Yue Jiao

Flexible, highly conductive, and free-standing reduced graphene oxide/polypyrrole/cellulose hybrid papers for supercapacitor electrodes

We report a facile scale-up process to fabricate a novel type of hybrid paper electrode composed of reduced graphene oxide (RGO), polypyrrole (PPy) and cellulose. Through the optimization of preparation parameters (including the processes of in situ polymerization of pyrrole and chemical reduction of graphene oxide by using NaBH4), the fabricated hybrid paper had an extremely low sheet resistance of 1.7 Ω sq−1. Also, the hybrid paper possessed favorable mechanical flexibility and outstanding conductance stability. When the paper was evaluated as a free-standing and binder-free supercapacitor electrode, the unique construction (i.e., the cellulose fiber frame supporting interpenetrated RGO–PPy nanoacrhitectures) endowed it with high electrochemical activity, such as high areal capacitance of 1.20 F cm−2 at 2 mA cm−2 and good cycling stability with a capacitance retention of 89.5% after cycling 5000 times, which was tested in a three-electrode configuration. In addition, an all-solid-state laminated symmetric supercapacitor was prepared by assembling two pieces of hybrid paper electrodes and using a H3PO4/PVA gel as the electrolyte. The solid-state supercapacitor had a high areal capacitance of 0.51 F cm−2 at 0.1 mA cm−2 and a high energy density of 1.18 mW h cm−3. These results suggest that the hybrid paper is a promising electrode material and may be useful for the development of flexible high-performance and hand-held energy storage devices. More importantly, this work provides a good reference for the fabrication of other types of hybrid paper electrodes.

Fabrication of hydrophobic, electrically conductive and flame-resistant carbon aerogels by pyrolysis of regenerated cellulose aerogels.

In this paper, we reported miscellaneous carbon aerogels prepared by pyrolysis of regenerated cellulose aerogels that were fabricated by dissolution in a mild NaOH/PEG solution, freeze-thaw treatment, regeneration, and freeze drying. The as-prepared carbon aerogels were subsequently characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), nitrogen adsorption measurements, X-ray diffraction (XRD), Raman spectroscopy, and water contact angle (WCA) tests. The results showed that the carbon aerogels with pore diameters of 1-60 nm maintained interconnected three-dimensional (3D) network after the pyrolysis, and showed type-IV adsorption isotherm. The pyrolysis process leaded to the decomposition of oxygen-containing functional groups, the destruction of cellulose crystalline structure, and the formation of highly disordered amorphous graphite. Moreover, the carbon aerogels also had strong hydrophobicity, electrical conductivity and flame retardance, which held great potential in the fields of waterproof, electronic devices and fireproofing.

Cellulose-derived carbon aerogels supported goethite (α-FeOOH) nanoneedles and nanoflowers for electromagnetic interference shielding

We describe a rapid and facile chemical precipitation method to grow goethite (α-FeOOH) nanoneedles and nanoflowers on the carbon aerogels which was obtained from the pyrolysis of cellulose aerogels. When evaluated as electromagnetic interference (EMI) shielding materials, the α-FeOOH/cellulose-derived carbon aerogels composite displays the highest SEtotal value of 34.0dB at the Fe3+/Fe2+ concentration of 0.01M, which is about 4.8 times higher than that of the individual α-FeOOH (5.9dB). When the higher or lower Fe3+/Fe2+ concentrations were used, the EMI shielding performance deterioration occurred. The integration of α-FeOOH with the carbon aerogels transforms the reflection-dominant mechanism for α-FeOOH into the adsorption-dominant mechanism for the composite. The adsorption-dominant mechanism undoubtedly makes contribution to alleviating secondary radiation, which is regarded as more attractive alternative for developing electromagnetic radiation protection products.

Core–shell composite of wood-derived biochar supported MnO2 nanosheets for supercapacitor applications

Eco-friendly wood-derived biochar (WDB) was used as a substrate material to support sheet-like nano-MnO2 via an easily-operated in situ redox reaction between the biochar and KMnO4. WDB was readily obtained by pyrolyzing wood waste of agriculture and industry. The MnO2/WDB composite displays a core–shell structure and can be utilized as a free-standing and binder-free supercapacitor electrode. The MnO2/WDB electrode has a moderate specific capacitance of 101 F g−1, an excellent coulombic efficiency of 98–100%, and a good cyclic stability with a capacitance retention of 85.0% after 10 000 cycles, making it useful for supercapacitor applications. Moreover, it is expected that such porous inexpensive WDB can serve as a novel harmless substrate material to combine with other electrochemical active substances for the development of high-performance energy storage devices.

Cellulose aerogels from cellulose-NaOH/PEG solution and comparison with different cellulose contents

Abstract A green mild NaOH/polyethylene glycol solution was employed to dissolve the cellulose extracted from waste wheat straw. Subsequently combined with the freezing−thawing treatment, regeneration process and freeze drying, the cellulose aerogels with different cellulose contents were fabricated at mass ratios of 1∶100, 3∶100, 5∶100 and 7∶100 cellulose to the solution. Moreover, the influences of cellulose contents on the morphologies, crystal structures, crystallinity indexes, thermal stabilities and pore characteristic parameters of the aerogels were investigated by scanning electron microscope, X-ray diffraction, thermogravimetric analysis and nitrogen adsorption. Meanwhile, the oil adsorption properties of the aerogels with different cellulose contents were also surveyed; besides, for improving lipophilicity, the hydrophobic modifications of trimethylchlorosilane for the aerogels were carried out before the adsorption tests.

A cellulose fibers-supported hierarchical forest-like cuprous oxide/copper array architecture as a flexible and free-standing electrode for symmetric supercapacitors

Herein, we for the first time develop two facile and fast steps (including magnetron sputtering and electro-oxidation) to grow a hierarchical forest-like Cu2O/Cu array architecture onto the three-dimensional fiber framework of cellulose paper. The Cu rods serve as the trunk and the oxidation product (Cu2O) acts as branches. When utilized as a flexible and free-standing electrode, the unique architecture made full use of a large interfacial area from the hierarchical multi-scale structure of the forest-like array, numerous channels for rapid diffusion of electrolyte ions from the porous fiber skeleton of hydrophilic cellulose paper, and fast electron transport and high electrochemical activity from the Cu2O/Cu complex. These merits endowed the electrode with a high specific capacitance of 915 F g−1 (238 mF cm−2) at 3.8 A g−1, a large specific energy of 53.7 W h kg−1 at 1.25 kW kg−1, superior rate capability, and excellent cycling stability with a capacitance retention of 91.7% after cycling 10 000 times. More importantly, an easy interesting strategy was proposed to assemble a symmetric supercapacitor based on the Cu2O/Cu/cellulose hybrid paper, that is, growing the forest-like Cu2O/Cu array onto the two surfaces of cellulose paper. The device delivered a high specific capacitance of 409 F g−1 (213 mF cm−2) at 1.9 A g−1, a superior specific energy of 24.0 W h kg−1 at 0.625 kW kg−1 and good cycling stability (90.2% capacitance retention after 10 000 cycles). These fascinating results unveil the potential of the hybrid paper as a high-performance electrode material for flexible energy storage devices and portable electronics.

Facile hydrothermal synthesis of Fe 3 O 4 @cellulose aerogel nanocomposite and its application in Fenton-like degradation of Rhodamine B

A magnetic cellulose aerogel-supported Fe3O4 nanoparticles composite was designed as a highly efficient and eco-friendly catalyst for Fenton-like degradation of Rhodamine B (RhB). The composite (coded as Fe3O4@CA) was formed by embedding well-dispersed Fe3O4 nanoparticles into the 3D structure of cellulose aerogels by virtue of a facile and cheap hydrothermal method. Comparative studies indicate that the RhB decolorization ratio is much higher in co-presence of Fe3O4 and H2O2 than that in presence of Fe3O4 or H2O2 only, revealing that the Fe3O4@CA-catalyzed Fenton-like reaction governed the RhB decolorization process. It was also found that almost 100% RhB removal was achieved in the Fenton-like system. Moreover, the composite exhibited higher catalytic activity than that of the individual Fe3O4 particles. In addition, the Fe3O4@CA catalyst retained ∼97% of its ability to degrade RhB after the six successive degradation experiments, suggesting its excellent reusability. All these merits indicate that the green and low-cost catalyst with strong magnetic responsiveness possesses good potential for H2O2-driven Fenton-like treatment of organic dyestuff wastewater.

Anatase TiO2/cellulose hybrid paper: Synthesis, characterizations, and photocatalytic activity for degradation of indigo carmine dye

We report a facile easy method to deposit anatase titania (TiO2) on cellulose paper. The anatase TiO2/cellulose paper (ATCP) was characterized by scanning electron microscopy, transmission electron microscope, energy dispersive X-ray spectrometer, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. This hybrid paper with the anatase TiO2 content of around 13.86wt.% can serve as an eco-friendly flexible photocatalyst, which can rapidly degrade blue indigo carmine dye into a colorless solution within 30min under UV radiation. Moreover, compared to commercially available TiO2 P25 and anatase TiO2 powder, a faster decomposition rate of indigo carmine dye was acquired when using ATCP. These results suggest that this hybrid paper might be useful in the treatment of organic dye wastewater.