Cellulose-Rich Nanofiber-Based Functional Nanoarchitectures

Surface Engineering of Regenerated Cellulose Nanocomposite Films with High Strength, Ultraviolet Resistance, and a Hydrophobic Surface

Regenerated cellulose packaging materials can alleviate the environmental pollution and carbon emissions caused by conventional plastics and other chemicals. They require regenerated cellulose films with good barrier properties, such as strong water resistance. Herein, using an environmentally friendly solvent at room temperature, a straightforward procedure for synthesizing these regenerated cellulose (RC) films, with excellent barrier properties and doping with nano-SiO2, is presented. After the surface silanization modification, the obtained nanocomposite films exhibited a hydrophobic surface (HRC), in which the nano-SiO2 provided a high mechanical strength, whereas octadecyltrichlorosilane (OTS) provided hydrophobic long-chain alkanes. The contents of the nano-SiO2 and the concentrations of the OTS/n-hexane in regenerated cellulose composite films are crucial, as they define its morphological structure, tensile strength, UV-shielding ability, and the other performance of these composite films. When the nano-SiO2 content was 6%, the tensile stress of the composite film (RC6) increased by 41.2%, the maximum tensile stress was 77.22 MPa, and the strain-at-break was 14%. Meanwhile, the HRC films had more superior multifunctional integrations of tensile strength (73.91 MPa), hydrophobicity (HRC WCA = 143.8°), UV resistance (>95%), and oxygen barrier properties (5.41 × 10−11 mL·cm/m2·s·Pa) than the previously reported regenerated cellulose films in packaging materials. Moreover, the modified regenerated cellulose films could biodegrade entirely in soil. These results provide an experimental basis for preparing regenerated-cellulose-based nanocomposite films that exhibit a high performance in packaging applications.

Reusable catalysts based on CeO2/cellulose derivative with visible light photocatalytic activity tuned by noble metal nanoparticles inclusion

For environmental preservation, it is crucial to effectively remove organic waste from water. Several approaches have been put forth, but photocatalysis stands out as a quick and effective solution. In this study, some hybrid polymeric structures that were created by photopolymerizing cellulose acetate/castor oil urethane methacrylates with embedded CeO₂ nanoparticles (NPs) and in situ photogenerated noble metal nanoparticles (Ag, Au, Pd) are characterized, and photochemically thoroughly evaluated. The effective modification of cellulose acetate with urethane methacrylate sequences and the degree of functionalization were first observed using ¹H NMR and FTIR spectra. Additionally, scanning and transmission electron microscopy, X-ray diffraction, FT-IR and UV-visible spectroscopy were utilized to analyse the resultant nanocomposites. The homogeneous dispersion of CeO₂ NPs (10-40 nm) into an organic matrix with the suitable functionalities, namely urethane and hydroxyl groups, favour the interfacial charge transfer reducing the E_g up to 2.85 eV. Moreover, noble metal nanoparticles (5-15 nm), such as Ag, Au and Pd introduction in nanocomposites, significantly lowered the E_g: 2.1 eV for CeAg samples, 1.7 eV for CeAu films and 1.5 eV for CePd films, respectively. This opens up new avenues for the creation of flexible cellulose-based photocatalysts that are active in visible light.

Three-Dimensional Cross-Linked Nb2O5 Polymorphs Derived from Cellulose Substances: Insights into the Mechanisms of Lithium Storage

Niobium pentoxide (Nb₂O₅)-based materials have been regarded as promising anodic materials for lithium-ion batteries due to their abundant crystalline phases and stable and safe lithium storage performances. However, there is a lack of systematic studies of the relationship among the crystal structures, electrochemical characteristics, and lithium storage mechanisms for the various Nb₂O₅ polymorphs. Herein, pure pseudohexagonal Nb₂O₅ (TT-Nb₂O₅), orthorhombic Nb₂O₅ (T-Nb₂O₅), tetragonal Nb₂O₅ (M-Nb₂O₅), and monoclinic Nb₂O₅ (H-Nb₂O₅) with three-dimensional interconnected structures are reported, which were synthesized via a hydrothermal method using the commercial filter paper as the structural template followed by specific annealing processes. Impressively, the TT- and T-Nb₂O₅ species both possess bronze-like phases with "room and pillar" structures, while M- and H-Nb₂O₅ ones are both in the Wadsley-Roth phases with crystallographic shear structures. Among the pristine Nb₂O₅ materials, H-Nb₂O₅ exhibits the highest initial specific capacity (270 mA h g^-1), while T-Nb₂O₅ performs with the lowest (197 mA h g^-1) at 0.02 A g^-1, meaning that crystallographic shear structures provide more lithium storage sites. TT-Nb₂O₅ realizes the best rate capability (207 mA h g^-1 at 0.02 A g^-1 and 103 mA h g^-1 at 4.0 A g^-1), indicating that the "room and pillar" crystal structures favor fast lithium storage. Electrochemical analyses reveal that the TT- and T-Nb₂O₅ phases with "room and pillar" crystal structures utilize a pseudocapacitive intercalation mechanism, while the M- and H-Nb₂O₅ phases with the Wadsley-Roth shear structures follow a typical battery-type intercalation mechanism. A fresh insight into the further understanding of the intercalation pseudocapacitance on the basis of the unit cells of the electrode materials and a meaningful guidance for crystalline structural design/construction of the electrode materials for the next-generation LIBs are thus provided.

Cubic Manganese Potassium Hexacyanoferrate Regulated by Controlling of the Water and Defects as a High-Capacity and Stable Cathode Material for Rechargeable Aqueous Zinc-Ion Batteries

Aqueous zinc ion batteries (A-ZIBs) have been used as new alternative batteries for grid-scale electrochemical energy storage because of their low cost and environmental protection. Finding a suitable and economical cathode material, which is needed to achieve high energy density and long cycle stability, is one of the most important and arduous challenges at the present stage. Potassium manganese hexacyanoferrate (KMHCF) is a kind of Prussian blue analogue. It has the advantages of a large 3D frame structure that can accommodate the insertion/extraction of zinc ions, and is nontoxic, safe, and easy to prepare. However, regularly synthesized KMHCF has higher water and crystal defects, which reduce the possibility of zinc ions' insertion/extraction, and subsequently the discharge capacity and cycling stability. In this work, a KMHCF material with less water and low defects was obtained by adding polyvinylpyrrolidone during the synthesis process to control the reaction process. The KMHCF serves as the cathode of A-ZIBs and exhibits an excellent electrochemical performance providing a specific capacity of 140 mA h g^-1 for the initial cycle at a current density of 100 mA g^-1 (1 C). In particular, it can maintain a reversible capacity of 85 mA h g^-1, even after 400 cycles at 1 C. Moreover, unlike the traditional zinc storage mechanism of A-ZIBs, we found that the KMHCF electrode undergoes a phase transition process when the KMHCF electrode was activated by a small current density, which is attributed to part of the Mn on the lattice site being replaced by Zn, thus forming a new stable phase to participate in the subsequent electrochemical reaction.

Customized Cellulose Fiber Paper Enabled by an In Situ Growth of Ultralong Hydroxyapatite Nanowires

Cellulose fiber (CF) paper is a low-cost, sustainable, and flexible substrate, which has gained increasing interest recently. Before practical usage, the functionalization of the pristine CF paper is indispensable to meet requirements of specific applications. Different from conventional surface modification or physical mixing methods, we report in situ growth of ultralong hydroxyapatite nanowires (HAPNWs) with lengths larger than 10 μm on the CF paper. HAPNWs are radially aligned on the surface of CFs, creating a micro/nanoscale hierarchical structure. By means of the excellent ion exchange ability of HAP and the hierarchical structure, the functions of the CF paper can be easily customized. As a proof-of-concept, we demonstrate two kinds of functional CF paper: (1) the photoluminescent CF paper by doping Eu³⁺ and Tb³⁺ ions into the crystal lattice of HAPNWs and (2) the superhydrophobic CF paper by coating poly(dimethylsiloxane) on the HAPNW hierarchical structure, which can be applied for self-cleaning and oil/water separation. It is expected that an in situ growth of ultralong HAPNWs will provide an instructive guideline for designing a CF paper with specific functions.

Natural Cellulose Substance Based Energy Materials

Natural cellulose substances have been proven to be ideal structural templates and scaffolds for the fabrication of artificial functional materials with designed structures, psychochemical properties and functionalities. They possess unique hierarchically porous network structures with flexible, biocompatible, and environmental characteristics, exhibiting great potentials in the preparation of energy-related materials. This minireview summarizes natural cellulose-based materials that are used in batteries, supercapacitors, photocatalytic hydrogen generation, photoelectrochemical cells, and solar cells. When natural cellulose substances are employed as the structural template or carbon sources of energy materials, the three-dimensional porous interwoven structures are perfectly replicated, leading to the enhanced performances of the resultant materials. Benefiting from the mechanical strengths of natural cellulose substances, wearable, portable, free-standing, and flexible materials for energy storage and conversion are easily obtained by using natural cellulose substances as the substrates.

A Bio-Inspired Nanotubular Na2MoO4/TiO2 Composite as a High-Performance Anodic Material for Lithium-Ion Batteries

A train of bio-inspired nanotubular Na₂MoO₄/TiO₂ composites were synthesized by using a natural cellulose substance (e.g., commercial ordinary filter paper) as the structural template. The TiO₂ gel films were coated on the cellulose nanofiber surfaces via a sol-gel method firstly, followed with the deposition of the poly(diallyldimethylammonium chloride)/Na₂MoO₄ (PDDA/Na₂MoO₄) bi-layers several times, through the layer-by-layer self-assembly route, yielding the (PDDA/Na₂MoO₄)_n/TiO₂-gel/cellulose composite, which was calcined in air to give various Na₂MoO₄/TiO₂ nanocomposites containing different Na₂MoO₄ contents (15.4, 24.1, and 41.4%). The resultant nanocomposites all inherited the three-dimensionally porous network structure of the premier cellulose substance, which were formed by hierarchical TiO₂ nanotubes anchored with the Na₂MoO₄ layers. When employed as anodic materials for lithium-ion batteries, those Na₂MoO₄/TiO₂ nanocomposites exhibited promoted electrochemical performances in comparison with the Na₂MoO₄ powder and pure TiO₂ nanotubes, which was resulted from the high capacity of the Na₂MoO₄ component and the buffering effects of the TiO₂ nanotubes. Among all the nanotubular Na₂MoO₄/TiO₂ composites, the one with a Na₂MoO₄ content of 41.4% showed the best electrochemical properties, such as the cycling stability with a capacity of 180.22 mAh g⁻¹ after 200 charge/discharge cycles (current density: 100 mA g⁻¹) and the optimal rate capability.

Direct Visualization of Crystalline Domains in Carboxylated Nanocellulose Fibers

Direct visualization of soft organic molecules like cellulose is extremely challenging under a high-energy electron beam. Herein, we adopt two ionization damage extenuation strategies to visualize the lattice arrangements of the β-(1→4)-d-glucan chains in carboxylated nanocellulose fibers (C-NCFs) having cellulose II crystalline phase using high-resolution transmission electron microscopy. Direct imaging of individual nanocellulose fibrils with high-resolution and least damage under high-energy electron beam is achieved by employing reduced graphene oxide, a conducting material with high electron transmittance and Ag⁺ ions, with high electron density, eliminating the use of sample-specific, toxic staining agents, or other advanced add-on techniques. Furthermore, the imaging of cellulose lattices in a C-NCF/TiO₂ nanohybrid system is accomplished in the presence of Ag⁺ ions in a medium revealing the mode of association of C-NCFs in the system, which validates the feasibility of the presented strategy. The methods adopted here can provide further understanding of the fine structures of carboxylated nanocellulose fibrils for studying their structure-property relationship for various applications.

Cellulose-Derived Hierarchical g-C3N4/TiO2-Nanotube Heterostructured Composites with Enhanced Visible-Light Photocatalytic Performance

A novel cellulose-derived hierarchical g-C₃N₄/TiO₂-nanotube heterostructured nanocomposite was fabricated by in situ coating thin g-C₃N₄ layers onto the surfaces of the TiO₂ nanotubes, which were synthesized by utilizing the natural cellulose substance (e.g., commercial ordinary filter paper) as the structural template. These g-C₃N₄/TiO₂-nanotube composites with varied thicknesses (ca. 3-30 nm) of the outer g-C₃N₄ layers displayed improved visible-light (λ > 420 nm)-driven photocatalytic degradation performances toward methylene blue. The optimal nanocomposite with an outer g-C₃N₄ layer of ca. 7.5 nm composed of 46 wt % g-C₃N₄ displayed an apparent rate constant of 0.0035 min^-1, which was 8.5- and 4-fold larger than those of the referential TiO₂-nanotube and g-C₃N₄ powder. The excellent and durable photocatalytic activities of these cellulose-derived g-C₃N₄/TiO₂-nanotube composites were ascribed to their hierarchically network porous structures replicated from the cellulose template, as well as the formation of close heterojunctions in-between the g-C₃N₄ and TiO₂ phases. Moreover, it was demonstrated that the photocatalytic mechanism matched with the type-II heterostructured model, while the main effective species during the photocatalytic processes of the nanocomposite were proved to be superoxide radicals.

One-step synthesis of core shell cellulose-silica/n-octadecane microcapsules and their application in waterborne self-healing multiple protective fabric coatings

Exploiting water-based fabric coatings outfitted with multiple protections (e.g., waterproofness, ultraviolet (UV) resistance and thermal insulation) are urgently demanded. Nevertheless, achieving the multifunction and durability poses the major challenge. In the present study, novel multifunctional cellulose/silica hybrid microcapsules were developed by one-step emulsion-solvent diffusion; these microcapsules were well dispersed into waterborne silicone resins to form waterborne multiple protective fabric coatings. Since the encapsulated phase change materials were in the core of capsules, and the hydrophobic coupling reagent and UV absorber were grafted onto the silicas in the shell of capsules, these fabric coatings exhibited high superhydrophobicity, UV protection and thermal insulation. Moreover, because hydrophobic coupling reagent and UV absorber in the shell-cellulose of capsules exhibited easy mobility, the fabric coatings displayed self-repairability of superhydrophobicity and UV protection even after being damaged chemically or mechanically. The fabric coating presented in this study could have a range of applications, covering special protective fabric, high-altitude garments as well as self-cleaning materials.

Microfluidic Generation of Nanomaterials for Biomedical Applications

As nanomaterials (NMs) possess attractive physicochemical properties that are strongly related to their specific sizes and morphologies, they are becoming one of the most desirable components in the fields of drug delivery, biosensing, bioimaging, and tissue engineering. By choosing an appropriate methodology that allows for accurate control over the reaction conditions, not only can NMs with high quality and rapid production rate be generated, but also designing composite and efficient products for therapy and diagnosis in nanomedicine can be realized. Recent evidence implies that microfluidic technology offers a promising platform for the synthesis of NMs by easy manipulation of fluids in microscale channels. In this Review, a comprehensive set of developments in the field of microfluidics for generating two main classes of NMs, including nanoparticles and nanofibers, and their various potentials in biomedical applications are summarized. Furthermore, the major challenges in this area and opinions on its future developments are proposed.

Optical Recognition of Sulfamethoxazole by a Colored Chiral Nematic Imprinted Film

In this article, an alterable structural color in the reflected light of a chiral nematic imprinted film was fabricated. Bio-template nanocrystalline celluloses were applied as structural oriented templates. Selectivity of the sensor was endowed by the molecular imprinting process which applied sulfamethoxazoles (SMXs) as template molecules, urea and phenol as double functional monomers, and formaldehyde as cross-linkers. The sensor exhibited a chiral nematic blue mesoporous structure, which could selectively recognize SMXs on account of the abundant predetermined rebinding sites. Once SMXs were detected, the sensor showed a visible color variance from blue to yellow and the sensitive concentration range was from 3.9 × 10^-3 to 3.9 mmol L^-1. Both quantitative analyses, selective testing and recycling performance of the sensor were demonstrated. This optical response to SMXs can provide a portable, low-cost and easy-to-use strategy for the convenient detection of SMXs.

Functional biohybrid materials based on halloysite, sepiolite and cellulose nanofibers for health applications

Biohybrid materials were prepared by co-assembling the three following components: nanotubular halloysite, microfibrous sepiolite, and cellulose nanofibers dispersed in water, in order to exploit the most salient features of each individual component and to render homogeneous, flexible, yet strong films. Indeed, the incorporation of halloysite improves the mechanical performance of the resulting hybrid nanopapers and the assembly of the three components modifies the surface features concerning wetting properties compared to pristine materials, so that the main characteristics of the resulting materials become tunable with regard to certain properties. Owing to their hierarchical porosity together with their diverse surface characteristics, these hybrids can be used in diverse biomedical/pharmaceutical applications. Herein, for instance, loading with two model drugs, salicylic acid and ibuprofen, allows controlled and sustained release as deduced from antimicrobial assays, opening a versatile path for developing other related organic-inorganic materials of potential interest in diverse application fields.

Dehydration of Alginic Acid Cryogel by TiCl4 vapor: Direct Access to Mesoporous TiO2 @C Nanocomposites and Their Performance in Lithium-Ion Batteries

A new strategy for the synthesis of mesoporous TiO₂ @C nanocomposites through the direct mineralization of seaweed-derived alginic acid cryogel by TiCl₄ through a solid/vapor reaction pathway is presented. In this synthesis, alginic acid cryogel can have multiple roles; i) mesoporous template, ii) carbon source, and iii) oxygen source for the TiO₂ precursor, TiCl₄ . The resulting TiO₂ @alginic acid composite was transformed either into pure mesoporous TiO₂ by calcination or into mesoporous TiO₂ @C nanocomposites by pyrolysis. By comparing with a nonporous TiO₂ @C composite, the importance of the mesopores on the performance of electrodes for lithium-ion batteries based on mesoporous TiO₂ @C composite was clearly evidenced. In addition, the carbon matrix in the mesoporous TiO₂ @C nanocomposite also showed electrochemical activity versus lithium ions, providing twice the capacity of pure mesoporous TiO₂ or alginic acid-derived mesoporous carbon (A600). Given the simplicity and environmental friendliness of the process, the mesoporous TiO₂ @C nanocomposite could satisfy the main prerequisites of green and sustainable chemistry while showing improved electrochemical performance as a negative electrode for lithium-ion batteries.

Biomass-Templated Fabrication of Metallic Materials for Photocatalytic and Bactericidal Applications

In this paper, we report a simple, feasible and low-cost method to fabricate self-standing metallic materials using cellulose-based biomass as sacrificial templates. This process involves the impregnation of metallic precursors to the cellulose fibers of biomass templates and the transformation of the precursors to corresponding metals or metal oxides (as well as the removal of the cellulose framework) at an elevated temperature. The structures of the metallic materials as fabricated take the form of architectures of biomass templates (e.g., chromatography paper, medical absorbent cotton, catkins of reed, seed balls of oriental plane, and petals of peach blossom), and the various kinds of metals and metal oxides fabricated with these templates include silver, gold, anatase, cupric oxide, zinc oxide, etc. We have demonstrated photocatalytic and bactericidal applications of such metallic materials, and they should find more applications in electronics, catalysis, energy storage, biomedicine and so on.

Highly Transparent, Flexible, and Mechanically Strong Nanopapers of Cellulose Nanofibers @Metal-Organic Frameworks

Freestanding nanopapers were fabricated by the assembly of metal-organic frameworks (MOFs) onto cellulose nanofibers (CNFs). The CNFs are wrapped by continuously nucleated MOF layers (CNF@MOF) by interfacial synthesis, with the charge density on the surface of the CNFs and the dosage of the surfactant polyvinylpyrrolidone (PVP) being carefully adjusted. The obtained CNF@MOF nanofibers with long-range, continuous, hybrid nanostructures were very different to the composites formed by aggregation of MOF nanoparticles on the substrates. Four typical MOFs (HKUST-1, Al-MIL-53, Zn-MOF-74, ZIF-CO₃ -1) were successfully grown onto CNFs in aqueous solutions and further fabricated into freestanding nanopapers. Because of their unique nanostructures and morphologies, the corresponding flexible nanopapers exhibit hierarchical meso-micropores, high optical transparency, high thermal stability, and high mechanical strength. A proof-of-concept study shows that the CNF@MOF nanopapers can be used as efficient filters to separate volatile organic compounds (VOCs) from the air. This work provides a new path for structuring MOF materials that may boost their practical application.

Hierarchical nanostructures derived from cellulose for lithium-ion batteries

Recent advances in natural cellulose substance derived hierarchical nanomaterials applied as anodic materials for lithium-ion batteries are summarized.

Fabrication of tubular braid reinforced PMIA nanofiber membrane with mussel-inspired Ag nanoparticles and its superior performance for the reduction of 4-nitrophenol

A novel tubular braid reinforced (TBR) PMIA/CA-PEI/Ag nanofiber membrane for application in dynamic catalysis was introduced in this study. The preparation method of the TBR PMIA/CA-PEI/Ag nanofiber membrane was facile and efficient. The TBR PMIA/CA-PEI/Ag nanofiber membrane was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The mechanical properties were evaluated by a universal material testing machine. The tensile strength of TBR nanofiber membrane exceeded 500 MPa, whereas that of the nanofiber membrane without reinforcement was merely 10 MPa. Besides, the compressive strength of the TBR nanofiber membrane was also reinforced, which indicated that the TBR nanofiber membrane could withstand a higher operating pressure. The reduction of 4-NP to 4-AP was selected as the model reaction to evaluate the catalytic property of TBR PMIA/CA-PEI/Ag nanofiber membrane. The apparent rate constant of dynamic catalysis was 34.58 times higher than that of static catalysis. After 10 cycles, the conversion of 4-NP was still higher than 95.3%. This indicated that the TBR PMIA/CA-PEI/Ag nanofiber membrane had superior stability and recyclability. Besides, the TBR PMIA/CA-PEI/Ag nanofiber membrane also showed superior catalytic performance when it was used for catalyzing other environmental pollutants.

Nanocomposite Film Containing Fibrous Cellulose Scaffold and Ag/TiO₂ Nanoparticles and Its Antibacterial Activity

Cellulose is a natural polymer that is widely used in daily life, but it is susceptible to microorganism growth. In this study, a simple sol⁻gel technique was utilized to incorporate the cellulose scaffold with Ag/TiO₂ nanoparticles. The morphology and crystal structure of the as-prepared Ag/TiO₂/cellulose composite film were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. Antibacterial tests involving the use of Escherichia coli (E. coli) were carried out under dark and UV-light conditions to evaluate the efficiency of the Ag/TiO₂/cellulose composite film in comparison with pristine cellulose paper and TiO₂/cellulose composite film. The results indicated that the antibacterial activity of the Ag/TiO₂/cellulose composite film outperformed all other samples, where the Ag content of 0.030 wt% could inhibit more than 99% of E. coli. This study suggests that finely dispersed nanocale Ag/TiO₂ particles in the cellulose scaffold were effective at slowing down bacterial growth, and the mechanisms of this are also discussed.

Paleo-inspired Systems: Durability, Sustainability, and Remarkable Properties

The process of mimicking properties of specific interest (such as mechanical, optical, and structural) observed in ancient and historical systems is designated here as paleo-inspiration. For instance, recovery in archaeology or paleontology identifies materials that are a posteriori extremely resilient to alteration. All the more encouraging is that many ancient materials were synthesized in soft chemical ways, often using low-energy resources and sometimes rudimentary manufacturing equipment. In this Minireview, ancient systems are presented as a source of inspiration for innovative material design in the Anthropocene.

Water Resistant Cellulose - Titanium Dioxide Composites for Photocatalysis

Novel water resistant photocatalytic composites of microfibrillated cellulose (MFC)-polyamide-amine-epichlorohydrin (PAE)-TiO2 nanoparticles (NPs) were prepared by a simple two-step mixing process. The composites produced are flexible, uniform, reproducible and reusable; they can readily be removed from the pollutant once used. Small amount of TiO2 NPs are required for the loaded composites to exhibit a remarkable photocatalytic activity which is quantified here as achieving at least 95% of methyl orange degradation under 150 min of UV light irradiation for the composite with best combination. The cellulose network combined with PAE strongly retains NPs and hinders their release in the environment. PAE dosage (10 and 50 mg/g MFC) controls the NP retention in the cellulose fibrous matrix. As TiO2 content increases, the photocatalytic activity of the composites levels off to a constant; this is reached at 2wt% TiO2 NPs for 10 mg/g PAE and 20wt% for 50 mg/g PAE. SEM and SAXS analysis confirms the uniform distribution of NPs and their formation of aggregates in the cellulose fibre network. These economical and water resistant photocatalytic paper composites made by a simple, robust and easily scalable process are ideal for applications such as waste water treatment where efficiency, reusability and recyclability are important.

Evaluation of engineered hydrochar from KMnO4 treated bamboo residues: Physicochemical properties, hygroscopic dynamics, and morphology

In this study, a novel approach was developed to prepare engineered hydrochar from KMnO₄ treated bamboo residues through hydrothermal carbonization. The hydrochar yields were within a specified range of 61.8-67.8% at 180 °C and 39.8-45.0% at 260 °C, respectively. The higher temperature led to the higher C content, lower H/C and O/C ratio, whereas the ash content increased with increasing KMnO₄ concentration, causing the increase of solid yield as well as the decrease of C content. Pseudo-second kinetic model was optimal to describe bamboo hydrochar's hygroscopic dynamic, and the engineered hydrochar produced at 260 °C and 1.0 wt% concentration obtained the better hydrophobicity of 0.82%. SEM-EDS and XRD analysis confirmed the existence of manganese carbonate on the surface of engineered hydrochar, from which we inferred the chemical complexation between KMnO₄ and hydrochar.

Synthesis and characterization of sisal fibre polyurethane network cross-linked with triple-shape memory properties

In this paper, a thermo-responsive network shape-memory polymer (SMP) which has high elasticity, triple shape-memory properties and rapid shape recovery effects was reported.

Reductive mineralization of cellulose with vanadium, iron and tungsten chlorides and access to MxOy metal oxides and MxOy/C metal oxide/carbon composites

M_xO_y and M_xO_y/C composites (M=V, Fe and W) were obtained by mineralization of cellulose with several metal chlorides. Cellulose was used both as a templating agent and as an oxygen and a carbon source. Soluble chloride molecules (VOCl₃ and WCl₆) and a poorly soluble ionic chloride compound (FeCl₃) were chosen as metal oxide precursors. In a first time, primary metal oxide/cellulose composites were obtained via a thermal treatment by reacting urea impregnated filter paper with the corresponding metal chlorides in an autoclave at 150°C after 3days. After either pyrolysis or calcination steps of these intermediate materials, interesting metal oxides with various morphologies were obtained (V₂O_5, V₂O₃, Fe₃O₄, WO_3, H_0.23WO₃), composites (V₂O₃/C) as well as carbides (hexagonal W₂C and WC, Fe₃C) This result highlight the reductive role that can play cellulose during the pyrolysis step that allows to tune the composition of M_xO_y/C composites. The materials were characterized by FTIR, Raman, TGA, XRD and SEM. This study highlights that cellulose can be used for a convenient preparation of a variety of highly demanded M_xO_y and M_xO_y/C composites with original shapes and morphologies.

A Consecutive Spray Printing Strategy to Construct and Integrate Diverse Supercapacitors on Various Substrates

The rapid development of printable electronic devices with flexible and wearable characteristics requires supercapacitor devices to be printable, light, thin, integrated macro- and micro-devices with flexibility. Herein, we developed a consecutive spray printing strategy to controllably construct and integrate diverse supercapacitors on various substrates. In such a strategy, all supercapacitor components are fully printable, and their thicknesses and shapes are well controlled. As a result, supercapacitors obtained by this strategy achieve diverse structures and shapes. In addition, different nanocarbon and pseudocapacitive materials are applicable for the fabrication of these diverse supercapacitors. Furthermore, the diverse supercapacitors can be readily constructed on various objects with planar, curved, or even rough surfaces (e.g., plastic film, glass, cloth, and paper). More importantly, the consecutive spray printing process can integrate several supercapacitors together in the perpendicular and parallel directions of one substrate by designing the structure of electrodes and separators. This enlightens the construction and integration of fully printable supercapacitors with diverse configurations to be compatible with fully printable electronics on various substrates.

Luminescent, Fire-Resistant, and Water-Proof Ultralong Hydroxyapatite Nanowire-Based Paper for Multimode Anticounterfeiting Applications

Counterfeiting of valuable certificates, documents, and banknotes is a serious issue worldwide. As a result, the need for developing novel anticounterfeiting materials is greatly increasing. Herein, we report a new kind of ultralong hydroxyapatite nanowire (HAPNW)-based paper with luminescence, fire resistance, and waterproofness properties that may be exploited for anticounterfeiting applications. In this work, lanthanide-ion-doped HAPNWs (HAPNW:Ln³⁺) with lengths over 100 μm have been synthesized and used as a raw material to fabricating a free-standing luminescent, fire-resistant, water-proof paper through a simple vacuum filtration process. It is interesting to find that the luminescence intensity, structure, and morphology of HAPNW:Ln³⁺ highly depend on the experimental conditions. The as-prepared HAPNW:Ln³⁺ paper has a unique combination of properties, such as high flexibility, good processability, writing and printing abilities, luminescence, tunable emission color, waterproofness, and fire resistance. In addition, a well-designed pattern can be embedded in the paper that is invisible under ambient light but viewable as a luminescent color under ultraviolet light. Moreover, the HAPNW:Ln³⁺ paper can be well-preserved without any damage after being burned by fire or soaked in water. The unique combination of luminescence, fire resistance, and waterproofness properties and the nanowire structure of the as-prepared HAPNW:Ln³⁺ paper may be exploited toward developing a new kind of multimode anticounterfeiting technology for various high-level security antiforgery applications, such as in making forgery-proof documents, certificates, labels, and tags and in packaging.

Quantitative Immobilization of Phthalocyanine onto Bacterial Cellulose for Construction of a High-Performance Catalytic Membrane Reactor

We report the fabrication of a tetra-amino cobalt (II) phthalocyanine (CoPc)-immobilized bacterial cellulose (BC) functional nanocomposite, CoPc@BC, by quantitative immobilization of CoPc onto a BC membrane. Lab-cultured BC was oxidized by NaIO₄ to generate aldehyde groups on BC for the subsequent CoPc immobilization, the processing conditions were optimized by monitoring both the generated aldehyde content and the resulting CoPc loading. X-ray photoelectron spectroscopy (XPS) was employed to characterize the change of the element bonding environment during the functionalization processes. The CoPc@BC functional nanocomposite was utilized for the treatment of reactive red X-3B dye wastewater. The CoPc molecules in the CoPc@BC nanocomposite can function as an “antenna” to adsorb the target anionic dye molecules, the adsorption takes place both on the surface and in the interior of CoPc@BC. A catalytic membrane reactor (CMR) was assembled with the CoPc@BC nanocomposite, the performance of CMR was evaluated based on the catalytic oxidation behavior of reactive red X-3B, with H₂O₂ as an oxidant. Highly-reactive hydroxyl radical (OH) was involved in the catalytic oxidation process, as detected by electron paramagnetic resonance (EPR). Under optimal operating conditions of a flow rate of 6 mL/min, a reaction temperature of 50 °C, and an H₂O₂ concentration of 10 mmol/L, the decoloration rate of CMR was as high as 50 μmol⋅min⁻¹⋅g⁻¹.

Nanocoating cellulose paper based microextraction combined with nanospray mass spectrometry for rapid and facile quantitation of ribonucleosides in human urine

A rapid and facile analytical method for quantification of ribonucleosides in human urine was developed by the combination of nanocoating cellulose paper based microextraction and nanoelectrospray ionization-tandem mass spectrometry (nESI-MS/MS). Cellulose paper used for microextraction was modified by nano-precision deposition of uniform ultrathin zirconia gel film using a sol-gel process. Due to the large surface area of the cellulose paper and the strong affinity between zirconia and the cis-diol compounds, the target analytes were selectively extracted from the complex matrix. Thus, the detection sensitivity was greatly improved. Typically, the nanocoating cellulose paper was immersed into the diluted urine for selective extraction of target analytes, then the extracted analytes were subjected to nESI-MS/MS detection. The whole analytical procedure could be completed within 10min. The method was evaluated by the determination of ribonucleosides (adenosine, cytidine, uridine, guanosine) in urine sample. The signal intensities of the ribonuclesides extracted by the nanocoating cellulose paper were greatly enhanced by 136-459-folds compared with the one of the unmodified cellulose paper based microextraction. The limits of detection (LODs) and the limits of quantification (LOQs) of the four ribonucleosides were in the range of 0.0136-1.258μgL^-1 and 0.0454-4.194μgL^-1, respectively. The recoveries of the target nucleosides from spiked human urine were in the range of 75.64-103.49% with the relative standard deviations (RSDs) less than 9.36%. The results demonstrate the potential of the proposed method for rapid and facile determination of endogenous ribonucleosides in urine sample.

Nanostructured carbon–metal hybrid aerogels from bacterial cellulose

Nanostructured carbon–metal hybrid aerogels by carbothermal reduction of nickel or iron hydroxide inside bacterial cellulose at remarkably low temperatures.

A hierarchically structured anatase-titania/indium-tin-oxide nanocomposite as an anodic material for lithium-ion batteries

A nanotubular titania/ITO nanocomposite is synthesized, exhibiting enhanced electrochemical performance as an anodic material for lithium-ion batteries.