나노튜브/화학연료의 동축 구조에서 생성되는 열동력 파도를 이용한 전기 에너지 생성

최원준(Wonjoon Choi),마이클 스트라노(Michael Strano) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

There is significant interest in developing energy sources capable of larger power densities than what is possible with conventional materials. In our previous works, we proved that by coupling an exothermic chemical reaction with 1D nanostructures, a self-propagating reactive wave can be driven along its length with extremely fast reaction velocity, with a concomitant electrical pulse of high specific power that we identify as a thermopower wave. We realized such waves using an annular shell of highly energetic fuel (cyclotrimethylene-trinitramine, TNA) around a carbon nanotube (CNT). Herein, for further understanding, we discuss details in many different aspects about the thermopower wave. Different alignment degree in vertically aligned CNT films is evaluated in reactive wave speed, correlated with its thermal reaction that affects the change of magnitude of energy generation. The effects of the temperature dependent properties of chemical fuels and CNTs are evaluated. Also, we would explore the portions of convection and radiation in this thermal wave as well as synchronization between thermal reaction transfer and oscillation of electrical signal.

나노튜브/화학연료의 동축 구조에서 생성되는 열동력 파도를 이용한 전기 에너지 생성

최원준(Wonjoon Choi),마이클 스트라노(Michael S. Strano) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.6

이전 연구에서 우리는 나노구조와 화학연료의 동축 구조를 제작하여 이를 점화시켰을 때, 축방향으로 매우 빠르게 화학 반응이 전파되며, 이와 동시에 높은 비출력을 가지는 화학-전기 에너지를 생성할 수 있음을 증명하였으며, 이러한 현상을 열동력 파도로 명명하였다. 본 연구에서는 열동력 파도와 관련된 여러가지 물리적인 현상을 심도있게 다루려 한다. 나노구조의 다른 배열 상태에 따라 반응 전파속도, 에너지 생성 정도가 어떻게 달라지는지, 그리고 이와 동시에 발생하는 전기 신호와는 어떤 연관 관계가 있는 지를 연구하였다. 또한 이론적으로 온도 변화에 따라 달라지는 나노튜브와 화학연료의 성질, 대류와 복사에 의한 영향을 고려했을 때 열동력 파도의 전파 양상이 어떻게 달라지는 지를 규명하였다. There is considerable interest in developing energy sources capable of larger power densities. In our previous works, we proved that by coupling an exothermic chemical reaction with 1D nanostructures, a self-propagating reactive wave can be driven along its length with a concomitant electrical pulse of high specific power, which we identified as a thermopower wave. Herein, we discuss details about many different aspects of a thermopower wave. Different alignment degree in vertically aligned CNT films is evaluated in the reactive wave speed and correlated with its thermal reaction that affects the change in the magnitude of energy generation. The effects of the temperature-dependent properties of chemical fuels and CNTs are evaluated. Furthermore, we explore the convection and radiation portions in this thermal wave as well as the synchronization between the thermal reaction transfer and the oscillation of the electrical signal.

Highly efficient exfoliation of individual single-walled carbon nanotubes by biocompatible phenoxylated dextran.

Kwon, Taeyun,Lee, Gyudo,Choi, Hyerim,Strano, Michael S,Kim, Woo-Jae RSC Pub 2013 Nanoscale Vol.5 No.15

<P>Highly efficient exfoliation of individual single-walled carbon nanotubes (SWNTs) was successfully demonstrated by utilizing biocompatible phenoxylated dextran, a kind of polysaccharide, as a SWNT dispersion agent. Phenoxylated dextran shows greater ability in producing individual SWNTs from raw materials than any other dispersing agent, including anionic surfactants and another polysaccharide. Furthermore, with this novel polymer, SWNT bundles or impurities present in raw materials are removed under much milder processing conditions compared to those of ultra-centrifugation procedures. There exists an optimal composition of phenoxy groups (13.6 wt%) that leads to the production of high-quality SWNT suspensions, as confirmed by UV-vis-nIR absorption and nIR fluorescence spectroscopy. Furthermore, phenoxylated dextran strongly adsorbs onto SWNTs, enabling SWNT fluorescence even in solid-state films in which metallic SWNTs co-exist. By bypassing ultra-centrifugation, this low-energy dispersion scheme can potentially be scaled up to industrial production levels.</P>

Catalytic synthesis of few-layer graphene on titania nanowires

Kudo, Akira,Jung, Sung Mi,Strano, Michael S.,Kong, Jing,Wardle, Brian L. Royal Society of Chemistry 2018 Nanoscale Vol.10 No.3

<P>Growth mechanisms of graphitic nanostructures on metal oxides by chemical vapor deposition (CVD) are observed at 750 °C, using titania nanowire aerogel (NWAG) as a three-dimensional substrate and without metal catalysts. We temporally observed catalytic transformation of amorphous carbon into few-layer graphene on the surface of 5-10 nm diameter titania nanowires. The graphitization spontaneously terminates when the titania nanowires are encapsulated by a shell of approximately three graphene layers. Extended CVD time beyond the termination point (>1125 seconds) yields only additional amorphous carbon deposits on top of the few-layer graphene. Furthermore, it was discovered that the islands of amorphous carbon do not graphitize unless they catalytically grow beyond a threshold size of 5-7 nm along the nanowire length, even after an extended thermal treatment. The electrical conductivity of the NWAG increased by four orders of magnitude, indicating that the graphene shell mediated by titania nanowires yielded a network of graphene throughout the three-dimensional nanostructure of the aerogel. Our results help us understand the growth mechanisms of few-layer graphene on nanostructured metal oxides, and inspire facile and controllable processing of metal oxide-nanocarbon fiber-shell composites.</P>

Energy Efficiency of the Vulcanization Process of a Bicycle Tyre

Lohit Kumar Pentakota,Paolo Albertelli,Matteo Strano 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.4

The production of tyres is one of the most energy consuming manufacturing activities in the rubber sector. In the production cycle of a tyre, the curing operation has the maximum energy loss. This is mostly due to the extensive use of steam as a source of heat and pressure in the vulcanization process. To the author’s knowledge, no scientific work is available in the literature where the energy efficiency of a tyre vulcanization press is estimated by means of a comprehensive model of all main components, including the moulds, the press with its heated plates, the bladder and, of course, the tyre. The present work aims at filling this gap. First, the press used for developing the model is described, along with its components and its typical product, a bicycle tyre. The instruments used for measuring flow rates, temperatures and pressures are also listed. Then, a numerical model is presented, that predicts the energy transfers occurring in the vulcanization press during a full process cycle. The numerical model, developed with the software Simcenter Amesim 2021.1, has been validated by means of measurements taken at the press. The results indicate that the amount of energy which is actually consumed by the tyre for its reticulation process amounts to less than 1% of the total energy expenditure. The paper demonstrates that the tyre industry is in urgent need of an electrification conversion of the traditional steam-based processes.

Controllable viscoelastic behavior of vertically aligned carbon nanotube arrays

Eom, K.,Nam, K.,Jung, H.,Kim, P.,Strano, M.S.,Han, J.H.,Kwon, T. Pergamon Press ; Elsevier Science Ltd 2013 Carbon Vol.65 No.-

We have characterized the mechanical behavior of aligned carbon nanotube (CNT) arrays that serve as foam-like energy absorbing materials, by using atomic force microscope indentation. It is shown that the mechanical properties (e.g. elastic modulus, adhesion force, and energy dissipation) of aligned CNT arrays are dependent on the length of CNTs as well as chemical environment that surrounds CNT arrays. More remarkably, it is found that CNT array made of CNTs with their length of 10μm exhibits the excellent damping property (i.e. energy dissipation) higher than that of a conventional composite such as Kevlar. It is also shown that the energy dissipation of CNT arrays during loading-unloading process can be reduced by the solution surrounding CNT array, and that the decrease of energy dissipation for CNT array due to solution depends on the solution type, which mediates the interaction between individual nanotubes. Our study sheds light on the design principles for CNT array-based foam-like materials.

DNA Aptamer-Passivated Nanocrystal Synthesis: A Facile Approach for Nanoparticle-Based Cancer Cell Growth Inhibition

Choi, Jong Hyun,Chen, Kok Hao,Han, Jae-Hee,Chaffee, Amanda M.,Strano, Michael S. WILEY-VCH Verlag 2009 Small Vol.5 No.6

<B>Graphic Abstract</B> <P>A class of DNA aptamers, recognizing and therapeutically targeting cancer cells, remains functional while forming stable colloidal PbS and Fe<SUB>3</SUB>O<SUB>4</SUB> nanocrystals. The aptamer-passivated nanocrystals (see image) are non-cytotoxic to normal cells, whereas MCF-7 human breast cancer cells incorporated with these particles have significantly reduced proliferation. The nanoparticle-aptamer systems provide a platform for novel nanoparticle therapeutics. <img src='wiley_img/16136810-2009-5-6-SMLL200801821-content.gif' alt='wiley_img/16136810-2009-5-6-SMLL200801821-content'> </P>

Anomalously Large Reactivity of Single Graphene Layers and Edges toward Electron Transfer Chemistries

Sharma, Richa,Baik, Joon Hyun,Perera, Chrisantha J.,Strano, Michael S. American Chemical Society 2010 NANO LETTERS Vol.10 No.2

<P>The reactivity of graphene and its various multilayers toward electron transfer chemistries with 4-nitrobenzene diazonium tetrafluoroborate is probed by Raman spectroscopy after reaction on-chip. Single graphene sheets are found to be almost 10 times more reactive than bi- or multilayers of graphene according to the relative disorder (<I>D</I>) peak in the Raman spectrum examined before and after chemical reaction in water. A model whereby electron puddles that shift the Dirac point locally to values below the Fermi level is consistent with the reactivity difference. Because the chemistry at the graphene edge is important for controlling its electronic properties, particularly in ribbon form, we have developed a spectroscopic test to examine the relative reactivity of graphene edges versus the bulk. We show, for the first time, that the reactivity of edges is at least two times higher than the reactivity of the bulk single graphene sheet, as supported by electron transfer theory. These differences in electron transfer rates may be important for selecting and manipulating graphitic materials on-chip.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2010/nalefd.2010.10.issue-2/nl902741x/production/images/medium/nl-2009-02741x_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl902741x'>ACS Electronic Supporting Info</A></P>

Extraordinary High Microwave Absorption Cross Section of Ultralong Carbon Nanotubes

Yun, Jongju,Jeon, Wonjae,Drahushuk, Lee W.,Baik, Seunghyun,Strano, Michael S. American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.25

<P>The microwave-induced heating of nanoparticles has been actively studied in pursuit of more efficient microwave absorbers. Here we systematically investigated the microwave absorption cross section of conductive particles (Al), magnetic particles (Fe<SUB>3</SUB>O<SUB>4</SUB>), and carbon nanotubes with different lengths. The particles were suspended in silicone oil and irradiated with a microwave at 2.45 GHz using a single-mode microwave reactor. The experimentally measured heating rate was analytically modeled based on the modified Lambert–Beer law to obtain the microwave absorption cross section per mass. The microwave-induced heating rate was primarily dependent on optical absorbance, which is proportional to the mass concentration of suspended particles. Under the similar optical absorbance, longer nanotubes provided greater microwave absorption cross section which could be described by the short dipole antenna theory. The microwave absorption cross section of 5 mm long multiwalled carbon nanotubes was ∼4080 times greater than that of Al particles. One-dimensional ultralong carbon nanotubes provide a unique opportunity as super microwave absorbers which may be useful in chemical, biomedical, and process applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-25/jp500831c/production/images/medium/jp-2014-00831c_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp500831c'>ACS Electronic Supporting Info</A></P>

Well-defined single-walled carbon nanotube fibers as quantum wires: Ballistic conduction over micrometer-length scales

R. Maruyama,Y.W. Nam,한재희,M.S. Strano 한국물리학회 2011 Current Applied Physics Vol.11 No.6

We report quasi-ballistic conduction in single-walled carbon nanotube (SWNT) fibers at room temperature,with a measured mean free path of 1.0―2.6 μm. The dynamic submersion of vertical SWNT fibers into liquid mercury (Hg) electrode shows plateaus and steps indicative of quasi-ballistic electron transport. This response is described with a newly developed network model that uses surface impurities to simplify the parallel conducting channels. The quasi-ballistic SWNT fibers exhibit a resistance per unit length of 2.5―6.5 kΩ/μm and a mean free path exceeding 1 μm, a length longer than typical via dimensions in existing Si-chip technologies. These results highlight that SWNT fiber conductivity can be enhanced by increasing the metallic to semiconducting SWNT ratio and reducing the surface impurities.