bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Carbon Nanostructure for Flexible Zinc Ion Storage
Authors: Zhi Chunyi
Published: May 2020

We will discuss various carobn nanostructures and their derivates for zinc ion storage, for example, a zinc ion capacitor based on carbon nanotubes. In addition, prussian blue analogue (PBA)-type metal hexacyanoferrates have been considered as significant cathode materials for aqueous rechargeable zinc batteries (ZBs) due to the open face centered cubic framework, multiple active sites, and environmental benign. However, these PBA-type cathodes, such as cyanogroup iron hexacyanoferrate (FeHCF), suffer from ephemeral lifespan (≤1000 cycles), inferior rate capability (1A g-1), and low operating voltage (ca. 1.2 V). This is because the redox active sites of multivalent iron (Fe(III/II)), which dominates its electrochemical activities, can only be very limited activated and thus utilized. The limited activity is attributed to the spatial resistance caused by the compact cooperation interaction between Fe and the surrounded six cyanogroup per unit, and the inferior conductivity. In this paper, surprisingly, we found high-voltage-scanning can effectively activate the C-coordinated Fe (redox active sites) in FeHCF cathode in ZBs. The activation spurred the increase of capacity at a high operating voltage plateau of ca. 1.5 V. Thanks to this activation, the Zn-FeHCF hybrid-ion battery achieved a record-breaking cycling performance of 5000 (82% capacity retention) and 10000 cycles (73% capacity retention), respectively, together with a superior rate capability of maintaining 53.2% capacity at super-high current density of 8 A g-1 (ca. 97 C).

Figure 1
(Invited) Electrochemical Production of Graphene and Controlled Assembly of 3D Graphene Electrodes for Energy Storage Applications
Authors: Lee Michael J , Lee Hoyoung , Lee Kyungbin , Lee Byeongyong , Lee Seung Woo
Published: May 2020

Graphene has been intensively studied for electrode material for electrochemical energy storage devices utilizing its high electrical conductivity and high surface area. Recently introduced electrochemical exfoliation process has many advantages over conventional chemical methods, including low-cost, simple operation, fast production-rate, and in-situ functionalization. In particular, anodic electrochemical exfoliation process is one of the promising methods for fast and simple production of graphene at low cost.

In this presentation, we will first discuss the detailed mechanisms of the electrochemical exfoliation process of graphite into graphene using sulfate containing electrolyte systems. We systematically monitored the structural changes in graphite and associated gas formation during the electrochemical exfoliation process, revealing that water molecules are the main source of gaseous species for the effective exfoliation of graphite into graphene. Next, we will introduce our recent efforts to fabricate 3D structured graphene anodes for Li-, Na-, K-ion batteries. Moreover, we evaluated the temperature-dependent performance of 3D graphene anodes, demonstrating their superior charge storage performance in extreme cold environments.
(Invited) Carbon Nanotubes As an Effective and Stable p-Type Contact for Perovskite Solar Cells
Authors: Habisreutinger Severin N. , Noel Nakita K.
Published: May 2020

The enormous strides researchers have made in advancing perovskite-based photovoltaics in the past few years are fueling the dream of a rapid entry of this highly promising technology into the global energy market. This seems like serendipitous timing since solar power has gained an enormous momentum over the past decade exceeding all projections. This expansion in solar power is driven by an increasing understanding that climate change requires immediate action, in particular with regards to power generation; and simultaneously, the price for photovoltaic modules has remarkably quickly fallen to make solar power generation competitive vis-à-vis conventional technologies.

Compositional tuning of the perovskite absorber has led to immense improvements in stability and efficiency of perovskite solar cells leading to a certified efficiency of over 25% for a single-junction laboratory device. The successful transition of a photovoltaic technology from the lab into the field requires, however, two additional important parameters aside from efficiency which are essential for real-world deployment: stability and scalability.

We propose using single-walled carbon nanotubes (SWCNTs) as an alternative p-type layer for future application in perovskite solar cells.

Carbon nanotubes combine several highly attractive characteristics such as chemical inertness and mechanical resilience with intrinsically high charge-carrier mobilities endowing them with a unique potential for a much more stable dopant-free charge-selective contact. Furthermore, the SWCNT deposition techniques for large-scale use, such as spray coating, are already well-established opening clear avenues for direct implementation in a real-world industrial setting.

We demonstrate that a cascade-like transfer extraction through SWCNTs can minimize photovoltage losses by suppressing non-radiative recombination. By further improving the absorber quality, the voltage losses in solar cells can be reduced to around 340 mV which is comparable to conventional III-V semiconductor-based photovoltaics.

By further enhancing the selective charge extraction at the perovskite-SWCNT interface through interfacial charge transfer doping, we achieve steady-state efficiencies approaching 22% for alloyed narrow bandgap perovskites, illustrating the versatility and excellent performance of SWCNTs as contact material.
Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide Using CVD N-Doped Graphene on Copper Foam As Carbo-/Electro-Catalyst
Authors: Srimanon Krisara , Krittayavathananon Atiweena , Sarawutanukul Sangchai , Sawangphruk Montree
Published: May 2020

Nowadays, the increasing concentration of CO2 emission in our atmosphere is a serious environmental issue. According to an issue for preserving Earth’s Climate in the 13th UN Sustainable Development Goal, technologies that reduce both the carbon emissions of existing processes and those that efficiently utilize CO2 as feedstock for chemicals and fuels are necessarily required. Electrochemical reduction of CO2 (CO2R) is a promising method for converting this greenhouse gas into value-added products, utilizing renewable energy. A limitation is that CO2 is inert molecule () that requires considerable energy for chemical activation. In addition, the CO2R includes multiple steps of electron and proton transfer on catalyst surface. In general, the reduction potentials and product distribution for CO2R depend on experimental conditions, electrolytic solutions, and electrode materials. Herein, we used CVD nitrogen‐doped graphene on copper foam as carbo-/electro-catalyst (N-GP/Cu). To understand the selectivity of the as-prepared catalyst, we observe the electrochemical reduction product from CO2R using a combination of cyclic voltammetry (cv) and on-line mass spectrometry (DEMS). The presence of nitrogen heteroatom on the graphene sheet reduces the onset potential at ca. 0.5 V (vs. SCE) in 0.1M KHCO3 under CO2 gas. The N-GP/Cu can mainly convert CO2 into CO. We hope that this study may provide a guideline to develop the improved CO2 conversion catalyst.
Synthesis and Electrochemical Study of Graphene-Based Nanocomposites for Hydrogen Sorption and Storage
Authors: Boateng Emmanuel Q. , Thiruppathi Antony R. , Chen Aicheng
Published: May 2020

With impending serious concerns associated with climate change and the depletion of fossil fuels, an envisaged hydrogen economy remains a viable alternative for addressing future energy issues. However, the significant technical challenges from vehicular hydrogen storage systems such as weight, efficiency, safety and cost constraints must be properly resolved before a commercial application is possible. Compared to compressed high-pressure and liquid hydrogen storage systems, storing hydrogen in solid systems via chemisorption and physisorption is emerging as a promising approach for hydrogen storage [1-3]. In this presentation, recent advances in the solid-state hydrogen storage with a high volumetric density are highlighted.

In addition, graphene-based nanomaterials have been considered as a promising candidate for hydrogen storage due to its lightweight and high surface area [4]. We have synthesized graphene oxide (GO), reduced graphene oxide (rGO) and boron-doped reduced graphene oxide (B-rGO) and investigated their performance for hydrogen storage. To enhance their capacity for hydrogen storage, the fabricated graphene oxide based nanomaterials were further modified with palladium (Pd) nanoparticles. The morphological features, structure and chemical compositions of the synthesized nanomaterials (GO, rGO and B-rGO) and nanocomposites (Pd/GO, Pd/rGO and Pd/B-rGO) were characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy, showing that Pd nanoparticles were uniformly dispersed on the B-rGO surface. Cyclic voltammetry and galvanostatic charging-discharging technique were employed to probe the hydrogen storage capacity of the graphene based nanomaterials and the nanocomposites. The effect of the boron substitution and the Pd nanoparticle decoration on the hydrogen storage are discussed.

References:

[1] A. Chen, C. Ostrom. Palladium-based nanomaterials: synthesis and electrochemical applications. Chem. Rev. 115 (2015) 11999 - 12044.

[2] S. Konda, A. Chen, Palladium based nanomaterials for enhanced hydrogen spillover and storage. Mater. Today 19 (2016) 100 - 108.

[3] E. Boateng, A. Chen, Recent advances in nanomaterials-based solid-state hydrogen storage. Mater. Today Adv. (2019) in press.

[4] S. K. Konda, A. Chen, One-step synthesis of Pd and reduced graphene oxide nanocomposites for enhanced hydrogen sorption and storage. Electrochem. Commun. 60 (2015) 148–152.
A One-Dimensional Carbon Nanotube‒Metalloporphyrin Hybrid Material for Lithium Storage
Authors: Jeong Kihun , Kim Ju-Myung , Lee Sang-Young
Published: May 2020

Multi-redox organic and organometallic electrode materials have been emerging alternatives to the widespread inorganic counterparts in advanced power sources due to their design diversity, light weight, flexibility, and environmental benignity.1 However, their electrically insulating nature, limited capacity, and poor durability should be resolved for the practical application.

Here, we present a one-dimensional (1D) nanohybrid composed of a multiwalled carbon nanotube (MWCNT) core and a cobalt porphyrin shell (Figure) as a new class of electrode materials for rechargeable lithium batteries.2 Highly π-conjugated and multielectron redox-active meso-tetrakis(4-carboxyphenyl) porphyrinato cobalt (CoTCPP) shows strong noncovalent interactions with the MWCNT, leading to the successful formation of the 1D nanohybrid. The resultant nanohybrid, due to its structural uniqueness and maximal use of active areas, facilitates electron transport and electrolyte accessibility, which thus contribute to exhibiting a high specific capacity and improving redox kinetics. Furthermore, intrigued by the 1D structure of the nanohybrid, an all-fibrous nanomat electrode was fabricated through concurrent electro-spraying/-spinning processes. The nanomat electrode provides bicontinuous electron and ion conduction pathways, which eventually reveals the well-distinguishable lithiation behavior of CoTCPP and exceptional electrochemical performances with a long-term stability (ca. 226 mAh g
‒1
based on the electrode sheet weight at a current density of 5 C for over 1500 electrochemical cycles).

We hope that the material design strategy described in this study offers new insight into the development of high-performance electrode materials for next-generation power sources and energy storage systems.

References:

1. T. B. Schon, B. T. McAllister, P. F. Li, D. S. Seferos, Chem. Soc. Rev.
2016, 45, 6345.

2. K. Jeong, J.-M. Kim, S. H. Kim, G. Y. Jung, J. Yoo, S.-H. Kim, S. K. Kwak, and S.-Y. Lee, Adv. Funct. Mater.
2019, 29, 1806937.

Figure 1
Developing Ovarian Cancer Sensors Using Molecular Perceptron
Authors: Yaari Zvi A , Yang Yoona , Jagota Anand , Zheng Ming , Heller Daniel A.
Published: May 2020

Ovarian cancer patient prognosis and quality of life are significantly affected by the failure to accurately diagnose disease at early stage. Currently, less than 15% of ovarian cancer patients are diagnosed at stage 1, when 5-year survival rates are near 93%. Early detection may save more than 80% of women diagnosed with ovarian cancer. Our goal is to develop long-term implantable carbon nanotube-based sensors for ovarian cancer biomarkers to transiently detect and monitor their levels in patients. The proposed sensors will harness the unique optical properties and sensitivity of single-walled carbon nanotubes. To improve sensitivity and specificity of such sensors, previously developed to detect ovarian cancer biomarkers in vivo, we used molecular perceptron—data analytics-based methods to detect specific spectroscopic fingerprints from the binding of protein biomarkers to the nanotube surface.
(Invited) Exciton Dynamics in Air-Suspended Carbon Nanotubes Coupled to Nanobeam Cavities
Authors: Machiya Hidenori , Ishii Akihiro , Kato Yuichiro K.
Published: May 2020

Air modes in photonic crystal nanobeam cavities offer efficient coupling to air-suspended carbon nanotubes [1,2]. Here we investigate exciton dynamics in the time domain at room temperature. The cavities are fabricated from silicon-on-insulator wafers, and nanotubes are synthesized over the cavities by chemical vapor deposition. Time-resolved photoluminescence measurements are performed on individual nanotubes, and we compare the bright exciton lifetime with and without coupling to the cavity. Purcell enhancement of the exciton recombination is observed [3].

Work supported in part by MIC (SCOPE 191503001), RIKEN (Incentive Research Projects), JSPS (KAKENHI JP16H05962), and MEXT (Nanotechnology Platform). H.M. is supported by JSPS Research Fellowship. We thank the Advanced Manufacturing Support Team at RIKEN for technical assistance.

[1] R. Miura, S. Imamura, R. Ohta, A. Ishii, X. Liu, T. Shimada, S. Iwamoto, Y. Arakawa, Y. K. Kato, Nat. Commun. 5, 5580 (2014).

[2] H. Machiya, T. Uda, A. Ishii, Y. K. Kato, Appl. Phys. Lett. 112, 021101 (2018).

[3] H. Machiya, A. Ishii, Y. K. Kato, in preparation.
Radiative Pumping of Exciton-Polaritons by Luminescent sp3 Defects in Single Walled Carbon Nanotubes
Authors: Lüttgens Jan Matthias , Berger Felix Julian , Zaumseil Jana
Published: May 2020

Exciton-polaritons are part-light, part-matter quasiparticles that form when an exciton interacts strongly with photons in a suitable optical cavity. They have been demonstrated for a wide range of excitonic materials and have gained attention owing to their unique properties, e.g., Bose-Einstein condensation and inversion-less polariton lasing. Sorted single-walled carbon nanotubes (SWCNTs) have emerged as an excellent material to generate exciton-polaritons in the near-infrared by optical and electrical pumping [Nat. Mater. 2017, 16, 911]. We find that these SWCNT polaritons are most efficiently created when the cavity is tuned to the photoluminescent sidebands (PSB) of the SWCNTs. Using time-correlated single photon counting, we are able to attribute this observation to radiative pumping from the PSB. In order to increase polariton pumping even further, we introduce luminescent and red-shifted sp3 defects by diazonium functionalization of polymer-wrapped (6,5) nanotubes [ACS Nano 2019, 13, 8, 9259]. This new synthetic sideband also radiatively pumps the polaritons and substantially increases the polariton emission at low angles and energies. Furthermore, the emission is tunable over the whole synthetic sideband range (telecommunication O-band). The direct population of the lower polariton branch via the sp3 defect might even enable polariton lasing in this system.

Figure 1
Oxidized Multiwalled Carbon Nanotubes (ox-MWCNTs) As an Oxidation Agent for Pyrrole (PY) Polymerization: MWCNT@Polypy Composite Formation
Authors: Winkler Krzysztof , Wysocka-Zolopa Monika , Gradzka Emilia
Published: May 2020

Composites of conducting polymers and carbon nanomaterials has attracted great attention both in fundamental and applied research. They exhibits high conductivity, large specific surface area, and excellent mechanical properties. These systems can be fabricated either by simple mixing of carbon material and conducting polymer or by in-situ oxidative polymerization of monomer in the presence of carbon nanostructures. Polypyrrole has been deposited on the SWCNTs or MWCNTs by chemical or electrochemical oxidation of monomer in solution containing carbon nanotubes. In the case of chemical polymerization, Fe(III) ions or are used as an oxidation agents. For the formation of MWCNT@polyPY composite, oxidized MWCNTs were used for pyrrole oxidation and polymerization process initiation.

MWCNTs were oxidized in solution containing hydrogen peroxide 30 wt% , sulphuric acid 96 wt%, and a mixture of H2SO4 96 wt% and H2O2 30 wt% in ratio 70:30. The oxidized MWCNTs were characterized with FTIR and Ramat spectroscopy, XPS, and thermogravimetric analysis. Nature of the functional groups and the presence of structural defects on the nanotube surface were determined. The MWCNTs oxidized in sulphuric acid and hydrogen peroxide mixture, containing ca. 5% of carboxylate groups were used as an oxidation agent for pyrrole polymerization. The composite was formed in toluene solution containing pyrrole and ox-MWCNTs. Polymer was deposited at the MWCNTs surface and the MWCNT@polyPY composite is formed (inset in Figure 1). The thickness of the polymeric layer coating the carbon nanotube surface (in range from 10 to 100 nm) can be controlled by the time of polypyrrole deposition, concentration of pyrrole in solution, and the stirring conditions.

The electrochemical properties of MWCNT@polyPY composites in different solutions were also investigated. The effects of the supporting electrolyte nature and the solvent were examined. Figure 1 shows the voltammetric behavior of MWCNT@polyPY thin layer deposited at the surface of gold electrode by drop coating method recorded in water containing NaClO4. Voltammogram exhibits two large oxidation peaks. The second one at ca. 0.4 V corresponds to the process of polypyrrole oxidation. The rate of oxidation process of polypyrrole that is deposited at the MWCNTs surface (MWCNT@polyPY) is much higher in comparison the oxidation of pristine polymer formed under conventional chemical conditions. Also, an efficiency of the polymer phase oxidation significantly increases in the case of composite. The nature of the large surface peak at ca. 0 V (Figure 1) is still under investigation.

Composite MWCNT@polyPY material can be used as an electroactive material in charge storage devices due to its capacitance properties and the fast rate of charge transfer.

Figure 1
Electrochemistry of Controlled-Diameter Carbon-Nanotube Fibers at the Cross Section and Sidewall
Authors: Gupta Pankaj , Lazenby Robert A. , Rahm Connor E , Heineman William R. , Buschbeck Elke , White Ryan Jeffrey , Alvarez Noe T.
Published: May 2020

Electrochemistry at open ends and sidewalls of carbon nanotubes (CNTs) has been under debate, with opposing viewpoints as to which sites are more electro-chemically active. A particular challenge in this field has been the ability to conduct electrochemical studies at the open ends of CNTs, without measuring contributions from the sidewalls. Among the detailed studies on CNT electrochemistry by various research groups, no reports show a direct comparison between the electrochemistry of open ends and sidewalls. That is to say, electrochemical studies at open ends have always had some contribution from sidewalls. Multiple research groups have reported electrochemistry at CNT sidewalls and close ends, although there are no reports that examine the electron transfer rate at open ends exclusively. In cases where rapid electron transfer at open ends has been reported, this has been on either defective dispersed CNTs at an electroactive surface, or on vertically aligned CNTs which are inherently porous. More interestingly, it was also observed that the electrochemical response at CNT modified electrode surfaces could be dominated by thin layer cell behavior, which arises due to the change in diffusional regime or mass transport. Therefore, in such electrode assemblies, we cannot completely assign the electrochemical response to open ends since sidewalls also contributed significantly to the measured current. In this work, we report on electrochemical measurements taken from the sidewall and the cross-section (i.e., open ends) of highly densified multi-walled carbon nanotube fiber (HD-CNTfs) embedded in a polymer matrix. The cross section of the HD-CNTfs was exposed to reveal only open ends to the electrolyte interface and this platform allowed us to compare electrochemistry at the open ends and sidewalls of HD-CNTfs. Cyclic voltammetry was employed to examine the electrochemical properties of HD-CNTfs using a conventional bulk electrochemical cell and micro-capillary electrochemical measurements. The cross sections and side walls of HD-CNTfs are shown to promote similar electron transfer kinetics with reversible redox behavior. However, side walls of HD-CNTfs also showed large capacitive background current which was found to increase in proportional to CNT fiber diameter.

Figure 1
(Invited) Photoswitchable Near-Infrared Emitters Based on Single-Walled Carbon Nanotube Hybrids
Authors: Godin Antoine G , Setaro Antonio , Gandil Morgane , Haag Rainer , Adeli Mohsen , Reich Stephanie , Cognet Laurent
Published: May 2020

Super-resolution microscopy (SRM) has set a new paradigm in the field of optical imaging by delivering images with resolution much better than the diffraction limit. We demonstrated over the last years that such approaches can be designed to understand basic excitonic processes in carbon nanotubes [1-2]. In the field of bioimaging, SRM is currently limited to the visible range, missing the near-infrared region where biological tissues are however the most transparent. One reason for this is that single-molecule photoswitchable emitters, which are the basic ingredients to achieve single-molecule SRM, have not yet been developed in the near-infrared. To fill this gap, we have recently introduced a novel type of hybrid nanomaterials consisting of single-wall carbon nanotubes covalently functionalized with photo-switching molecules that are used to control the intrinsic luminescence of the single nanotubes in the near-infrared (beyond 1 µm) [3]. Through the control of photoswitching, we demonstrate super-localization imaging of nanotubes unresolved by diffraction limited microscopy opening the route toward SRM in the near-infrared for biological applications. Photocontrol of individual near-infrared emitters will also be highly desirable for elementary optical molecular switches or information storage elements since most communication data transfer protocols are established in this spectral range.

References

[1] Cognet et al Nanoletters, 8 (2008) 749 - 753.

[2] Danné et al. ACS Nano, 12 (2018) 6059

[3] Godin et al Science Advances, 5, (2019) eaax1166
(Invited) Photostability of Core-Shell Structures at Low Temperature
Authors: Orcin-Chaix Lucile , Campidelli Stephane , Rondin Loïc , Chassagneux Yannick , Voisin Christophe , Lauret Jean-Sébastien
Published: May 2020

The use of carbon nanotubes as single emitters is currently developing. Being made only of surface atoms carbon nanotubes are very sensitive to their environment. A fingerprint of this sensitivity is the variation with time of their emission intensity (blinking) and energy (spectral jitter) in low temperature experiments. To improve the stability of nanotubes, we have synthesized core-double shell structures where two shells of polymers are rolled around the nanotube [1]. Here, we will show the influence of these shells on the stability of both the emission intensity and energy [2].

[1] L. Orcin-Chaix et al, Journal of Material Chemistry C 6, 4786 (2018)

[2] L. Orcin-Chaix et al, in preparation
(Invited) Origin of Lineshape Asymmetry in the Photoluminescence Spectra of Cryogenic Carbon Nanotubes
Authors: Högele Alexander
Published: May 2020

Photoluminescence spectra of cryogenic carbon nanotubes exhibit a peculiar lineshape asymmetry that has been interpreted as arising from the interplay of temperature-driven exciton localization and the one-dimensional reservoir of acoustic phonons [1] with pronounced phonon sidebands in the limit of a gapped phonon reservoir [2,3]. Based on our recent experimental studies of PFO-wrapped nanotubes at cryogenic temperatures, we present an alternative model to explain the origin of the lineshape asymmetry.

[1] C. Galland et al., Non-Markovian decoherence of localized nanotube excitons by acoustic phonons, Phys. Rev. Lett. 101, 067402 (2008).

[2] F. Vialla et al., Unifying the low-temperature photoluminescence spectra of carbon nanotubes: The role of acoustic phonon confinement, Phys. Rev. Lett. 113, 057402 (2014).

[3] I. Sarpkaya et al., Strong acoustic phonon localization in copolymer-wrapped carbon nanotubes, ACS Nano 9, 6383 (2015).
(Invited) 20 Years of Carbon Nanotube Evolution
Authors: Doorn Stephen K.
Published: May 2020

From the advent of individualized carbon nanotubes nearly 20 years ago to the current ability to control their properties at multiple levels, the world of CNTs has changed tremendously. Through the lens of my group’s efforts, I will provide a retrospective on how our understanding of CNTs has changed through this period. An overview will be given of our efforts on Raman and photoluminescence (PL) spectroscopy to identify and characterize fundamental CNT properties. While spectroscopic separation enabled many revelations on CNT photophysics, the limitations imposed by mixed-chirality samples ultimately were overcome with the advent of effective and efficient methods for chirality enrichment. Examples will be given of advances in photophysics established through Raman performed on pure chirality samples. New separations techniques presented new questions on nanotube surface chemistry, ultimately leading to studies of surface chemistry, surface structure, and defects, at the ensemble and single tube levels. Most recently, development of functionalization methods to introduce optically active defect states has opened an exciting new direction in nanotube studies. An overview of the new photophyics and quantum light emission enabled by defects will be given, along with some perspective on future outlook.
Globally Aligned, Wafer-Scale Deposition of Carbon Nanotubes Via Interfacial Assembly
Authors: Jinkins Katherine R. , Gopalan Padma , Arnold Michael S.
Published: May 2020

Floating evaporative self-assembly (FESA) is a solution-based technique for fabricating highly-aligned semiconducting carbon nanotube films.1,2 Field-effect transistors (FETs) based on carbon nanotubes aligned via FESA have exhibited current densities exceeding that of GaAs and Si, demonstrating the promise of this technique.3 However, the global uniformity of FESA films is poor, as the films are composed of stripes of aligned and randomly oriented carbon nanotubes. Additionally, this technique is inherently difficult to scale. In the work presented here, we demonstrate a scalable technique to overcome the shortcomings of FESA and to achieve globally uniform films of aligned carbon nanotubes at desirable packing densities for FETs.

In our technique, carbon nanotubes are continuously aligned across target substrates by lifting the substrates through a flowing nanotube ink/water interface. The ink/water interface collects and confines the nanotubes, which is vital to achieving a high degree of alignment. Polarized Raman spectroscopy mapping is used to quantify the degree of alignment in the resulting aligned nanotube films. The full width at half maximum (FWHM) of the alignment distribution within the films is 6.0° measured across a 1 mm2 area. We control the aligned carbon nanotube packing density from 0.2 to 59 µm-1 by varying the ink concentration from 0.1 to 100 µg mL-1. Using optimized conditions, we demonstrate the scalability of this technique by aligning carbon nanotubes across a 100 mm wide wafer. Charge transport measurements are performed using FETs with the aligned carbon nanotube films as the active channels, and the performance is compared to FETs based on FESA films.

1. Jinkins, K., R. et al. Nanotube Alignment Mechanism in Floating Evaporative Self-Assembly. Langmuir
33, 13407–13414 (2017).

2. Joo, Y., Brady, G. J., Arnold, M. S. & Gopalan, P. Dose-Controlled, Floating Evaporative Self-assembly and Alignment of Semiconducting Carbon Nanotubes from Organic Solvents. Langmuir
30, 3460–3466 (2014).

3. Brady, G. J. et al. Quasi-ballistic carbon nanotube array transistors with current density exceeding Si and GaAs. Sci. Adv.
2, (2016).
(Invited) Carbon Nanotube-Hybrid Nanoscale Devices
Authors: Palma Matteo
Published: May 2020

The controlled organization of individual molecules and nanostructures with nanoscale accuracy is key for the fabrication of the next generation optoelectronic devices and the investigation of events in biological and chemical assays. In this regard, we developed different platforms based on the in-solution assembly of classes of molecular materials (organic, inorganic, and biological with promising attributes) to single-walled carbon nanotubes (SWCNTs), employed as building blocks that allow for nanoscale studies to be performed in a variety of research fields.

Through this approach, we assembled and investigated: molecular transport junctions,[1] metal nanowire devices using CNTs as vector templates,[2] static and dynamic organic-inorganic heterostructures consisting of Quantum Dot-CNT hybrids,[3,4] stimuli-responsive CNT-CdS/CNT-PbS devices[5] and DNA-CNT junctions,[6] protein-CNT nanohybrids,[7] and multiplexed biosensing devices based on aptamer- and protein-CNT heterostructures.[8,9] In this presentation, we will discuss relevant and recent examples among the aforementioned studies.

[1] Journal of the American Chemical Society, 2016, 138, 2905-2908

[2] Angewandte Chemie International Edition, 2019, DOI: 10.1002/anie.201902857

[3] Small, 2017, 13, 1603042

[4] Advanced Science, 2018, 5, 1800596

[5] Submitted

[6] Chemistry of Materials, 2019, 31, 1537-1542

[7] Journal of the American Chemical Society, 2017, 139, 17834-17840

[8] Nano Letters, 2018, 18, 4130-4135

[9] Submitted
Preclinical Imaging and Spectroscopy in the NIR-II Window with Single-Walled Carbon Nanotubes
Authors: Beaulieu Ouellet Emilie , Galassi Thomas Vito , Harvey Jackson Dean , Baker Hanan , Heller Daniel A.
Published: May 2020

We developed a near-infrared small animal imaging system, IR VIVO, that provides real-time images, videos, and spectral imaging in the NIR-I and shortwave infrared (SWIR or NIR-II) regions. We found that SWIR wavelengths can give optimal resolution for in vivo optical imaging of deep organs in mice due to the low tissue autofluorescence, scattering and absorption of light at these wavelengths. We also show how this higher penetration depth can enable the detection of small wavelength changes in the emission of carbon nanotube-based sensors implanted in vivo using a continuously tunable filter.

First, we demonstrated superior image clarity and penetration depth at NIR-II wavelengths (1000-1700 nm) in vivo using an FDA approved dye, indocyanine green (ICG). We used 780 nm excitation and detection using a Zephir 1.7 InGaAs camera and 1250 nm long-pass emission filter. We found low tissue autofluorescence at 1250 nm. The ICG dye imaging resulted in superior visualization of microvasculature, perfusion, measurement of heart rate, respiratory rate, hepatobiliary, and intestinal contractions. Further anatomical and functional imaging was carried out by looking at the kinetics of ICG, resulting in identification of different organs.

In vivo near-infrared hyperspectral imaging of carbon nanotubes was conducted using a continuously-tunable filter in the imager. A diffraction volume Bragg grating (VBG), was used to provide narrow-band wavelength selection. Coupled with a homogeneous global illumination, spectrally-defined images were acquired in the entire field of view. The result was a dataset containing both 2D spatial information and the full spectrum for each point in the image. We conducted near-infrared hyperspectral imaging of single-walled carbon nanotubes to measure small wavelength changes of the nanotubes implanted into live mice. Hyperspectral measurements of carbon nanotube sensors for lipids in the liver as well as implantable sensors for doxorubicin were conducted, facilitating liver disease monitoring and drug pharmacokinetics measurements.

We believe wide-area NIR-II imaging and spectral/hyperspectral measurements have broad potential applications for the use of carbon nanotubes and other NIR-I/II materials in basic materials/biology, translational, and clinical work, including sensor arrays, point-of-care measurements, implants, whole-animal imaging, and intraoperative/surgical imaging.
Groove-Assisted Global Spontaneous Alignment of Carbon Nanotubes in Vacuum Filtration
Authors: Komatsu Natsumi , Nakamura Motonori , Ghosh Saunab , Kim Daeun , Chen Haoze , Katagiri Atsuhiro , Yomogida Yohei , Gao Weilu , Yanagi Kazuhiro , Kono Junichiro
Published: May 2020

Recently, He and coworkers have developed a method for fabricating films of aligned single-wall carbon nanotubes (SWNCTs) using slow vacuum filtration [1]. Their fabricated SWCNT films are wafer-scale (centimeter size), highly packed (~ 1 nanotube per cross-sectional area of 1 nm2) and have nearly perfect alignment (nematic order parameter S ~ 1). However, the mechanism driving the aligned structures to grow into monodomains of macroscopic size has not been fully understood. In particular, what dictates the direction of SWNCT alignment has been under discussion. Here, we first examine a model suggested by He et al., where SWCNTs interact with each other and result in global alignment in a potential energy minimum near the surface [1]. We show experimental data that invalidates this model, suggesting that there must be a characteristic of the entire membrane that determines the alignment direction. We found a large number of parallel grooves that exist on most commercial filter membranes used for vacuum filtration, and show experimental results demonstrating that the grooves determine the direction of SWCNT alignment. Furthermore, when we eliminated the grooves by heating treatment, we observed multidomain alignment instead of monodomain alignment. Finally, we introduced intentionally created grooves on the filter membrane by an imprinting method, which successfully controlled the alignment direction. This procedure, groove-assisted CVF, provides a simple and reproducible way to align CNTs in a desired direction.

Reference:

[1] He, X.; Gao, W.; Xie, L.; Li, B.; Zhang, Q.; Lei, S.; Robinson, J. M.; Hároz, E. H.; Doorn, S. K.; Wang, W.; Vajtai, R.; Ajayan, P. M.; Adams, W. W.; Hauge, R. H.; Kono, J. Nat. Nanotechnol. 2016, 11, 633–638.
(Invited) Spontaneous and Intentional Exciton Trapping in Carbon Nanotubes
Authors: Raynaud Christophe , Chassagneux Yannick , Claude Théo , Borel Antoine , Zaumseil Jana , Lauret Jean-Sébastien , Voisin Christophe
Published: May 2020

We use a combination of hyperspectral superlocalization microscopy and excitation photoluminescence spectroscopy techniques to study the localization of one-dimensional excitons in pristine and functionalized single wall carbon nanotubes at low and room temperature. Using numerical simulations, we interpret the nearly resonant excitation spectra either in terms of excited trapped states leading a selective excitation of a trap or in terms of delocalized one dimensional excitonic states. We discuss the implications of this localization for the use of carbon nanotubes as quantum-light emitters.

Raynaud et al. Nano Lett. 19, 7210 (2019)
(Invited) Backside Absorbing Layer Microscopy: A New Tool to Study the Optical, Chemical and Electrochemical Properties of 2D Materials
Authors: Jaouen Kevin , Lebon Florian , Jousselme Bruno , Campidelli Stephane , Cornut Renaud , Derycke Vincent
Published: May 2020

Optical microscopy based on anti-reflective coatings is a simple yet powerful characterization tool which notably allowed the first observation of graphene in 2004 and of other single-layered materials in the following years. Since then, the field of two-dimensional materials has developed rapidly both at the fundamental and applied levels. Yet, these ultrathin materials present inhomogeneities (edges, grain boundaries, defects, multilayers...) which strongly impact their intrinsic (physical, chemical) properties and the performances of the electronic, optoelectronic and energy-conversion devices. The use of local characterization techniques (spectroscopy mapping, scanning probe techniques...) is thus essential. Recently, D. Ausserré et al. introduced a new enhanced-contrast optical microscopy technique, named BALM (Backside Absorbing Layer Microscopy), based on ultrathin (2-5 nm) and strongly light-absorbing (metallic) anti-reflective layers. This talk aims at presenting the remarkable assets of this technique for the study of 2D materials. BALM notably allows observing mono-layered materials with very strong contrast even in the case of transparent ones such as graphene oxide [1]. The inverted microscope geometry allows imaging in solvents so that it is possible to investigate molecular adsorption dynamics on 2D materials in real-time and with extreme sensitivity.[1-2] With its wavelength sensitivity, it can also be used as a precise technique to determine the refractive index and extinction coefficient of TMDCs (MoS2, WS2). But one of the main benefits of BALM comes from its combination to other techniques. We particularly considered the coupling between optical measurements and electrochemistry for which the anti-reflective substrate serves as working electrode. We investigated optically the dynamic of the electrochemical reduction of Graphene Oxide (GO), the electro-grafting of organic layers by diazonium salts reduction on GO and its reduced form (rGO),[3] as well as the intercalation of metallic ions within stacked GO sheets. By combining versatility and high-contrast, BALM is established as a promising tool for the study of 2D materials, especially for the local and in situ characterization of their optical, chemical and electrochemical properties.

[1] S. Campidelli, R. Abou Khachfe, K. Jaouen, J. Monteiller, C. Amra, M. Zerrad, R. Cornut, V. Derycke, D. Ausserré, Backside absorbing layer microscopy: Watching graphene chemistry, Science Advances
3, e1601724 (2017).

[2] K. Jaouen, R. Cornut, D. Ausserré, S. Campidelli, V. Derycke, Ideal optical contrast for 2D materials observation using bi-layer antireflection absorbing substrates, Nanoscale
11, 6129 (2019).

[3] K. Jaouen, F. Lebon, B. Jousselme, S. Campidelli, R. Cornut, V. Derycke, Optical monitoring of diazonium electrografting on gold and graphene oxide using Backside Absorbing Layer Microscopy, submitted.
(Invited) 1D Confinement of Dyes inside Boron Nitride Nanotubes: Photo-Stability and Aggregation Effects
Authors: Gaufres Etienne
Published: May 2020

The encapsulation of organic molecules inside nanotubes forms a class of nano-heterostructures with optical properties driven by the 1D properties of the nanotube host template.

When confined and aligned inside a carbon nanotube (CNT), organic dyes (e.g. sexithiophene) exhibit for instance a strong Raman signal and a quenched fluorescence by the CNT [1-3]. Here we show that boron nitride nanotubes (BNNTs) having inner diameters between 1 nm to 5 nm provide similar 1D confinement effects with the difference that the BNNTs (Eg~5 eV) preserve the luminescence of the dyes. Experiments on individual and assembly of Dyes@BNNT demonstrate that the walls of the BNNTs provide protection to the dyes against photobleaching under continuous photo-excitation in ambient conditions. High Resolution Transmission Electron Microscopy on Dyes@BNNTs shows ordered aggregation of the encapsulated depending on the BNNT diameter. [4] Finally, fluorescence imaging and spectroscopy on Dyes@BNNTs reveal that the emitted light can be highly polarized along the nanotube axis and that both absorption and emission energies is strongly red-shifted compared to non-encapsulated dyes. That is, a shift as high as 0.8 eV between DPP2 dyes and DPP2@BNNT fluorescence has been observed, which allows a tuning of the dye optical activity from the visible to near-infrared (NIRII).

Work done in collaboration with C. Allard, L. Schué, F. Fossard, G. Recher,R. Nascimento, E. Flahaut, P. Desjardins, R. Martel and A. Loiseau

[1] E. Gaufrès et al Nature Photon. 8, 72-78 (2014)

[2] S. Cambré et al Nature Nano. 10, 248-252 (2015)

[3] E. Gaufrès et al ACS Nano, 10, 11 (2016)

[4] C. Allard et al, submitted and ChemRxiv (2019), https://doi.org/10.26434/chemrxiv.8011268.v1
(Invited) Challenges in Quantifying the Purity of Semiconducting Single-Walled Carbon Nanotubes
Authors: Lefebvre Jacques
Published: May 2020

Semiconducting carbon nanotubes (sc-SWCNT) sit amongst the most promising nanomaterials for a new generation of electronic devices. Progress towards commercial applications is combined with challenges related to materials development and characterization, fabrication methods as well as device modeling. This talk will focus primarily on the enrichment process and the related ink formulation for printed electronics and integrated circuits. [1] The quality of carbon nanotube ink solutions is closely tied with the rapid feedback provided by optical spectroscopy methods: UV-vis, Raman and fluorescence. [2] I will describe our efforts on improving the material’s assessment when purity exceeds well beyond 99%. [3]

[1] Ding, J.; Li, Z.; Lefebvre, J.; Cheng, F.; Dubey, G.; Zou, S.; Finnie, P.; Hrdina, A.; Scoles, L.; Lopinski, G. P.; Kingston, C. T.; Simard, B.; Malenfant, P. R. L. Enrichment of Large-Diameter Semiconducting SWCNTs by Polyfluorene Extraction for High Network Density Thin Film Transistors. Nanoscale
2014, 6, 2328-2339.

[2] J. Lefebvre, J.; Finnie, P.; Fagan, J.; Zheng, M.; Hight Walker, A. R. Metrological Assessment of Single-Wall Carbon Nanotube Materials by Optical Methods. Handbook of Carbon Nanomaterials 2019, 9, R. B. Weisman and J. Kono editors (World Scientific) ISBN 978-981-3235-45-8.

[3] Lefebvre, J.; Ding, J.; Li, Z.; Finnie, P.; Lopinski, G.; Malenfant, P. R. L. High-Purity Semiconducting Single-Walled Carbon Nanotubes: A Key Enabling Material in Emerging Electronics. Acc. Chem. Res.
2017, 50 (10), 2479-2486.

Figure 1
Large Carbon Clusters with Entrapped Gadolinium Atoms
Authors: Seeler Tiffany L. , Franklin Hannah M. , Tepper Katelyn R. , Stevenson Steven
Published: May 2020

Gadolinium metallofullerenes have long shown promise as potential MRI contrast agents. The ability to entrap up to three gadolinium atoms permits a high concentration of metal content per fullerene cage. The protective carbon cage prevents the escape of otherwise toxic free Gd ion. In this presentation, we will discuss purification strategies to isolate gadolinium clusters entrapped within larger carbon cages (C96-C120). We have recently isolated a series of fullertubes, which consist of a nanotube belt of carbons with fullerene endcaps. It is unknown if the entrapped Gd atoms are inside fullerene or fullertube cages.
(Invited) Endohedral Fullerene Hybrids: From Gold Nanoparticles to Graphene
Authors: Porfyrakis Kyriakos
Published: May 2020

Endohedral fullerenes are at the forefront of nanotechnology due to their rich electronic structure. In this talk I will focus on some examples of endohedral fullerenes used in hybrid nanostructures with other nanomaterials. For example, gold nanoparticles have been found to significantly increase or alternatively quench the photoluminescence of dyes, enhance the Raman scattering of organic molecules and the photocatalytic activity of semiconductors. We have reported for the first time the use of the singlet oxygen sensor green for the evaluation of the generation of singlet oxygen from a series of fullerenes (including endohedral fullerenes) and gold nanoparticle hybrids. The C70 mono adducts appear to be more efficient sensitizers compared to C60 in accordance with previous studies that were based on the 1270 nm emission of the singlet oxygen. Lu3N@C80 had a performance somewhat between the two empty cages. Overall, pyrene derivatives appeared to be efficient photo-sensitizers, especially when coupled with gold nanoparticles, with the 2.24 and 3.48 times increase on the fluorescence intensity.

I will also elaborate on how Gd-based metallofullerene (Gd3N@C80) molecules can be used to create single adatoms and nanoclusters on a graphene surface. We have shown that endohedral metallofullerenes can adhere to graphene surfaces at temperatures well above their bulk sublimation point, indicating that the surface bound metallofullerenes have strong adhesion to dangling bonds on graphene surfaces. The ability to create dispersed single Gd adatoms, and Gd nanoclusters on graphene may have impact in spintronics and magnetism.

Endohedral metallofullerenes continue to fascinate us with their versatility and attractive electronic properties.
Prevalence, Severity, and Correlates of Anaemia in Pregnancy among Antenatal Attendees in Warri, South-Southern Nigeria: A Cross-Sectional and Hospital-Based Study
Authors: Omote Victor , Ukwamedua Henry Awele , Bini Nathaniel , Kashibu Emmanuel , Ubandoma Joel Rimamnde , Ranyang Akafa
Published: May 2020

Introduction. Anaemia in pregnancy affects about half of all pregnant women globally and constitutes an important reproductive health issue. The World Health Organization estimates that the prevalence of anaemia in pregnancy varies from 53.8% to 90.2% in developing countries and 8.3% to 23% in developed countries. Anaemia in pregnancy is common in developing countries and prevalence statistics required for its effective management and control is not adequately available in Nigeria. Thus, this study seeks to provide prevalence statistics of anaemia in pregnancy for the study region and its severity and highlight some possible correlates. Methods. A total of 218 pregnant women were recruited from the antenatal clinic of Central Hospital Warri using simple random technique after approval from the institutional review board and consent from the participants. Data on sociodemographics, economic status, and clinical history were collected using a pretested structured interviewer’s questionnaire. Participant’s haematocrit levels were estimated using standard laboratory techniques and anaemia was diagnosed using WHO-recommended cutoff. Results. The overall prevalence of anaemia was 37.6%. This prevalence dropped to 10.6% when a cutoff of less than 30% haematocrit was used. There was a direct relationship between haematocrit values and the participants’ age while mild anaemia accounted for the bulk (72%) of the anaemic cases. Participants younger than 20 years of age gave the highest age-based prevalence while parity-based prevalence was even among subgroups. Participants without formal education and those who were unemployed accounted for the highest prevalence in their different categories. Conclusion. Based on the findings from our study, anaemia in pregnancy is still of primary public health concern if WHO cutoff is used for the diagnosis. However, the reduction observed when less than 30% haematocrit was used tags our study zone to be of moderate severity. Although all variables lacked statistical significance, younger age, no formal education, and unemployment were highlighted to be predisposing factors.