Fluorescent brightener CBS-X doped polypyrrole as smart electrode material for supercapacitors

Fluorescent polypyrrole nanospheres (PPy/CBS-X) with uniform diameter were synthesized via a chemical oxidation polymerization with fluorescent brightener, 2,2'-([1,1'-biphenyl]-4,4'-diyldi-2,1-ethenediyl)bis-benzenesulfonic acid disodium salt (CBS-X), as dopant. The sample S-2 containing 1 mol% CBS-X simultaneously exhibited the highest electrical conductivity of 31.3 S/cm and the largest specific area of 98.33 m(2)/g. When being used as electrode material for supercapacitors, it also possessed the high electrochemical specific capacitance (245.8 F/g) at a scan rate of 5 mV/s and the better rate capability and improved electrochemical stability than neutral (undoped) PPy, essentially attributed to a synergistic effect on the high doping level, large specific area and good pi-pi interactions from both PPy chains and CBS-X dopant. Most interestingly, the electrochemical activity of the fluorescent PPy/CBS-X could be easily monitored by photoluminescence. These features make the fluorescent polypyrrole nanospheres potential smart electrode material for high performance supercapacitors. (C) 2014 Elsevier Ltd. All rights reserved.