Construction of wood-PANI supercapacitor with high mass loading using "pore-making, active substance-filling, densification" strategy.

Wood-conducting polymer materials have been widely used as supercapacitor electrode; however, it remains challenging to achieve a simple method to improve the homogeneity of the conductive material on wood and to reach high mass loading. Herein, a novel "pore-making, active substance-filling, densification (dissolution, in-situ polymerization of polyaniline (PANI), self-shrinking)" strategy is proposed for the preparation of wood electrodes with a high mass loading (41.4 wt%) and homogeneity. Ingeniously, ZnCl2 as a dissolving agent and pore-making agent to treat delignified wood can generate more pores on the wood, which is more conducive to the penetration of aniline small molecules, besides, the dissolved fine fibers can be entangled with more PANI, which can improve the loading and homogeneity of PANI. After drying treatment, there will be shrinkage again, playing a certain physical densification effect on the large lumen. The optical electrode was RWP2 showing high electrochemical performance (2328.9 mF/cm2, 1 mA/cm2), and stability (5000 cycles, 89.3 %). Moving forward, the RWP2//RWP2 SSC showed an excellent energy density of 164.24 µwh/cm2 at a power density of 250 µw/cm2. Remarkably, the simple and versatile strategy of designing wood-based materials with high mass loading provides new research ideas for realizing multifunctional applications.

Modified Wood Fibers Spontaneously Harvest Electricity from Moisture.

With the rapid development of modern society, our demand for energy is increasing. And the extensive use of fossil energy has triggered a series of problems such as an energy crisis and environmental pollution. A moisture-enabled electric generator (MEG) is a new type of energy conversion method, which can directly convert the ubiquitous moisture in the air into electrical energy equipment. It has attracted great interest for its renewable and environmentally friendly qualities. At present, most MEGs still have low power density, strong dependence on high humidity, and high cost. Herein, we report the development of a high-efficiency MEG based on a lignocellulosic fiber frame with high-power-density, all-weather, and low-cost characteristics using a simple strategy that optimizes the charge transport channel and ion concentration difference. The MEG devices we manufactured can generate the open-circuit voltage of 0.73 V and the short-circuit current of 360 µA, and the voltage can still reach 0.6 V at less than 30% humidity. It is possible to drive commercial electronic devices such as light-emitting diodes, electronic displays, and electronic calculators by simply connecting several electric generators in series. Biomass-based moisture-enabled electric generation has a low cost, is easy to integrate on a large scale, and is green and pollution-free, providing clean energy for low-humidity or high-electricity-cost areas.

Aldehyde modified nanocellulose-based fluorescent hydrogel toward multistage data security encryption.

In view of the insecurity of encode information storage based on fluorescence switch single-stage encryption, a fluorescent hydrogel for multistage data security encryption were proposed, named as polyvinyl alcohol/dialdehyde cellulose nanofibrils/carbon quantum dots hydrogel. Herein, the interpenetrating network was formed by chemically crosslinking between polyvinyl alcohol (PVA) and dialdehyde cellulose nanofibrils (DACNF). Additionally, nitrogen-doped carbon quantum dots (CDs) synthesized by one-step hydrothermal method were introduced into the above hydrogel system by hydrogen bonds. The resultant fluorescent hydrogels possessed high stretchability up to 530 %, good strength of 0.96 MPa, Fe3+-responsive fluorescence quenching, fluorescence recovery triggered by ascorbic acid and borax-triggered shape memory. Moreover, various complex 3D hydrogel geometries were fabricated by folding/assembling 2D fluorescent hydrogel sheets, extending data encryption capability from 2D plane to 3D space. More remarkably, the 3D data encryption-erasing process of fluorescent hydrogel was realized by the strategy of alternating treatment of Fe3+ solution and ascorbic acid solution. This work provided a facile and general strategy for constructing high security important information encryption and protection.

Aldehyde modified cellulose-based dual stimuli responsive multiple cross-linked network ionic hydrogel toward ionic skin and aquatic environment communication sensors.

Recently, materials with complicated environmentally-sensitive abilities, high stretchability and excellent conductive sensitivity are interesting actuators in future applications. Herein, we fabricated a versatile and facile polyvinyl alcohol/polyacrylic acid/dialdehyde cellulose nanofibrils-Fe3+ hydrogel integrated with programmable dual-shape memory properties, high mechanical strength, good recoverability, and heat-induced self-healing capability. Benefiting from the synergistic effect of hydrogen bonds and dual metal coordination bonds of cellulose-based dialdehyde and carboxyl with Fe3+and then heating-freeze-thawing cycle treatment, the obtained hydrogel exhibited dual shape memory abilities, high tensile strain (up to 600 %), good self-recovery, and anti-fatigue properties. Moreover, the resultant hydrogel sensors showed revealed high strain sensitivity (gauge factor = 2.95) and satisfactory electrochemical performance; and such hydrogel-based sensor could be used as ionic skin to detect various human motions in real-time and barrier-free communication in the aquatic environment. The composite hydrogel with superior and versatile performances reported in this study could offer a great promise to be applied under extreme conditions as multifunctional sensors.

High hydrophobic ZIF-8@cellulose nanofibers/chitosan double network aerogel for oil adsorbent and oil/water separation.

Ultralight aerogels with low bulk density, highly porous nature, and functional performance have received significant focus in the field of water pollution treatment. Here, high-crystallinity, large surface-aera metal frame-work (ZIF-8) was efficiently utilized to assist in the preparation of ultralight yet highly oil and organic solvent adsorption capacity, double-network cellulose nanofibers/chitosan-based aerogels through a physical entanglement and scalable freeze-drying approach. After chemical vapor deposition with methyltrimethoxysilane, a hydrophobic surface was obtained with a water contact angle of 132.6°. The synthetic ultralight aerogel had low density (15.87 mg/cm3) and high porosity (99.01 %). Moreover, the aerogel had a three-dimensional porous structure, which endowed it with high adsorption capacity (35.99 to 74.55 g/g) for organic solvent, and outstanding cyclic stability (>88 % of the adsorption capacity after 20 cycles). At the same time, aerogel removes oil from various oil/water mixtures by gravity alone and has excellent separation performance. This work holding excellent properties in terms of convenient, low-cost, scalability to manufacture environmentally friendly biomass-based materials for oily water pollution treatment.

Nanocellulose-Based Adsorbents for Heavy Metal Ion.

Heavy metal ions in industrial sewage constitute a serious threat to human health. Nanocellulose-based adsorbents are emerging as an environmentally friendly material platform for heavy metal ion removal based on their unique properties, which include high specific surface area, excellent mechanical properties, and biocompatibility. In this review, we cover the most recent works on nanocellulose-based adsorbents for heavy metal ion removal and present an in-depth discussion of the modification technologies for nanocellulose in the process of assembling high-performance heavy ion adsorbents. By introducing functional groups, such as amino, carboxyl, aldehyde, and thiol, the assembled nanocellulose-based adsorbents both remove single heavy metal ions and can selectively adsorb multiple heavy ions in water. Finally, the remaining challenges of nanocellulose-based adsorbents are pointed out. We anticipate that this review will provide indispensable guidance on the application of nanocellulose-based adsorbents for the removal of heavy metal ions.

Thermal insulating, light-weight and conductive cellulose/aramid nanofibers composite aerogel for pressure sensing.

Conductive nanocellulose aerogels have attracted significant attention in pressure sensing for wearable devices owing to lightweight, sustainability and good chemical stability. Limited by its flammability and weak mechanical properties, aramid nanofiber (ANF) was designed as reinforcement to overcome the shortcoming mentioned above. Herein, the unidirectional freeze casting method was proposed to fabricate nanocellulose/aramid nanofiber (CA) aerogel. Then, the CA/PPy (CAP) aerogel was obtained by using the oriented structure of CA aerogel as a template for inducing conductive polypyrrole (PPy) in-situ formation inside the composite aerogel. The conductive aerogel with the ordered microstructure exhibited the anisotropic mechanical properties and thermal conductivity. And it could withstand high temperature without any destruction phenomenon. Moreover, the aerogel sensor revealed high strain sensitivity and satisfactory electrochemical performance. Lightweight CAP aerogel with controllable alignment, sensitive sensing property and thermal stability is very promising in pressure sensor under some extreme conditions.

MXene/wood-derived hierarchical cellulose scaffold composite with superior electromagnetic shielding.

Electromagnetic-interference (EMI) shielding materials that are green, lightweight, and with high mechanical properties need to be urgently developed to address increasingly severe radiation pollution. However, limited EMI shielding materials are successfully used in practical applications, due to the intensive energy consumption or the absence of sufficient strength. Herein, an environmentally friendly and effective method was proved to fabricate wood-based composites with high mechanical robustness and EMI shielding performance by a MXene/cellulose scaffold assembly strategy. The lignocellulose composites with a millimeter-thick mimic the "mortar-brick" layered structure, resulting in excellent mechanical properties that can achieve the compressive strength of 288 MPa and EMI shielding effectiveness of 39.3 dB. This "top-down" method provides an alternative for the efficient production of robust and sustainable EMI shielding materials that can be used in the fields of structural materials for next-generation communications and electronic devices.

[The influence of reference data noise on the NIR prediction results].

This article used hemicelluloses content in acacia spp. wood as a case study to demonstrate the influence of noise in the reference data on the results of NIR calibration model. The results indicated that the accuracy of NIR calibration model was affected by the reference data noise. The less noisy data was used in calibration model, the better result could be obtained. But when the noise was larger, NIR calibration model which was built by using regression mathematics methods can perform better than using primary reference data.

[Preparation and properties of wood/modified UF prepolymer composite materials].

In the present research, the urea-formaldehyde prepolymer and multilayer hot-press drying were used to modify poplar plantation. The prepolymer was impregnated into cell lumen space by pulse-dipping machine. Then the timbers were compressed and dried by the multilayer hot-press drying kiln. The results showed that the physical and chemical properties of poplar were changed in this investigation. The basic density of modified wood increased 1.06 times compared with the natural wood, and the bending strength increased 33% for modified wood, compressive strength parallel to grain increased 74%, the water absorption decreased to 97% from 104%. The crystallinity decreased slightly from 39.65 to 36.89 because of the modifier impregnated. TGA analysis showed that the heat resistance of modified wood increased, the three exothermic peaks in DTA curve of modified wood were 280, 360 and 485 degrees C which were higher than natural wood in the corresponding position FTIR analysis showed that the hydroxyl modified material has a good association phenomenon, and carbonyl content decreased. The SEM spectrum showed the distribution of the prepolymer in the modified timber.

[Preparation and characterization of wood/methylolurea composite with in-situ polymerization].

Wood/methylolurea composite was prepared with the in-situ polymerization. The green timber with high moisture content was impregnated by a pulse-dipping machine and then was dried in a hot-press drying kiln. The cross-linking reaction was taken under the heat treatment between the wood modifier and the wood composition, including cellulose, hemicelluloses, and lignin. The chemical composition was analyzed according to the Chinese standard, including X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) and energy dispersive analysis of X-rays (EDXA). The changes in chemical composition of modified wood and carbon and nitrogen element were disused in the research The results showed that the content of water extraction and benzene alcohol extraction increased 187.43% and 230.87% respectively compared with the natural wood, while the lignin and holocellulose decreased 26.55% and 26.39% respectively. XPS showed that the concentrations of O and C atoms increased 9.4% and N element content increased 137.2%. 13C-NMR analysis showed that chemical reaction of the hydroxyl methyl urea with the hydroxyl in timber structure took place, with the reduction of hydroxyl content and increase in ether bond content. EDXA showed that the processing method can get impregnated modification wood and nitrogen element is evenly distributed in wood cell walls and intercellular space.

[Extending hemicelluloses content calibration of Acacia spp using NIR to new sites].

In this research, hemicellulose contents of 78 wood meal samples of Acacia spp trees grown in Guangxi and another 33 wood meal samples of Acacia spp trees grown in Fujian were measured by wet chemistry. NIR spectra were also collected by a Bruker MPA spectrometer within 4 000-12 500 cm(-1) of wavenumbers using a standard sample cup. Equations were developed using partial least squares (PLS) regression and cross validation for multivariate calibration in this study. High coefficients of determination (R2) and low root mean square errors of cross-validation (RMSECV) were obtained for hemicellulose content (R2 = 0.947, RMSECV = 0.464) of Guangxi woodmeal samples. Prediction produced high correlation coefficients between laboratory and predicted values, with R2 and RMSEP values being 0.925 and 0.455, respectively. A variable numbers of Fujian samples ranging from one to thirteen were used to enhance the Guangxi calibration so as to be widely used for routine assessment of wood chemistry. It was demonstrated that the addition of a single Fujian sample to the Guangxi calibration set was sufficient to greatly reduce predictive errors and that the inclusion of 3 Fujian samples in the Guangxi set was sufficient to give relatively stable predictive errors. The R2 is 0.904 and RMSEP is 0.759. The addition of different sets of 3 Fujian samples to the Guangxi calibration, however, caused predictive errors to vary between sets.

[Application of near infrared spectroscopy in analysis of wood properties].

There is substantial interest in the improvement of wood properties through genetic selection or a change in silviculture prescription. Tree breeding purpose requires measurement of a large number of samples. However, traditional methods of assessing wood properties are both time consuming and destructive, limiting the numbers of samples that can be processed, so new method would be needed to find. Near infrared spectroscopy (NIR) is an advanced spectroscopic tool for nondestructive evaluation of wood and it can quickly, accurately estimate the properties of increment core, solid wood or wood meal. The present paper reviews the advances in the research on the wood chemistry properties and anatomical properties using NIR.