFE)-carbon nanotube (CNT)-Fe3O4 layer (FCFe), CNT nanofibers interweave with PTFE fibers to form a stable "silk-like" structure that effectively captures Fe3O4 particles. By incorporating a highly conductive MXene layer, the FCFe/MXene (FCFe/M) membrane exhibits excellent electrical/thermal conductivity, mechanical properties, and flame retardancy. Impressively, benefiting from the rational regulation of component proportions and the design of a Janus structure, the FCFe/M membrane with a thickness of only 84.9 µm delivers outstanding EMI shielding effectiveness of 44.56 dB in the X-band, with a normalized specific SE reaching 10,421.3 dB cm2 g-1, which is attributed to the "absorption-reflection-reabsorption" mechanism. Furthermore, the membrane demonstrates low-voltage-driven Joule heating and fast-response photothermal performance. Under the stimulation of a 3 V voltage and an optical power density of 320 mW cm-2, the surface temperatures of the FCFe/M membranes can reach up to 140.4 and 145.7 °C, respectively. In brief, the FCFe/M membrane with anti-electromagnetic radiation and temperature regulation is an attractive candidate for the next generation of wearable electronics, EMI compatibility, visual heating, thermotherapy, and military and aerospace applications.

Utilizing electrospinning to fabricate porous polyvinylidene fluoride/cellulose nanocrystalline/MXene films for wearable pressure sensors

Flexible, stable, and highly sensitive pressure sensors have garnered significant interest for their potential applications in wearable electronics and human-computer interaction. However, pressure sensor substrates prepared by electrospinning currently face challenges related to inadequate mechanical properties and low conductivity. Therefore, fabricating films with high flexibility, excellent mechanical properties, and sensing capabilities is still a great challenge. Herein, through the application of MXene onto spun PVDF/CNC films, we developed pressure-sensitive materials boasting outstanding air permeability, mechanical properties (14.77 MPa, 80 %), and electrical conductivity. The pressure-sensitive material was used to fabricate a pressure sensor with excellent sensing performance. Benefiting from the porous structure of the spun film and the high conductivity of the MXene coating, the sensor demonstrates high sensitivity (52-225 kPa-1), wide sensing range (0.196-31 kPa), fast response/recovery time (0.3/0.2 s), and excellent mechanical stability (over 5000 times). These superior properties favor the application of physical health monitoring and pressure spatial distribution detection. The films have broad applications in the fields of wearable electronics, artificial electronic skin, and comprehensive motion detection.

Antibacterial Janus cellulose/MXene paper with exceptional salt rejection for sustainable and durable solar-driven desalination

The scarcity of freshwater resources and increasing demand for drinking water have driven the development of durable and sustainable desalination technologies. Although MXene composites have shown promise due to their excellent photothermal conversion and high thermal conductivity, their high hydrophilicity often leads to salt precipitation and low durability. In this study, we present a novel Cellulose (CF)/MXene paper with a Janus hydrophobic/hydrophilic configuration for long-term and efficient solar-driven desalination. The paper features a dual-layer structure, with the upper hydrophobic layer composed of CF/MXene paper exhibiting convexness to serve as a photothermal layer with exceptional salt rejection properties. Simultaneously, the bottom porous layer made of CF acts as an efficient thermal insulation. This unique design effectively minimizes heat loss and facilitates efficient water transportation. The Janus CF/MXene paper demonstrates a high evaporation rate of 1.11 kg m-2h-1 and solar thermal conversion efficiency of 82.52 % under 1 sun irradiation. Importantly, even after 2500 h of operation in a simulated seawater environment, the paper maintains a stable evaporation rate without significant salt deposition and biodegradation due to an antibacterial rate exceeding 90 %. These findings highlight the potential of the Janus CF/MXene paper for scalable manufacturing and practical applications in solar-driven desalination.

Multi-scale microstructural construction in ultralight graphene aerogels enables super elasticity and unprecedented durability for impact protection materials

Ultralight graphene aerogels have gained extensive recognition in the impact protection field. However, attaining both elasticity and durability at low material density is challenging due to their intrinsic conflicts. Inspired by the mantis ootheca, we present a simultaneous improvement in the elasticity, durability, and density restrictions of ultralight graphene aerogels via constructing a multiscale honeycomb microstructure (MHM) within the graphene skeleton. This approach enables resulting graphene aerogel to achieve a strength per unit volume of 284.6 cm3 mg-1, the ability to recover its shape within 10 ms after an impact at 3.569 m/s, and maintain 97.2 % of its sample height after 20,000 cycles at 90 % strain. The operand analyses and calculation results reveal that the MHM structure facilitates this aerogel's dual-stage stress transfer pathway. Initially, the macroscale honeycomb structure (millimeter-scale) of the graphene aerogels bear and transmit stress to the surrounding regions, followed by the microscale honeycomb structure (micron-scale) deformation to convert stress kinetic energy into elastic potential energy. This two-stage stress transition mechanism of the MHM structure can effectively mitigate excessive local stress and suppress strain localization, thus providing remarkable elasticity and durability. Ultimately, the obtained graphene aerogel demonstrates promising applications as a fall height detection device and impact protective material.

3-aminopropyltriethoxysilane modified MXene on three-dimensional nonwoven fiber substrates for low-cost, stable, and efficient solar-driven interfacial evaporation desalination

Recently, the solar-driven interfacial evaporation desalination has attracted more and more attentions due to the advantages of low cost, zero energy consumption, and high water purification rate, etc. One of the bottlenecks of this emerging technique lies in a lack of simple and low-cost ways to construct three-dimensional (3D) hierarchical microstructures for photothermal membranes. To this end, a two-step strategy is carried out by combining surface functionalization with substrate engineering. Firstly, a silane coupling agent 3-aminopropyltriethoxysilane (APTES) is grafted onto an ideal photothermal material of Ti3C2Tx MXene, to improve the nanochannel sizes and hydrophilicity, which are attributed to enlarged interspaces of MXene and introduced hydrophilic group e.g., -NH2 and -OH, respectively. Secondly, a low-cost and robust nonwoven fiber (NWF) substrate, which has a 3D micron-sized mesh structure with interlaced fiber stacks, is employed as the skeleton to load enough APTES-grafted MXene by a simple soaking method. Benefited from above design, the Ti3C2Tx-APTES/NWF composite membrane with a 3D hierarchical structure shows enhanced light scattering and utilization, water transport and vapor escape. A remarkable evaporation rate of 1.457 kg m-2 h-1 and an evaporation efficiency of 91.48 % are attained for a large-area (5 × 5 cm2) evaporator, and the evaporation rate is further increased to 1.672 kg m-2 h-1 for a small-area (2 × 2 cm2) device. The rejection rates of salt ions and heavy metal ions are higher than 99 % and 99.99 %, respectively, and the removal rates of organic dye molecules are nearly to 100 %. Besides, the composite photothermal membrane exhibits great stabilities in harsh conditions such as high salinities, long cycling, large light intensities, strong acid/alkali environments, and mechanical bending. Most importantly, the photothermal membrane shows a considerable cost-effectiveness of 89.4 g h-1/$. Hence, this study might promote the commercialization of solar-driven interfacial evaporation desalination by collaboratively considering surface modification and substrate engineering for MXene.

Interface Structure Strengthening of a Mesoporous Silicon/Expanded Perlite Microevaporator for Efficient Solar-Driven Interfacial Evaporation

Solar-driven interfacial evaporation is one of the cutting-edge technologies for seawater desalination and wastewater purification. Herein, a floating carbon-coated silica microsphere/expanded perlite integrated interfacial microevaporator (HEPCL) is reported. The carbon nanolayer allows the HEPCL to have better broadband light absorption performance than natural graphite and graphene oxide. Through the low density of expanded perlite, HEPCL particles can self-float on the water surface and self-aggregate into an integrated whole under surface tension, which enhances the heat collection capacity. The hierarchical porous structure of the HEPCL has a continuous water absorption capacity. Notably, water molecules adsorbed in the HEPCL have a high desorption energy, which reduces the water evaporation enthalpy (1621 kJ/kg), making it easy to remove with external energy. Thanks to the design merits, the HEPCL achieves a water evaporation rate of 1.551 kg m-2 h-1 (efficiency of 94.85%) under 1 sun irradiation and may inspire a practicable solution of water scarcity.

Multifunctional Super-Hydrophilic MXene/Biomass Composite Aerogel Evaporator for Efficient Solar-Driven Desalination and Wastewater Treatment

Solar-driven interfacial evaporation is recognized as a sustainable and effective strategy for desalination to mitigate the freshwater scarcity issue. Nevertheless, the challenges of oil contamination, salt accumulation, and poor long-term stability of the solar desalination process limit its applications. Herein, a 3D biomass-based multifunctional solar aerogel evaporator is developed for water production with fabricated chitosan/lignin (CSL) aerogel as the skeleton, encapsulated with carbonized lignin (CL) particles and Ti3C2TiX (MXene) nanosheets as light-absorbing materials. Benefitting from its super-hydrophilic wettability, interconnected macropore structure, and high broadband light absorption (ca. 95.50%), the prepared CSL-C@MXene-20 mg evaporator exhibited a high and stable water evaporation flux of 2.351 kg m-2 h-1 with an energy conversion efficiency of 88.22% under 1 Sun (1 kW m-2) illumination. The CSL-C@MXene-20 mg evaporator performed excellent salt tolerance and long-term solar vapor generation in a 3.5 wt.% NaCl solution. Also, its super-hydrophilicity and oleophobicity resulted in superior salt resistance and anti-fouling performance in high salinity brine (20 wt.% NaCl) and oily wastewater. This work offers new insight into the manufacture of porous and eco-friendly biomass-based photothermal aerogels for advanced solar-powered seawater desalination and wastewater purification.

Versatile GO/ANFs Aerogel for Highly Efficient Solar-Powered Water Purification in Wide Environments

Solar-driven interfacial evaporation is a very promising choice for producing clean water. Despite the considerable investigation of pure NaCl brine purification, solar-driven complex water purification, such as real-world seawater desalination as well as domestic and industrial wastewater treatment, has rarely been investigated, mainly due to its compositions being much more complicated than NaCl brine. Herein, we developed a graphene oxide/aramid nanofiber (GO/ANFs) aerogel by a freeze-drying process. The GO/ANFs aerogel combined opened porous microchannels, superhydrophilicity, anti-oil-fouling capacity, enhanced broad-spectrum light absorption (more than 92%), and good solar/heat management. These integrated properties enabled the GO/ANFs aerogel to be an advanced solar interfacial evaporator for efficient freshwater production with the characteristics of localized heat conversion, quick water transport, and salt crystallization inhibition, and the rate of steam production rate was as high as 2.25 kg m-2 h-1 upon exposure to 1 solar irradiation. Importantly, the high-water-vapor generation rate was maintained even under complicated conditions, including real-world seawater, dye water, emulsions, and corrosive liquid environments. Considering its promising adaptability to a wide range of environments, this work hopes to inspire the development of brine desalination, wastewater purification, clean water production, and solar energy utilization.

Cellulose-based light-management film exhibiting flame-retardant and thermal-healing properties

The increased use and expansion of biomass applications offer a viable approach to diminish reliance on petroleum-derived resources and promote carbon neutrality. Cellulose, being the most abundant natural polymer on Earth, has garnered considerable attention. This study introduces a straightforward method to fabricate a cellulose-based multifunctional composite film designed for efficient light management, specifically featuring flame retardant and thermal-healing capabilities. The film incorporates a microfibrillated cellulose (MFC) matrix with functional components, namely benzoxazine resin (BR) and 2-hydroxyethyl methacrylate phosphate (HEMAP). Utilizing dynamic covalent crosslinking, the composite films exhibit satisfactory self-healing properties. The combined effects of BR and HEMAP contribute to the effective flame retardancy of the composite film. Furthermore, the resulting film shields ultraviolet and blue light, offering comfortable interior lighting by mitigating harsh light and extending light propagation. The film also demonstrates favorable water resistance and high tensile strength. The exceptional multifunctional properties, coupled with its safety and extended service life, position it as a potential optical management film for smart building materials.

Flexible cellulose nanofibers/MXene composite films for UV-shielding packaging

Cellulose nanofibers (CNF) based films are promising packaging materials, but the lack of special functions (especially UV-shielding property) usually restrict their further applications. In this work, MXene was incorporated into the CNF film by a direct solvent volatilization induced film forming method to study its UV-shielding property for the first time, which avoided the using of a vacuum filtration equipment. The composite films containing glycerin could be folded repeatedly without breaking, showing good flexibility. The structure and properties of MXene/CNF composite films (CMF) were characterized systematically. The results showed that MXene distributed uniformly in the CNF film matrix and there was strong hydrogen bonding interaction between CNF and MXene. The tensile strength and Young's modulus of the composite films could reach 117.5 MPa and 2.23 GPa, which was 54.1 % and 59.2 % higher than those of pure CNF film, respectively. With the increase of MXene content, both the UVA and UVB shielding percentages increased significantly from 17.2 % and 25.5 % to 100.0 %, showing excellent UV-shielding property. Moreover, CMF exhibited a low oxygen permeability (OP) value of 0.39 cc μm d-1 m-2 kPa-1, a low water vapor permeability (WVP) value of 5.13 × 10-11 g-1s-1Pa-1 and a high antibacterial rate against E. coli (94.1 % at 24 h), showing potential application in the packaging field.

Robust and Multifunctional Ti3 C2 Tx /Modified Sawdust Composite Paper for Electromagnetic Interference Shielding and Wearable Thermal Management

Robust, ultrathin, and environmental-friendliness papers that synergize high-efficiency electromagnetic interference (EMI) shielding, personal thermal management, and wearable heaters are essential for next-generation smart wearable devices. Herein, MXene nanocomposite paper with a nacre-like structure for EMI shielding and electrothermal/photothermal conversion is fabricated by vacuum filtration of Ti3 C2 Tx MXene and modified sawdust. The hydrogen bonding and highly oriented structure enhance the mechanical properties of the modified sawdust/MXene composite paper (SM paper). The SM paper with 50 wt% MXene content shows a strength of 23 MPa and a toughness of 13 MJ·M-3 . The conductivity of the SM paper is 10 195 S·m-1 , resulting in an EMI shielding effectiveness (SE) of 67.9 dB and a specific SE value (SSE/t) of 8486 dB·cm2 ·g-1 . In addition, the SM paper exhibits excellent thermal management performance including high light/electro-to-thermal conversion, rapid Joule heating and photothermal response, and sufficient heating stability. Notably, the SM paper exhibits low infrared emissivity and distinguished infrared stealth performance, camouflaging a high-temperature heater surface of 147-81 °C. The SM-based e-skin achieves visualization of Joule heating and realizes human motions monitoring. This work presents a new strategy for designing MXene-based wearable devices with great EMI shielding, artificial intelligence, and thermal management applications.

Hierarchical nanofibrous and recyclable membrane with unidirectional water-transport effect for efficient solar-driven interfacial evaporation

Solar-driven interfacial evaporation technology has attracted significant attention for water purification. However, design and fabrication of solar-driven evaporator with cost-effective, excellent capability and large-scale production remains challenging. In this study, inspired by plant transpiration, a tri-layered hierarchical nanofibrous photothermal membrane (HNPM) with a unidirectional water transport effect was designed and prepared via electrospinning for efficient solar-driven interfacial evaporation. The synergistic effect of the hierarchical hydrophilic-hydrophobic structure and the self-pumping effect endowed the HNPM with unidirectional water transport properties. The HNPM could unidirectionally drive water from the hydrophobic layer to the hydrophilic layer within 2.5 s and prevent reverse water penetration. With this unique property, the HNPM was coupled with a water supply component and thermal insulator to assemble a self-floating evaporator for water desalination. Under 1 sun illumination, the water evaporation rates of the designed evaporator with HNPM in pure water and dyed wastewater reached 1.44 and 1.78 kg·m-2·h-1, respectively. The evaporator could achieve evaporation of 11.04 kg·m-2 in 10 h under outdoor solar conditions. Moreover, the tri-layered HNPM exhibited outstanding flexibility and recyclability. Our bionic hydrophobic-to-hydrophilic structure endowed the solar-driven evaporator with capillary wicking and transpiration effects, which provides a rational design and optimization for efficient solar-driven applications.

Highly efficient MoS2/MXene aerogel for interfacial solar steam generation and wastewater treatment

Interfacial solar steam generation using aerogels holds great promise for seawater desalination and wastewater treatment. However, to achieve aerogels with both durable, high-efficiency evaporation performance and excellent salt resistance remains challenging. Here, a molybdenum disulphide (MoS2) and MXene composite aerogel with vertical pore channels is reported, which has outstanding advantages in mechanical properties, water transportation, photothermal conversion, and recycling stability. Benefiting from the plasmon resonance effect of MXene and the excellent photothermal conversion performance of MoS2, the aerogel exhibits excellent light absorption (96.58 %). The aerogel is resistant to deformation and able to rebound after water absorption, because of the support of an ordered vertical structure. Moreover, combined with the low water evaporation enthalpy, low thermal conductivity, and super hydrophilicity, the aerogel achieves an efficient and stable evaporation rate of about 2.75 kg m-2h-1 under one sun and exhibits excellent self-cleaning ability. Notably, the evaporator achieves removal rates of 99.9 % for heavy metal ions and 100 % for organic dyes, which has great potential in applications including seawater desalination and wastewater purification.