Huaping Wang

Flexible electrically conductive nanocomposite membrane based on bacterial cellulose and polyaniline.

The novel conductive polyaniline/bacterial cellulose (PANI/BC) nanocomposite membranes have been synthesized in situ by oxidative polymerization of aniline with ammonium persulfate as an oxidant and BC as a template. The resulting PANI-coated BC nanofibrils formed a uniform and flexible membrane. It was found that the PANI nanoparticles deposited on the surface of BC connected to form a continuous nanosheath by taking along the BC template, which greatly increases the thermal stability of BC. The content of PANI and the electrical conductivity of composites increased with increasing reaction time from 30 to 90 min, while the conductivity decreased because of the aggregation of PANI particles by further prolonging the reaction time. In addition, the acids remarkably improve the accessibility and reactivity of the hydroxyl groups of BC. The results indicate that the composites exhibit excellent electrical conductivity (the highest value was 5.0 × 10(-2) S/cm) and good mechanical properties (Youngs modulus was 5.6 GPa and tensile strength was 95.7 MPa). Moreover, the electrical conductivity of the membrane is sensitive to the strain. This work provides a straightforward method to prepare flexible films with high conductivity and good mechanical properties, which could be applied in sensors, flexible electrodes, and flexible displays. It also opens a new field of potential applications of BC materials.

Free-standing zirconia nanofibrous membranes with robust flexibility for corrosive liquid filtration

Novel zirconia nanofibrous (ZNF) membranes with robust flexibility were prepared for the first time by a facile combination of electrospinning and sol–gel methods. By employing yttrium oxide incorporation, the as-prepared ZNF membranes can be dramatically changed from the extreme fragility to robust flexibility. Meanwhile, the flexibility and mechanical properties of ZNF membranes can be finely controlled by regulating the crystallite phase and crystallite size in zirconia fibers. Additionally, the porous analysis using synchrotron radiation small-angle X-ray scattering measurements have confirmed the correlation between the porous structure and flexibility. Interestingly, the mechanical properties of the ZNF membranes were also controlled by manipulating the precursor composition in hybrid fibers. Furthermore, the as-prepared flexible ZNF membranes exhibit excellent corrosion resistance and high filtration efficiency for zirconia nanoparticles from strong acid and alkaline solutions, which makes them a good candidate as microfiltration membranes in waste water treatment, and new insight also suggested them as a promising candidate for thermal insulation, high temperature filtration, catalyst carriers, etc.

Astridia velutina-like S, N-codoped hierarchical porous carbon from silk cocoon for superior oxygen reduction reaction

The development of heteroatom-doped nanostructured metal-free carbon materials for the oxygen reduction reaction (ORR) is a critical challenge. In this work, through a one-step heat treatment, Astridia velutina-like S, N-codoped micro–mesoporous carbon (SNC-x) was synthesized from silk cocoon. The product was fully characterized by physicochemical and electrochemical techniques. The sample obtained at 800 °C possessed a unique hierarchical porous structure with 9.75 at% N and 1.79 at% S content, providing abundant active sites and thus facilitating efficient mass transport. The ORR activity was observed with an onset potential of 0.853 V (vs. RHE), comparable current density (4.5 mA cm−2 at 0 V) to commercial Pt/C as well as good methanol tolerance and electrochemical stability in alkaline electrolyte. Benefiting from the cheap biomass precursor and unique structural features, the product may serve as a potential candidate for energy storage, conservation and environmental applications, etc.