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This study aims to investigate the degradation and stability of pulp treated in heterogeneous and homogeneous phases. The results showed that the homogeneous system 1-Allyl-3-Hexylimidazolium chloride (AHIMCl) ionic liquid exhibited special dissolubility for pulp samples, but showed lower thermal stability than the heterogeneous treatments by 20 wt% NaOH or 2-ethanediamine (EDA) solution. Compared with the 20 wt% NaOH solution, the 20 wt% EDA solution and AHIMCl treatments had special decrystallizing ability, and the 20 wt% EDA solution had lower reductions in the mean degree of polymerization of pulp after the treatments for 72 h at 5 oC. X-ray diffractogram (XRD) analysis showed that after the AHIMCl and 20 wt% EDA solution treatments, the 002 crystal plane size of the treated pulp samples (＜1 nm) became much lower than that of the raw pulp (5.09 nm). The diffracted intensity indicating 101 crystal planes nearly disappeared from the XRD curve of AHIMCl treated pulp samples. The X-ray photoelectron spectroscopy (XPS) analysis indicated that the significant reduction in C1s2 and O1s2 contents of the regenerated samples after the AHIMCl treatment implies that AHIMCl severely destroy the hydrogen bonds in crystalline and amorphous regions.

Abstract The conversion of ubiquitous hygrothermal resources into renewable energy offers significant potential for cable‐free, self‐powered systems that can operate worldwide without regard to climatic or geographic limitations. Here, an all‐printed flexible hygro‐thermoelectric paper generator is demonstrated that uses bifunctional mobile ions and electrons to make the moist‐diffusion effect, the Soret effect, and the Seebeck effect work synergistically. In the ordinary hygrothermal settings, it generates an unconventional hygro‐thermoelectric output pattern and shows almost a dozen‐fold increase in positive hygro‐thermopower of 26.70 mV K−1 and also another negative hygro‐thermopower of −15.71 mV K−1 compared to pure thermopower. A single paper generator can produce a giant 680 mV displaying typical cyclic sinusoidal waveform characters with volt‐sized amplitudes. The ion‐electron conductive ink is easily printable and consists primarily of a Bi2Te3/PEDOT:PSS thermoelectric matrix modulated with a hygroscopic glycerol that releases ion charges for moist‐diffusion effect and Soret effect, as well as electron charges for Seebeck effect. The emerged hygro‐thermoelectric harvesting strategy from surrounding hygrothermal resources offers a revolutionary approach to the next generation of hybrid energy with cost‐efficiency, flexibility, and sustainability, and also enables large‐scale roll‐to‐roll production.

Here we report a simple efficient one-step strategy to fabricate Oxidation Reduction Reaction (ORR) or/and Oxygen Evolution Reaction (OER) electrocatalysts directly from agricultural cornstalks waste with hierarchical porous structures and massive active hydroxyl groups. CaCl2 and NH4Cl activators were utilized to corrode the cornstalks in order to create a mesopore N-doped hybrid structure that was sufficiently stable under the high-temperature pyrolysis process, which prevented neighboring aggregates of transition metals. The synergistic effect of N, B and Fe, Co within the hierarchical biochar structures guaranteed a favorable ORR activity of 0.848 V and OER activity of 393 mV for the CaCl2 sample, showed better stability than commercial Pt/C and IrO2 catalysts.

Novel organic-inorganic hybrids were synthesized by using HfCl4 and organic ligand 1H-pyrrole-2, 5-dicarboxylic acid (PDCA) via a simple hydrothermal method. The as-prepared Hf-PDCA were characterized by various techniques, such as electron microscope, N2 adsorption/desorption, and X-ray photoelectron spectroscopy. Among them, the porous and nitrogen-containing Hf-PDCA as heterogeneous acid/base bifunctional catalyst was then applied to the catalytic hydrogenation of furfural to produce furfuryl alcohol (FFA). It exhibited excellent catalytic performance, with high conversion (98.8%) and selectivity (98.5%) by using 2-propanol as hydrogen source under a relatively mild condition. Moreover, the Hf-PDCA has strong stability and durability, and can be recovered after the catalyst reaction. In addition, the Hf-PDCA as catalyst can be extended to fabricate corresponding alcohols by catalytic conversion of other biomass derived aldehydes.

The flexible and transparent film heaters (FTFHs) with the advantages of mechanical flexibility, portability, and excellent electrothermal performance, are key to the next generation portable, wearable heaters and thermal protection systems. However, the present flexible and transparent substrates of FTFHs are fabricated by typical plastic PET films, which suffer from poor interfacial adhesion with the thermally conductive materials. In this work, the transparent regenerated cellulose fibers made of completely dissolved in NMMO solution followed by regeneration process is presented to disperse and support carbon nanotubes (CNTs) by a vacuum-dewatering process. In the presence of cellulose fibers, these CNTs have strong hydrogen bonding properties in the dehydration-deposition process and thus respond to tight intertwining structures in fibrous composites. The resulting regenerated cellulose fibers exhibit high optical transparency of 88% (@550 nm) and good mechanical properties (30 MPa). Interestingly, the FTFHs show a rapid heating response, high generation temperature, and resistance stability for up to 2 h. The FTFHs made with earth-abundant, cost-effective, and recyclable materials, have excellent potential in the areas of green flexible and transparent film heaters.

Aramid fibers exhibit impressive mechanical properties, electrical insulation properties, and chemical stability. However, physical properties of the aramid paper are poor because of the chemical inertness and smooth surface of aramid fibers. This study reports a simple and efficient method for substantially improving the performance of the para-aramid/meta-aramid composite paper by introducing the N,N-dimethylacetamide (DMAc)/LiCl solution to induce partial dissolution or by adding the DMAc/LiCl/para-aramid solution to induce regeneration. Experimental results state that the tensile strength, specific strength, folding resistance, and interlayer bonding strength of the aramid paper are increased by 2.17, 2.13, 34.7, and 9.39 times, respectively, because of the dense and compact structure of the paper. Furthermore, the water resistance of the paper was also considerably improved. After immersing the paper samples in water for 24 h, their moisture absorption rate decreased to approximately 54% from approximately 143% for the original paper. Results indicate that partial dissolution/regeneration welding is a viable method for the efficient reinforcement of the aramid composite paper, providing additional possibilities for manufacturing the high-performance aramid paper-based materials. Keywords: Aramid composites, Partial dissolution, Regeneration welding, Mechanical properties, Reinforcement

Abstract Biodegradable highly nanostructured paper has received great interest in past years due to its excellent optical properties which facilitate its wide applications in green flexible electronics and devices. However, energy and/or time-consuming procedure during the process of fabricating most nanostructured transparent paper are presently the main obstacle to their scalable production. In this work, we demonstrated a novel nanostructured paper with dually high transparency (∼91%) and high haze (∼89%) that was directly fabricated from original paper with rapid ILs-polishing processes. The whole fabricating time only requires 10 min. Compared to the previously reported nanopaper made of the isolated cellulose nanofibers by pure mechanical and/or chemical approaches, this work presented herein is devoted to use green ILs to polish directly the micrometer-sized fibrous paper into the nanostructured paper. This new method brings a rapid fabrication of transparent nanostructured paper while also retaining dual intriguing properties both in optical transmittance and haze. This work is capable of fabricating next-generation flexible and highly transparent and haze paper by a high-speed roll-to-roll manufacturing process with a much lower cost.

Sustainability and eco-efficiency are presently directing the development of the next generation of acoustic materials. In this work, foamed cellulose-polymer microsphere (PM) hybrid materials, having sound-absorbing capability, were prepared by incorporating the PMs into cellulose fibers by dehydration and foaming processes. The evolution in morphology of PMs during foaming process was investigated for different heating temperatures. The beating process disintegrated the microscopic cellulose fiber into the smaller fibers, which connected the PMs by a unique fibrous network. The influences of foaming temperature, PM content, and total areal density on the sound absorbing property of composites were studied. The results showed that incorporating the acoustic unit of elastic PMs into the porous cellulose fiber-based network significantly improved the sound absorbing ability of the composites. The sound-absorbing hybrid materials appear to be a promising alternative to non-degradable organic or inorganic acoustic composites, being economical, simple, and eco-friendly.

Abstract Steering the crystallization of two-dimensional (2D) perovskite film is an important strategy to improve the power conversion efficiency (PCE) of 2D perovskite solar cells (PVSCs). In this paper, the deionized water (H2O) additive is introduced into the perovskite precursor solution to prepare high-quality 2D perovskite films. The 2D perovskite film treated with 3% H2O shows a good surface morphology, increased crystal size, enhanced crystallinity, preferred orientation, and low defect density. The fabricated 2D PVSC with 3% H2O exhibits a higher PCE compared with that without H2O (12.15% vs 2.29%). Furthermore, the shelf stability of unsealed devices with 3% H2O under ambient environment is significantly improved. This work provides a simple method to prepare high-quality 2D perovskite films for efficient and stable 2D PVSCs.

Abstract The trap-state density in perovskite films largely determines the photovoltaic performance of perovskite solar cells (PSCs). Increasing the crystal grain size in perovskite films is an effective method to reduce the trap-state density. Here, we have added NH4SCN into perovskite precursor solution to obtain perovskite films with an increased crystal grain size. The perovskite with increased crystal grain size shows a much lower trap-state density compared with reference perovskite films, resulting in an improved photovoltaic performance in PSCs. The champion photovoltaic device has achieved a power conversion efficiency of 19.36%. The proposed method may also impact other optoelectronic devices based on perovskite films.

Abstract Lead-free solution-processed solid-state photovoltaic devices based on formamidinium tin triiodide (FASnI3) and cesium tin triiodide (CsSnI3) perovskite semiconductor as the light harvester are reported. In this letter, we used solvent engineering and anti-solvent dripping method to fabricate perovskite films. SnCl2 was used as an inhibitor of Sn4+ in FASnI3 precursor solution. We obtained the best films under the function of toluene or chlorobenzene in anti-solvent dripping method and monitored the oxidation of FASnI3 films in air. We chose SnF2 as an additive of CsSnI3 precursor solution to prevent the oxidation of the Sn2+, improving the stability of CsSnI3. The experimental results we obtained can pave the way for lead-free tin-based perovskite solar cells (PSCs).

Abstract Lead halide perovskite solar cells (PSCs) appear to be the ideal future candidate for photovoltaic applications owing to the rapid development in recent years. The electron transport layers (ETLs) prepared by low-temperature process are essential for widespread implementation and large-scale commercialization of PSCs. Here, we report an effective approach for producing planar PSCs with Al3+ doped SnO2 ETLs prepared by using a low-temperature solution-processed method. The Al dopant in SnO2 enhanced the charge transport behavior of planar PSCs and increased the current density of the devices, compared with the undoped SnO2 ETLs. Moreover, the enhanced electrical property also improved the fill factors (FF) and power conversion efficiency (PCE) of the solar cells. This study has indicated that the low-temperature solution-processed Al-SnO2 is a promising ETL for commercialization of planar PSCs.

Nanocrystalline cellulose (NCC) has many potential applications because of its special properties. In this paper, NCC was prepared from bamboo pulp. Bamboo pulp was first pretreated with sodium hydroxide, followed by hydrolysis with sulfuric acid. The concentration of sulfuric acid and the hydrolysis time on the yield of NCC were studied. The results showed that sulfuric acid concentration had larger influence than the hydrolysis time on the yield of NCC. When the temperature was 50oC, the concentration of sulfuric acid was 48wt% and the reaction time was 30 minutes, a high quality of nanocrystalline cellulose was obtained; under these conditions, the length of the nanocrystalline cellulose ranged from 200 nm to 500 nm, the diameter was less than 20 nm, the yield was 15.67wt%, and the crystallinity was 71.98%, which is not only higher than those of cellulose nanocrystals prepared from some non-wood materials, but also higher than bamboo cellulose nanocrystals prepared by other methods.