@article{yildiz_dirican_fang_fu_jia_stano_zhang_bradford_2019, title={Hybrid Carbon Nanotube Fabrics with Sacrificial Nanofibers for Flexible High Performance Lithium-Ion Battery Anodes}, volume={166}, ISSN={["1945-7111"]}, url={https://publons.com/publon/26924627/}, DOI={10.1149/2.0821902jes}, abstractNote={Silicon is one of the most promising anode materials for lithium-ion batteries because of its highest known theoretical charge capacity (4,200 mAh g−1). However, it has found limited application in commercial batteries because of the significant volume change (up to 400%) of silicon during cycling, which results in pulverization and capacity fading. Here, we present a new method to develop a silicon - carbon nanotube (CNT) hybrid anode architecture using CNT-polymer nanofiber hybridization method. The anode material is produced by electrospinning PMMA-Si nanofibers onto aligned CNT sheets, which are drawn on a grounded, rotating take-up roller, and then subsequently decomposing the PMMA electrospun fibers at elevated temperature to create a uniform distribution of Si particles within the CNT sheets. The whole structure is then coated with pyrolytic carbon via chemical vapor deposition (CVD). The architecture provides sufficient space to accommodate the volume expansion of the Si nanoparticles. The CVD pyrolytic carbon coating helps to anchor the Si nanoparticles within CNT sheets and stabilize solid-electrolyte-interface (SEI) formation. The novel freestanding, binder free CNT-Si-C sheet hybrid exhibited improved performance in terms of excellent cycling capacity (1470 mAh g−1), high coulombic efficiency (98%), and good capacity retention of 88% after 150 cycles.}, number={4}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Yildiz, Ozkan and Dirican, Mahmut and Fang, Xiaomeng and Fu, Kun and Jia, Hao and Stano, Kelly and Zhang, Xiangwu and Bradford, Philip D.}, year={2019}, month={Feb}, pages={A473–A479} } @article{faraji_yildiz_rost_stano_farahbakhsh_zhu_bradford_2017, title={Radial growth of multi-walled carbon nanotubes in aligned sheets through cyclic carbon deposition and graphitization}, volume={111}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2016.10.012}, abstractNote={Carbon coated aligned multi-walled carbon nanotube (AMWCNT/C) sheets were used for studying the controlled radial growth of MWCNTs. Pyrolytic carbon (PyC) was deposited on the surface of nanotubes using multiple cycles of chemical vapor infiltration. Morphological and structural characterization showed that when graphitization was done in one step, after the deposition of multiple cycles of PyC, the presence of a large amount of disordered carbon on the surface of nanotubes led to a poorly graphitized coating structure that did not resembled nanotube walls anymore. Graphitization of the AMWCNT/C sheets after each deposition cycle prevented the development of disordered carbon during the subsequent PyC deposition cycles. Using the cyclic-graphitization method, thick PyC coating layers were successfully graphitized into a crystalline structure that could not be differentiated from the original nanotube walls. TEM observation and X-ray data confirmed radial growth of nanotubes, while spectra collected from Raman spectroscopy revealed that radially grown CNTs had the same quality as graphitized pristine nanotubes. The focus of this study was to compare the effect of cyclic graphitization with a one-step graphitization method to gain insight on the necessary parameters needed to radially grow high quality CNTs.}, journal={CARBON}, author={Faraji, Shaghayegh and Yildiz, Ozkan and Rost, Christina and Stano, Kelly and Farahbakhsh, Nasim and Zhu, Yuntian and Bradford, Philip D.}, year={2017}, month={Jan}, pages={411–418} } @article{stano_faraji_yildiz_akyildiz_bradford_jur_2017, title={Strong and resilient alumina nanotube and CNT/alumina hybrid foams with tuneable elastic properties}, volume={7}, ISSN={["2046-2069"]}, DOI={10.1039/c7ra02452e}, abstractNote={Excellent chemical and heat resistance combined with the attractive properties of aerogels, including large surface area and low density makes alumina aerogels an attractive material for high temperature catalysis, thermal insulation, and vibration damping. Brittle behaviour, a high propensity to sinter, and poor moisture stability, however, have drastically inhibited the practical use of alumina aerogels produced using traditional methods. Herein, we report the scalable fabrication of low density, anisotropic carbon nanotube (CNT)/alumina hybrid foams synthesized via atomic layer deposition (ALD) on aligned carbon nanotube foams (CNTFs). Calcination of the hybrid foams in air resulted in removal of the CNTFs, leaving behind a free-standing three-dimensional network of interconnected alumina nanotubes. Both CNT/alumina hybrid foams and pure alumina nanotube foams exhibit unprecedented elastic recovery following 50% compression, and possess values for strength and Young's moduli which exceed those of aerogels with similar densities. The scaling behaviour of Young's modulus to foam density for pure alumina foams exhibits a power-law dependence of n ≈ 1.9, attributed to superb ligament connectivity. These unique structures remain stable to the large capillary forces induced upon liquid infiltration and removal, and can absorb up to 100 times their own weight in water. Furthermore, alumina nanotube foams demonstrate enhanced thermal insulation capabilities at temperature of 1000 °C with no evidence of shrinkage.}, number={45}, journal={RSC ADVANCES}, author={Stano, Kelly L. and Faraji, Shaghayegh and Yildiz, Ozkan and Akyildiz, Halil and Bradford, Philip D. and Jur, Jesse S.}, year={2017}, pages={27923–27931} } @article{akyildiz_stano_roberts_everitt_jur_2016, title={Photoluminescence Mechanism and Photocatalytic Activity of Organic-Inorganic Hybrid Materials Formed by Sequential Vapor Infiltration}, volume={32}, ISSN={["0743-7463"]}, DOI={10.1021/acs.langmuir.6b00285}, abstractNote={Organic-inorganic hybrid materials formed by sequential vapor infiltration (SVI) of trimethylaluminum into polyester fibers are demonstrated, and the photoluminescence of the fibers is evaluated using a combined UV-vis and photoluminescence excitation (PLE) spectroscopy approach. The optical activity of the modified fibers depends on infiltration thermal processing conditions and is attributed to the reaction mechanisms taking place at different temperatures. At low temperatures a single excitation band and dual emission bands are observed, while, at high temperatures, two distinct absorption bands and one emission band are observed, suggesting that the physical and chemical structure of the resulting hybrid material depends on the SVI temperature. Along with enhancing the photoluminescence intensity of the PET fibers, the internal quantum efficiency also increased to 5-fold from ∼4-5% to ∼24%. SVI processing also improved the photocatalytic activity of the fibers, as demonstrated by photodeposition of Ag and Au metal particles out of an aqueous metal salt solution onto fiber surfaces via UVA light exposure. Toward applications in flexible electronics, well-defined patterning of the metallic materials is achieved by using light masking and focused laser rastering approaches.}, number={17}, journal={LANGMUIR}, author={Akyildiz, Halil I. and Stano, Kelly L. and Roberts, Adam T. and Everitt, Henry O. and Jur, Jesse S.}, year={2016}, month={May}, pages={4289–4296} } @article{stano_faraji_hodges_yildiz_wells_akyildiz_zhao_jur_bradford_2016, title={Ultralight Interconnected Metal Oxide Nanotube Networks}, volume={12}, ISSN={["1613-6829"]}, DOI={10.1002/smll.201503267}, abstractNote={Record-breaking ultralow density aluminum oxide structures are prepared using a novel templating technique. The alumina structures are unique in that they are comprised by highly aligned and interconnected nanotubes yielding anisotropic behavior. Large-scale network structures with complex form-factors can easily be made using this technique. The application of the low density networks as humidity sensing materials as well as thermal insulation is demonstrated.}, number={18}, journal={SMALL}, author={Stano, Kelly L. and Faraji, Shaghayegh and Hodges, Ryan and Yildiz, Ozkan and Wells, Brian and Akyildiz, Halil I. and Zhao, Junjie and Jur, Jesse and Bradford, Philip D.}, year={2016}, month={May}, pages={2432–2438} } @article{yildiz_stano_faraji_stone_willis_zhang_jur_bradford_2015, title={High performance carbon nanotube - polymer nanofiber hybrid fabrics}, volume={7}, ISSN={["2040-3372"]}, url={https://publons.com/publon/26924675/}, DOI={10.1039/c5nr02732b}, abstractNote={Stable nanoscale hybrid fabrics containing both polymer nanofibers and separate and distinct carbon nanotubes (CNTs) are highly desirable but very challenging to produce. Here, we report the first instance of such a hybrid fabric, which can be easily tailored to contain 0-100% millimeter long CNTs. The novel CNT - polymer hybrid nonwoven fabrics were created by simultaneously electrospinning nanofibers onto aligned CNT sheets which were drawn and collected on a grounded, rotating mandrel. Due to the unique properties of the CNTs, the hybrids show very high tensile strength, very small pore size, high specific surface area and electrical conductivity. In order to further examine the hybrid fabric properties, they were consolidated under pressure, and also calendered at 70 °C. After calendering, the fabric's strength increased by an order of magnitude due to increased interactions and intermingling with the CNTs. The hybrids are highly efficient as aerosol filters; consolidated hybrid fabrics with a thickness of 20 microns and areal density of only 8 g m(-2) exhibited ultra low particulate (ULPA) filter performance. The flexibility of this nanofabrication method allows for the use of many different polymer systems which provides the opportunity for engineering a wide range of nanoscale hybrid materials with desired functionalities.}, number={40}, journal={NANOSCALE}, publisher={Royal Society of Chemistry (RSC)}, author={Yildiz, Ozkan and Stano, Kelly and Faraji, Shaghayegh and Stone, Corinne and Willis, Colin and Zhang, Xiangwu and Jur, Jesse S. and Bradford, Philip D.}, year={2015}, pages={16744–16754} } @article{faraji_stano_yildiz_li_zhu_bradford_2015, title={Ultralight anisotropic foams from layered aligned carbon nanotube sheets}, volume={7}, ISSN={["2040-3372"]}, DOI={10.1039/c5nr03899e}, abstractNote={In this work, we present large scale, ultralight aligned carbon nanotube (CNT) structures which have densities an order of magnitude lower than CNT arrays, have tunable properties and exhibit resiliency after compression. By stacking aligned sheets of carbon nanotubes and then infiltrating with a pyrolytic carbon (PyC), resilient foam-like materials were produced that exhibited complete recovery from 90% compressive strain. With density as low as 3.8 mg cm(-3), the foam structure is over 500 times less dense than bulk graphite. Microscopy revealed that PyC coated the junctions among CNTs, and also increased CNT surface roughness. These changes in the morphology explain the transition from inelastic behavior to foam-like recovery of the layered CNT sheet structure. Mechanical and thermal properties of the foams were tuned for different applications through variation of PyC deposition duration while dynamic mechanical analysis showed no change in mechanical properties over a large temperature range. Observation of a large and linear electrical resistance change during compression of the aligned CNT/carbon (ACNT/C) foams makes strain/pressure sensors a relevant application. The foams have high oil absorption capacities, up to 275 times their own weight, which suggests they may be useful in water treatment and oil spill cleanup. Finally, the ACNT/C foam's high porosity, surface area and stability allow for demonstration of the foams as catalyst support structures.}, number={40}, journal={NANOSCALE}, author={Faraji, Shaghayegh and Stano, Kelly L. and Yildiz, Ozkan and Li, Ang and Zhu, Yuntian and Bradford, Philip D.}, year={2015}, pages={17038–17047} } @article{stano_carroll_padbury_mccord_jur_bradford_2014, title={Conformal Atomic Layer Deposition of Alumina on Millimeter Tall, Vertically-Aligned Carbon Nanotube Arrays}, volume={6}, ISSN={["1944-8244"]}, DOI={10.1021/am505107s}, abstractNote={Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain.}, number={21}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Stano, Kelly L. and Carroll, Murphy and Padbury, Richard and McCord, Marian and Jur, Jesse S. and Bradford, Philip D.}, year={2014}, month={Nov}, pages={19135–19143} } @article{faraji_stano_rost_maria_zhu_bradford_2014, title={Structural annealing of carbon coated aligned multi-walled carbon nanotube sheets}, volume={79}, ISSN={0008-6223}, url={http://dx.doi.org/10.1016/J.CARBON.2014.07.049}, DOI={10.1016/j.carbon.2014.07.049}, abstractNote={Sheets of aligned multi-walled carbon nanotubes (AMWCNTs) were used to study the structural annealing of pyrolytic carbon (PyC) coatings with various thicknesses on MWCNTs. PyC was deposited using chemical vapor infiltration and the thickness was controlled via the infiltration time. Structural annealing of the PyC coated AMWCNT (AMWCNT/C) sheets at 2150 °C provided different results for different thickness coatings. Transmission electron microscopy images showed that the carbon deposited from acetylene formed laminar PyC coatings, resembling rough tube walls, on the CNT surfaces. Following the high temperature heat treatment, coatings from short PyC deposition times changed their structure, resulting in radial growth of the MWCNTs. Raman and X-ray diffraction measurements also revealed that the radially grown MWCNTs had graphitic quality very close to pristine nanotubes after annealing. Electrical conductivity of AMWCNT/C sheets after high temperature heat treatment was twice that of pristine AMWCNT sheets. The focus of this study was to determine the PyC coating thickness at which a rough PyC coating would no longer change its structure into new CNT walls. The samples treated longer than 30 min had much more disordered PyC deposited on the surface and the additional material did not form additional tube walls after thermal annealing.}, journal={Carbon}, publisher={Elsevier BV}, author={Faraji, Shaghayegh and Stano, Kelly and Rost, Christina and Maria, Jon-Paul and Zhu, Yuntian and Bradford, Philip D.}, year={2014}, month={Nov}, pages={113–122} } @article{fu_yildiz_bhanushali_wang_stano_xue_zhang_bradford_2013, title={Aligned Carbon Nanotube-Silicon Sheets: A Novel Nano-architecture for Flexible Lithium Ion Battery Electrodes}, volume={25}, ISSN={["1521-4095"]}, url={https://publons.com/publon/7178364/}, DOI={10.1002/adma.201301920}, abstractNote={Aligned carbon nanotube sheets provide an engineered scaffold for the deposition of a silicon active material for lithium ion battery anodes. The sheets are low-density, allowing uniform deposition of silicon thin films while the alignment allows unconstrained volumetric expansion of the silicon, facilitating stable cycling performance. The flat sheet morphology is desirable for battery construction.}, number={36}, journal={ADVANCED MATERIALS}, publisher={Wiley}, author={Fu, Kun and Yildiz, Ozkan and Bhanushali, Hardik and Wang, Yongxin and Stano, Kelly and Xue, Leigang and Zhang, Xiangwu and Bradford, Philip D.}, year={2013}, month={Sep}, pages={5109–5114} } @article{ojha_stevens_stano_hoffman_clarke_gorga_2008, title={Characterization of electrical and mechanical properties for coaxial nanofibers with poly(ethylene oxide) (PEO) core and multiwalled carbon nanotube/PEO sheath}, volume={41}, ISSN={["1520-5835"]}, DOI={10.1021/ma702634a}, abstractNote={The present work focuses on the electrical and mechanical characterization of nanocomposite fibers having core−sheath (or bicomponent) morphologies. Owing to their unique mechanical and electrical properties, multiwalled carbon nanotubes (MWNTs) have been utilized in the nanocomposite construction. Submicron diameter nanofibers (200–300 nm) with core−sheath morphology were fabricated from a polymer/MWNT solution and collected in random mats. By constraining the MWNTs to the sheath, significant increases in the mechanical properties were observed at lower MWNT concentrations when compared to mats made from single-layer fibers. The electrical properties of the core−sheath mats showed similar gains, having a critical weight percent more than 10 times lower than that of the single-layer mats.}, number={7}, journal={MACROMOLECULES}, author={Ojha, Satyajeet S. and Stevens, Derrick R. and Stano, Kelly and Hoffman, Torissa and Clarke, Laura I. and Gorga, Russell E.}, year={2008}, month={Apr}, pages={2509–2513} } @article{ojha_stevens_hoffman_stano_klossner_scott_krause_clarke_gorga_2008, title={Fabrication and characterization of electrospun chitosan nanofibers formed via templating with polyethylene oxide}, volume={9}, ISSN={["1526-4602"]}, DOI={10.1021/bm800551q}, abstractNote={Chitosan is an abundantly common, naturally occurring, polysaccharide biopolymer. Its biocompatible, biodegradable, and antimicrobial properties have led to significant research toward biological applications such as drug delivery, artificial tissue scaffolds for functional tissue engineering, and wound-healing dressings. For applications such as tissue scaffolding, formation of highly porous mats of nanometer-sized fibers, such as those fabricated via electrospinning, may be quite important. Previously, strong acidic solvents and blending with synthetic polymers have been used to achieve electrospun nanofibers containing chitosan. As an alternative approach, in this work, polyethylene oxide (PEO) has been used as a template to fabricate chitosan nanofibers by electrospinning in a core-sheath geometry, with the PEO sheath serving as a template for the chitosan core. Solutions of 3 wt % chitosan (in acetic acid) and 4 wt % PEO (in water) were found to have matching rheological properties that enabled efficient core-sheath fiber formation. After removing the PEO sheath by washing with deionized water, chitosan nanofibers were obtained. Electron microscopy confirmed nanofibers of approximately 250 nm diameter with a clear core-sheath geometry before sheath removal, and chitosan nanofibers of approximately 100 nm diameter after washing. The resultant fibers were characterized with IR spectroscopy and X-ray diffraction, and the mechanical and electrical properties were evaluated.}, number={9}, journal={BIOMACROMOLECULES}, author={Ojha, Satyajeet S. and Stevens, Derrick R. and Hoffman, Torissa J. and Stano, Kelly and Klossner, Rebecca and Scott, Mary C. and Krause, Wendy and Clarke, Laura I. and Gorga, Russell E.}, year={2008}, month={Sep}, pages={2523–2529} } @article{mccullen_stano_stevens_roberts_monteiro-riviere_clarke_gorga_2007, title={Development, optimization, and characterization of electrospun poly(lactic acid) nanofibers containing multi-walled carbon nanotubes}, volume={105}, ISSN={["1097-4628"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000247576000079&KeyUID=WOS:000247576000079}, DOI={10.1002/app.26288}, abstractNote={Abstract}, number={3}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={McCullen, Seth D. and Stano, Kelly L. and Stevens, Derrick R. and Roberts, Wesley A. and Monteiro-Riviere, Nancy A. and Clarke, Laura I. and Gorga, Russell E.}, year={2007}, month={Aug}, pages={1668–1678} }