bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Carbon Nanotube/Polymer Hole Transporting Layers Bring Enhanced Performance to Perovskite, Quantum Dot and Organic Photovoltaic Devices
Authors: Nicholas Robin john , Habisreutinger Severin , Snaith Henry , Watt Andrew , Sharkey J. Joseph
Published: February 2020

Novel materials for solar cells have been developing very rapidly, for example perovskite based solar cells have recently experienced an unprecedented increase in efficiency to values exceeding 20% within just two years. An important part of the performance of these cells are issues such as stability, cost and manufacturability. In this presentation we demonstrate that the hole transporting layer in such cells can be replaced with polymer-functionalized single-walled carbon nanotubes (SWNTs) embedded in an insulating polymer matrix. With such a composite structure a power conversion efficiency of up to 15.3% is achieved. This layer shows a much improved moisture resistance and at the same time has a thermal stability significantly superior to other hole-transporting materials employed in high-performance perovskite solar cells. This is likely to be a critical development for enhancing the long-term stability of high-efficiency perovskite solar cells.

In addition the same type of SWNT/polymer hole transporting layer can be employed in both conventional organic PhotoVoltaic devices and devices made using colloidal quantum dots, both of which show efficiencies close to 10%.  This type of novel hole transporting layer made from carbon nanotube may well have a very extensive range of applications based on its combination of selective conduction and robust performances
(Invited) Charge Separation and Recombination at Single-Walled Carbon Nanotube Photovoltaic Interfaces
Authors: Blackburn Jeffrey L. , Ferguson Andrew John , Reid Obadiah , Ihly Rachelle , Dowgiallo Anne-Marie , Schulz Philip , Yang Mengjin , Zhu Kai , Berry Joseph
Published: February 2020

Single-wall carbon nanotubes (SWCNTs) have several fundamental properties that make them attractive for photovoltaics, including high electron and hole mobilities, size-tunable ionization potentials and electron affinities in an energy range relevant to many PV devices, and strong optical transitions in the visible and near-infrared spectral regions. These properties have motivated the use of thin SWCNT films for both charge extraction in PV electrodes and charge generation in PV active layers. In both of these applications, the time scales and mechanisms for interfacial charge separation and recombination play crucial roles in determining the resulting photovoltaic efficiencies. In this presentation, I will discuss time-resolved spectroscopic studies of charge separation and recombination across PV-relevant interfaces with SWCNTs. I will discuss two model interfaces – (1) SWCNT/perovskite interfaces, where the SWCNTs are used to extract holes from the perovskite active layer, and (2) SWCNT/fullerene interfaces, where charges are generated via interfacial dissociation of SWCNT excitons. Following the evolution of excitons and charges with multiple techniques provides a platform for understanding the time scales and quantum yields for interfacial charge transfer, recombination rates and mechanisms, and the dependence of charge transfer rates and yields on interfacial energetics. These time-resolved measurements are correlated with device results to provide a window into the connection between interfacial energetics/kinetics and device function.
Electrosynthesised Metal (Ni, Fe, Co) Oxide Films on Single-Walled Carbon Nanotube Platforms and Their Supercapacitance in Acidic and Neutral pH Media
Authors: Adekunle Abolanle Saheed , Ozoemena Kenneth I. , Ebenso Eno E
Published: February 2020

The need for alternative energy sources has led to renewed research interests in electrochemical energy storage systems, especially supercapacitors [1]. Carbon materials such as carbon blacks, carbon fibres, cloths and nanotubes [2], have been used as electrode supports in supercapacitors. Carbon nanotubes (CNTs) have attracted attention due to their unique properties such as high surface area and high porosity that lead to high power densities of supercapacitors [2]. In the quest for an alternative sources, researchers have explored the charge storage properties of different metal oxide systems such as anhydrous Co-Ni oxides in alkaline medium, MnO2 in neutral and acidic conditions, NiO in an acidic conditions [3], Co3O4 in an alkaline medium [4], and Fe3O4 in neutral solution (Na2SO4) and in both neutral and alkaline media [5], as an inexpensive alternatives to RuO2. In addition to good supercapacitive behaviour, metal oxides also have the advantage that they can be readily made into thin films.

Although, supercapacitive properties of metal oxides on different substrates have been reported, this work represents the first time a comparative study of the supercapacitive properties of three metal (Ni, Fe, Co) oxide nanoparticles electrochemically deposited onto SWCNTs was carried out. In this work, Supercapacitive properties of single-walled carbon nanotubes/metal oxides nanocomposites (SWCNT-MO where M=Ni, Fe, Co) is described. The SWCNT-MO nanocomposites were confirmed with SEM, EDX and XPS techniques. Supercapacitive properties of the modified electrodes in H2SO4 and Na2SO4 electrolytes was investigated using cyclic voltammetry (CV), galvanostatic constant current charge-discharge (CD) and the electrochemical impedance spectroscopy (EIS) techniques. Electrodecorating acid-functionalised SWCNTs with metal (Ni, Fe, Co) oxide nanoparticles leads to significant enhancements on the supercapacitive properties of these materials in acidic and neutral media compared to many other literature reports. SWCNT-NiO nanocomposite modified electrodes gave better supercapacitive performance with a specific capacitance of 186 mFcm-2 (or 928 Fg-1). This value compared quite favourably and even higher than values hitherto reported in several literature.

References

1. M. Winter, R. J. Brodd, Chem. Rev. 2004, 104, 4245.

2. A. T. Chidembo, K. I. Ozoemena, B. O. Agboola, V. Gupta, G. G. Wildgoose, R. G. Compton, Energy Environ. Sci. 2010, 3, 228.

3. Q. Wang, Z. Wen, J. Li, Adv. Funct. Mater. 2006, 16, 2141.

4. L. Cao, M. Lu, H. L. Li, J. Electrochem. Soc. 2005, 152, A871.

5. S. Y. Wang, K. C. Ho, S. L. Kuo, N. L. Wu, J. Electrochem. Soc. 2006, 153, A75.
Preparations of Turpentine Based Carbon Nanospheres As Anode Materials for Lithium Ion Batteries
Authors: Arie Arenst Andreas , Devina Konstantia Inez , Halim Martin , Lee Joong-Kee
Published: February 2020

Nanocarbon such as carbon nanotubes (CNTs) and carbon nanospheres (CNSs) have excellent electrical properties so that they can be used to substitute graphite as anode material for lithium-ion battery. The use of nanocarbon as anode material provides a short path for the ion and electron movement in electrodes. Therefore, the energy density of the battery can be improved. In this research, the production of CNT and CNS was carried out through spray nebulization at 650, 700, and 750oC  with 15, 30, and 45 min reaction time in the presence of ferrocene as catalyst with the concentration of 0.015; 0.02; 0.025 g/ml of hydrocarbon. Turpentine oil, an environmentally friendly precursor, was used as carbon source. The materials obtained was physically characterized by SEM, TEM, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Meanwhile, the electrochemical properties will be analized by plotting charge-discharge capacity vs cycle number and electrochemical impedance spectroscopy.
Searching for Fullerene Electron Conductors for Perovskite Solar Cells
Authors: Xie Su-Yuan
Published: February 2020

Fullerene derivatives are useful as electron-transport materials (ETMs) in planar heterojunction perovskite solar cells, but the guideline for an efficient fullerene electron conductor is still unclear. Recently we have been able to evaluate photovoltaic performances of a series of typical fullerene derivatives, such as indene-C60 bisadduct (ICBA), 2-(3-ethoxycarbonylpropyloxy)-(5,8)-dihydronaphthyl-(6,7)-[6,6]-C60 (EDNC), and 2- benzyloxy-(5,8)-dihydronaphthyl-(6,7)-[6,6]-C60 (BDNC) as well as [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), in inverted planar heterojunction perovskite solar cells with the cell structure of ITO/PEDOT:PSS/CH3NH3PbI3/fullerenes/Al. The LUMO energy level of PCBM matches well with that of CH3NH3PbI3, but ICBA has ~0.2 eV higher LUMO energy level than that of PCBM. The devices using PCBM and ICBA as ETMs exhibited power conversion efficiency (PCE) of 15.4% and 1.45%, respectively, with implication about LUMO energy level of fullerene derivative is critical to influence photovoltaic behaviors of perovskite solar cells. Although EDNC has the similar LUMO with PCBM, lower electron mobility of EDNC resulted in slightly lower PCE (12.64%). Both EDNC and BDNC have almost the same LUMO energy level and electron mobility, on the other hand, better surface morphology of EDNC contributes to better photovoltaic performance for EDNC [than that of BDNC (7.36%)]. This work demonstrated that guidelines such as LUMO energy level, electron mobility, and surface morphology should be envisaged in searching for fullerene derivatives as efficient ETM in perovskite solar cells.
Platinum-Cobalt Alloy/Reduced Graphene Oxide Nanohybrid Counter Electrode for Dye-Sensitized Solar Cells
Authors: Yoon Seok-Woo , Dao Van-Duong , Larina Liudmila L. , Choi Ho-Suk
Published: February 2020

This study reports on the synthesis of a PtCo alloy/reduce graphene oxide (RGO) nanohybrid materials and their application as an efficient counter electrodes (CEs) in dye–sensitized solar cells (DSCs). Bimetallic Pt0.1Co0.9 nanoparticles (NPs) with average size of ~ 5 nm were successfully and uniformly immobilized on the surface of RGO after co-reduction of metal precursor ions and graphene oxide into bimetallic alloy and RGO, respectively, via dry plasma reduction (DPR) under an atmospheric pressure and near room temperature. Furthermore, the set of bimetallic PtCo/RGO nanohybrids were also synthesized using various volume ratios of Pt to Co precursors. Uniform and dense distribution of bimetallic PtCo NPs on the RGO surface was obtained. The highest electrocatalytic performance, which corresponded to the lowest charge transfer resistance of 2.26 Ω, was achieved with the Pt0.1Co0.9 NPs/RGO nanohybrid. The application of developed nanohybrid as an alternative CE for DSCs leads to increase in efficiency by 5.7% over that of the Pt/RGO-based DSC, and by 40.6% over the efficiency of the Pt-free device. We believe that this work provides an effective strategy for optimizing Pt utilization in photovoltaic-device targeted nanohybrid, suggesting the decrease of the production cost of DSCs along with the improvement of efficiency.
Effect of Edge-Carboxylation in Graphene Nanoplatelets on the Performance of Electrochemical Energy Storage
Authors: Nath Narayan Chandra Deb , Lee Jae Joon
Published: February 2020

Graphene is considered prospective electrode materials for the electrochemical supercapacitor due to their higher surface area, good electronic conductivity, high chemical stability, and wide operating temperature range. The hetero-atom doping and surface functionalization of graphene are also advantageous to enhance the electrochemical active surface area, thermal and electronic conductivity, wettability and ion transport, and stability. The edge-carboxylated graphene nanoplatelets have been used as oxygen-rich efficient counter electrodes for dye-sensitized solar cells. The catalytic activity in graphene may be due to the oxygen containing functional groups (e.g., carboxyls, hydroxyls, epoxides, and carbonyls), achieved by controlling the amount of oxygen functional groups via thermal annealing or acid oxidation. The surface functional groups or heteroatoms can help the adsorption of ions and then improve the hydrophilicity/lipophilicity of the carbon materials, leading to enhanced wettability and facilitated rapid electrolyte ion transport within the micropores. At the same time, the presence of functional groups (e.g., oxygenated groups) on the surface of carbonaceous materials may induce faradaic redox reactions, leading to a 5–10% increase in the total capacitance. Thus, introducing surface functional groups or heteroatoms on the surface of carbon materials appears to be an effective way of improving an electrode’s capacitance. In the present study, we control the degree of carboxylation in the surface of graphene nanoplatelets by thermal and acidic oxidation processes and studied it effects on the performance of electrochemical supercapacitor.
Photoluminescent Carbon Nanotubes Interrogate the Permeability of Multicellular Tumor Spheroids
Authors: Shamay Yosef , Jena Prakrit Vaibhav , Shah Janki , Roxbury Daniel , Paknejad Navid , Heller Daniel A
Published: February 2020

The near-infrared photoluminescence from non-covalently dispersed single-walled carbon nanotubes (SWCNT) is optimally suited to probe distinct classes of biological environments. With aspect ratios of >100:1, nanotubes present an opportunity to observe atypical interactions between linear filamentous particles and three-dimensional biological environments. A pressing concern in therapeutic biomedicine is the inability of drug-carrying nanoparticles that function well in two dimensional cell cultures, to show efficacy in vivo. The inability of spherical nanoparticles to penetrate dense three-dimensional structures in a well defined point of failure. By exploiting the ability to image single carbon nanotubes via widefield fluorescence microscopy, we quantified the relative permeability of multi cellular tumor spheroids to a linear nanoparticle1. The results indicate the ability of nanoparticles to penetrate tumor spheroids depends strongly on the nanoparticle shape. Additionally, this platform portends a new approach to characterize the permeability of living multicellular environments.

References:

Photoluminescent carbon nanotubes interrogate the permeability of multicellular tumor spheroids, Yosef Shamay*, Prakit V. Jena*, et al, Carbon 97 (2016) 99-109
Carbon Nanotubes for Theranostics
Authors: Gajewska Agnieszka , Gonzalez Dominguez Jose Miguel , DaRos Tatiana
Published: February 2020

The current technological development and application of Carbon Nanotubes (CNTs) unfailingly require the use of chemical tools. Pristine CNTs often need to be chemically processed or functionalized in order to exhibit the most suitable features and to optimize their handling in specific applications. Chemical functionalization stands therefore as a universal means to overcome CNTs insolubility in water, by rendering their surface hydrophilic, a necessary step towards promising biomedical outcomes.[1]

As a matter of fact, water-dispersible CNTs may not trigger immunitary responses, and also may present high cell uptake along with very low cytotoxicity as compared to their not functionalized counterparts,[2]stressing out the crucial role of the affinity and stability of CNTs in aqueous media.

Our recent efforts in the functionalization of carbon nanotubes are focused on the condition optimization to achieve a fast and versatile derivatization by introduction of appendages apt to increase dispersibility of the starting materials in polar solvent. The so obtained derivatives may be used as theranostic platform.

[1]      N. Saito, H. Haniu, Y. Usui, K. Aoki, K. Hara, S. Takanashi, M. Shimizu, N. Narita, M. Okamoto, S. Kobayashi, H. Nomura, H. Kato, N. Nishimura, S. Taruta, M. Endo, Chem. Rev.
2013, 11, 6040-6079.

[2]       S. Chen, S. Hu, E. F. Smith, P. Ruenraroengsak, A. J. Thorley, R. Menzel, A. E. Goode, M. P. Ryan, T. D. Tetley, A. E. Porter, M. S. P. Shaffer, Biomaterials
2014, 35, 4729-4862.
Targeting Type-I Eicosacationic [70]Fullerene-(Light Harvesting Antenna) PDI Agents for Efficient Photokilling of Multiantibiotics-Resistant Bacteria
Authors: Wang Min , Huang Yingying , Hamblin Michael , Chiang Long
Published: February 2020

We are particularly interested in mediating broad-spectrum killing of pathogenic Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria targets. Systematic evaluation was taken to evaluate a structure–function relationship of fullerene-(light harvesting antenna) conjugative diads and triads on the influence of their biological activity, aiming to achieve the optimized photodynamic inactivation (PDI) efficiency against multiantibiotics-resistant bacteria.

Accordingly, we found a rational design of effective fullerene-based nano-photosensitizers by chemical modification of the carbon cage with two cell-targeting moieties each with a well-defined high number of cationic charges that allowed us to demonstrate the feasibility of these compounds giving cytotoxicity toward both Gram-positive and Gram-negative species. We also uncovered the large enhancement of PDI efficiency in photokilling of infectious bacteria by replacing the C60 cage with a C70 leading to novel type-I eicosacationic [70]fullerenes as potential nano-PDI agents.
Synthesis of Red Fluorescent Graphene Quantum Dots for the Bioimaging Platform
Authors: Fan Louzhen
Published: February 2020

Graphene quantum dots (GQDs) have attracted much recent attention due to their ultrafine dimensions, tunable surface functionalities and economical synthetic routes. The stable photoluminescence (PL) and low toxicity make them outstanding as an alternative to organic dyes and inorganic quantum dots (QDs) in biological applications.1 On the other hand, due to the auto-fluorescence and light scattering background of biological specimens in the short-wavelength region, fluorescent materials of choice are expected to emit in the long-wavelength region in order to provide a deeper light penetration into the specimens, resulting in a higher imaging contrast. To date, most of the reported GQDs emit the blue to green fluorescence, which usually exhibits excitation wavelength dependence2. Herein, we report the facile electrochemical exfoliation of graphite in K2S2O8 solution for the synthesis of uniform small-sized red fluorescent GQDs (RF-GQDs) without any chemical modification, which has been used for cellular imaging.2

Acknowledgement: This work is supported by NSFC (21073018), the Major Research Plan of NSFC (21233003), the Fundamental Research Funds for the Central Universities.

Reference:

(a) S. N. Baker, G. A.Baker, Angew
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49, 6726-6744; (b) J. Shen, Y. Zhu, C. Chen, X. Yang, C. Li, Chem
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2011,
47, 2580; (c) K. Habiba, V. I. Makarov, J. Avalos, M. J. F. Guinel, B. R. Weiner, G. Morell,  Carbon 2013,
64, 341.

 (a) Z. Fan, Y. Li, X. Li, L. Fan, S. Zhou, D. Fang, S. Yang, Carbon 2014, 70, 149; (b) M. Zhang, L. Bai, W. Shang, W. Xie, H. Ma,  D. Fang, H. Sun, L. Fan, L.; Han, M.; Liu, C.; Yang, S., J
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2012, 22, 7461.
(Invited) Revisited Roles of Bimetallic Catalysts for Controlled CVD Growth of Single-Walled Carbon Nanotubes
Authors: Maruyama Shigeo , Xiang Rong , An Hua , Qian Yang , Cui Kehang , Kumamoto Akihito , Inoue Taiki , Chiashi Shohei , Ikuhara Yuichi
Published: February 2020

Bimetallic catalysts such as Co-Mo have been used for efficient growth of vertically aligned single-walled carbon nanotube (SWNTs) for a decade [1]. Recently, different kinds of bimetallic catalyst such as Co-W [2] or Co-Cu [3] are employed for structure controlled growth of SWNTs. Different roles of bimetallic catalysts are revisited by newly proposed in-plane transmission electron microscopy (TEM) technique, which enables a direct TEM characterization of catalysts and CVD grown nanotubes on SiO2 TEM grid. Sputtered and dip-coated cobalt-based catalysts, i.e., Co, Co-Mo, Co-Cu, Co-W are used in alcohol catalytic CVD (ACCVD).

We found the Co oxide catalysts can efficiently grow narrower diameter and smaller average diameter SWNTs compared with pre-reduced Co catalysts. The in-plane TEM and X-ray photoelectron spectroscopy (XPS) reveal that Co catalysts are transformed to Co3O4 after reduction-calcination process and then decompose to CoO before growth at a typical growth temperature (800 ºC) in Ar atmosphere. We conclude that an in-situ reduction process occurred on low-mobility CoO after the introduction of ethanol is essential to activate small metallic Co catalysts. The in-plane TEM studies confirmed that Co-Mo bimetallic catalysts have the same mechanism as oxidized Co system, i.e. low mobility oxides and reduced metal, consistent with our previous report [1].

By using Co-Cu catalysts, we can synthesize vertically aligned SWNTs with subnanometer diameters on quartz (and SiO2/Si) substrates [3]. Scanning transmission electron microscopic energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into larger size, which contributed to the small diameter of SWNTs.

High-melting point W6Co7 alloy is reported to grow a single chirality, (12,6) with over 90 % abundance through high-temperature (1030 ºC) reduction and growth [2]. Here, we show that a sputtered Co-W catalyst can selectively grow (12,6) SWNTs by CVD at lower temperatures. Statistical Raman mapping analysis and optical absorption spectrum of the as-grown SWNTs reveal that the abundance of (12,6) is over 50%. The morphology and structure of catalyst is investigated by the in-plane TEM, which discloses the complicated structure changes before and after growth.

References:

[1] M. Hu, Y. Murakami, M. Ogura, S. Maruyama, T. Okubo, J. Catalysis, 225 (2004) 230.

[2] F. Yang et al., Nature 510 (2014) 522.

[3] K. Cui, A. Kumamoto, R. Xiang, H. An, B. Wang, T. Inoue, S. Chiashi, Y. Ikuhara, S. Maruyama, Nanoscale, (2015) [DOI: 10.1039/C5NR06007A].
Raman Spectroscopic Evidence of the Selective Extraction of Metallic SWNTs By Polymethyl(1-undecylic acidyl)Silane
Authors: Gao Jinling , Huang Yao , Lian Yongfu
Published: February 2020

Water soluble polymethyl(1-undecylic acidyl)silane was synthesized by the hydrosilylation of 10-undecylenic acid with polymethylsilane catalyzed by 2,20-azobisisbutyronitrile. The arc-discharged SWNTs were ultrasonically dispersed in an aqueous solution of polymethyl(1-undecylic acidyl)silane and then subjected to ultracentrifugation. Raman spectroscopic characterization confirmed that  the supernatant is enriched in the metallic SWNTs, especially those with chiral indexes of (14,2), (15,0), (13,1), (12,3) and (19,1) metallic SWNTs. In this work, the SWNTs of larger diameters and smaller chiral angles than those reported previously were selectively extracted. Moreover, FT-IR spectroscopy and Raman scattering evidence the charge transfer between polymethyl(1-undecylic acidyl)silane and SWNTs. It is assumed that polymethyl(1-undecylic acidyl) silane could wrap chiral-index-selectively onto SWNTs through a fairly weak CH–p interaction, and that the stiffness and length of main chains and side chains as well as the charge state of the polymethylsilane derivative play vital roles in the selective extraction of metallic SWNTs.
(Invited) Porphyrin/Carbon Nanotube Supramolecular Self-Assembly : A Thermodynamical Approach
Authors: Delport Géraud , Vialla Fabien , Campidelli Stephane , Voisin Christophe , Lauret Jean-Sébastien
Published: February 2020

Non covalent interactions through pi-stacking between carbon aromatic cores appear as an essential building block to engender the structural stability and electronic coupling of organic and biologic supramolecular assemblies (DNA, proteins, photosynthetic reaction center...). Interestingly pi-stacking functionalization has emerged as a rich and powerful way to synthesize hybrid compounds made from carbon nanotubes with organic molecules adsorbed on their sidewall. This scheme opens avenues for various applications including photo-voltaics, photo-detection, bio-sensing or imaging. In this context, we recently demonstrated that the decoration of nanotubes with dye molecules (porphyrins) brings remarkable properties including an efficient and ultrafast photo-induced energy transfer as well as good stability [1-3].

    In the present work, we unveil through a thermodynamics study an original diameter dependence of the interaction between nanotubes and porphyrin monomers, which favors the larger diameters. We extract parameters such as the reaction time constant and the Gibbs energy of the reaction, which can be described by the classical cooperative adsorption Hill model. Moreover, the evolution of the Gibbs energy as a function of the nanotube diameter is studied for 16 nanotube chiral species [4], and compared with DFT calculations [5].

Finally, we show how tiny changes in the molecules structure influence their self assembly around the nanotube.

References

[1] C. Roquelet, et al, ChemPhysChem 2010,  11, 1667

[2] G. Clave, G. Delport et al, Chem. Mat. 2013, 25, 2700

[3] C. Roquelet, et al, Appl. Phys. Lett. 2010, 97,141918

[4] F. Vialla, G. Delport et al, Nanoscale, accepted

[5] W. Orellana et al, J. Mater Sci 2015, 50, 898
Degradation of Carbon Nanomaterials Using Electrochemical Oxidation on BDD Electrodes
Authors: Reipa Vytas , Petersen Elijah , Hanna Shannon , Elliott John
Published: February 2020

Toxic potential of carbon nanomaterials (CN) to environmental species and humans is well documented. As carbon nanomaterials are produced in kiloton quantities worldwide, so is the risk of environmental contamination through industrial discharge and use (1).  Eventually such discharge may diffuse through aquifers and residential drinking water. Significant challenges exist in decontaminating the effluent water, containing carbon nanomaterials. Carbon nanomaterials can be destroyed or degraded by incineration, however it requires the ability to locate, collect and concentrate carbon nanomaterial sample from the environment, which is often quite complicated. We have investigated the way to rapidly and significantly decrease the CN concentration in aqueous suspensions, thus reducing its toxic potential.

Carbon nanomaterial degradation is based on generating strong oxidizing agents on a boron doped diamond anode, combined with a vigorous solution turbulence due to gas evolution inside a thin layer flow-through cell at high current densities. These agents react with carbon nanomaterials, damage them through multiple oxidations, destroy their structural integrity and rapidly reduce their concentration in aqueous solvents. In addition, the inert cathode surface facilitates hydrogen peroxide production due to the dissolved oxygen reduction reaction. As a result of strong oxidative reactions between nanomaterials and oxidative radicals, the outflowing water has a significantly lower concentration of suspended nanomaterials and, consequently is less toxic to the environment.

The method was tested with pristine single and multiwall carbon nanotube, graphene and fullerene aqueous suspensions. UV-VIS-NIR absorbance show that CN concentration is reduced below 1%  in a single pass through the single compartment electrochemical cell, thus offering a much faster way to degrade environmental toxicants compared to enzymatic or Fenton reaction approaches (2). Raman spectroscopy and analysis of the reaction products shows that oxidative attack on CN sp
2
–based structure by electrochemically generated reactive oxygen species leads to nanoparticle integrity loss and subsequent oxidation to CO2 .

References

Petersen, E. J. et al., Environ. Sci. Technol. 2011, 45, 9837-9856.

Allen, B. L. et al., J. Am. Chem. Soc. 2009, 131, 17194-17205.
(Invited) Cell Membrane Proteins Modulate the Carbon Nanotube Optical Bandgap Via Surface Charge Accumulation
Authors: Roxbury Daniel , Jena Prakrit Vaibhav , Shamay Yosef , Horoszko Christopher , Heller Daniel A
Published: February 2020

Single-walled carbon nanotubes exhibit photostable near-infrared photoluminescence with excitation and emission energies that respond to fluctuations in the micro-environment. In the creation of robust nanotube-based optical sensors, it is desirable to identify shifts in excitation and emission of an ensemble nanotube sample (HiPco) in response to analytes. Here, we constructed a novel instrument to rapidly acquire two-dimensional excitation/emission photoluminescence data from nanotubes bound to the surfaces of live mammalian cells. We found that the process of contacting the surface of the cell induced a red-shift in nanotube emission with magnitudes that varied by cell-type. Removal of membrane proteins further red-shifted the nanotube sample to a common value independent of cell-type. The magnitudes of shifts due to the membrane proteins were correlated to the whole cell electrostatic potential and could be recapitulated in ionic solutions. These findings may enable the optical measurement of surface electrostatic potentials for biophysical measurements and biomedical applications.
Carbon Nanotube Photoluminescence for Bioelectroanalytical Measurements
Authors: Heller Daniel A , Roxbury Daniel , Jena Prakrit Vaibhav , Budhathoki-Uprety Januka , Williams Ryan M. , Shamay Yosef , Shah Janki , Harvey Jackson Dean , Horoszko Christopher , Langenbacher Rachel E , Galassi Thomas Vito
Published: February 2020

The intrinsic near-infrared photoluminescence of semiconducting single-walled carbon nanotubes exhibits environmental sensitivity which has been employed to detect various analytes in complex environments, including biological media. To build biomedical technologies that employ carbon nanotube photoluminescence, a better understanding of the optical response, as well as new methods to measure it in biological systems, are needed. We have developed new imaging platforms to quantify nanotube emission, including a method to conduct photoluminescence excitation/emission spectroscopy on living samples. We are also exploring ionic screening phenomena during ambient pseudocapacitive charging as a modulator of nanotube photoluminescence for electroanalytical measurements in biological media.
(Invited) Cavity Enhanced Light Emission from Electrically Driven Carbon Nanotubes
Authors: Krupke Ralph
Published: February 2020

An important advancement towards optical communication on a chip would be the development of  integrable, nanoscale photonic emitters with tailored optical properties. Here we demonstrate the use of carbon nanotubes as electrically driven high-speed emitters in combination with a nanophotonic cavity which allows for exceptionally narrow linewidths [1].  The one-dimensional photonic crystal cavities are shown to spectrally select desired emission wavelengths, enhance intensity and efficiently couple light into the underlying photonic network with high reproducibility. Under pulsed voltage excitation we realize on-chip modulation rates in the GHz range, compatible with active photonic networks. Because the linewidth of the molecular emitter is determined by the quality factor of the photonic crystal, our approach effectively eliminates linewidth broadening due to temperature, surface interaction and hot-carrier injection.

This work was supported by the Volkswagen Foundation, by the Helmholtz Society through the program STN and the KNMF.

[1] Felix Pyatkov, Valentin Fütterling, Svetlana Khasminskaya, Benjamin Flavel, Frank Hennrich, Manfred M. Kappes, Ralph Krupke, and Wolfram H.P. Pernice, under review
Advanced Spectral Analysis for Characterizing Single-Walled Carbon Nanotube Samples
Authors: Weisman R. Bruce , Bachilo Sergei M. , Kadria-Vili Yara
Published: February 2020

Single-walled carbon nanotubes (SWCNTs) are a family of 1D nanomaterials with the potential for a range for novel applications. However, accurate and convenient characterization is still an important challenge, since most SWCNT samples contain mixtures of many structural forms ((n,m) species) with different electronic, optical, mechanical, and chemical properties. Fluorescence emission, fluorescence excitation, and absorption spectra of such mixed samples are complex superpositions, with each (n,m) species giving multiple peaks. Therefore proper sample analysis requires detailed knowledge of the positions, widths, and intensities of those spectral features. Here we report progress in determining semiconducting SWCNT sample compositions by carefully analyzing the absorption and emission spectra simultaneously.

One step in this approach is determining detailed fluorescence excitation spectra. For this we have prepared samples enriched in a single (n,m) and carefully measured their excitation spectra. Each such spectrum was broken down and modeled as features representing SWCNT electronic and vibronic transitions. We then deduced Voigt or Pearson line shapes that represent positions, widths, and intensities of these peaks as a function of nanotube structure. This has allowed us to construct a model for fluorescence excitation spectra that can be applied to (n,m) species beyond those that were directly measured.

Similarly, to represent (n,m)-dependent emission spectra, we have made careful bulk and single-nanotube studies of features from the singlet bright exciton (E11) and three secondary emissive sidebands. We deduced parameters describing these features as a function of nanotube structure to construct a robust model for SWCNT emission spectra. This model, when combined with the one for excitation, allows the fluorescence spectra of nanotube mixtures to be properly analyzed as a sum of contributions from multiple (n,m) species.

Although this procedure does not reveal absolute species concentrations, the fluorescence analysis can be combined with absorption analysis and recent data for SWCNT absolute absorption cross sections to obtain quantitative sample compositions. For this purpose, the absorption spectrum of a mixed sample is simulated as a background function plus components determined from the fluorescence emission and excitation profiles for the (n,m) species that were found to be present. Then the separate E11 (n,m) absorbance components are divided by their structure-specific absorption cross sections to find absolute species concentrations.
Intensity Ratio of Resonant Raman Modes for (n,m) Enriched Semiconducting Carbon Nanotubes
Authors: Piao Yanmei , Simpson Jeffrey R , Streit Jason K. , Ao Geyou , Zheng Ming , Fagan Jeffrey A. , Hight Walker Angela R.
Published: February 2020

Relative intensities of resonant Raman spectral features, specifically the radial breathing mode (RBM) and G modes, of eleven, chirality-enriched, single-wall carbon nanotube (SWCNT) species were established under second-order optical transition excitation. The results demonstrate an under-recognized complexity in the evaluation of Raman spectra for the assignment of (n,m) population distributions in agreement with theory predicted by a symmetry-adapted nonorthogonal tight-binding model.[1] Strong chiral angle and mod dependencies affect the intensity ratio of the RBM to G modes.  Furthermore, we report five additional values for chirality dependent G+ and G- Raman peak positions and intensity ratios extending the available data to cover more of the smaller diameter regime by including the first (5,4) second-order, resonance Raman spectra.[2] Together, the Raman spectral library is demonstrated to be sufficient for decoupling multiple species viaa spectral fitting process, and enables fundamental characterization even in mixed chiral population samples.  

References:

[1] Popov, V. N.; Henrard, L.; Lambin, P. Resonant Raman Intensity of the Radial Breathing Mode of Single-Walled Carbon Nanotubes within a Nonorthogonal Tight-Binding Model. Nano Lett.
2004, 4, 1795–1799.

[2] Telg, H.; Duque, J. G.; Staiger, M.; Tu, X.; Hennrich, F.; Kappes, M. M.; Zheng, M.; Maultzsch, J.; Thomsen, C.; Doorn, S. K. Chiral Index Dependence of the G+ and G– Raman Modes in Semiconducting Carbon Nanotubes. ACS Nano
2012, 6, 904–911.
Alkane Filled Single-Wall Carbon Nanotubes: Endohedral Volume Control for Improved Nanotube Properties
Authors: Campo Jochen , Piao Yanmei , Lam Stephanie , Streit Jason K. , Hight Walker Angela R. , Fagan Jeffrey A.
Published: February 2020

Liquid-phase processing of single-wall carbon nanotubes (SWCNTs) generally results in the exposure of their core to the environment (opening) due to the energy input necessary for purification and solubilization, and this often affects the SWCNT properties [1-3]. For instance, for aqueous processing, SWCNTs are routinely getting filled with water, which leads to significant redshifts to, and inhomogeneous broadening of, the electronic transitions of the SWCNTs, as well as a substantial decrease of their fluorescence quantum efficiency [1]. Selection of (remaining) empty (end-capped) SWCNTs to avoid these detrimental effects is possible by means of ultracentrifugation, but is a natively low yield process [4]. In this work, adverse filling is prevented by intentionally prefilling the SWCNTs with alkanes, serving as a passive and highly homogeneous spacer. In contrast to water and other encountered fillants, the alkane core is of low dielectric nature and therefore only weakly affects the electronic structure of the SWCNTs, and hence effectively simulates empty core conditions. This yields highly resolved optical spectra with strongly shifted peak positions compared to water filled SWCNTs (see Figure 1), and fluorescence efficiencies approaching those of empty SWCNTs. It is demonstrated that this can be realized using a wide variety of linear as well as cyclic alkanes, in combination with various SWCNT materials having very different diameter distributions.

References

[1] Cambré, S.; Wenseleers, W. Separation and Diameter-Sorting of Empty (End-Capped) and Water-Filled (Open) Carbon Nanotubes by Density Gradient Ultracentrifugation.  Angew. Chem. Int. Ed. 2011, 50, 2764–2768.

[2] Cambré, S.; Santos, S. M.; Wenseleers, W.; Nugraha, A. R. T.; Saito, R.; Cognet, L.; Lounis, B. Luminescence Properties of Individual Empty and Water-Filled Single-Walled Carbon Nanotubes. ACS Nano 2012, 6, 2649.

[3] Duque, J. G.; Oudjedi, L.; Crochet, J. J.; Tretiak, S.; Lounis, B.; Doorn, S. K.; Cognet, L. Mechanism of Electrolyte-Induced Brightening in Single-Wall Carbon Nanotubes. J. Am. Chem. Soc. 2013, 135 (9), 3379–3382.

[4] Fagan, J.A; Huh, J.Y.; Simpson, J.R.; Blackburn, J.L.; Holt, J.M.; Larsen, B.A.; Walker, A.R.H. Separation of Empty and Water-Filled Single-Wall Carbon Nanotubes.  ACS Nano 2011, 5, 3943–3953.

Figure 1. Optical absorption spectra of electric Arc SWCNTs filled with linear alkanes (C
n
H2n+2) of different lengths, compared to the spectra of water-filled, ethyl acetate-filled (rinsing solvent) and empty Arc SWCNTs. The improved spectral resolution upon alkane encapsulation compared to water filling is clearly visible.

Figure 1
(Invited) New Vistas on Chemistry of Endohedral Metallofullerenes
Authors: Akasaka Takeshi , Yamada Michio , Kurihara Hiroki , Suzuki Mitsuaki , Guo Jing-Dong , Olmstead Marilyn M. , Balch Alan L. , Nagase Shigeru , Maeda Yutaka , Lu Xing
Published: February 2020

The isolated pentagon rule (IPR) states that stable fullerenes have each of their 12 pentagons surrounded by five hexagons. On the contrary, in 2000, that idea was altered by the discovery of the first non-IPR fullerenes, Sc2@C66 and Sc3N@C68. Themolecular structure of Sc2@C66 was assigned to possess a C2v(4348)-C66 cage that contained two sets of double fused pentagons by using 13C NMR spectroscopy and powder X-ray diffraction data analysis. However, that structure has remained a long-standing controversy, since it is thermodynamically unfavorable. Here, we demonstrate definitively that Sc2@C66 does not have the structure that was long believed to be but a brand new type. 2D-NMR spectroscopic and single-crystal X-ray analysis disclose that Sc2@C66 has a C2v(4059)-C66 cage containing two sets of unsaturated linear triquinanes (ULTs), in which three pentagons abut one another and two scandium ions are located within the folds of each of the ULT units. Our identication of Sc2@C66 as Sc2@C2v(4059)-C66 shows that new motifs in carbon cage geometry continue to be discovered and calls attention to the ULT unit, whose aromaticity and coordination chemistry deserve further study.
(Invited) Preparation of [60]Fulleropyrrolidines and Their Photovoltaic Applications
Authors: Feng Lai , Zhou Yi
Published: February 2020

A series of fulleropyrrolidine derivatives (FPx, x=1-8) with alternating N-phenyl or N-methyl group were prepared as acceptors for polymer solar cells (PSCs) with the purpose of investigating the effect of N-substitutions on the photovoltaic properties of fullerene materials. More importantly, the morphology studies by means of atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and space charge limited current (SCLC) measurements revealed that FP1 with N-phenyl group possessed not only appropriate miscibility with P3HT but also high electron mobility, which may account for its optimal photovoltaic properties. In addition, we will also demonstrate our recent progress on the preparation of graphene-based composites and their applications as the electron or hole extraction layer (EEL or HEL) in PSCs.

Figure 1
(Invited) Regioselective Bis-Prato Addition on TNT-EMF (M3N@Ih
-C80, M = Y, Gd) Controlled By Endohedral Metal Cluster
Authors: Yamakoshi Yoko , Aroua Safwan
Published: February 2020

Aiming the development of stable and controlled way of the chemical functionalization of fullerenes, there have been many reactions so far reported. The Prato reaction1 (1,3-dipolar cycloaddition reaction) has been used by many groups as one of the efficient chemical conversion methods in the preparation of functional fullerene derivatives. This method usually provides sufficiently stable fullerene derivatives in reasonable synthetic yields. Addressing the preparation of biocompatible fullerene derivatives, we are using this Prato reaction for the controlled functionalization of C60, C70 and TNT-EMF2 (M3N@Ih
-C80 or M3N@C80).

C60 usually produces the mono-Prato adduct selectively on the [6,6]-junction. However, as reported by the groups of Dorn3 and Echegoyen,4 M3N@C80 provides the mono-Prato adduct on both [6,6]- and [5,6]-junctions as a results of [6,6]-to-[5,6] isomerization via a [1,5]-sigmatropic rearrangement. The ratio of the thermodynamic regioisomers ([6,6]-mono and [5,6]-mono) was dependent on the size of metal cluster (M3N) inside C80
5 and was not affected by the exohedral functional groups outside C80 cage. 6

Although the bis-Prato addition of C60 proceeded uncontrolled manner, interestingly, bis-Prato addition of M3N@C80 proceeded in a regioselective manner especially in the presence of larger size of endohedoral metal clusters such as Y3N and Gd3N.7 Thermal treatment of bis-Prato adduct of Y3N@C80 caused random isomerization, but the bis-Prato adduct of Gd3N@C80 stayed rather stable presumably by the effect of larger endohedral metal cluster.

(1) Maggini, M.; Scorrano, G.; Prato, M. J. Am. Chem. Soc. 1993, 115, 9798. (2) Stevenson, S.; Rice, G.; Glass, T.; Harich, K.; Cromer, F.; Jordan, M. R.; Craft, J.; Hadju, E.; Bible, R.; Olmstead, M. M.; Maitra, K.; Fisher, A. J.; Balch, A. L.; Dorn, H. C. Nature
401, 898. (3) Cai, T.; Slebodnick, C.; Xu, S.; Harich, L.; Glass, T. E.; Chancellor, C.l Fettinger, J. C.; Olmstead, M. M.; Balch, A. L.; Gibson, H. W.; Dorn, H. C. J. Am. Chem. Soc. 2006, 128, 6486. (4) Cardona, C. M.; Eliott, B.; Echegoyen, L. J. Am. Chem. Soc. 2006, 128, 6480. (5) Aroua, S.; Yamakoshi, Y. J. Am. Chem. Soc. 2012, 134, 20242. (6) Aroua, S.; Garcia-Borras, M.; Osuna, S.; Yamakoshi, Y. Chem. Eur. J. 2014, 20, 14032. (7) Aroua, S.; Garcia-Borràs, M.; Bölter M. F.; Osuna, S.; Yamakoshi, Y. J. Am. Chem. Soc. 2015, 137, 58.

Figure 1
(Invited) 1,3-Dipolar Cycloadditions on Endohedral Fullerenes M3N@I

h
-C80 (M = Sc-Gd): Remarkable Endohedral-Cluster Regiochemical Control
Authors: Osuna Sílvia , Garcia-Borràs Marc , Yamakoshi Yoko , Echegoyen Luis
Published: February 2020

Since the C60 discovery in 1985, many fullerene structures have been synthesized and a variety of experimental and computational studies regarding the fullerene stability, characterization, properties such as aromaticity, and reactivity have been reported.1 The huge interest engendered by these fullerene-based materials is mainly attributed to their potential applications in the electronics, photovoltaics, biology, and medicine fields. Obstacles to such bio-applications include their poor solubility in water necessitating the preparation of water-soluble materials by suitable modifications. One of the most useful methods to functionalize fullerenes is via 1,3-dipolar cycloaddition (i.e. Prato reaction). The complete structural, chemical and electronic properties of (metallo)fullerenes are not totally understood at the present time. Specifically, the factors controlling the regiochemistry of multiple additions remain largely unexplored and poorly understood. In this communication, we rationalize using DFT calculations both the effect of the exohedral moiety and the orientation of the encapsulated cluster on the regioselectivity of the Prato (bis)addition to the Ih-C80 based endohedral metallofullerenes, M3N@Ih
-C80 (M=Sc, Lu, Y, and Gd).2-4

1M. Garcia-Borràs, S. Osuna, M. Swart, J. M. Luis, M. Solà, Chem. Soc. Rev., 2014, 43, 5089.

2S. Aroua, M. Garcia-Borràs, S. Osuna, Y. Yamahoshi, Chem. Eur. J. 2014, 20, 14032.

3S. Aroua, M. Garcia-Borràs, M. Bölter, M., S. Osuna, Y. Yamakoshi, J. Am. Chem. Soc. 2015, 137, 58.

4M. R. Cerón, M. Izquierdo, M. Garcia-Borràs, S. S. Lee, S. Osuna, L. Echegoyen, J. Am. Chem. Soc. 2015,
137, 11775.

Figure 1
(Invited) The Adaptive Structure of Carbon Nanohybrids Toward High-Relaxivity for the New MRI Contrast Agent
Authors: Sun Bao yun , Cui Rongli
Published: February 2020

Abstract: Water-soluble GO-Gd@C82 nanohybrids exhibited high relaxivities and could be explored as potential magnetic resonance imaging (MRI) contrast agents. To better understand the relaxation mechanism in the novel carbon nanohybrids, in this presentation, after the layers of in-depth analysis and exploration, we proposed that the structure and the physicochemical properties of carbon nanohybrids contributed a lot to the enhanced relaxivity. The better electron transfer from Gd@C82 to the GO nanosheet, the appropriate electric conductivity and the size of GO, the increased number of H proton exchange sites and the enough concentration of Gd3+ should be in the optimal equilibrium for higher relaxivity of GO-Gd@C82. This result is important for constructing and optimizing the novel architecture of nanoscale with higher relaxivity.
(Invited) Isolation and Structure Determination of La@C70(CF3)3
Authors: Aoyagi Shinobu , Wang Zhiyong , Omachi Haruka , Kitaura Ryo , Shinohara Hisanori
Published: February 2020

We report the single-crystal X-ray structure of La@C70(CF3)3, which was obtained through in situ exohedral functionalization by means of trifluoromethylation [1]. The X-ray crystallographic study reveals that La@C70(CF3)3 is the first example of an endohedral rare-earth fullerene based onD
5
h-C70. The dramatically enhanced stability of La@C70(CF3)3 compared to La@C70 can be ascribed to trifluoromethylation-induced bandgap enlargement.

[1] Z. Wang et al., Angew. Chem. Int. Ed. 2015, 54