Freestanding, thin, and bendable electrodes for supercapacitors are fabricated by filtering DNA-dispersed double walled carbon nanotubes ͑DWNTs͒ into a thin film and thermally treating the film in argon. We found that DNA has the ability to disperse the strongly bundled DWNTs and is converted to phosphorus-enriched carbons, which give rise to strong redox peaks at around 0.4 V. The combination of the large capacitance from the DNA-derived carbons and the high electrical conductivity of carbon nanotubes allow DWNT/DNA films to be used as a potential electrode material for supercapacitors. © 2009 American Institute of Physics. ͓doi:10.1063/1.3271768͔Biomolecule-engineered nanosized active materials targeted for energy storage devices have attracted lots of attention because of their high charge rate capability and large storage capacity.1,2 Supercapacitors have several advantages over lithium ion batteries, such as higher power density and higher efficiency, due to simple ion adsorption on their electrodes.3 It is well known that the electrochemical performance of the supercapacitor strongly depends on the morphology, texture, and composition of the electrode material. 3Among the many types of active materials, carbon nanotubes have been studied as a potential candidate for achieving a high performance supercapacitor due to both their intrinsically high electrical conductivity and their nanosized diameter. [4][5][6] However, presently available carbon nanotube samples are in a bundled structure and contain metallic impurities that limit the capacitance of carbon nanotube-based supercapacitors. To solve these problems, we used high purity ͑99%͒ double walled carbon nanotubes ͑DWNTs͒ prepared by a catalytic chemical vapor deposition and subsequent oxidation process.7 Their high purity relative to residual catalyst particles has been confirmed by diamagnetic susceptibility experiments.8 In addition, we have chosen single stranded DNA ͑ssDNA͒ for dispersing the strongly bundled DWNTs, and we have confirmed the dispersion state of the tubes in an aqueous ssDNA solution using optical spectroscopy. Then, the filtered DWNT/DNA films were thermally treated at 600°C in argon in order to convert the insulating ssDNA into porous carbon materials. We have found that the freestanding DWNT-derived thin electrodes thus prepared exhibited two times more capacitance than a pure DWNT film, due to the evolution of the pseudocapacitance from the phosphorous-containing functional groups. We also found that these films were mechanically strong enough to show flexibility. This is due to their intrinsic morphology, such as the small diameter and the long length of the nanotubes, which also made them easy to fabricate.We used high purity and crystalline ͓shown by the absence of the Raman D band in Fig. 1͑c͔͒ DWNTs in which nanotubes with an outer diameter of approximately 1.6 nm were packed in hexagonal arrays ͓Fig. 1͑a͔͒ within largersized bundles ͓Fig. 1͑b͔͒. By dispersing the DWNTs ͑ap-proximately 20 mg͒ in an aqueous solution ͑10 ml͒ w...

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Synthesis of 5-Alkynyl-2,2,6-trimethyl-1,3-dioxin-4-ones and 1,4-Disubstituted--1,2,3-triazoles. -Optimized conditions are applied to the Suzuki-Miyaura cross-coupling of potassium alkynyl trifluoroborates with the iodinated 1,3-dioxin--4-one (I). The silyl derivative (V) is further coupled with organic azides. Ring opening of products (VIIa,e) with benzyl alcohol is demonstrated. -(STEFANI*, H. A.; VIEIRA, A. S.; AMARAL, M. F. Z. J.; COOPER, L.; Tetrahedron Lett. 52 (2011) 33, 4256-4261, http://dx.