DOCSLIB.ORG

Mesoporous Carbon Nanofibers Embedded with Mos2 Nanocrystals

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mesoporous Carbon Nanofibers Embedded with Mos2 Nanocrystals DOI:10.1002/chem.201503356 Full Paper & Lithium-IonBatteries Mesoporous CarbonNanofibersEmbedded with MoS2 Nanocrystals for Extraordinary Li-Ion Storage Shan Hu,[a, b] Wen Chen,*[a] Evan Uchaker,[b] Jing Zhou,[a] and Guozhong Cao*[b, c] 1 Abstract: MoS2 nanocrystals embedded in mesoporous rent density of 100 mAgÀ ,aswell as an outstanding rate ca- carbon nanofibers are synthesized through an electrospin- pability. The greatly improved kinetics and cycling stability ning process followed by calcination. The resultant nanofib- of the mesoporous MoS2@C nanofiberscan be attributed to ers are 100–150nmindiameter and constructedfrom MoS2 the crosslinked conductive carbon nanofibers, the large spe- nanocrystals with alateral diameter of around 7nmwith cific surface area, the good crystallinity of MoS2,and the 2 1 specificsurface areas of 135.9 m gÀ .The MoS2@C nanofib- robust mesoporousmicrostructure. The resulting nanofiber ers are treated at 4508CinH2 and comparison samples an- electrodes, with short mass- and charge-transport pathways, nealed at 8008CinN2.The heat treatments are designed to improved electrical conductivity,and large contact area ex- achievegood crystallinity and desiredmesoporous micro- posedtoelectrolyte,permitting fast diffusional flux of Li structure, resulting in enhanced electrochemical per- ions, explainsthe improved kinetics of the interfacial charge- formance. The small amount of oxygeninthe nanofibersan- transfer reactionand the diffusivity of the MoS2@C mesopo- nealed in H2 contributes to obtaining alower internalresist- rous nanofibers. It is believedthat the integration of MoS2 ance, and thus, improving the conductivity.The resultsshow nanocrystals and mesoporouscarbon nanofibers may have that the nanofibers obtained at 4508CinH2 deliver an extra- asynergistic effect, giving apromisinganode,and widening 1 ordinary capacity of 1022 mAhgÀ and improvedcyclic sta- the applicability range into high performanceand mass pro- bility,with only 2.3 %capacity loss after 165 cycles at acur- ductioninthe Li-ion battery market. 1. Introduction Amongvarious nanostructured materials, considerable interest has been directed to 1D nanostructures such as nanowires, There is increasing demand for the development of clean nanotubes, nanorods,and nanofibers as promising electrode energy-storage devices for applications in portable electronics, materials for LIBs. In general,the advantages of 1D nanomate- electric vehicles (EVs), and hybrid electric vehicles (HEVs), rials are:1)their large specific surfacearea between the active which must have the advantages of high powerdensity,high materials and electrolyte, which increases surface/interface energy density,and high safety.[1] Lithium-ion batteries(LIBs) storage; 2) ashort diffusion length for Li ions, which gives rise have dominated energy-storage technologiesand power- to ahigh-ratecharge/discharge capability;and 3) their ability source markets because of their highenergy density,high volt- to absorb alarge volumeexpansion, which leads to stable age, and long lifespan, which are desirable features for large- cycle performance.[3] However,there also are some disadvan- scale energy applications.[2] Currently,numerous research ef- tages of 1D nanomaterials, such as low energy density and forts are aimed at designing electrode materials with nano- self-aggregation, which may block the electron/Li-ion trans- structuredarchitectures to achieve high-performanceLIBs. port.[4]Specially designed nanostructures should be considered to address these problems. Mesoporous nanostructured mate- [a] Dr.S.Hu, Prof. W. Chen, Prof. J. Zhou rials, which possessalarge specific surfacearea and exhibit State Key Laboratory of Advanced Technology for Materials Synthesisand the intrinsic nanomaterial nature of self-aggregation, have Processing, SchoolofMaterialsScience and Engineering been desirable structures allowing efficient contact with the Wuhan University of Technology, Wuhan, 430070 (P.R.China) electrolyte and fast Li-ion transport, leadingtoimproved LIB Fax:(+ 86)27-87760129 E-mail:[email protected] electrochemical performance. For example, mesoporous V2O5 1 [b] Dr.S.Hu, Dr.E.Uchaker,Prof. G. Cao nanofibersexhibited ahigh discharge capacity of 370 mA hgÀ , 1 Department of Materials Science and Engineering and ahigh rate capability at 800 mAgÀ with little cyclic degra- University of Washington,Seattle, Washington, 98195 (USA) [5] dation. Mesoporousgraphene-based TiO2/SnO2 nanosheets E-mail:[email protected] 2 1 with alarge surfacearea of 138 m gÀ and large pore volume [c] Prof. G. Cao 3 1 (0.133 cm gÀ ), synthesized through afacile and scalable step- BeijingInstituteofNanoenergyand Nanosystems Chinese Academy of Sciences, Beijing100083 (P.R.China) wise method, could effectively accommodate the volume Supportinginformation for this article is available on the WWW under changeand shorten the transport lengths for Li ions and elec- 1 http://dx.doi.org/10.1002/chem.201503356. trons,and presented areversible capacity of 600 mAhgÀ for Chem. Eur.J.2015, 21,18248 –18257 18248 2015 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim Full Paper over 300 cycles.[6] Therefore, mesoporousnanostructured ma- nanoflakes embedded in carbon nanofibers synthesized terials are of particular interestaselectrodes owing to their through ahydrothermalmethod combined with electrospin- large surfaceareas, structuralintegrity,and effectivemechani- ning and carbonization exhibited areversible capacity of 1 cal support and void space to mitigatevolume expansion, approximately 350 mAhgÀ at ahighcurrent density of 1 [14] which make them arational nanoarchitecture for LIB anode/ 1000 mA gÀ . In our work, electrospinning has been adopted cathodematerials. for the controllable fabrication of MoS2 nanocrystals embed- In recent years, avariety of preparation methods have been ded in mesoporous carbon nanofiberstogenerate functional developed to obtain mesoporous nanostructured materials. materialmats as anodesfor LIBs. Furthermore, among carbo- The hard-template approach is very common for the fabrica- naceousmaterials, carbon nanofibers have agood diffusion co- 7 2 1 [15] tion of mesoporous nanostructured materials. Shen et al. suc- efficient ( 210À cm sÀ ), whichisacritical parameter de- cessfully prepared mesoporous Li4Ti5O12/C nanocomposites termining the powerdensity of the Li-ion battery.Compared throughananocasting technique, using CMK-3 as the hard with our previous studies on flower-like C@MoS2 composites template.[7] However, this process requires severe and costly re- obtained through the hydrothermalmethod,[10a] we have fabri- action conditions. Subsequently,solution-based routes and cated MoS2@C mesoporous nanofibers successfully through electrodeposition methods for the synthesis of mesoporous electrospinning with low-costand accessible raw materials, nanostructured materials were introduced.[8] These methods which may be of benefit for the application of LIBs in industrial are easily accessible, but scale-up for mass production is still production.Inaddition, our results demonstrate that MoS2@C challenging. Electrospinning, aversatile, facile, and economical mesoporousnanofibers with improved interfacial charge-trans- method, can be appliedtothe large-scale synthesis of nano- fer kinetics and arobustmicrostructure exhibit highreversible structured materials.[9] In addition, electrospinning can gener- capacities and excellent cycling stabilityupon evaluation as ate mass-controllable 1D nanostructures and sophisticated ar- anode materials for LIBs. chitectures, and does not require complex technology. Atypical layered transition metal sulfide, MoS2,which con- sists of Mo atoms sandwiched betweentwo layers of closely 2. Experimental Section packed Satoms, is the focus of much attention as an anode 2.1 Materials synthesis materialfor applicationinLIBs. It is an inorganic analogueof the graphene layered structure, in whichthe 2D molecular Poly(vinyl alcohol) (PVA, Mw =67000 Sigma-Aldrich Co.,Ltd.,USA), layers are weakly linked by van der Waals interactions. The ammonium tetrathiomolybdate (ATTM, Alfa Aesar Co.,Ltd.,USA), and dimethyl sulfoxide (DMSO, Alfa Aesar Co.,Ltd.,USA) were weak van der Waalsforces allow afast diffusion path for the used without further purification. Aqueous PVAsolution (15 wt%) movement of Li ions without asignificant increase in was first prepared by dissolving the PVAindeionized water at [10] volume. The specialS-Mo-S layered structure enables expe- 908C, and stirring for 3h.The concentration of ATTM in DMSO was 1 ditious Li-ion insertion/extractionduring the discharge/charge set to be 0.33 gmLÀ and the solution was stirred at room temper- process.Theoretically,MoS2 can store four moles of Li ions on ature for 30 min. The above PVAwas added into the precursor so- the basis of aredox conversion reaction, in which the MoS2 is lution and stirred until ahomogeneous reddish-brown solution was obtained. The weight ratio of PVAtoATTM was 1.05. The pre- reducedtoMonanocrystals dispersed in aLi2Smatrix upon lithiation, and is then reversibly restored to the corresponding cursor solution was then transferred into a3mL plastic syringe with astainless steel needle and driven by asyringe pump at acon- disulfideafter delithiation, leading to acapacity 3.5 times 1 stant flow rate of 0.15 mLhÀ .The needle was connected to greater than that of commercial graphite anodes ahigh-voltage power supply (ES40P-5W,Gamma High Voltage, 1 (372 mA hgÀ ). However,akey limiting factor in employing Inc.), with the
Load more

Recommended publications
  • Diamonds from the Sky -‐ C2CNT, the Inexpensive Transforma[On of CO2 To
    Diamonds from the Sky - C2CNT, the inexpensive transformaon of CO2 to carbon nanotubes Stuart Licht, [email protected] presentaon to: the Naonal Academy Washington, DC, March 2018 Not for reproducon. All rights retained by George Washington University. Stuart Licht – 30 years solar chemistry & climate change mitigation expertise Academic credenals Deans’s Research Prof. George Washington Univ. Former NSF Program Director (Chemistry Division) Former Professor Technion Professor of Chemistry Former Chair – UMass Dept. of Chemistry Former Carlson Chair Assoc. Prof. of Chemsitry Postdoc: MIT (with Prof. Mark Wrighton) Ph.D. in chemistry: Weizmann Instute of Science B.Sc. & M.Sc. in chem&phys: Wesleyan University 2 Stuart Licht – 30 years solar chemistry & climate change mitigation expertise ~400 peer reviewed papers & patents 2014 3 Addressing climate change: What if we could convert CO2 to a product worth over 1,000 times more than coal? Money talks loudly. This would provide economic incenve to remove CO2. We can. We do it now. Today, we present an alternave transformaon of carbon dioxide into a compact, stable, valuable product. This process provides an economic incenve to remove the greenhouse gas carbon dioxide. 1 Introduc;on of a soluon to remove atmospheric carbon dioxide & migate climate change A novel, high-yield, low energy process is shown to remove the greenhouse gas carbon dioxide. We have found a chemistry to produce high-yield, high purity, carbon nanotubes and carbon nanofibers products directly from either atmospheric or smokestack CO2. Such carbons are used to make strong carbon composites, such as used in the Boeing Dreamliner, as well as in high-end sports equipment, wind turbine blades and a host of other lightweight, high strength, flexible, products.
    [Show full text]
  • Carbon Nanofiber Mats for Electromagnetic Interference Shielding
    Carbon 111 (2017) 529e537 Contents lists available at ScienceDirect Carbon journal homepage: www.elsevier.com/locate/carbon Carbon nanofiber mats for electromagnetic interference shielding * Xinghua Hong a, b, D.D.L. Chung a, a Composite Materials Research Laboratory, Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260-4400, USA b Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai, 201620, China article info abstract Article history: This paper reports the electromagnetic interference shielding effectiveness of carbon nanofiber (CNF, Received 13 September 2016 originally called carbon filament) mats made from 0.16-mm-diameter catalytically grown CNFs by the Received in revised form paper-making process (1.7e13.1 MPa compaction pressure). These low-cost lightweight binderless mats 13 October 2016 (2.9e5.4 mm thick, 0.13e0.22 g/cm3 bulk density, 6.1e10 vol% solid) provide high shielding effectiveness Accepted 14 October 2016 (SE,52e81 dB, 1.5 GHz) and high SE/density (370e470 dB cm3/g), though SE/thickness is low (14e18 dB/ Available online 14 October 2016 mm). Compared to the spun CNF mats of prior work, they exhibit higher SE, but lower SE/thickness. With consideration of SE, SE/thickness, and SE/density, the CNF mats are superior to graphene aerogel, reduced-graphene-oxide polyurethane foam and reduced-graphene-oxide aerogel of prior work, but are inferior to carbon nanotube mats, graphene film, carbon foam and flexible graphite of prior work. Ab- sorption is the dominant shielding mechanism of CNF mats, so both SE and absorption loss tend to decrease with decreasing thickness.
    [Show full text]
  • Methane Pyrolysis for Carbon Nanotubes and Cox‑Free H2 Over
    Article Cite This: Energy Fuels XXXX, XXX, XXX−XXX pubs.acs.org/EF ‑ Methane Pyrolysis for Carbon Nanotubes and COx Free H2 over Transition-Metal Catalysts † † I-Wen Wang, Deepa Ayillath Kutteri, Bingying Gao, Hanjing Tian, and Jianli Hu* Chemical & Biomedical Engineering Department, West Virginia University, Morgantown, West Virginia 26506, United States *S Supporting Information ABSTRACT: Recently, researchers at West Virginia University reported a promising catalyst innovation for nonoxidative thermochemical conversion of methane to CO2-free hydrogen and solid carbon nanotubes (CNTs). A catalyst system was discovered that promotes “base growth” CNT formation rather than conventional “tip growth”. This enables catalyst regenerability while also generating highly pure and crystalline carbon products. In this study, simultaneous productions of CNTs and CO2-free hydrogen were studied over Fe-based catalysts supported on Al2O3, SiO2, and H-ZSM-5. The experimental results showed that metal−support interaction played a key role in the base growth mechanism. Methane conversion and the property of CNTs depended significantly on metal loading and the type of support. To elucidate the formation mechanism of CNTs, the spent catalysts were characterized by a number of analytical instrumentations including transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and thermogravimetric analysis (TGA). The formation of the active intermediate phase, Fe3C, was discovered. The results of XPS analysis revealed that Fe/Al2O3 had a stronger interaction between metal particles and support than Fe/SiO2 and Fe/ZSM-5. The characterization result is consistent with the performance test results from the methane decomposition reaction. To further explore the fi application of the CNTs, separation and puri cation were carried out using spent Fe/Al2O3 and 9Ni-1Fe/SiO2 catalysts.
    [Show full text]
  • Carbon Nanotube and Nanofiber Reinforcement for Improving
    CARBON NANOTUBE AND NANOFIBER REINFORCEMENT FOR IMPROVING THE FLEXURAL STRENGTH AND FRACTURE TOUGHNESS OF PORTLAND CEMENT PASTE A Thesis by BRYAN MICHAEL TYSON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 2010 Major Subject: Civil Engineering CARBON NANOTUBE AND NANOFIBER REINFORCEMENT FOR IMPROVING THE FLEXURAL STRENGTH AND FRACTURE TOUGHNESS OF PORTLAND CEMENT PASTE A Thesis by BRYAN MICHAEL TYSON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Rashid Abu Al-Rub Committee Members, Zachary Grasley Eyad Masad Jaime Grunlan Head of Department, John Niedzwecki May 2010 Major Subject: Civil Engineering iii ABSTRACT Carbon Nanotube and Nanofiber Reinforcement for Improving the Flexural Strength and Fracture Toughness of Portland Cement Paste. (May 2010) Bryan Michael Tyson, B.S., Texas A&M University Chair of Advisory Committee: Dr. Rashid Abu Al-Rub The focus of the proposed research will be on exploring the use of nanotechnology- based nano-filaments, such as carbon nanotubes (CNTs) and nanofibers (CNFs), as reinforcement in improving the mechanical properties of portland cement paste as a construction material. Due to their ultra-high strength and very high aspect ratios, CNTs and CNFs have been used as excellent reinforcements in enhancing the physical and mechanical properties of polymer, metallic, and ceramic composites. Very little attention has been devoted on exploring the use of nano-filaments in the transportation industry. Therefore, this study aims to bridge the gap between nano-filaments and transportation materials.
    [Show full text]
  • Comparative Study of the Electrochemical, Biomedical, And
    Ghaemi et al. Nanoscale Research Letters (2018) 13:112 https://doi.org/10.1186/s11671-018-2508-3 NANOEXPRESS Open Access Comparative Study of the Electrochemical, Biomedical, and Thermal Properties of Natural and Synthetic Nanomaterials Ferial Ghaemi1*, Luqman Chuah Abdullah1,2, Hanieh Kargarzadeh3, Mahnaz M. Abdi1,4, Nur Farhana Waheeda Mohd Azli5 and Maryam Abbasian6 Abstract In this research, natural nanomaterials including cellulose nanocrystal (CNC), nanofiber cellulose (NFC), and synthetic nanoparticles such as carbon nanofiber (CNF) and carbon nanotube (CNT) with different structures, sizes, and surface areas were produced and analyzed. The most significant contribution of this study is to evaluate and compare these nanomaterials based on the effects of their structures and morphologies on their electrochemical, biomedical, and thermal properties. Based on the obtained results, the natural nanomaterials with low dimension and surface area have zero cytotoxicity effects on the living cells at 12.5 and 3.125 μg/ml concentrations of NFC and CNC, respectively. Meanwhile, synthetic nanomaterials with the high surface area around 15.3–21.1 m2/g and significant thermal stability (480 °C–600 °C) enhance the output of electrode by creating a higher surface area and decreasing the current flow resistance. Keywords: Natural and synthetic nanomaterials, Electrochemical properties, Cytotoxicity effect, Thermal stability Background The high cellulose content ranging between 44 and 63. Natural nanomaterials involve nanocellulose in different 5% in kenaf has generated interest for many applications shapes such as cellulose nanofiber (NFC) and cellulose [3, 4]. The CNC and NFC can be obtained via acid hy- nanocrystal (CNC). Roughly, individual cellulose molecular drolysis and mechanical treatment, respectively.
    [Show full text]
  • Processing, Characterization and Performance of Carbon Nanopaper Based Multifunctional Nanocomposites
    University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2012 Processing, Characterization And Performance Of Carbon Nanopaper Based Multifunctional Nanocomposites Fei Liang University of Central Florida Part of the Materials Science and Engineering Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Doctoral Dissertation (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Liang, Fei, "Processing, Characterization And Performance Of Carbon Nanopaper Based Multifunctional Nanocomposites" (2012). Electronic Theses and Dissertations, 2004-2019. 2400. https://stars.library.ucf.edu/etd/2400 PROCESSING, CHARACTERIZATION AND PERFORMANCE OF CARBON NANOPAPER BASED MULTIFUNCTIONAL NANOCOMPOSITES by FEI LIANG B.S. Donghua University, 2006 M.S. Donghua University, 2008 M.S. University of Central Florida, 2010 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Mechanical, Materials, and Aerospace Engineering in the College of Engineering and Computer Sciences at the University of Central Florida Orlando, Florida Fall Term 2012 Major Professor: Jihua Gou ○C 2012 Fei Liang ii ABSTRACT Carbon nanofibers (CNFs) used as nano-scale reinforcement have been extensively studied since they are capable of improving the physical and mechanical properties of conventional fiber reinforced polymer composites. However, the properties of CNFs are far away from being fully utilized in the composites due to processing challenges including the dispersion of CNFs and the viscosity increase of polymer matrix.
    [Show full text]
  • Arxiv Carbon Nanofiber Electric Power Plants Part 1
    Consists of this supplement: submitted as a US Provisional Patent, Oct. 13, 2015, as well as after page 11, the original submitted 3/23/15 arXiv 1503.06727 posting, submitted as a US Provisional Patent 2/26/15, prepared as a George Washington University Invention Disclosure 12/19/14. Carbon Nanofiber (from fossil fuel) Electric Power Plants: Transformation of CO2 Exhaust to Stable, Compact, Valued Commodities Stuart Licht Department of Chemistry, George Washington University Washington, DC USA Abstract Modes of power plant operation are presented which remove the greenhouse carbon dioxide from fossil fuel plant power station exhausts and transform the carbon dioxide into a valuable carbon nanofiber product. The first mode uses the emissions from a natural gas CC power plant to provide hot CO2 to a molten electrolysis chamber which generates both carbon nanofiber and oxygen. The valuable carbon nanofiber product is removed, heat from the carbon nanofiber and oxygen products is transferred into heating steam for the steam turbine, and the pure oxygen is blended into the air inlet to allow the gas turbine to operate at higher temperature and higher efficiencies. A second mode converts a conventional coal power plant to a STEP coal CNF power plant by directing the hot carbon dioxide combustion emission into carbon nanofiber production electrolysis chamber, and transforming the carbon dioxide to carbon nanofibers with the use of renewable or nuclear energy. Other intermediate modes of fossil fuel carbon nanofiber electric power plants with partial solar input are also evident, as well as a simplified, smaller version (for heating/cooking) rather than electrical production.
    [Show full text]
  • IF-WS2/Nanostructured Carbon Hybrids Generation and Their Characterization
    Inorganics 2014, 2, 211-232; doi:10.3390/inorganics2020211 OPEN ACCESS inorganics ISSN 2304-6740 www.mdpi.com/journal/inorganics Article IF-WS2/Nanostructured Carbon Hybrids Generation and Their Characterization Claudia C. Luhrs *, Michael Moberg, Ashley Maxson, Luke Brewer and Sarath Menon Mechanical and Aerospace Engineering Department. Naval Postgraduate School 700 Dyer Rd. Watkins Hall. Monterey, CA 9394. USA; E-Mails: [email protected] (M.M.); [email protected] (A.M.); [email protected] (L.B.); [email protected] (S.M.) * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +1-831-656-2568. Received: 5 March 2014; in revised form: 24 April 2014 / Accepted: 28 April 2014 / Published: 9 May 2014 Abstract: With the aim to develop a new generation of materials that combine either the known energy absorbing properties of carbon nanofibers (CNF), or the carbon-carbon bond strength of graphene sheets (G), with the shock resistance properties reported for Inorganic Fullerene type WS2 structures (IF-WS2), hybrid CNF/IF-WS2 and G/IF-WS2 were generated, characterized and tested. Experimentation revealed that in situ growth of carbon nanostructures with inorganic fullerene tungsten disulfide particulates had to be performed from particular precursors and fabrication conditions to avoid undesirable byproducts that hinder fiber growth or deter graphene generation. The novel protocols that allowed us to integrate the IF-WS2 with the carbon nanostructures, producing dispersions at the nanoscale, are reported. Resulting hybrid CNF/IF-WS2 and G/IF-WS2 products were analyzed by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and TEM (Transmission Electron Microscopy).
    [Show full text]
  • Carbon Nanomaterials for Advanced Energy Conversion and Storage Liming Dai , * Dong Wook Chang , Jong-Beom Baek , and Wen Lu *
    Carbon Nanomaterials Carbon Nanomaterials for Advanced Energy Conversion and Storage Liming Dai , * Dong Wook Chang , Jong-Beom Baek , and Wen Lu * From the Contents 1. Introduction .............................................2 I t is estimated that the world will need to double its 2. Carbon Nanomaterials ..............................2 energy supply by 2050. Nanotechnology has opened up new frontiers in materials science and engineering 3. Carbon Nanomaterials for Energy to meet this challenge by creating new materials, Conversion ...............................................7 particularly carbon nanomaterials, for effi cient energy 4. Carbon Nanotubes for conversion and storage. Comparing to conventional Energy Storage .........................................21 energy materials, carbon nanomaterials possess unique size-/surface-dependent (e.g., morphological, electrical, 5. Concluding Remarks .................................30 optical, and mechanical) properties useful for enhancing the energy-conversion and storage performances. During the past 25 years or so, therefore, considerable efforts have been made to utilize the unique properties of carbon nanomaterials, including fullerenes, carbon nanotubes, and graphene, as energy materials, and tremendous progress has been achieved in developing high-performance energy conversion (e.g. , solar cells and fuel cells) and storage (e.g. , supercapacitors and batteries) devices. This article reviews progress in the research and development of carbon nanomaterials during the past twenty
    [Show full text]
  • Correlating Microstructure and Optoelectronic Performance of Carbon-Based Nanomaterials
    Correlating Microstructure and Optoelectronic Performance of Carbon-Based Nanomaterials By Caitlin Rochford Submitted to the graduate degree program in Department of Physics and Astronomy and the Graduate Faculty of the University of Kansas in partial fulfillment of the requirements for the degree of Doctor of Philosophy. ________________________________ Dr. Judy Wu, Chairperson ________________________________ Dr. Hsin-Ying Chiu ________________________________ Dr. Siyuan Han ________________________________ Dr. Hui Zhao ________________________________ Dr. Cindy Berrie Date Defended: June 8, 2012 The Dissertation Committee for Caitlin Rochford certifies that this is the approved version of the following dissertation: Correlating Microstructure and Optoelectronic Performance of Carbon-Based Nanomaterials ________________________________ Dr. Judy Wu, Chairperson Date approved: June 8, 2012 ii Abstract There is a great deal of interest in carbon nanostructures such as graphene and various forms of carbon nanotubes due to their exceptional physical, electronic, and optical properties. Many technological applications have been proposed for these nanostructures, but despite the promise many carbon nanostructure-based optoelectronic devices fail to compete with their conventional counterparts. This is often due in large part to a non-optimized material or device microstructure. Factors such as crystallinity, contact quality, defect structure, and device configuration can critically affect device performance due to the high sensitivity and extreme surface to volume ratio of carbon nanostructures. In order for the exceptional intrinsic properties of the nanostructures to be exploited, a clear understanding of the microstructure and its correlation with device-relevant optoelectronic properties is needed. This dissertation presents four projects which demonstrate this principle. First, a TiO2-coated carbon nanofiber is studied in order to optimize its structure for use in a novel dye-sensitized solar cell.
    [Show full text]
  • Free-Standing Sulfur Host Based on Titanium-Dioxide-Modified Porous
    Journal of Power Sources 356 (2017) 172e180 Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour Free-standing sulfur host based on titanium-dioxide-modified porous- carbon nanofibers for lithium-sulfur batteries ** Xiong Song a, Tuo Gao a, Suqing Wang a, b, , Yue Bao a, Guoping Chen a, Liang-Xin Ding a, * Haihui Wang a, a School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou 510640, China b Institute of Superconducting & Electronic Materials, Australian Institute of Innovative Materials, University of Wollongong, NSW 2522, Australia highlights graphical abstract A flexible porous carbon nanofiber film was fabricated by electrospinning. Ultrafine titanium dioxide and gra- phene were adopted to modify the nanofibers. The sulfur cathode film exhibits good flexibility and foldability. The flexible film cathode shows excellent electrochemical performance. article info abstract Article history: Lithium-sulfur (Li-S) batteries are regarded as a promising next-generation electrical-energy-storage Received 27 November 2016 technology due to their low cost and high theoretical energy density. Furthermore, flexible and wearable Received in revised form electronics urgently requires their power sources to be mechanically robust and flexible. However, the 24 April 2017 effective progress of high-performance, flexible Li-S batteries is still hindered by the poor conductivity of Accepted 26 April 2017 sulfur cathodes and the dissolution of lithium polysulfides as well as the weak mechanical properties of sulfur cathodes. Herein, a new type of flexible porous carbon nanofiber film modified with graphene and ultrafine polar TiO2 nanoparticles is designed as a sulfur host, in which the artful structure enabled the Keywords: fi fi Flexible highly ef cient dispersion of sulfur for a high capacity and a strong con nement capability of lithium fi fi Free-standing polysul des, resulting in prolonged cycle life.
    [Show full text]
  • Running Head: TITANIUM DIOXIDE on CARBON NANOTUBES DETERMINE OXIDATIVE 1 STRESS
    Running head: TITANIUM DIOXIDE ON CARBON NANOTUBES DETERMINE OXIDATIVE 1 STRESS The Loadings of Titanium Dioxide on Multi-Walled Carbon Nanotubes Determine Different Oxidative Stress in vitro Sabrina H. Han University of Florida TITANIUM DIOXIDE ON CARBON NANOTUBES DETERMINES OXIDATIVE STRESS 2 Abstract Titanium dioxide (TiO2) has been engineered with multi-walled carbon nanotubes (MWCNT) to optimize their performance with different loading ratios. With their expanded industrial and commercial utilization, there is a parallel concern for their potential health risks. Evidence has shown that MWCNT can induce oxidative stress and cause pulmonary injury. However, little is known if different loadings of TiO2 on MWCNT can modulate their toxicity. We hypothesize that higher loading MWCNT-TiO2 hybrids will lead to increased reactive oxygen species (ROS) production, impaired mitochondrial respiration, and increased antioxidant gene expression in small airway epithelial cells (SAEC). MWCNT with varied loading of TiO2, 10:1 MWCNT-TiO2 (high), 20:1 MWCNT-TiO2 (medium), and 30:1 MWCNT-TiO2 (low) were tested for cytotoxicity, ROS production, oxygen consumption rates, and antioxidant gene expression. Cytotoxicity assays indicate that these nanohybrids are not acutely toxic to SAEC at the tested doses. Bioenergetics were insignificantly affected by the tested doses based on the Seahorse assay data. All treatments, except TiO2 alone, significantly induced ROS production with a dose- dependent trend. The qPCR results demonstrated that expression of antioxidant genes was altered by the treatment of MWCNT-TiO2 hybrids. Loading of TiO2 to MWCNT can lead to oxidative stress, distinct from that induced by MWCNT alone. TITANIUM DIOXIDE ON CARBON NANOTUBES DETERMINES OXIDATIVE STRESS 3 Introduction With the growing development of nanotechnology, carbon nanotubes (CNTs) are widely used in various applications with seemingly unlimited potential.
    [Show full text]