Search

Achieving long‐lived room temperature phosphorescence (RTP) in nonconventional luminophores devoid of any conjugated units is fascinating but remains formidably challenging due to their low intersystem crossing efficiency and strong nonradiative decay. Herein, a stepwise rigidification strategy is developed to suppress the nonradiative decay and fully exploit the clusterization‐triggered RTP performance of cellulose. Specifically, the crystallinity is enhanced, and hydrogen bonding is reconstructed by a directed oxidation‐reduction reaction to afford a more rigid environment of cellulose; then, the reconstructed cellulose is further cross‐linked by boric acid to activate double confinement architecture. In return, the phosphorescence lifetime of the target cellulose increases almost one order of magnitude, and the phosphorescence quantum yield increases more than 27 folds. Moreover, the afterglow of the RTP cellulose can be regulated from blue to green by changing excitation wavelength, which is useful for advanced information encryption and anti‐counterfeiting. The stepwise rigidification strategy is also applicable for preparing other nature polysaccharides‐based long‐lived RTP materials, such as chitosan and sodium alginate. Nature polysaccharides are completely biodegradable; thus, this work paves the way for the development of eco‐friendly and practical color‐variable RTP materials. [ABSTRACT FROM AUTHOR]

MXene, a new class of 2D layered materials, is considered a candidate for the reverse electrodialysis (RED) film because the laminated MXene nanochannels with charged functional groups provide an excellent ionic selectivity and conductivity. However, the MXene‐based ion‐exchange films suffer from weak mechanical properties and instability in water due to the poor binding force between the nanosheets, which limits their RED performance. Here, inspired by natural nacre structure, a class of cation‐MXene/cation holocellulose nanofibers (C‐MXene/C‐HNF) composite film with high performance for harvesting nanofluidic osmotic is developed. C‐HNF acts as interlocking agent to connect the MXene nanosheets by hydrogen bonding, resulting a mechanically robust and water stable film. The introduction of C‐HNF not only increases the interlayer interaction force, but also enhances the ion transport flux. When the content of C‐HNF is 20%, the tensile stress, fracture strain, and toughness of the composite film reach up to 127.75 ± 1.61 MPa, 3.50 ± 0.1%, and 2.95 ± 0.52 MJ m−3, respectively. Additionally, the composite film can produce an impressive output power density of up to 1.09 W m−2 under a 50‐fold salinity gradient (0.01/0.5 m NaCl), and only decreases by 4.58% after 50 days, demonstrating good stability and durability. [ABSTRACT FROM AUTHOR]

In this study, experiments and molecular dynamics simulations were combined to get insights into the role of solvent during the process of xylose conversion under catalyst-free conditions. Solvents used for furfural production were comparatively discussed, including traditional and emerging biomass-derived solvents – water, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), isopropanol (ISO), γ-butyrolactone (GBL) and γ-valerolactone (GVL). The degradation behavior of solvents, the solubility and α/β ratio of xylose, the distribution of the solvent around xylose/furfural and the hydrogen bonding between them were also studied. The results showed that in pure solvents, the different hydrogen bonding between xylose and the solvent resulted in different products. Water was a favourable solvent for xylose to form furfural among these pure solvents because less formic acid was produced from xylose in water under catalyst-free conditions. Furfural could be produced in mixed solvents if there was more water around xylose, which was similar to the case in pure water. Otherwise, the situation in mixed solvents was similar to that in the corresponding pure organic solvents. GBL and GVL, as green solvents, had weaker affinities with xylose than DMSO, DMF and ISO, but were intensively attracted by furfural, thus they could provide protective shells for furfural, which played a positive role during the production of furfural. The highest furfural yield of 46.4% was achieved in GBL–H2O at 180 °C – 150 min in the absence of catalysts. [ABSTRACT FROM AUTHOR]

A simple and template-free method for the fabrication of modified pulp fiber (PF)–polyacrylamide (PAM)–graphene (RGO) composite electrodes was developed. The pulp fiber–graphene electrodes decorated with polyacrylamide were synthesized via a facile vacuum-filtration process, and further optimized through different mass ratios. Benefiting from the porous structure and large amounts of hydrophilic groups in the paper fiber, the PF–PAM–RGO composite electrode demonstrated good hydrophilic property and ion transport capacity within the electrode. After adding the polyacrylamide molecule (PF–RGO), the PF–PAM–RGO composite electrode exhibited good mechanical properties and capacitance performance due to PF–RGO hydrogen bonding. Moreover, the PF–PAM–RGO composite electrode displayed a high area specific capacitance of 498.4 mF cm−2 with a mass of 2.32 mg cm−2 (specific capacitance of 214.8 F g−1) at 0.2 mA cm−2. The assembled PF–PAM–RGO composite electrode showed a good cycling stability (92.36% capacitance retention after 8000 charging/discharging cycles) and mechanical flexibility (87.65% capacitance retention after 500 bending/unbending cycles). Remarkably, the flexible device could achieve superior energy density of 80.59 μWh cm−2 and high power density of 2549.83 μW cm−2. [ABSTRACT FROM AUTHOR]

Abstract: Hemicelluloses are types of plant cell wall polysaccharides, and the world''s second most abundant renewable polymers after cellulose in lignocellulosic materials. They represent a type of hetero-polysaccharide with complex structure containing glucose, xylose, mannose, galactose, arabinose, rhamnose, glucuronic acid, and galacturonic acid in various amounts, depending on the source. Hemicelluloses are usually bonded to other cell-wall components such as cellulose, cell-wall proteins, lignin, and phenolic compounds by covalent and hydrogen bonds, and by ionic and hydrophobic interactions. This paper provides a review on hemicelluloses from lignocellulosic materials, especially in regard to their isolation and purification methods, and bioconversion. Current isolation and purification strategies are summarized, including: alkali peroxide extraction, organic solvent extraction, steam explosion, ultrasound-assisted extraction, microwave-assisted extraction, column chromatography, and membrane separation. In addition, the bioconversion of hemicelluloses including pretreatment, enzymatic hydrolysis, and fermentation are discussed. [Copyright &y& Elsevier]

A facile and environmentally friendly method was introduced to incorporate montmorillonite (MMT) as an inorganic phase into quaternized hemicelluloses (QH) for forming hemicellulose-based films. Two fillers, polyvinyl alcohol (PVA) and chitin nanowhiskers (NCH), were added into the hemicelluloses/MMT hybrid matrices to prepare hybrid films, respectively. The hybrid films were nanocomposites with nacre-like structure and multifunctional characteristics including higher strength and good oxygen barrier properties via the electrostatic and hydrogen bonding interactions. The addition of PVA and NCH could induce changes in surface topography, and effectively enhance mechanical strength, thermal stability, transparency, and oxygen barrier properties. The tensile strengths of the composite films FPVA(0.3), FPVA(0.5), and FNCH(0.8) were 53.7, 46.3, and 50.1 MPa, respectively, which were 171%, 134%, and 153% larger than the FQH-MMT film (19.8 MPa). The tensile strength, and oxygen transmission rate of QH-MMT-PVA film were better than those of quaternized hemicelluloses/MMT films. Thus, the proper filler is very important for the strength of the hybrid film. These results provide insights into the understanding of the structural relationships of hemicellulose-based composite films in coating and packaging application for the future. [ABSTRACT FROM AUTHOR]

• Surface oxidized nano-cobalt wrapped by N-doped carbon nanotubes (Co@CoO/NC) is prepared. • Co@CoO/NC has a strong adsorption capacity for both some dyes and antibiotics. • The magnetic nano-Co@CoO/NC exhibits excellent stability and reusability. • The main adsorption force is hydrogen bonding and π-π EDA interaction. Dyes and antibiotics in the wastewater discharged by factories have caused immeasurable harm to natural water bodies. It is of great significance to remove the organic pollutants from wastewater. Herein, a novel magnetic nanomaterial of surface oxidized nano-cobalt wrapped by nitrogen-doped carbon nanotubes (Co@CoO/NC) was prepared through a one-step annealing method and used as efficient adsorbing material for tetracycline (TC) and rhodamine B (RhB). The maximum adsorption capacity of the optimal Co@CoO/NC for RhB and TC was 679.56 mg·g−1 and 385.60 mg·g−1, respectively. As a kind of magnetic recyclable and reused adsorbent, Co@CoO/NC could respectively maintain 75% and 84% of absorption capacities for TC and RhB after four repetitions. The adsorption processes were well matched with the pseudo-second-order kinetic model and the Langmuir model. The Zeta potential, XPS, FT-IR and theoretical calculation results showed that the hydrogen bonding and π-π electron donor-acceptor interaction dominated the adsorption of TC and RhB. Due to the presence of CoO on the surface of Co nanoparticles, cation exchange and surface complexation also played an essential role in the adsorption of TC. This work provides a new opportunity for the rational design and construction of efficient, stable and easily recyclable adsorbents in environmental remediation. [ABSTRACT FROM AUTHOR]