Block-Copolymer-Assisted One-Pot Synthesis of Ordered Mesoporous WO3− x/Carbon Nanocomposites as High-Rate-Performance Electrodes for Pseudocapacitors.

Autor: Jo, Changshin, Hwang, Jongkook, Song, Hannah, Dao, Anh Ha, Kim, Yong‐Tae, Lee, Sang Hyup, Hong, Seok Won, Yoon, Songhun, Lee, Jinwoo
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Zdroj: Advanced Functional Materials; Dec2013, Vol. 23 Issue 30, p3747-3754, 8p
Abstrakt: An ordered mesoporous tungsten-oxide/carbon (denoted as m-WO3− x-C-s) nanocomposite is synthesized using a simple one-pot method using polystyrene- block-poly(ethylene oxide) (PS- b-PEO) as a structure-directing agent. The hydrophilic PEO block interacts with the carbon and tungsten precursors (resol polymer and WCl6), and the PS block is converted to pores after heating at 700 °C under a nitrogen flow. The m-WO3− x-C-s nanocomposite has a high Brunauer-Emmett-Teller (BET) surface area and hexagonally ordered pores. Because of its mesoporous structure and high intrinsic density of tungsten oxide, this material exhibits a high average volumetric capacitance and gravimetric capacitance as a pseudocapacitor electrode. In comparison with reduced mesoporous tungsten oxide (denoted as m-WO3− x-h), which is synthesized by a tedious hard template approach and further reduction in a H2/N2 atmosphere, m-WO3− x-C-s shows a high capacitance and enhanced rate performance, as confirmed by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The good performance of m-WO3− x-C-s is attributed to the high surface area arising from the mesoporous structure, the large interconnected mesopores, and the low internal resistance from the well-dispersed reduced tungsten oxide and amorphous carbon composite structure. Here, the amorphous carbon acts as an electrical pathway for effective pseudocapacitor behavior of WO 3-x. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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