bluuebunny/crossref_metadata_2025 huggingface dataset:
Stabilization of Tunnel Manganese Oxide Electrodes in Li-Ion and Na-Ion Batteries
Authors: Byles Bryan , Pomerantseva Ekaterina
Published: February 2020

Tunnel structured manganese oxides, built from corner and edge sharing MnO6 octahedra arranged around stabilizing cations and water molecules, are of significant interest for energy storage applications such as Li-ion and Na-ion batteries (LIBs and SIBs, respectively) due to their low cost, environmental friendliness, and high electrochemical activity. Moreover, the structural tunnels in these materials act as 1D diffusion channels and provide crystallographic sites for ion insertion. However, tunnel manganese oxide phases face challenges in regards to long term cycling stability in intercalation-based batteries, which has been attributed to structural instabilities resulting from Jahn-Teller distortions induced by manganese reduction [1, 2]. Therefore, it is imperative to stabilize the structure of tunnel manganese oxides for improved electrochemical stability as cathode materials in intercalation-based batteries.

Here, we demonstrate stabilization of a newly reported tunnel manganese oxide phase, 2xn-MnO2, with the crystal structure consisting of 2x2, 2x3, and 2x4 octahedra tunnels containing Na+ stabilizing cations and water molecules. Building off of previous work by C.S. Johnson et al. [3], where the smaller tunnel structured α-MnO2 was stabilized with Li2O, we modified the structure and chemical composition of 2xn-MnO2 via mixing in methanol and lithium hydroxide, resulting in insertion of Li2O into the structural tunnels of 2xn-MnO2. In LIBs, the Li2O-stabilized 2xn-MnO2 demonstrates both higher initial capacity and superior capacity retention after 100 cycles. The initial capacity is improved from 93 mAh g-1 for the pristine material to 168 mAh g-1 for the stabilized 2xn-MnO2. Moreover, the galvanostatic discharge-charge profile for the stabilized 2xn-MnO2 exhibits a better pronounced plateau-shaped region compared to the original 2xn-MnO2 phase, indicating that the stabilized material contains more well-defined insertion sites. Similarly, in SIBs, the capacity of the stabilized 2xn-MnO2 was improved by 35% to 81 mAh g-1, and capacity retention increased from 43% to 75% after 100 cycles, demonstrating the effectiveness of this stabilization approach in both Li-ion and Na-ion battery systems. Thus, we show that stabilization with Li2O can be applied to various tunnel manganese oxide phase to improve their electrochemical performance as intercalation-based battery electrodes.

References

Y. Yuan et al., Nano Energy (2016) 19, 382

A. Tompsett and M.S. Islam, Chem. Mater. (2013) 25, 2515

S. Johnson et al., J. of Power Sources (1997) 68, 570
Preparation of Li1-XNi1+XO2 Thin Films By Pulsed Laser Deposition and the Electrochemical Performance for Oxygen Evolution Reaction in Alkaline Media
Authors: Yuki Yabuta , Uchiyama Tomoki , Yamamoto Kentaro , Uchimoto Yoshiharu
Published: February 2020

The oxygen evolution reaction (OER, 2H2O→O2 + 4H+ + 4e-) is one of the important key of the energy devices, especially for the water electrolysis cells for hydrogen production. Since the OER proceeds via a multistep process and, thus the reaction has a large overpotential, the precious metal oxides such as IrO2 were used for OER electrocatalysts. However, the such precious metal oxides are not appropriate for large-scale applications considering their high cost and low reserves. Alkaline water electrolysis is one of the easiest methods for hydrogen production and it has a simple configuration using low-cost materials. LiNiO2 have exhibited highly potential toward OER due to its high conductivity among 3d transition metal oxides, and stability in alkaline condition.

LiNiO2 is a layered structure consisting of NiO2 slabs made of edge-sharing NiO6 octahedrons and lithium ions inserted in the slabs at the octahedral sites. In this layered LiNiO2 material, Ni3+ ions are in the low-spin configuration, and they are thought to be correlated with high OER activity. Although the layered structure of LiNiO2 can stabilize significant amounts of Ni3+ species, the OER activity of LiNiO2 is still lower than expected. Although many papers have reported the performance of LiNiO2-corted anode, the morphology and surface area as well as synthesis method could affect the OER and the intrinsic activity of LiNiO2 is not well investigated. In this study, we prepared Li1-xNi1+xO2 thin films by pulsed laser deposition and investigated the electrochemical performance for OER activity of Li1-xNi1+xO2.

LiNiO2 thin film was successfully prepared by pulsed laser deposition (PLD). A Nd:YAG laser operating at a wavelength of 532 nm was focused on a sintered LiNiO2 target. We used a chamber which can be evacuated to a base pressure of 5.0 x 10-4 Pa by means of a turbo-molecular pump. When depositing LiNiO2 thin film, the total pressure of O2 was fixed to 10 Pa. A Ni-corted Si(100) substrate was used for film deposition. The substrate temperature was fixed to 200 oC. The target (f10) was produced by sintering Li2O and NiO2 powder at 1000 oC for 8.5 h in air. Structural analysis of LiNiO2 was carried out by XRD. The electrochemical measurements were conducted in an aqueous 7M KOH solution using a potentiostat (Hokuto Denko HSV-110) connected to as a working electrode an RHE reference electrode, and Ni wire as a counter electrode. The solution was purged with N2 gas for 30 min before the measurement. Cyclic voltammetry (CV) were obtained between 0.2 V and 1.6 V vs. RHE at 50 mV/s. The surface morphology was analyzed by AFM. The doping level of Li+ and OER activity as well as the state of Ni were mainly discussed in this paper.
An All-Transparent Thin Film Flexible Supercapacitor Based on Oblique Angle Deposited NiO Nanowires Arrays
Authors: Ma Jing , Liu Wen , Zhang Shuyuan , Yang Fuhua , Wang Xiaodong
Published: February 2020

With high power density, fast charging-discharging speed and long cycling life, supercapacitors have been a kind of highly developed novel energy-storage device these years, showing growing performance and various unconventional shapes such as flexible, linear type, stretchable, self-healing, etc. Here, we proposed a rational design of an all-transparent thin film flexible supercapacitor based on oblique angle deposited NiO nanowires arrays. By integrating PET substrate, thin layer of Pt electrode, surround-finger-shape NiO nanowires film and PVA-KOH electrolyte, the as-fabricated supercapacitor has a good flexibility, transparency, and satisfactory energy-storage performance. This supercapacitor showed a high specific capacity of 8 F/cm3, high energy density of 1 mWh/cm3, a power density up to 1.5 W/cm3 and good stability during thousands of bending-recover test and charge-discharge cycles, respectively. This transparent flexible thin film supercapacitor and be used as ingenious energy storage devices for future portable and wearable electronic applications.
Microstructured Polymer-Ionic Liquid Composite Film for Capacitive Pressure Sensors
Authors: Kim Kang Lib , Hwang Ihn , Park Cheolmin
Published: February 2020

The realization of wearable electronic devices that operate under mechanical strain is essential for the next generation of smart electronic application. Moreover, the transmittance is one of the key factors for realization of wearable electronic device in our life. The development of input device technology such as pressure sensors is crucial for the future skin applicable wearable electronic devices. Here, We fabricated transparent and flexible capacitive pressure sensors with composite of Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMI][TFSA]). Also, this ion-gel films are incorporated with graphene electrode for flexible and transparent sensors. This capacitive sensors have superior pressure-sensing performance, with a broad sensing range from a few pascals up to 20 kPa, with fast response times of < 30 ms and a low operating voltage of 1 V. The polymer-ionic liquid composite films have sensitivity more than 4 kPa-1 in the long-range pressure regime of 0-20kPa. Our highly reliable and sensitive, low voltage operation and broad pressure range sensor was suitable for the efficient detection of a various pressure sources arising from human life such as sound, pulse and finger motions.
Cubic Phase of α-CsPbI3 Perovskite Nanocrystals for Photodiode Application
Authors: Sim Kyu Min , Cho Jangwhan , Yoon Seongwon , Yu Seonghoon , Jang Min Su , Kang Mingyun , Kim Kyounghwan , Chung Dae Sung
Published: February 2020

High-performance and high-stability photodiodes are introduced by using α-CsPbI3 perovskite nanocrystals (NCs) phase-stabilized with a low-temperature solution-treated active layer. In addition to the high charge mobility, the high absorption coefficient, and IR-blind characteristics of the perovskite material, the defect-tolerant nature of α-CsPbI3 perovskite NCs are combined to realize hysteresis-free and high detectivity photodiodes. To further minimize defects state of interface, originating from multi-layer photodiode construction, a poly(3-hexylthiophene) layer is strategically introduced as a passivation layer, resulting in a low diode ideality and a noise equivalent power. As a result, high detectivity is introduced with hysteresis-free devices. Furthermore, the optimized photodiode exhibits excellent stability under high humidity conditions owing to the intrinsic nature of the defect-tolerant α-CsPbI3 perovskite NCs.
Ultra-Low Density Metallic Foams Synthesized By Cathodic Plasma Electrolysis
Authors: Botrel Ronan
Published: February 2020

In order to study laser-matter interactions on the Megajoule Laser facility, CEA needs to synthesize metallic foams with specific characteristics. The goal is to realize in a millimetric scale, metallic foam samples with a density lower than 10% of the bulk material and structured with a micrometric porosity (< 5 µm). To obtain these specific materials, CEA has developed an innovative process using the Contact Glow Discharge Electrolysis technique (CGDE) to grow metallic foam at a cathode surface. Under specific conditions and when a critical potential is applied, an uniform and stable gaseous envelop is formed around the immersed cathode in the ionic solution. Due to the high electrical field at the electrode surface, channels plasma are formed with the propagation of streamers between the cathode and the liquid surface. When the electric arcs meet the liquid, metallic cations are reduced to form metallic strands with a bush-like shape. In these conditions, several metallic foams can be obtained ( Au, Cu, Pt, Ag, alloys, ...) with a relative density of 0.5 %. All strands of the foam are about 100 nm in diameter and are interconnected together to form porosity about 1 µm. This very fast process allows synthesizing 1 mm thick of foam in less than 10 seconds. This presentation explains the patented process offering a versatile technological way to synthesized microporous and ultra-light metal foams.
Investigation on Aerosol Jet Etching for Thin Film Patterning
Authors: Cho Doo Hyeon , Lim Eun Taek , Lee Seung Hwa , Ryu Jin Su , Chung Chee Won
Published: February 2020

As the critical dimension of the semiconductor memory device keeps shrinking, new etching method is required to etch nanometer-scale patterned thin film. Accordingly, we propose novel etching method called aerosol jet etching. This etching technique is to use an aerosol jet containing tiny liquid droplets which are made of an etchant. Liquid droplets are generated and accelerated onto the thin film by nozzle expansion into a vacuum chamber where the substrates are located. This method is intended to perform vertical anisotropic etching without redeposition by combining the chemical mechanism of wet etching and physical bombardment of particles in dry etching. Formation of nanometer-scale patterns by nanoetching process of thin films should be developed for the future semiconductor memory devices. Therefore, this new etching technique can be a prospective etching method. Also, this technique can be applied to nano-device, MEMS and various thin-film sensors.

In this study, we have investigated the etch characteristics of nanometer-scale patterned thin films using aerosol jets which contain the tiny droplets of proper liquid etchants. We designed and optimized etching equiment for aerosol jet etching, and proceeded the characterization and development of nanometer-scale patterns by using it. As the major experimental parameters, there are the nozzle geometry (nozzle shape and nozzle diameter), nozzle to substrate distance, chamber pressure, and substrate temperature. The etch rates were obtained by the surface profilometer and field emission scanning electron microscopy (FESEM) and etch profiles were observed by FESEM. In addition, X-ray photoelectron spectroscopy were used for the investigation on the etched surfaces for the etch mechanism.

Acknowldgments This work was supported by NRF-2017R1D1A1B03033143
Synthesis and Processing of Nasicon/Polymer Membranes
Authors: Chiang Shan-Ju , Liu Caihong , Shaw Leon
Published: February 2020

The development of renewable energy sources has attracted the attention of researchers. Energy storage techniques of flexible production and demand on batteries based on electrochemistry have been explored during past decades. However, the state-of-the-art developments have been impeded due to the lack of sustainable cell component materials. One way to improve the energy density is through the solid ion exchange membrane, called sodium super ionic conductor (NaSICON). The fundamental challenges in synthesizing high purity NaSICON/polymer membrane lies in achievable of porous sintered body and polymer infiltration. NaSICON is intrinsically brittle as a ceramic. To avoid fracture, NaSICON membranes are typically fabricated with a thickness of 1 mm. However, even with 1 mm thickness the reliability of long-term operation and safety concerns are still present. Thus, we manufactured transformative NaSICON/polymer composite thin films thinner than 50 µm through a process termed as Integrated Mechanical and Thermal Activation (IMTA), sintering and followed by polymer infiltration. The low cost synthesis of NaSICON powder via IMTA as well as the polymer infiltration technique of NaSICON/polymer composite membranes will be discussed.
Development of Reversible Solid Oxide Cell System at Korea Institute of Energy Research
Authors: Myung Jae-ha , Park Seong-Ryong , Woo Sang-Kuk
Published: February 2020

Korea Institute of Energy Research (KIER) is placed on Daejeon, South Korea, which has had focused on energy technology R&D related with our living standards and national security since 1977. KIER`s R&D areas include improving efficiency and securing environment friendly way in use of limited conventional energy resources (oil, coal, natural gas) and exploring new energy sources (solar, wind, hydrogen and water).

The KIER is conducting a consortium project (~ $ 10m/yr) of MSIT( Ministry of Science and ICT), ME (Ministry of Environment), MOTIE(Ministry of Trade, Industry and Energy). This is about Research and Development of Future Energy Storage Technology by Using Hybrid Renewable Energy System, based on solid oxide electrolysis technology.

In this project, Energy Materials Laboratory in KIER is charge of development of 30 kW stack consisted with modules of flat-tube type unit cells to produce electricity on fuel cell mode and hydrogen on electrolysis mode. The unit cell is consisting with Ni-YSZ anode support, YSZ electrolyte, GDC buffer layer, LSCF cathode and LSF interconnector. Ni-YSZ support and LSF layer exposed to reducing/high steam environment, has been optimizing to stabilize their phases. Energy saving Laboratory in KIER is development of combustion boiler using waste to supply steam and heat. In addition, Hydrogen Laboratory is developing Hydrogen storage system.

In this presentation, the detailed research plans and cooperation system for diverse groups will be presented, as well as current core research results from SOC unit cell to stack system.
Energy Storage in a Transition Metal Doped MOF Derived Carbon Nanostructure
Authors: Banerjee Parama Chakraborty , Lobo Derrek , Shaibani Mahdokht , Majumder Mainak
Published: February 2020

We illustrate a novel concept in tailoring the architecture of MOF-derived carbons by doping MOF crystals with transition metal ions prior to carbon structure growth via chemical vapor deposition (CVD). MOF-5 was isomorphously doped with various concentrations of Ni2+ during synthesis and was subsequently subjected to CVD to grow a labyrinth of carbon nanofibers (CNF) with high electrical conductivity and higher surface area than that of the parent MOF. TEM of the inner structure of the CNFs revealed a chevron arrangement with ~0.34 nm visible fringe spacing. The CNF diameters increased with increasing Ni concentration. This is attributed to the decreasing distance between Ni dopants with increasing Ni concentration, which may facilitate coalescence of the Ni catalyst during the heat treatment and thereby increase the diameter of the resultant CNF. However, Ni doping concentration greater than 30% led to large agglomerations of Ni particles which eventually ceased CNF growth. The electrical conductivity and the electrochemical double layer capacitance of the CNFs also increased with increasing Ni concentrations. The highest electrochemical double layer capacitance and the lowest resistance was observed at a Ni doping concentration of 30%. An alkaline electrolyte was used to engage the Ni particles inside the CNFs to participate in a reversible redox reaction shuttling between Ni and Ni(OH)2, which resulted in a specific capacitance as high as 349 F/g. The possibility of doping transition metals into a wide variety of MOF structures can provide a new method to synthesize novel carbon structures with high energy storage capabilities.
Addition of Redox Additives to Ionic Liquid Electrolyte for High-Performance Supercapacitors of N-Doped Graphene Aerogel
Authors: Ma Nattapol , Phattharasupakun Nutthaphon , Sawangphruk Montree
Published: February 2020

We propose a new concept of using a redox additive potassium ferrocyanide in 1-butyl-1-methylpyrrolidinium dicyanamide ionic liquid electrolyte for high-performance supercapacitors. Coupling with a unique nanostructure of N-doped reduced graphene oxide, the supercapacitor using this new hybrid electrolyte exhibits the excellent specific energy and power of 89 Wh kg-1 and 3677 W kg-1, respectively. An excellent long-term stability is demonstrated up to 10000 cycles of charge-discharge with 87% capacitance retention.
Novel Multi-Dimensional Nanocarbons and Their Applications in Electrochemical Energy Storage
Authors: Lee Churl Seung , Bae Joon-ho
Published: February 2020

In order to realize next generation energy storage devices with high efficiency, large energy/power density, and long life cycle, novel carbon-based nanomaterials are needed as electrodes. In here, we present interesting multidimensional carbon nanostructures which could find potential applications in electrodes for energy storage devices. We synthesized carbon nanoplatelets (CNPs) by simple thermal treatment of expandable graphites. By using carbon nanoplatelets (CNPs), multi- dimensional (1D+2D) carbon nanostructures (CNP-CNTs) were synthesized by use of metal catalysts and CVD process. Basic cyclic voltammetry study on the CNPs and CNP-CNTs reveals that CNP-CNTs possessed enhanced mass specific capacitances compared to those of CNPs. We will also present recent progress on our multi-dimensional carbons including WGO-CNTs and silica coated CNP-CNTs.

Our multi-dimensional carbon nanostructures showed excellent electrochemical properties probably due to large surface area and unique geometry. These results suggest that the multi-dimensional carbon nanostructures could be promising in the applications for electrodes of next generation energy storage devices.
(Invited) Carbon Based Electrocatalysts
Authors: Coleman Eric , Lopes Pietro Papa , Strmcnik Dusan , Wang Rongyue , Markovic Nenad M , Stamenkovic Vojislav
Published: February 2020

It is of paramount importance to design highly active and durable cost effective catalysts that can be employed in energy conversion and storage systems in order to enable broad deployment of electrochemical technologies such as fuel cells, electrolyzers, ultra-capacitors and batteries. This report will provide an in-depth overview of recent activities aimed towards understanding of critical parameters that are behind catalytically active systems based on different forms of carbon. The main focus has been on necessity to resolve the reaction mechanism at atomic/molecular scale, which can ultimately lead towards design of materials with advanced properties.

Current state-of-the-art suffers from insufficient activity and poor durability, especially on cathode side in case of fuel cells. These obstacles place priority in research on the design of catalyst, which should not involve just catalyst itself, but rather the entire electrochemical interfaces. Parameters such as specific surface area, active sites, morphology, pH and nature of electrolyte are directly associated with adsorption properties of an electrocatalysts and will be thoroughly discussed in correlation with its performance.
(Invited) Improved Charge and Exciton Transport in Polymer-Removed SWCNT Thin Films: Implications for Photovoltaic and Thermoelectric Energy Harvesting
Authors: Ferguson Andrew John , Blackburn Jeffrey L. , Hart Stephanie , Kang Hyun Suk , Ihly Rachelle , MacLeod Bradley A. , Stanton Noah H.
Published: February 2020

The chemical and physical structure of semiconducting single-walled carbon nanotubes (SWCNTs) results in optical and electronic properties of promise for a wide variety of applications. Until quite recently the presence of metallic SWCNT impurities has hampered efforts to gain a deeper understanding of their true potential, with the additional complication that most commercially available materials contain tens of different chiral species. Significant effort has been devoted to elegant enrichment strategies aimed at extracting tailored semiconducting SWCNT species from the raw soot, from the use of subtly tunable surfactant interactions to the exploitation of specific DNA sequences. However, conjugated polymers, typically based on the fluorene moiety, appear to show the greatest promise with regards to their high selectivity and viability for scalable manufacturing approaches.

Unfortunately, the van de Waals forces between the pi-electron systems of the polymer and SWCNT that enable the selective extraction of semiconducting SWCNTs with high purity also make removal of the polymer difficult. Since these polymers typically have a wide bandgap they act as an insulating coating on the surface of the individual SWCNTs within functional networks, inhibiting the transport of energy in the form of excitons and/or charge carriers.

Here we demonstrate approaches aimed at replacing the strongly-bound polymers with variants that can be removed using simple solution-based chemical strategies, resulting in networks with vastly improved energy transport properties. We show that removal of the polymer results in a significant enhancement of the charge carrier mobility and electrical conductivity in the SWCNT networks, allowing optimization of the thermoelectric properties for both p-type and n-type transport. Finally, we extend the approach to samples strongly enriched in a single chiral SWCNT species, which allows us to employ transient spectroscopic techniques to probe enhanced exciton transport through the SWCNT network with high spectral fidelity. Our studies highlight a methodology by which high-performance SWCNT thin films can be prepared that could realize their potential for electronic and optoelectronic applications.
(Invited) Large Low Temperature Thermoelectric Power Factor from Completely Organic Thin Films Enabled By Carbon Nanostructures
Authors: Grunlan Jaime
Published: February 2020

In an effort to create a paintable/printable thermoelectric material, comprised exclusively of organic components, polyaniline (PANi), graphene, and double-walled carbon nanotubes (DWNT) were alternately deposited from aqueous solutions using the layer-by-layer assembly technique. Graphene and DWNT are stabilized with an intrinsically conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). A 1 µm thick film, composed of 80 PANi/graphene-PEDOT:PSS/PANi/DWNT-PEDOT:PSS quadlayers (QL) exhibits electrical conductivity (σ) of 1.88 X 105 S/m and a Seebeck coefficient (S) of 120 µV/K, producing a thermoelectric power factor (S
2∙σ) of 2710 µW/(m∙K2). This is the highest value ever reported for a completely organic material measured at room temperature. Furthermore, this performance matches or exceeds that of commercial bismuth telluride. These outstanding properties are attributed to the highly ordered structure in the multilayer assembly. The thermoelectric power output increased with the number of cycles deposited, yielding 8.5 nW at 80 QL for ΔT = 5.6 K. A simple thermoelectric generator was prepared with selectively-patterned, fabric-based system. The electric voltage generated by each TE device increased in a linear relationship with both ΔT and the number of TE legs, producing ~ 5 mV with just five legs and a ΔT of 9.5 K. This unique TE coating system is water-based and uses only organic components. For the first time, there is a real opportunity to harness waste heat from unconventional sources, such as body heat to power devices in an environmentally-benign way.

Figure 1
Tuning the Thermoelectric Properties of Carbon Nanotube Films By Molecular Doping
Authors: Nonoguchi Yoshiyuki
Published: February 2020

Carbon nanotubes are recognized to enable the investigation of one-dimensional thermoelectric transport and its application in flexible thermoelectric generators. Thermoelectric properties are in common evaluated using a dimensionless figure of merit zT = σα
2
T/κ, where σ is the electrical conductivity, α is the Seebeck coefficient, κ is the thermal conductivity, and T is the absolute temperature. Since σ, and α rely sensitively on carrier concentration, the development of a rational doping method is required for the investigation of carbon nanotubes’ thermoelectric properties. Additionally, it is empirically recognized that doped carbon nanotubes degrade rapidly in air.In this talk, the doping [i.e. n-type conversion] of carbon nanotubes and their stabilization are discussed in terms of supramolecular binding interactions. Power supply with an air-stable, nanotube-based thermoelectric generator is demonstrated.
Nitrogen/Phosphorus Co-Doped Side-Hole-Rich Carbon Nanotubes As Efficient Metal-Free Catalysts for Oxygen Reduction Reaction
Authors: Kim Mu Hyeon , Choi Eun Yeob , Kim Chang Keun
Published: February 2020

Nitrogen/phosphorus co-doped side-hole-rich carbon nanotubes (N,P-HCNT) were fabricated as metal-free electrocatalysts toward oxygen reduction reaction. The multi-walled carbon nanotubes (MWCNT) were simply reacted with hydrogen peroxide, and numerous of holes were formed at the MWCNT surface during the reaction. The resulting side-hole-rich carbon nanotubes (HCNT) were mixed with urea and triphenyl phosphine to incorporate nitrogen and phosphorus into the HCNT. The formation of N,P-HCNT was characterized by some analyses including X-ray photoelectron spectroscopy, field emission scanning electron microscopy and high resolution transmission electron microscopy. The Brunauer-Emmett-Teller analyses were also conducted to confirm the changes in surface properties of the N,P-HCNTs. Rotating ring disk electrode (RRDE) results indicated that the N,P-HCNTs exhibits excellent ORR activity in both acidic and alkaline conditions. In addition, the N,P-HCNT showed good long-term stability and resistance to methanol crossover effect than commercial platinum-based catalysts. Thus, the N,P-HCNT can be a new promising catalysts for oxygen reduction reaction.
(Invited) Length-Dependent Intracellular Bundling of Single-Wall Carbon Nanotubes Influences Retention
Authors: Islam Mohammad F.
Published: February 2020

Single-walled carbon nanotubes (SWCNTs) are increasingly being investigated for biomedical imaging, sensing, and drug delivery. Cell types, cellular entry mechanisms, and SWCNT lengths dictate SWCNT uptake, subsequent intracellular trafficking, and retention. Specialized immune cells known as macrophages are capable of two size-dependent entry mechanisms: endocytosis of small particles (diameter of 200 nm) and phagocytosis of large particles (diameter 4 500 nm). In comparison, fibroblasts uptake particles predominantly through endocytosis. We report dependence of cellular processing including uptake, subcellular distribution, and retention on the SWCNT length and immune cell-specific processes. We chose SWCNTs of three different average lengths: 50 nm (ultrashort, US), 150 nm (short) and 500 nm (long) to encompass two different entry mechanisms, and noncovalently dispersed them in water, cell culture media, and phosphate buffer (pH 5) with bovine serum albumin, which maintains the SWCNT optical properties and promotes their cellular uptake. Using confocal Raman imaging and spectroscopy, we quantified cellular uptake, tracked the intracellular dispersion state (i.e., individualized versus bundled), and monitored recovery as a function of SWCNT lengths in macrophages. Cellular uptake of SWCNTs increases with decreasing SWCNT length. Interestingly, short-SWCNTs become highly bundled in concentrated phase dense regions of macrophages after uptake and most of these SWCNTs are retained for at least 24 h. On the other hand, both US- and long-SWCNTs remain largely individualized after uptake into macrophages and are lost over a similar elapsed time. After uptake into fibroblasts, however, short-SWCNTs remain individualized and are exocytosed over 24 h. We hypothesize that aggregation of SWCNTs within macrophages but not fibroblasts may facilitate the retention of SWCNTs within the former cell type. Furthermore, the differential length dependent cellular processing suggests potential applications of macrophages as live cell carriers of SWCNTs into tumors and regions of inflammation for therapy and imaging.
(Invited) Antiviral Activity of Self-Assembled Glycodendro[60]Fullerene Monoadducts
Authors: Martín Nazario
Published: February 2020

A variety of different chemical and bio-inspired scaffolds have previously been used in the search for new glycoconjugates bearing the carbohydrates located in the appropriate spatial arrangement. Actually, there are a many examples where multivalency drastically enhances the interactions between biomolecules in comparison to the analogous monovalent binding.

In order to design multivalent peripheral ligands with glycomimetic properties that structurally can attach to the receptor sites of complex biological structures, a broad variety of ‘‘artificial glycoforms’’ have been created to study and understand the mechanisms involved in multivalent binding interactions. In this regard, we have recently shown that hexakis-adducts of [60]fullerene endowed with 12, 24 or 36 mannoses, act as strong inhibitors for DC-SIGN in an Ebola infection assay model.1 Furthermore, a drastic increase in the inhibition process at the subnanomolar scale has been observed when the size and mannoses´ number are increased in the firstly reported tridecafullerenes endowed with 120 mannose units decorating the periphery of the molecule.2

From the work carried out by our group on glycofullerenes with globular symmetry, it is possible to bring to light the significance of size and shape of the glycomimetic, being even more determinant that the number of carbohydrate moieties in the glycoparticle.

In the present work, the synthetic approach is simplified, using C60
mono-adducts instead of C60
hexakis-adducts, without compromising the spherical form of the final glycomimetic, provided by the supramolecular aggregate resulting from the self-assembly of mono-adducts.3 The efficiency to block DC-SIGN mediated viral infection by an artificial Ebola virus has been tested in a cellular experimental assay finding that, these systems are potent inhibitors of viral infection.

References

a) B. M. Illescas, J. Rojo, R. Delgado, N. Martín, "Multivalent Glycosylated Nanostructures To Inhibit Ebola Virus Infection" J. Am. Chem. Soc., 2017, 139, 6018−6025; b) J. Luczkowiak, A. Muñoz, M. Sánchez-Navarro, R. Ribeiro-Viana, A. Ginieis, B. M. Illescas, N. Martín, R. Delgado, J. Rojo, Biomacromolecules
2013, 14, 431-437; c) J.-F. Nierengarten, J. Iehl, V. Oerthel, M. Holler, B. M. Illescas, A. Muñoz, N. Martín, J. Rojo, M. Sánchez-Navarro, S. Cecioni, S. Vidal, K. Buffet, M. Durka, S. P. Vincent, Chem.
Commun.
2010, 46, 3860-3862; d) M. Sánchez-Navarro, A. Muñoz, B. M. Illescas, J. Rojo, N. Martín, Chem. Eur. J.
2011, 17, 766-769.

A. Muñoz, D. Sigwalt, B. M. Illescas, J. Luczkowiak, L. Rodríguez, I. Nierengarten, M. Holler, J.-S. Remy, K. Buffet, S. P. Vincent, J. Rojo, R. Delgado, J.-F. Nierengarten, N. Martín, Nat. Chem., 2016, 8, 50-57.

A. Muñoz, B. M. Illescas, J. Luczkowiak, F. Lasala, R. Ribeiro-Viana, J. Rojo, R. Delgado, N. Martín, J. Mater. Chem. B, 2017, 5, 6566-6571.
Graphene Derivatives As Effective Formulations for Drug Delivery, Imaging, and Sensing
Authors: Sizemore Elizabeth , Hasan Md Tanvir , Akkaraju Giridhar , Naumov Anton V
Published: February 2020

A field of molecular therapeutics has significantly advanced the treatment of many complex conditions, including cancer therapeutics. However many molecular formulations still lack the diagnostic power of tomography-guided approaches, and are restricted by dose-limiting toxicity. Multiple gene therapeutics, which have shown to be effective on a cellular level, require to be delivered in-vivo to protect the payload from degradation in blood. This technical gap outlines a clear need for multifunctional delivery/imaging agents. Nanomaterials provide these capabilities, safely delivering therapeutics concomitantly imaging their delivery pathways. Recently graphene derivatives (mainly, graphene oxide) became a focus of intense scientific inquiry including their applications in the biomedical field. Graphene Oxide (GO) is an attractive candidate for bioimaging due to its intrinsic fluorescence in the red/near-infrared spectral region with reduced biological autofluorescence background. This provides the capability of fluorescence imaging without the need for additional fluorophores. Additionally GO has a large platform for functionalization with drug molecules, is water soluble and exhibits pH-mediated response in its fluorescence emission. Nanoscale graphene oxide derivatives (NGO) produced via biocompatible bottom-up synthetic route have properties similar to GO, however, possessing a smaller size for more efficient cellular internalization. We explore these properties to develop a family of graphene-based imaging/sensing/delivery platforms for molecular therapeutics. GO or NGO utilized in our work show little to no cytotoxicity quantified via MTT assay up to the maximum imaging concentrations of 15 ug/mL. We use spectrally-resolved fluorescence imaging for in-vitro detection in the spectral ranges specific to GO or NGO emission. Both GO and NGO exhibit efficient cellular internalization assessed via their emission within HeLa cells, with significantly higher accumulation observed for NGO, suggesting a high potential for drug delivery applications and image-guided therapy. A pH dependence of both GO and NGO emission provides a sensing mechanism for the acidic environments of cancer cells; as many cancer cell types excrete lactic acid, their environments are more acidic than those of healthy cells. The difference between fluorescence in healthy (HEK-293)/cancer (HeLa, MCF-7) cell environments is quantified for graphene derivatives in this work via assessing the shifts in emission and/or variations in emission intensities at different wavelengths. As a result we propose a family of graphene derivatives, including GO and NGO functionalities, as efficient multifunctional candidates for in-vitro delivery of active agents, fluorescence imaging and pH-sensing of cancerous environments.
(Invited) Inner- and Outer-Wall Sorting of Double-Walled Carbon Nanotubes
Authors: Flavel Benjamin S
Published: February 2020

Double walled carbon nanotubes (DWCNTs) consist of two coaxially aligned single walled carbon nanotubes (SWCNTs) and previous sorting methods only achieved outer-wall electronic type selectivity. Here a separation technique capable of sorting DWCNTs by semiconducting (S) or metallic (M) inner- and outer- wall electronic type is presented. Electronic coupling between the inner- and outer- wall is used to alter the surfactant coating around each of the DWCNT types and aqueous gel permeation is used to separate them. Aqueous methods are used to remove SWCNT species from the raw material and prepare enriched DWCNT fractions. The enriched DWCNT fractions are then transferred into either chlorobenzene or toluene using the copolymer PFO-BPy to yield the four inner@outer combinations of M@M, M@S, S@M and S@S. The high-purity of the resulting fractions is verified by absorption measurements, TEM, AFM, resonance Raman mapping and high-density field effect transistor devices.

[1] Han Li, Georgy Gordeev, Soeren Wasserroth, Venkata Sai Kiran Chakravadhanula, Shyam Kumar Chethala Neelakandhan, Frank Hennrich, Ado Jorio, Stephanie Reich, Ralph Krupke, Benjamin Flavel, Nature Nanotechnology (2017) DOI: 10.1038/nnano.2017.207

[2] Katherine Moore, Moritz Pfohl, Daniel Tune, Frank Hennrich, Simone Dehm, Venkata Sai Kiran Chakravadhanula, Christian Kuebel, Ralph Krupke, Benjamin Flavel, ACS Nano (2015) DOI: 10.1021/nn506869h

[3] Katherine Moore, Moritz Pfohl, Frank Hennrich, Venkata Sai Kiran Chakravadhanula, Christian Kuebel, Manfred Kappes, Joe Shapter, Ralph Krupke, Benjamin Flavel, ACS Nano (2014) DOI: 10.1021/nn500756a
Effect of Organometallic Interconnects on Transverse Conductivity of Aligned Single-Walled Carbon Nanotubes
Authors: Bekyarova Elena , Chen Mingguang , Li Wangxiang
Published: February 2020

Thin films of aligned single-walled carbon nanotubes (SWNTs) are a promising candidate for future electronics technology because they offer the opportunity to the preparation of high performance devices. Aligned SWNT film exhibit a large electrical anisotropy with high electrical conductivity in the alignment direction and low conductivity in the transverse direction due to large energy barriers for tunneling between adjacent SWNTs. We demonstrate that transition metal atoms inserted between the sidewalls of parallel SWNTs effectively coordinate to the benzene rings of the nanotubes and serve as a conduit for electron transfer. The atomically interconnected aligned SWNTs exhibit dramatically reduced electrical anisotropy due to the increase of the transverse conductivity of aligned SWNT thin films.
Molecular Recognition at Local Doped Sites of Locally Functionalized Single-Walled Carbon Nanotubes for Selective Wavelength Shift of Near Infrared Photoluminescence
Authors: Shiraki Tomohiro , Onitsuka Hisashi , Shiga Tamehito , Nakashima Naotoshi
Published: February 2020

Locally functionalized single-walled carbon nanotubes (lf-SWNTs) have local defects on the sp2 carbon networks of the tube wall through a limited amount of chemical modification, by which they emit red-shifted and quantum yield-enhanced photoluminescence (PL) in comparison to that of pristine SWNTs.[1-6] The newly generated PL (E
11*) of lf-SWNTs shows spectral shifts depending on the chemical structures of the modified molecules and dynamic wavelength shifts have been observed by protonation of amino groups[1] and saccharide recognition[6] at the doped sites. Such external stimuli responsiveness would be applicable to develop advanced sensing and imaging materials and optical devices using the near infrared (NIR) PL functions.

Based on findings in the saccharide recognition study[6], we extend molecular designs of our molecular recognition approach for development of stimuli-responsive wavelength-shift systems using lf-SWNTs. Crown ethers, which bind cations such as metal ions with selectivity based on ring sizes and donor atoms, are useful molecular motifs for metal sensing and supramolecular self-assemblies. We newly synthesized azacrown ether-modified lf-SWNTs (crown-SWNTs) and crown-SWNTs showed a new PL peak at 1138 nm (E
11*), which was red-shifted and intensified in comparison to E
11 PL at 989 nm. When a AgNO3 solution was added to the crown-SWNTs solution, the E
11* PL showed a larger peak shift to a longer wavelength region compared to the E
11 PL. According to the cation recognition mechanism of the azacrown ether, it is considered that the observed wavelength shift is induced by electronic character changes from electron donating to withdrawing of the modified groups due to the Ag+ inclusion in the ring. The molecular recognition approach, therefore, is promising to create new types of NIR PL nanomaterials whose PL properties can be modulated by the molecular actions.

References: [1] Schatz, G. C. and Wang, Y. et al., J. Am. Chem. Soc.
2016, 138, 6878-6885. [2] Htoon, H. and Doorn, S. K. et al., Nat. Photon.
2017, 11, 577-582. [3] Shiraki, T. and Nakashima, N. et al., Chem. Commun.
2017, in press, DOI:10.1039/C7CC06663E. [4] Shiraki, T. and Nakashima, N. et al., Nanoscale.
2017, in press, DOI:10.1039/C7NR05480G. [5] Shiraki, T. and Nakashima, N. et al., Sci. Rep.
2016, 6, 28393. [6] Shiraki, T. and Nakashima, N. et al., Chem. Commun.
2016, 52, 12972-12975.

Figure 1
New Methods Towards Designer DNA Sequences for Enantiomeric-Chiral Selective Sorting of Single-Wall Carbon Nanotubes
Authors: Meany Brendan , Zheng Ming
Published: February 2020

To date methods in producing structurally defined single-wall carbon nanotubes are inadequate leaving purification or sorting a viable option for obtaining nanotubes of a certain chirality. While several procedures have been developed for structure specific isolation of nanotubes, there are differences in purity, scalability, and economic feasibility. The use of single-stranded DNA sequences has evolved and been refined to select for both nanotube helicity and handedness. These developments through brute force screening of hundreds of sequences show the unique recognition of DNA for nanotube structure. Going a step further DNA recognition combined with a second technique, aqueous two-phase separation, allows for high purity sorting of multiple chiralities.

We introduce a few new experimental and computational methods as the next step in discovering new DNA sequences for sorting single-wall carbon nanotubes. Utilizing these new methods followed by experimental verification, novel DNA sequences are discovered for dispersing and sorting single-wall carbon nanotubes.
(Invited) Substituted Aryl Structure Effects on Photoluminescence Properties of Locally Functionalized Single-Walled Carbon Nanotubes
Authors: Shiraki Tomohiro , Uchimura Shunsuke , Shiraishi Tomonari , Toshimitsu Fumiyuki , Nakashima Naotoshi
Published: February 2020

Sp3 defect doping to semiconducting single-walled carbon nanotubes (SWNTs) provides fascinating near infrared photoluminescence (NIR PL) properties, in which, compared to PL (E
11) of pristine SWNTs, redshifted PL with enhanced quantum yields (E
11*) is observed by local functionalization through the doping.[1-6] In the locally functionalized SWNTs (lf-SWNTs), chemical structures of the modified molecules on the doped sites play an important role to determine and control the E
11* PL wavelengths. For example, we have succeeded in generation of remarkably redshifted PL on the basis of a proximal modification approach [5] and development of dynamic wavelength shift systems driven by molecular recognition at the doped sites [6].

Here, we report recent findings of the chemical structure factors that modulate the E
11* PL properties of aryl functionalized lf-SWNTs. When positional isomeric structures of the substituted aryl groups are introduced for the doped sites of lf-SWNTs (Figure), significantly different PL is observed from that of typical para-aryl modified lf-SWNTs.[3] Namely, the meta-aryl modified lf-SWNTs show deviation from the reported liner relationship between the Hammett substituent constants and ΔE = E
11*-E
11 of the para-aryl modified lf-SWNTs. For the ortho-aryl modified lf-SWNTs, two PL peaks generate by the functionalization and one of them appears in the largely redshifted region compared to typically observed E
11* PL. The present findings, therefore, are expected to provide new designs for the molecule-based PL modulation of lf-SWNTs. In this presentation, more details about the structural factors will be discussed.

References: [1] Schatz, G. C. and Wang, Y. et al., J. Am. Chem. Soc.
2016, 138, 6878-6885. [2] Htoon, H. and Doorn, S. K. et al., Nat. Photon.
2017, 11, 577-582. [3] Shiraki, T. and Nakashima, N. et al., Chem. Commun.
2017, in press, DOI:10.1039/C7CC06663E. [4] Shiraki, T. and Nakashima, N. et al., Nanoscale.
2017, in press, DOI:10.1039/C7NR05480G. [5] Shiraki, T. and Nakashima, N. et al., Sci. Rep.
2016, 6, 28393. [6] Shiraki, T. and Nakashima, N. et al., Chem. Commun.
2016, 52, 12972-12975.

Figure 1
(Invited) Solvent and Wavelength Dependence of Carbon Nanotube Defect-State Photoluminescence Relaxation Dynamics
Authors: Doorn Stephen K. , He Xiaowei , Velizhanin Kirill , Bullard George , Kim Younghee , Hartmann Nicolai F. , Htoon Han , Therien Michael J.
Published: February 2020

Covalent introduction of photoluminescent defect states in carbon nanotubes is introducing new functionality such as room-temperature single photon emission1,2 and associated novel photophysical behaviors. Harnessing defect-state emission will depend on a thorough understanding of their electronic structure3,4 and relaxation dynamics.5 While providing relaxation timescales and mechanistic insight,5 study of photoluminescence relaxation can also be a route to obtaining complementary information on electronic structure and relaxation pathways. We present here a study of how relaxation dynamics are affected by dielectric environment. Changes in relaxation times with dielectric constant of the solvent will be discussed as evidence for an electronic to vibrational energy transfer from the defect-trapped exciton to the solvent degrees of freedom. Solvent interactions are thus seen to be an important component of relaxation that also includes multi-phonon decay processes.5 Wavelength-dependent changes in relaxation times provide insight into the effects of both thermal detrapping and transition oscillator strength on decay times. Wavelength dependence will also be discussed in the context of temperature-dependent relaxation measurements.

References

Ma, X. et al.; Nat. Nanotechnol., 10, 671 (2015).

He, X. et al.; Nat. Photon., 11, 577 (2017).

Ma, X. et al.; ACS Nano, 8, 10782 (2014).

He, X. et al.; ACS Nano, DOI: 10.1021/acsnano.7b03022 (2017)

Hartmann, N. F. et al.; ACS Nano, 10, 8355 (2016).