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Binder-free and flexible oxygen-vacancy CeO2@C core-shell nanocomposites directly anchored on carbon cloth (CC) are prepared via a simple two-step process, in which CeO2 nanoparticles are hydrothermally fabricated and mixed with polyvinylpyrrolidone (PVP) composites, subsequently, as-formed CeO2@PVP composites coated on CC are calcined at 700 °C. The morphologies, structures and electrochemical properties of as-obtained CeO2@C nanocomposites are studied by SEM, HRTEM, XRD, XPS and electrochemical techniques, respectively. The CeO2@C nanocomposites are composed of the CeO2 core with diameter of about 10 nm and the carbon shell with thickness of about 1.5 nm. The electrochemical results reveal that the CeO2@C nanocomposites show a wide electrochemical active window of -1.0 ~ 0.8 V and a specific capacitance of 141.56 F g-1 at 1 A g-1 in 1.0 M Na2SO4 electrolyte. In addition, an asymmetric supercapacitor (ASC) assembled with CeO2@C and poly(3,4-ethylene dioxythiophene) (PEDOT) can work in the wide operational voltage region of 2.0 V and deliver the energy density of 11.12 Wh kg-1 at 2000 W kg-1. The present study indicates that the CeO2@C will have a greater advantage in terms of energy density for CeO2 and its carbon-based composites supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Poly(3,4-ethylenedioxythiophene) and its derivatives provide an excellent platform as electrode materials for supercapacitors due to their superior stability and conductivity. In this study, a poly(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methanol (PEDOTMeOH) porous nanonet (PEDOT-MeOH-PNN), PEDOT-MeOH hollow nanotube array (PEDOT-MeOH-HNA) and PEDOTMeOH- PNN coated PEDOT-MeOH-HNA (PEDOT-MeOH-PNN@PEDOT-MeOH-HNA) are successfully fabricated using a template-free electrodeposition of (2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methanol monomer. These three nanostructures were studied by Fourier transform infrared spectrum and Raman spectrum, scanning electron microscopy, thermal analysis and electrochemical methods, respectively. PEDOT-MeOH-PNN@PEDOT-MeOH-HNA has a specific capacitance of 40.5 mF cm-2 at 40 mV s-1, which is higher than PEDOT-MeOH-PNN (21.6 mF cm-2) and PEDOT-MeOH-HNA (35.5 mF cm-2). Moreover, the PEDOT-MeOH-PNN@PEDOT-MeOH-HNA based symmetric supercapacitor delivers excellent rate performance and superior cycling stability (90% of the initial capacitance remains after 10,000 cycles). The results indicate that the structural design of a supercapacitor electrode can improve their electrochemical performance, and promote the application and development of conducting polymers in the field of supercapacitors. [ABSTRACT FROM AUTHOR]

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanoribbons, nanotubes, nanorods were fabricated in a reverse microemulsion system by adjusting the ratio of sodium bis (2-ethylhexyl) sulfosuccinate (AOT) and FeCl3 aqueous solution. The morphologies and structures of nanostructured PEDOT were characterized by SEM, TEM, FTIR, XRD, and XPS. The PEDOT nanoribbons, nanotubes and nanorods can be obtained, when the volume ratio of FeCl3 aqueous solution to AOT hexane (Va/Vh) was between 2.0 × 10-2 and 3.0 × 10-2. As-obtained PEDOT nanotubes showed a high specific capacitance of 171.5 F g-1 at 0.4 A g-1, which was greater than the nanoribbons (134 F g-1) and nanorods (145.7 F g-1), respectively. Additionally, the PEDOT nanotubes exhibited excellent stability with a retention rate of 105% after 5000 cycles. This indicates that the as-prepared PEDOT nanotubes have potential applications in high capacity supercapacitors. [ABSTRACT FROM AUTHOR]

Freestanding and conducting poly[poly(N-vinyl-carbazole)] (PPVK) films with good fluorescence property were synthesized electrochemically by direct anodic oxidation of poly(N-vinyl-carbazole) (PVK) in tetrahydrofuran containing boron trifluoride diethyl etherate (BFEE) (12%. by volume) and Bu4NBF4 (0.05 M/. The oxidation onset potential of PVK in this medium was measured to be 1.07 V vs. SCE, PPVK films obtained from this medium showed good electrochemical behavior and good thermal stability with conductivity of 10-2 S cm-1. PPVK films were black in doped state and transparent white in dedoped state. Structural studies showed that the secondary polymerization of PVK occurred at benzene ring. These polymer films had good mechanical properties, which can be easily cut into a variety of structures with a knife or a pair of scissors. [ABSTRACT FROM AUTHOR]