Shuangshuang Jing

An ultralight, elastic, cost-effective, and highly recyclable superabsorbent from microfibrillated cellulose fibers for oil spillage cleanup

The fabrication of superabsorbents for oil spillage cleanup is a hot topic today. However, the development of a low cost and highly efficient superabsorbent is still a big challenge. In this paper, we demonstrate a simple method to produce a low-cost, ultralight, elastic, and highly recyclable superabsorbent from renewable cellulose fibers via simple and environmentally friendly microfibrillation treatment and freeze-drying. Since microfibrillation of cellulose fibers resulted in hierarchical fibers that possess both fiber bulk and considerable microfibrils on the fiber surface, hierarchically porous sponges with ultralow density (0.0024 g cm−3) and high porosity (up to 99.84%) were obtained after freeze drying. The porous sponges after hydrophobic modification were elastic and exhibited rapid and outstanding absorption performances for various oils and organic solvents. The hydrophobic superabsorbent could selectively absorb oil from an oil–water mixture and showed an ultra-high absorption capacity of 88–228 g g−1, which is comparable to those of other novel carbon-based superabsorbents. More importantly, the superabsorbent showed excellent flexibility and elasticity, and could be repeatedly squeezed without structure failure (more than 30 times). The absorbed oil could be readily and rapidly recovered by means of simple mechanical squeezing, while the superabsorbent could be reused at once without any other treatment. The superabsorbent showed excellent recyclability and could be reused for at least 30 cycles while still maintaining high oil absorption capacity (137 g g−1 for pump oil). These advantages make the superabsorbent an ideal alternative for oil spillage cleaning.

Choline chloride/urea as an effective plasticizer for production of cellulose films.

Recently, choline chloride/urea (ChCl/urea), a typical deep eutectic solvent (DES), has been found to possess various applications in organic synthesis, electrochemistry, and nanomaterial preparation. Herein we reported the first attempt to plasticize regenerated cellulose film (RCF) using ChCl/urea as an effective plasticizer. Meanwhile, RCFs plasticized with glycerol and sorbitol were also prepared for comparison. The plasticized RCFs were investigated by Fourier transform infrared (FT-IR) spectroscopy, wide-angle X-ray diffraction (XRD), atomic force microscopy (AFM), and mechanical testing. Transparent and soft RCFs could be successfully prepared in the presence of ChCl/urea, and high elongation at break (34.88%) suggested a significant plasticizing efficiency. No new crystal and phase separation occurred to ChCl/urea plasticized RCFs. The thermal stability of ChCl/urea plasticized RCF was lowered. These results indicated that ChCl/urea was an effective plasticizer for producing cellulose films.

Flexible nanocomposites with ultrahigh specific areal capacitance and tunable properties based on a cellulose derived nanofiber-carbon sheet framework coated with polyaniline

Flexible supercapacitors are extremely important for future various electronic devices. However, the development of cost-efficient and high-performance flexible supercapacitor electrodes remains a big challenge today. Herein, we present a novel flexible nanocomposite based on a cellulose-derived framework coated with polyaniline (PANI). In this nanocomposite, the cellulose nanofiber (CNF) provides mechanical strength due to its interconnected network, while the strapped cellulose-derived carbon sheet (CCS) with a unique morphology produces a porous structure and offers fast transfer pathways for the efficient diffusion of electrode ions. PANI imparts conductivity to the CNF and provides abundant active sites for charge storage. The porous structure and supercapacitive performance of this kind of nanocomposite can be easily tailored by changing the feeding mass ratio of the CNF, CCS, and PANI. A relatively low CCS loading can produce a flexible electrode with an ultrahigh specific areal capacitance of 1838.5 mF cm−2 (150 F g−1) (1 mA cm−2), while high CCS loading can produce a free-standing electrode with a higher specific areal capacitance of 3297.2 mF cm−2 (220 F g−1) (1 mA cm−2). Besides, the robust three-dimensional network guarantees good cycling stability of the nanocomposite electrode (more than 83% retention after 3000 cycles). The tunable structure and electrochemical performance make the nanocomposite an ideal electrode for various electronic devices.

Facile synthesis of cellulose-based carbon with tunable N content for potential supercapacitor application

Producing hierarchical porous N-doped carbon from renewable biomass is an essential and sustainable way for future electrochemical energy storage. Herein we cost-efficiently synthesized N-doped porous carbon from renewable cellulose by using urea as a low-cost N source, without any activation process. The as-prepared N-doped porous carbon (N-doped PC) had a hierarchical porous structure with abundant macropores, mesopores and micropores. The doping N resulted in more disordered structure, and the doping N content in N-doped PC could be easily tunable (0.68-7.64%). The doping N functionalities could significantly improve the supercapacitance of porous carbon, and even a little amount of doping N (e.g. 0.68%) could remarkably improve the supercapacitance. The as-prepared N-doped PC with a specific surface area of 471.7m2g-1 exhibited a high specific capacitance of 193Fg-1 and a better rate capability, as well as an outstanding cycling stability with a capacitance retention of 107% after 5000 cycles. Moreover, the N-doped porous carbon had a high energy density of 17.1Whkg-1 at a power density of 400Wkg-1.

A Supercompressible, Elastic, and Bendable Carbon Aerogel with Ultrasensitive Detection Limits for Compression Strain, Pressure, and Bending Angle

Ultralight and compressible carbon materials have promising applications in strain and pressure detection. However, it is still difficult to prepare carbon materials with supercompressibility, elasticity, stable strain-electrical signal response, and ultrasensitive detection limits, due to the challenge in structural regulation. Herein, a new strategy to prepare a reduced graphene oxide (rGO)-based lamellar carbon aerogels with unexpected and integrated performances by designing wave-shape rGO layers and enhancing the interaction among the rGO layers is demonstrated. Addition of cellulose nanocrystalline and low-molecular-weight carbon precursors enhances the interaction among rGO layers and thus produces an ultralight, flexible, and superstable structure. The as-prepared carbon aerogel displays a supercompressibility (undergoing an extreme strain of 99%) and elasticity (100% height retention after 10 000 cycles at a strain of 30%), as well as stable strain-current response (at least 10 000 cycles). Particularly, the carbon aerogel is ultrasensitive for detecting tiny change in strain (0.012%) and pressure (0.25 Pa), which are the lowest detection limits for compressible carbon materials reported in the literature. Moreover, the carbon aerogel exhibits excellent bendable performance and can detect an ultralow bending angle of 0.052°. Additionally, the carbon aerogel also demonstrates its promising application as wearable devices.

A foldable composite electrode with excellent electrochemical performance using microfibrillated cellulose fibers as a framework

There is an increasing demand for developing environment-friendly and cost-effective strategies to synthesize high-performance flexible supercapacitor electrode materials. Biomass-derived carbon materials are very promising and attractive candidates due to their outstanding advantages. Herein, we prepared a foldable composite electrode based on a chitosan-derived N-self-doped carbon sheet (N-CS) and a microfibrillated cellulose fiber (MCF) framework. The N-CS plays a key role in tailoring the electrochemical behavior of electrode, while the MCF framework offers a porous structure with excellent mechanical foldability. In situ PANI improves the conductivity of the MCF framework and provides abundant active redox sites for energy storage. This foldable composite electrode possesses a high specific areal capacitance of 1688.8 mF cm−2 (139.6 F g−1, 84.4 F cm−3) at 1 mA cm−2 and an energy density of 11.75 mW h cm−3 at a power density of 25 mW cm−3. Furthermore, benefitting from the mechanical foldability of the MCF framework, the composite can perform well in the folded state. Besides, as a PANI-containing electrode material, its long-term cycling stability is pretty good (more than 84% retention after 5000 cycles). Therefore, this work provides an environment-friendly, cost-effective and high-performance electrode material for foldable electronic devices.