Chunmei Ding

PANI nanowire film with underwater superoleophobicity and potential-modulated tunable adhesion for no loss oil droplet transport

We present here for the first time an electrochemical switching for reversible superoleophobic polyaniline (PANI) nanowire film from the pinned to the rolling state underwater. Importantly, based on the unique adhesive switching, a “mechanical hand” for oil droplet transportation without loss was easily achieved by applying a low electrochemical potential.

Reversible underwater switching between superoleophobicity and superoleophilicity on conducting polymer nanotube arrays

The underwater wetting behavior of aligned polypyrrole nanotube arrays was investigated. A reversible superoleophobicity to superoleophilicity transition was observed and intelligently controlled by tuning the electrochemical driving potential. The cooperation of electrochemical tunable doping, electrical double layer and alignment of nanostructures is considered to be responsible for this behavior.

Control of bacterial extracellular electron transfer by a solid-state mediator of polyaniline nanowire arrays

We report that polyaniline nanowire arrays (PANI-NAs) can serve as a tunable terminal polymeric mediator for bacterial extracellular electron transfer (EET) by members of the genus Shewanella. Multiple oxidation levels of PANI at different applied potentials lead to multiple abilities in mediating EET, while the aligned nanostructures enable enhanced local topological interactions with microbes and hence efficient electrical interaction. PANI-NA therefore exhibits a unique property that allows for efficient EET reactions to proceed in a controlled manner.

Wettability‐Regulated Extracellular Electron Transfer from the Living Organism of Shewanella loihica PV‐4

C-type cytochromes located on the outer membrane (OMCs) of genus Shewanella act as the main redox-active species to mediate extracellular electron transfer (EET) from the inside of the outer membrane to the external environment: the central challenge that must be met for successful EET. The redox states of OMCs play a crucial role in dictating the rate and extent of EET. Here, we report that the surface wettability of the electrodes strongly influences the EET activity of living organisms of Shewanella loihica PV-4 at a fixed external potential: the EET activity on a hydrophilic electrode is more than five times higher than that on a hydrophobic one. We propose that the redox state of OMCs varies significantly at electrodes with different wettability, resulting in different EET activities.

Self-assembled hierarchical micro/nano-structured PEDOT as an efficient oxygen reduction catalyst over a wide pH range

Micro/nano-structured poly (3,4-ethylenedioxythiophene) (PEDOT) has shown a broad range of potential applications in various fields. In this work, PEDOT micro/nanostructures including hollow spheres and double-layer bowls, which exhibit typical hierarchical three-dimensional micro-structures assembled from one-dimensional nanofibers, are firstly fabricated via a template-free self-assembly polymerization method. Importantly, these PEDOT microstructures can be controllably tuned by adjusting the molar ratio of monomer to oxidant. Moreover, these micro/nano-structured PEDOT exhibit high catalytic activity for oxygen reduction reaction in acid, alkaline and neutral solutions, and thus provide an alternative cheap and efficient catalytic cathode material for fuel cells or metal-air batteries.

Hybrid bio–organic interfaces with matchable nanoscale topography for durable high extracellular electron transfer activity

Here, we developed a novel hybrid bio-organic interface with matchable nano-scale topography between a polypyrrole nanowire array (PPy-NA) and the bacterium Shewanella, which enabled a remarkably increased extracellular electron transfer (EET) current from genus Shewanella over a rather long period. PPy-NA thus exhibited outstanding performance in mediating bacterial EET, which was superior to normal electrodes such as carbon plates, Au and tin-doped In₂O₃. It was proposed that the combined effect of the inherent electrochemical nature of PPy and the porous structured bacterial network that was generated on the PPy-NA enabled long-term stability, while the high efficiency was attributed to the enhanced electron transfer rate between PPy-NA and microbes caused by the enhanced local topological interactions.

Polyaniline microtubes with a hexagonal cross-section and pH-sensitive fluorescence properties.

Polyaniline (PANI) microtubes with a hexagonal cross-section are successfully synthesized by a self-assembly process in the presence of 8-hydroxyquinoline-5-sulfonic acid (HQS) as a dopant and FeCl(3) as an oxidant. The wall thickness of the PANI/HQS microtubes can be adjusted by the content of the oxidant. It is proposed that the aniline/HQS salts serve as a hard template for the formation of the hexagonal-cross-section microtubes. Moreover, PANI/HQS microtubes combined with ZnSO(4) show pH-dependent fluorescence. PANI hexagonal-cross-section microtubes combined with a pH-sensitive fluorescence may promise potential applications in fields such as chemical sensors and confined reaction vessels.

Facile One-Step Strategy for Highly Boosted Microbial Extracellular Electron Transfer of the Genus Shewanella

High performance of bacterial extracellular electron transfer (EET) is essentially important for its practical applications in versatile bioelectric fields. We developed a facile one-step approach to dramatically boost the bacterial EET activity 75-fold by exogenous addition of ethylenediamine tetraacetic acid disodium salt (EDTA-2Na, 1 mM) into the electrochemical cells, where the anodic process of microbial EET was monitored. We propose that EDTA-2Na enables both the alternation of the local environment around the c-type cytochromes located on the outer membrane channels (OMCs), which therefore changes the redox behavior of OMCs in mediating the EET process, and the formation of densely packed biofilm that can further facilitate the EET process. As a synergistic effect, the highly boosted bacterial EET activity was achieved. The method shows good generality for versatile bioelectrical bacteria. We envision that the method is also applicable for constructing various bioelectric devices.

Synthesis and characterization of structure-controlled micro-/nanocomposite TiO 2 fibers with enhanced photocatalytic activity

A series of structure-controlled composite TiO2 fibers combining micro- and nanostructures (hereafter, micro-/nanocomposite) were fabricated using a combination of electrospinning and calcination methods, and their photocatalytic activities were investigated. Smooth microscale fibers were obtained by electrospinning a precursor solution containing tetrabutyl titanate and TiF4. TiO2 nanocrystals formed on the microfibers with the help of HF which was produced from the decomposition of TiF4 in calcination. The size and quantity of TiO2 nanocrystals can be controlled by tuning the mass ratio of TiF4 in the sol-gel precursor solutions and the calcination time. The obtained micro-/nanocomposite TiO2 fibers were found to exhibit enhanced photocatalytic properties when compared with the bare microfibers. These micro-/nanocomposite structures exhibit the advantages of both the nanocrystals and microfibers, which will lead to new developments in photocatalysis.

ELECTROSPINNING PREPARATION AND CHARACTERIZATION OF SIZE CONTROLLABLE POLYANILINE COMPOSITE MICOSPHERES: ELECTROSPINNING PREPARATION AND CHARACTERIZATION OF SIZE CONTROLLABLE POLYANILINE COMPOSITE MICOSPHERES

Polyaniline(PANI) microspheres containing Fe3O4 nanoparticles are prepared by means of electrospinning technology using a blending chloroform solution of dodecylbenzene sulfonic acid(DBSA) doped polyaniline(PANI) with polyethylene glycol(PEG) and Fe3O4 nanoparticles.SEM images indicate that composite microspheres of PANI/PEG/Fe3O4 are prepared by means of electrospinning technology,and the diameters are in the range of 2~5 μm,which are significantly influenced by the concentration of PEG polymer,the applied voltage and the mass ratio of Fe3O4 in the polymers.With increasing the concentration of PEG,cohesive microspheres turn into regular ones,meanwhile the diameters increase.In comparison,the increasing applied voltage results in gradually reduced diameters of the microspheres.In addition,the microspheres are hardly affected by the addition of various amounts of Fe3O4nanoparticles.It is found that the addition of Fe3O4nanoparticles does not affect the polymeric chain structure of PANI.However,the added Fe3O4nanoparticles contribute superparamagnetic properties to the composite microspheres,especially the saturated magnetization(Ms) increases with the increase of the adding content of Fe3O4 nanoparticles.Furthermore,the conductive ratio of the electrospinning conduct is about 1×10-6 S/cm.