Kezheng Gao

Cellulose nanofiber– graphene all solid-state flexible supercapacitors

Cellulose nanofibers are selected as nano-spacers, electrolyte nano-reservoirs and hierarchical nanostructure makers of CNF–RGO hybrid aerogel. The CNF–RGO hybrid aerogel based flexible supercapacitor exhibits high capacitance (207 F g−1). Taking its higher capacitance, low cost and environmentally friendly nature, they have great potential for use in flexible supercapacitors.

Cellulose nanofibers/reduced graphene oxide flexible transparent conductive paper

The cellulose nanofibers (CNFs) paper exhibit high visible light transmittance, high mechanical strength, and excellent flexibility. Therefore, CNFs paper may be an excellent substrate material for flexible transparent electronic devices. In this paper, we endeavor to prepare CNFs-based flexible transparent conductive paper by layer-by-layer (LbL) assembly using divalent copper ions (Cu(2+)) as the crosslinking agent. The thickness of the reduced graphene oxide (RGO) active layer in the CNFs paper can be controlled by the cycle times of the LbL assembly. CNFs/[RGO]20 paper has the sheet resistances of ∼2.5 kΩ/□, and the transmittance of about 76% at a wavelength of 550 nm. Furthermore, CNFs/[RGO]20 paper inherits the excellent mechanical properties of CNFs paper, and the ultimate strength is about 136 MPa. CNFs-based flexible transparent conductive paper also exhibits excellent electrical stability and flexibility.

Cellulose nanofibers/multi-walled carbon nanotube nanohybrid aerogel for all-solid-state flexible supercapacitors

In recent years, much effort has been dedicated to achieve environmentally friendly, low cost, and excellent performance energy storage devices. In this work, cellulose nanofibers (CNFs)/multi-walled carbon nanotubes (MWCNTs) hybrid aerogels are prepared from CNFs/MWCNTs hydrogels by supercritical CO2 drying using CNFs as an effective, environmentally friendly, and steady dispersant of MWCNTs. All-solid-state flexible supercapacitors are fabricated using CNFs/MWCNTs hybrid aerogel film as the electrode material and charge collector. One-dimensional CNFs can effectively prevent the aggregation of MWCNTs, significantly enhance the re-wettability, and improve the utilization efficiency of the mesopores. Therefore, CNFs/MWCNTs hybrid aerogel film-based all-solid-state flexible supercapacitors exhibit excellent electrochemical properties: the specific capacitance is about 178 F g−1. The flexible supercapacitors also exhibit excellent cyclic stability. Our work provides a novel method using low cost, and environmentally friendly CNFs to realize the full potential of the MWCNTs in an assembled bulk form. Taking its low cost and environmentally friendliness, CNFs/MWCNTs hybrid aerogel has great potential as the electrode material for all-solid-state flexible supercapacitors.

Cellulose nanofiber/single-walled carbon nanotube hybrid non-woven macrofiber mats as novel wearable supercapacitors with excellent stability, tailorability and reliability

Non-woven macrofiber mats are prepared by simply controlling the extrusion patterns of cellulose nanofiber/single-walled carbon nanotube suspensions in an ethanol coagulation bath, and drying in air under restricted conditions. These novel wearable supercapacitors based on non-woven macrofiber mats are demonstrated to have excellent tailorability, electrochemical stability, and damage reliability.

Cellulose nanofibril based graft conjugated polymer films act as a chemosensor for nitroaromatic.

A cellulose nanofibril film is modified by chemical assembly of boronate-terminated conjugated polymer chains at its specific sites, C-6 carboxyl groups. The modified cellulose nanofibril film is used as a fluorescent sensor for nitroaromatic vapor. Thanks to the specific reactive sites, numerous loose cavities or pathways located in the film sensors out-layer have been formed, and the fraction of easily accessible cavities of the novel fluorescent film sensor is up to 0.97, which could benefit the penetration and diffusion of analyte vapor. Therefore, the novel fluorescent film sensor exhibits high sensitivity toward nitroaromatic vapor with a fast response. The fluorescence quenching efficiency of the chemical-assembly film sensor is about 3 times larger than that of the spin-cast film sensor using the same conjugated polymer for 600 s exposure to DNT vapor. In addition, the novel fluorescent film sensor shows good reversibility.

Alcogel and aerogel of nitrocellulose formed in nitrocellulose/acetone/ethanol ternary system

ABSTRACT Nitrocellulose (NC) alcogels were formed in NC/acetone/ethanol ternary system and NC aerogels were prepared from NC alcogels after drying under supercritical CO2 (scCO2). NC alcogel with lower modulus was formed in the ternary system with a higher ethanol ratio. The densities and porosities of NC aerogels were related directly to the initial ethanol content. The NC aerogels clearly retained the crystalline structure of NC powder. NC aerogels that were formed in the system with higher ethanol content had larger pore size distribution range, larger average pore diameter, and larger mesopore and macropore volume. The thermal decomposition of NC aerogel was more accelerated and more acute compared with NC powders. GRAPHICAL ABSTRACT

Tensile Properties of Nitrate Glycerol Ether Cellulose/Graphene Oxide Nanocomposites

A nanocomposite film of nitrate glycerol ether cellulose (NGEC)/graphene oxide (GO) was presented by a casting/evaporation technique. The effect of GO contents on mechanical properties of the NGEC/GO films was studied. Compared with pristine NGEC, the integration of 0.5 wt% GO resulted in 40%, 38% and 44% increase in Youngs modulus, tensile strength and elongation at break of the NGEC/GO film.

Rheological characteristics of nitrate glycerol ether cellulose gel based on phase separation in ternary system

By non-solvent-induced phase separation, nitrate glycerol ether cellulose (NGEC) gels were formed in ternary NGEC/acetone/ethanol system. The rheological behaviors of NGEC gels were investigated using dynamic rheological measurements. The final compositions and morphologies of NGEC gels were influenced by the initial solvent/non-solvent (acetone/ethanol) ratios and NGEC concentrations. In addition, the effect of initial acetone/ethanol ratios on the characteristics of NGEC gels is different from the effect of NGEC concentrations. The critical strain of NGEC gels decreased almost with increasing NGEC concentration of gels by increasing initial acetone ratio, but it increased with increasing NGEC concentration of gels by increasing NGEC concentration beyond a certain concentration in 2/3 (w/w) acetone/ethanol solution. For all gels, the storage modulus (G′) and loss modulus (G′′) of NGEC gels rapidly increased with increasing NGEC concentration of gels. In addition, the curves for G′ and G′′ were temperature sensitive throughout the entire temperature sweep, which implied that the interactions between NGEC/solvent could be disrupted upon heating to higher temperatures.