A Novel Flame-Retardant, Smoke-Suppressing, and Superhydrophobic Transparent Bamboo.

Silica glass, known for its brittleness, weight, and non-biodegradable nature, faces challenges in finding suitable alternatives. Transparent wood, made by infusing polymers into wood, shows promise but is hindered by limited availability of wood in China and fire risks associated with its use. This study explores the potential of utilizing bamboo, which has a shorter growth cycle, as a valuable resource for developing flame-retardant, smoke-suppressing, and superhydrophobic transparent bamboo. A 3-layered flame-retardant barrier, composed of a top silane layer, an intermediate layer of SiO2 formed through hydrolysis-condensation of Na2SiO3 on the surface, and an inner layer of Na2SiO3, has been confirmed to be effective in reducing heat release, slowing flame spread, and inhibiting the release of combustible volatiles, toxic smoke, and CO. Compared to natural bamboo and other congeneric transparent products, the transparent bamboo displays remarkable superiority, with the majority of parameters being notably lower by an entire order of magnitude. It achieves a long ignition time of 116 s, low total heat release (0.7 MJ/m2), low total smoke production (0.063 m2), and low peak CO concentration (0.008 kg/kg). Moreover, when used as a substrate for perovskite solar cells, the transparent bamboo displays the potential to act as a light management layer, leading to a marked efficiency enhancement of 15.29%. The excellent features of transparent bamboo make it an enticing choice for future advancements in flame-retardant glasses and optical devices.

Research Progress on the Application of Nanocellulose in Glucose Sensing.

BACKGROUND: Nanocellulose is not only a biocompatible and environmentally friendly material but also has excellent mechanical properties, biodegradability, and a large number of hydroxyl groups that have a strong affinity for water. These characteristics have attracted significant attention from researchers in the field of glucose sensing. OBJECTIVE: This review provides a brief overview of the current research status of traditional materials used in glucose sensors. The sensing performance, chemical stability, and environ-mental properties of nanocellulose-based glucose sensors are compared and summarized based on the three sensing methods: electrochemical sensing, colorimetric sensing, and fluo-rescence sensing. The article focuses on recent strategies for glucose sensing using nanocel-lulose as a matrix. The development prospects of nanocellulose-based glucose sensors are also discussed. CONCLUSION: Nanocellulose has outstanding structural characteristics that contribute signifi-cantly to the sensing performance of glucose sensors in different detection modes. However, the preparation process for high-quality nanocellulose is complicated and has a low yield. Furthermore, the sensitivity and selectivity of nanocellulose-based glucose sensors require further improvement.

Constructing N-doped and 3D Hierarchical Porous graphene nanofoam by plasma activation for supercapacitor and Zn ion capacitor.

Traditional electrode materials still face vital challenges of few active sites, low porosity, complex synthesis process, and low specific capacitance. Herein, N-doped and 3D hierarchical porous graphene nanofoam (N-GNF) is created on carbon fibers (CFs) by employing a facile, fast, and environmentally friendly strategy of N2 plasma activation. After an appropriated N2 plasma activation, the graphene nanosheets (GNSs) synthesized by Ar/CH4 plasma deposition transform into N-GNF successfully. N doping donates rich active sites and increases the hydrophilia, while hierarchical nanoarchitecture exposes an enlarged effective contact area at the interface between electrode and electrolyte and affords sufficient space for accommodating more electrolytes. The as-assembled flexible N-GNF@CFs//Zn NSs@CFs Zn ion capacitor delivered a high energy density of 105.2 Wh kg-1 at 378.6 W kg-1 and initial capacity retention of 87.9% at the current of 2 A g-1 after a long cycle of 10,000.

Dual-network self-healing hydrogels composed of graphene oxide@nanocellulose and poly(AAm-co-AAc).

A nature-inspired strategy is developed to build dual-network hydrogels made up of rigid graphene oxide-functionalized nanocellulose (GO@NC) network and flexible poly[acrylamide-co-(acrylic acid)] (poly(AAm-co-AAc)) network. A pre-stretching method is used to form a muscle-shape anisotropic architecture. The penetration of poly(AAm-co-AAc) flexible network relieves the stiffness of NC network, thus improving the average elongation at break from 86.2 % to 748.0 %. Compared with the poly(AAm-co-AAc), the average rupture tensile strength rises remarkably by 228.6 %. The dual-crosslinked strategy endows the GO@NC-poly(AAm-co-AAc) hydrogels with a fast, stable and repeatable self-healing ability, which can achieve 85.0 % of healing efficiency after only 600 s of self-healing and maintain 76.2 % of initial strength after 10 cycles of breaking-self-healing. The superb self-healing ability is similar to the muscle function. For potential applications, the hydrogels can achieve real-time, stable, and long-term sensing as smart wearable strain sensors (high gauge factor: 5.13), and can effectively purify Sudan IV wastewater as green recyclable adsorbents.

Dual Application of Waste Grape Skin for Photosensitizers and Counter Electrodes of Dye-Sensitized Solar Cells.

Dye-sensitized solar cells (DSSCs), a powerful system to convert solar energy into electrical energy, suffer from the high cost of the Pt counter electrode and photosensitizer. In this study, the dual application of waste grape skin is realized by employing the grape skin and its extract as the carbon source of the carbon-based counter electrode and photosensitizer, respectively. The ultraviolet-visible absorption and Fourier transform infrared spectroscopy verify the strong binding between the dye molecules (anthocyanins) in the extract and the TiO2 nanostructure on the photoanode, contributing to a high open-circuit voltage (VOC) value of 0.48 V for the assembled DSSC device. Moreover, the waste grape skin was subjected to pyrolysis and KOH activation and the resultant KOH-activated grape skin-derived carbon (KA-GSDC) possesses a large surface area (620.79 m2 g-1) and hierarchical porous structure, leading to a high short circuit current density (JSC) value of 1.52 mA cm-2. Additionally, the electrochemical impedance spectroscopy reveals the efficient electron transfer between the electrocatalyst and the redox couples and the slow recombination of electrolytic cations and the photo-induced electrons in the conduction band of TiO2. These merits endow the DSSC with a high photovoltaic efficiency of 0.48%, which is 33% higher than that of a common Pt-based DSSC (0.36%). The efficiency is also competitive, compared with some congeneric DSSCs based on other natural dyes and Pt counter electrode. The result confirms the feasibility of achieving the high-value application of waste grape skin in DSSCs.

Pore-Rich Cellulose-Derived Carbon Fiber@Graphene Core-Shell Composites for Electromagnetic Interference Shielding.

Because of serious electromagnetic pollution caused by the widespread use of radio frequency equipment, the study of electromagnetic interference (EMI) shielding materials has been a long-standing topic. Carbon fiber and graphene composites have great potential as EMI shielding materials due to their unique microstructure and electrical conductivity. In this work, a novel kind of core-shell composite is fabricated based on the pore-rich pine needles-derived carbon fibers (coded as PNCFs) core and the graphene shell. The pore-rich PNCFs are created by KOH activation, and the integration between the pore-rich PNCFs and the graphene relies on a plasma-enhanced chemical vapor deposition (PECVD) method. The conductivity of the pore-rich PNCFs@graphene core-shell composite reaches 4.97 S cm−1, and the composite has an excellent EMI shielding effectiveness (SE > 70 dB over X-band (8.2−12.4 GHz)) and achieves a maximum value of ~77 dB at 10.4 GHz, which is higher than many biobased EMI shielding materials in the recent literature. By calculation and comparison, the large absorption loss (accounting for 90.8% of total loss) contributes to reducing secondary radiation, which is quite beneficial for stealth uses. Thus, this work demonstrates a promising design method for the preparation of green high-performance composites for EMI shielding and stealth applications (such as warcrafts, missiles, and stealth wears).

A Brief Review of Transparent Wood: Synthetic Strategy, Functionalization and Applications.

Severe pressure from energy consumption and serious pollution from non-renewable resources have urged human beings to develop green and energy-efficient materials. Transparent wood, consisting of original wood channel structure filled with resins, has favorable environmental friendliness and high transparency and haze, which holds huge potential in various important fields. Herein, a brief review of the current research activities centered on the development of transparent wood is provided. This review begins with an introduction to the background of transparent wood. Next, the cellular wall structure of wood and the synthetic strategy of transparent wood (including decolorization and impregnation) are summarized. Furthermore, the functionalization of transparent wood through doping nanomaterials or modifying resins is highlighted, and the relationship between the physicochemical properties and the potential uses (like optoelectronics, building materials, and furniture decoration) of transparent wood is clarified. Finally, a brief overview of the prospects and challenges for transparent wood is provided.

Ultra-high rate capability of nanoporous carbon network@V2O5 sub-micron brick composite as a novel cathode material for asymmetric supercapacitors.

A green biomass-derived nanoporous carbon network (NCN) has been prepared and integrated with V2O5 sub-micron bricks (SMBs). The large surface area and high pore volume of the NCN can not only provide abundant sites for electrochemical reactions but also stabilize the structure of the V2O5 SMBs. The NCN@V2O5 SMB composite, acting as a novel cathode material, delivers a high areal capacitance of 786 mF cm-2 at 0.2 mA cm-2 and superior cycling stability with 89.5% capacitance retention after 5000 cycles. Besides, the electrode achieves an ultra-high rate capability (82% capacitance retention as the current density increases from 0.2 to 5 mA cm-2) since the contribution from the non-diffusion-controlled process is estimated to be as high as 95.5%-98.5% according to the kinetic analysis. Furthermore, the micropores are more favorable than the mesopores at lower current densities (0.2-2 mA cm-2), while the contribution of the external surface area becomes more significant for current densities higher than 2 mA cm-2. Moreover, an asymmetric supercapacitor assembled using this cathode and the NCN anode shows superior electrochemical properties, such as wide operating voltage, long cycle life and large energy density (72.2 µW h cm-2). Their excellent electrochemical features and good eco-friendliness confirm the potential of the NCN@V2O5 SMBs for use as supercapacitors.

A multi-dimensional and level-by-level assembly strategy for constructing flexible and sandwich-type nanoheterostructures for high-performance electromagnetic interference shielding.

To shield against massive electromagnetic pollution and meet increasing demand in portable electronics, the development of flexible, lightweight and high-performance electromagnetic interference (EMI) shielding materials with good environmental friendliness is an urgent but still challenging need. Herein, a creative multi-dimensional and level-by-level assembly strategy is proposed to construct free-standing and sandwich-type nanoheterostructures consisting of flexible cotton-derived carbon fibers (CFs), magnetic and conductive nickel nanoparticles (Ni NPs) and highly conductive and large-surface-area dandelion-like graphene (DLG), via a high-precision combination technology of magnetron sputtering-plasma enhanced chemical vapor deposition. The multiple spatial-scale DLG/Ni NPs/CF composites achieve a remarkable conductivity of 625 S m-1 and an outstanding EMI shielding effectiveness of ∼50.6 dB in the X-band (8.2-12.4 GHz) which can be classified as attenuation levels of "AAAA" for professional use. The dielectric loss from multiple polarizations is principally responsible for the electromagnetic loss of the composites. Besides, the large surface area of heterogeneous interfaces and defects in DLG contribute to enhancing the amount of polarization. In addition, the ultrathin and ultralight composites (d = 0.65 mm, ρ = 113 mg cm-3) can be bent, twisted and folded, revealing their excellent processability for commercial uses. More importanly, this novel structural design concept opens up an interesting promising research field of novel next-generation EMI shielding materials.

3D nanoflower-like MoSe2 encapsulated with hierarchically anisotropic carbon architecture: a new and free-standing anode with ultra-high areal capacitance for asymmetric supercapacitors.

A novel anode material with a delicate composite structure, which is assembled by growing 3D MoSe2 nanoflowers onto the hierarchically anisotropic carbon architecture, is designed for the first time. The structural superiority and synergistic effects from EDLC and pseudocapacitance endow the free-standing anode with an ultra-high areal capacitance of 1043 mF cm-2 at 1 mA cm-2 and high cycling stability. Moreover, an asymmetric supercapacitor device consisting of this anode and a common MnO2-based cathode yields a quite large energy density of 147 µW h cm-2 at the power density of 2 mW cm-2, which is higher than or comparable to that of some Li-ion batteries. These results verify the huge application potential of this new anode for supercapacitors.

Scalable Top-to-Bottom Design on Low Tortuosity of Anisotropic Carbon Aerogels for Fast and Reusable Passive Capillary Absorption and Separation of Organic Leakages.

Creation of sustainable, cost-effective, and scalable absorbents with ideal absorption properties is a worldwide challenge because many high-performance absorbents are still restricted in laboratory scope due to several critical defects (like complex and eco-unfriendly synthesis process, high cost, and difficulty in large-scale production). Herein, a facile and scalable top-to-bottom design is proposed to create a kind of novel anisotropic carbon aerogels with low tortuosity of stacked laminated structure, derived from the hierarchical cellular channels of balsa wood. By virtue of this unique structure and favorable oleophilicity, fast passive capillary absorption with low flow resistance is achieved (as demonstrated by the theoretical modeling). As a result, the anisotropic carbon aerogels have quite sensitive selectivity to separate organic pollutants from water, broad-spectrum and high absorption capacity for different organic liquids (13 277-31 597 mg g-1), and superior recyclability (98.7% absorption capacity retention after five cycles). Combining these outstanding performances with a cheap preparation strategy as well as good environmental friendliness, this work provides a kind of potential scalable materials for efficient reusable absorption and separation of organic leakages.

Carbon Fibers Encapsulated with Nano-Copper: A Core‒Shell Structured Composite for Antibacterial and Electromagnetic Interference Shielding Applications.

A facile and scalable two-step method (including pyrolysis and magnetron sputtering) is created to prepare a core‒shell structured composite consisting of cotton-derived carbon fibers (CDCFs) and nano-copper. Excellent hydrophobicity (water contact angle = 144°) and outstanding antibacterial activity against Escherichia coli and Staphylococcus aureus (antibacterial ratios of >92%) are achieved for the composite owing to the composition transformation from cellulose to carbon and nano-size effects as well as strong oxidizing ability of oxygen reactive radicals from interactions of nano-Cu with sulfhydryl groups of enzymes. Moreover, the core‒shell material with high electrical conductivity induces the interfacial polarization loss and conduction loss, contributing to a high electromagnetic interference (EMI) shielding effectiveness of 29.3 dB. Consequently, this flexible and multi-purpose hybrid of nano-copper/CDCFs may be useful for numerous applications like self-cleaning wall cladding, EMI shielding layer and antibacterial products.

Facile hydrothermal synthesis of Fe3O4@cellulose aerogel nanocomposite and its application in Fenton-like degradation of Rhodamine B.

A magnetic cellulose aerogel-supported Fe3O4 nanoparticles composite was designed as a highly efficient and eco-friendly catalyst for Fenton-like degradation of Rhodamine B (RhB). The composite (coded as Fe3O4@CA) was formed by embedding well-dispersed Fe3O4 nanoparticles into the 3D structure of cellulose aerogels by virtue of a facile and cheap hydrothermal method. Comparative studies indicate that the RhB decolorization ratio is much higher in co-presence of Fe3O4 and H2O2 than that in presence of Fe3O4 or H2O2 only, revealing that the Fe3O4@CA-catalyzed Fenton-like reaction governed the RhB decolorization process. It was also found that almost 100% RhB removal was achieved in the Fenton-like system. Moreover, the composite exhibited higher catalytic activity than that of the individual Fe3O4 particles. In addition, the Fe3O4@CA catalyst retained ∼97% of its ability to degrade RhB after the six successive degradation experiments, suggesting its excellent reusability. All these merits indicate that the green and low-cost catalyst with strong magnetic responsiveness possesses good potential for H2O2-driven Fenton-like treatment of organic dyestuff wastewater.

Synthesis and electromagnetic interference shielding of cellulose-derived carbon aerogels functionalized with α-Fe2O3 and polypyrrole.

Eco-friendly cellulose-derived carbon aerogels (CDCA) were employed as porous substrate to integrate with α-Fe2O3 and polypyrrole (PPy) via pyrolysis and vapor-phase polymerization. The SEM and TEM observations present that the wrinkled PPy sheets and the α-Fe2O3 nanoparticles were well dispersed in CDCA. The strong interactions (such as hydrogen bonding) between the substrate and the nanomaterials were demonstrated by the FTIR and XPS analysis. When utilized as electromagnetic interference (EMI) shielding materials, the α-Fe2O3/PPy/CDCA (FPCA) composite has the highest total shielding effectiveness (SEtotal) of 39.4dB, about 2.0, 2.9, and 1.3 times that of the acid-treated CDCA (19.3dB), PPy (13.6dB), and α-Fe2O3/CDCA (29.3dB), respectively. Moreover, the shielding effectiveness due to absorption accounts for 78.2%-84.2% of SEtotal for FPCA, indicative of the absorption-dominant shielding mechanism contributing to alleviating secondary radiation. These features make the composite a useful alternative candidate for EMI shielding.

Cellulose-derived carbon aerogels supported goethite (α-FeOOH) nanoneedles and nanoflowers for electromagnetic interference shielding.

We describe a rapid and facile chemical precipitation method to grow goethite (α-FeOOH) nanoneedles and nanoflowers on the carbon aerogels which was obtained from the pyrolysis of cellulose aerogels. When evaluated as electromagnetic interference (EMI) shielding materials, the α-FeOOH/cellulose-derived carbon aerogels composite displays the highest SEtotal value of 34.0dB at the Fe3+/Fe2+ concentration of 0.01M, which is about 4.8 times higher than that of the individual α-FeOOH (5.9dB). When the higher or lower Fe3+/Fe2+ concentrations were used, the EMI shielding performance deterioration occurred. The integration of α-FeOOH with the carbon aerogels transforms the reflection-dominant mechanism for α-FeOOH into the adsorption-dominant mechanism for the composite. The adsorption-dominant mechanism undoubtedly makes contribution to alleviating secondary radiation, which is regarded as more attractive alternative for developing electromagnetic radiation protection products.

Graphene oxide/cellulose aerogels nanocomposite: Preparation, pyrolysis, and application for electromagnetic interference shielding.

Hybrid aerogels consisting of graphene oxide (GO) and cellulose were prepared via a solution mixing-regeneration-freeze drying process. The presence of GO affected the micromorphology of the hybrid aerogels, and a self-assembly behavior of cellulose was observed after the incorporation of GO. Moreover, there is no remarkable modification in the crystallinity index and thermal stability after the insertion of GO. After the reduction of GO in the hybrid aerogels by l-ascorbic acid and the subsequent pyrolysis of the aerogels, the resultant displays some interesting characteristics, including good electromagnetic interference (EMI) shielding capacity (SEtotal=58.4dB), high electrical conductivity (19.1Sm(-1)), hydrophobicity, and fire resistance, which provide an opportunity for some advanced applications such as EMI protection, electrochemical devices, water-proofing agents, and fire retardants. Moreover, this work possibly helps to facilitate the development of both cellulose and GO-based materials and expand their application scope.

Cellulose aerogels functionalized with polypyrrole and silver nanoparticles: In-situ synthesis, characterization and antibacterial activity.

Green porous and lightweight cellulose aerogels have been considered as promising candidates to substitute some petrochemical host materials to support various nanomaterials. In this work, waste wheat straw was collected as feedstock to fabricate cellulose hydrogels, and a green inexpensive NaOH/polyethylene glycol solution was used as cellulose solvent. Prior to freeze-drying treatment, the cellulose hydrogels were integrated with polypyrrole and silver nanoparticles by easily-operated in-situ oxidative polymerization of pyrrole using silver ions as oxidizing agent. The tri-component hybrid aerogels were characterized by scanning electron microscope, transmission electron microscope, energy dispersive X-ray spectroscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, and X-ray diffraction. Moreover, the antibacterial activity of the hybrid aerogels against Escherichia coli (Gram-negative), Staphylococcus aureus (Gram-positive) and Listeria monocytogenes (intracellular bacteria) was qualitatively and quantitatively investigated by parallel streak method and determination of minimal inhibitory concentration, respectively. This work provides an example of combining cellulose aerogels with nanomaterials, and helps to develop novel forms of cellulose-based functional materials.

Synthesis of well-dispersed magnetic CoFe2O4 nanoparticles in cellulose aerogels via a facile oxidative co-precipitation method.

With the increasing emphasis on green chemistry, it is becoming more important to develop environmentally friendly matrix materials for the synthesis of nanocomposites. Cellulose aerogels with hierarchical micro/nano-scale three-dimensional network beneficial to control and guide the growth of nanoparticles, are suitable as a class of ideal green nanoparticles hosts to fabricate multifunctional nanocomposites. Herein, a facile oxidative co-precipitation method was carried out to disperse CoFe2O4 nanoparticles in the cellulose aerogels matrixes, and the cellulose aerogels were prepared from the native wheat straw based on a green NaOH/polyethylene glycol solution. The mean diameter of the well-dispersed CoFe2O4 nanoparticles in the hybrid aerogels is 98.5 nm. Besides, the hybrid aerogels exhibit strong magnetic responsiveness, which could be flexibly actuated by a small magnet. And this feature also makes this class of magnetic aerogels possibly useful as recyclable adsorbents and some magnetic devices. Meanwhile, the mild green preparation method could also be extended to fabricate other miscellaneous cellulose-based nanocomposites.

Fabrication of hydrophobic, electrically conductive and flame-resistant carbon aerogels by pyrolysis of regenerated cellulose aerogels.

In this paper, we reported miscellaneous carbon aerogels prepared by pyrolysis of regenerated cellulose aerogels that were fabricated by dissolution in a mild NaOH/PEG solution, freeze-thaw treatment, regeneration, and freeze drying. The as-prepared carbon aerogels were subsequently characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), nitrogen adsorption measurements, X-ray diffraction (XRD), Raman spectroscopy, and water contact angle (WCA) tests. The results showed that the carbon aerogels with pore diameters of 1-60 nm maintained interconnected three-dimensional (3D) network after the pyrolysis, and showed type-IV adsorption isotherm. The pyrolysis process leaded to the decomposition of oxygen-containing functional groups, the destruction of cellulose crystalline structure, and the formation of highly disordered amorphous graphite. Moreover, the carbon aerogels also had strong hydrophobicity, electrical conductivity and flame retardance, which held great potential in the fields of waterproof, electronic devices and fireproofing.