bluuebunny/crossref_metadata_2025 huggingface dataset:
Conjugation of an α-Helical Peptide to the Surface of Gold Nanoparticles
Authors: Wilder Logan , Fies Whitney , Rabin Charlie , Webb Lauren J. , Crooks Richard M
Published: February 2020

We are interested in functionalizing gold nanoparticles (AuNPs) with proteins using a biomimetic approach in which an intermediate peptide "glue" directs the orientation of a protein relative to the AuNP surface. The first step toward that goal is described in this presentation. Attachment of electrochemically active proteins to electrode surfaces is necessary for the interrogation of electron transfer kinetics in biological systems, as well as for the development of enzyme biosensors. Passive adsorption and covalent linking are the two main strategies used for protein-electrode attachment. Passive adsorption is experimentally simple but rarely controls protein orientation or stability, resulting in random structural orientation, denaturation, and/or uncontrolled desorption of proteins. Covalent linking provides greater binding strength to the protein-surface pair but exposes the protein to multiple abiological reagents, can disrupt structure due to the single rigid attachment point, and does not necessarily lead to optimal orientation. One strategy designed to overcome these limitations has been developed by Webb and coworkers, which is the formation of a surface layer of α-helical peptides on planar gold surfaces. This approach aims to design a tunable surface which can mimic protein-protein interactions and specifically orient proteins via the protein-peptide interaction. In order to make this approach more general and applicable to electrodes of various materials, we have endeavored to functionalize gold nanoparticles (AuNPs) with structure-controlled α-helical peptides. Using noble metal NPs as intermediates in electrode-protein attachment schemes is attractive due to the high surface to volume ratio and tunable surface curvature of NPs. Also, once attached to the NP, many surfaces can be functionalized with a protein via attachment of the NP-protein conjugate. The first step toward the goal of AuNP-protein attachment via structure-controlled peptide is described in this presentation. Specifically, we show that ~5 nm AuNPs can be functionalized with a mixed self-assembled monolayer consisting of oligo (ethylene glycol) alkanethiols terminated with either hydroxyl or azide groups, and that the resulting materials are stable and soluble in water. The azide groups on the surface of the AuNPs can subsequently be linked to alkyne-functionalized peptides via a copper-catalyzed azide-alkyne cycloaddition (click) reaction. Analysis of the resulting material by FTIR and circular dichroism spectroscopy demonstrates that the peptide is covalently linked to the SAM and that it exists in an α-helical conformation. These structure-controlled peptide-attached AuNPs are potentially useful in protein-electrode attachment schemes as intermediate structures between proteins and the electrode.
Utilization of Highly Purified Single Wall Carbon Nanotubes Dispersed in Polymer Thin Films for an Improved Performance of an Electrochemical Glucose Sensor
Authors: Tumkur Prathima Prabhu , Goornavar Virupaxi , Ramesh Govindarajan T.
Published: February 2020

In this work, we report the improved performance an electrochemical glucose sensor based on a glassy carbon electrode (GCE) that has been modified with highly purified single wall carbon nanotubes (SWCNTs) dispersed in polyethyleneimine (PEI), polyethylene glycol (PEG) and polypyrrole (PPy). The single wall carbon nanotubes were purified by both thermal and chemical oxidation to achieve maximum purity of ~98% with no damage to the tubes. The SWCNTs were then dispersed by sonication in three different organic polymers (1.0 mg/ml SWCNT in 1.0 mg/ml of organic polymer). The stable suspension was coated onto the GCE and electrochemical characterization was performed by Cyclic Voltammetry (CV) and Amperometry. The electroactive enzyme glucose oxidase (GOx) was immobilized on the surface of the GCE/(organic polymer–SWCNT) electrode. The amperometric detection of glucose was carried out at 0.7 V versus Ag/AgCl. The GCE/(SWCNT–PEI, PEG, PPY) gave a detection limit of 0.2633 μM, 0.434 μM, and 0.9617 μM, and sensitivities of 0.2411 ± 0.0033 μA mM−1 ,r2 = 0.9984, 0.08164 ± 0.001129 μA mM−1, r2 = 0.9975, 0.04189 ± 0.00087 μA mM−1, and r2 = 0.9944 respectively and a response time of less than 5 s. The use of purified SWCNTs has several advantages, including fast electron transfer rate and stability in the immobilized enzyme. The significant enhancement of the SWCNT modified electrode as a glucose sensor can be attributed to the superior conductivity and large surface area of the well dispersed purified SWCNTs.
New Analytical Method to Reveal the Adhesion Properties in the Composite Electrodes for Lithium-Ion Batteries
Authors: Lee Yong Min , Byun Seoungwoo , Roh Youngjoon , Jin Dahee , Ryou Myung-Hyun
Published: February 2020

Adhesion properties such as adhesion strength within the composite electrodes are receiving considerable attention as their loading levels increase ceaselessly for higher energy density. Without controlling those properties appropriately within the electrode, not only short-term electrochemical performance but also long-term reliability cannot be secured. To address this limitation, a new analysis tool, surface and interfacial cutting analysis system (SAICAS), has been developed and utilized to investigate the adhesion properties of the composite electrodes for lithium-ion batteries (LIBs). Comparing to the conventional peel test, the SAICAS can provide the horizontal force during peeling process at any depths in the composite electrode. So, those horizontal forces have some relationship with the real adhesion strength.

In this work, we will introduce the measuring principles and applications of the SAICAS for the composite electrodes of LIBs. With a number of composite electrodes having different compositions and design parameters (loading and density), we confirm that the SAICAS can provide reliable adhesion strengths in the bulk as well as at the interface. Moreover, with the adhesion strengths at different depths, the polymeric distribution within the electrode can be estimated directly and efficiently without conducting complex and time-consuming post analysis works.
Rapid 3D Imaging for Quality Assurance of Li-Ion Materials Using Lab-Based X-Ray Computed Tomography
Authors: Heenan Thomas M. M. , Leach Andrew , Tan Chun , Jervis Rhodri , Brett Daniel J.L. , Shearing Paul R.
Published: February 2020

In an effort to reduce the amount of cobalt within lithium-ion batteries (Li-ions), which is both expensive and toxic, many fabrication efforts are moving towards variations of nickel-rich materials such as nickel-manganese-cobalt-oxide: LiNi0.8Mn0.1Co0.1O2 (NMC811) and LiNi0.6Mn0.2Co0.2O2 (NMC622). However, these materials have several shortfalls which are currently not well understood [1, 2]. Therefore in order to reduce cobalt content while maintaining competitive performance these materials must the examined in great detail, often requiring complex, multi-dimensional studies [3].

X-ray computed tomography (CT) has revolutionised the field of materials characterisation in recent years through the ability to produce reconstructions of 3D microstructures without destruction of the sample [4]. Alas, until recently, X-ray CT methods have depended upon highly specialised synchrotron facilities which have limited availability, restricting the throughput of material that can be analysed. Nevertheless, developments in lab-based devices has produced instruments capable of comparable resolutions to their synchrotron counterparts [5].

Although the 3D volume produced from cutting-edge lab and synchrotron instruments are now comparable, the high-brilliance, tuneable radiation from a synchrotron source results in scan times that are orders of magnitude faster than those achieved within the lab. Due to the higher availability of lab-based instruments, long scan-times are typically not problematic; however, an instance where this does become an issue is in quality assurance (QA) for the screening of materials during fabrication. Therefore author’s objective was to develop a method capable of producing 3D images from electrode materials with voxel sizes in the hundreds of nanometres or smaller, while reducing the acquisition time by an order of magnitude, from hours to minuets.

This presentation will discuss how to obtain a 3D tomogram from Li-ion materials in minuets using only lab-based instruments; the possible applications of such a technique: from fundamental research to industrial QA; and, the expected implications on the Li-ion field.

Jung, R., et al., 2018. Journal of The Electrochemical Society, 165(2), pp.A132-A141.

Hwang, S., et al., 2016. APL Materials, 4(9), p.096105.

Finegan, D.P., et al., 2016. Advanced Science, 3(3), p.1500332.

Shearing, P.R., et al., 2010. Electrochemistry communications, 12(3), pp.374-377.

Heenan, T.M.M., et al., 2018. Nano Energy, 47, pp.556-565.

Figure 1
(Invited) Colloidal and Processing Science Characterization for Battery Systems
Authors: Armstrong Beth
Published: February 2020

Colloidal and processing science characterization techniques provide a valuable approach to the synthesis & processing of battery electrodes. The use of tools such as zeta potential & rheology paired with other spectroscopy techniques allows for a systematic development of slurry-based electrode fabrication. These techniques will be presented as they apply to the understanding and optimization of an aqueous, Si-based anode system. The effect of particle size, surface charge, and the selection of additives and processing aids on the rheological behavior will be discussed. In addition, the use of spectroscopy methods, such as FTIR and RAMAN, to further elucidate the understanding of the Si surface during processing will be considered.

This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) under contract DE-AC05-00OR22725. The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-publicaccess-plan). The work was supported by the Vehicle Technologies Office, Hybrid Electric Systems Program, Battery R&D, Brian Cunningham (Technology Manager), at the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy.
Fabrication and Characterization of Thick Sintered Lithium-Ion Battery Full Cells
Authors: Nie Ziyang , McCormack Patrick , Bilheux Hassina , Bilheux Jean , Robinson Pierce , Koenig Gary
Published: February 2020

Commercial battery electrodes are composites containing electroactive material and inactive material – typically carbon conductive additives and polymer binders. Eliminating the inactive components would increase the energy density at the cell level. In addition, processing the electrodes to be thicker would improve energy density. One way to achieve both these goals is to fabricate thick electrodes comprised of only sintered active material. Such electrodes have not been extensively investigated, in particular in full cell configurations. Sintered electrodes have very high energy density, but they have relatively low electronic conductivity and longer ion diffusion pathways. Understanding the limitations and designs of these electrodes is the focus of this presentation.

Li4Ti5O12 (LTO)/LiCoO2 (LCO) full cells with sintered electrodes were produced via custom synthesis, processing, and fabrication steps. The net movement of lithium was tracked using neutron imaging during electrochemical charge and/or discharge. The neutron imaging resulted in clear observation of the net movement of lithium in the cells. The neutron images provided insights into the lithiation and delithiation processes with different electrode thicknesses and different rates of discharge. The neutron imaging results were compared to electrochemical models of the discharge of the cell. The changes in concentration calculated using the model had good overall agreement with the neutron imaging observations, although improvements to the technique and model inputs will be discussed.
Surface Characterization of Battery Electrode/Electrolyte Materials Using XPS and Tof-SIMS
Authors: Harrison Elisa T , Peczonczyk Sabrina L , Sharafi Asma , Wujcik Kevin H , Drews Andy , Simko Steven
Published: February 2020

With a drive to develop hybrid electric and electric vehicles for improving fuel economy and lowering emissions, research of battery materials becomes necessary to increase the performance and durability of automotive batteries. Therefore, significant improvements in the energy capacity, stability, and safety of automotive batteries must be achieved. For the last two decades, traditional methods to characterize battery materials and interfaces have focused on the mechanical and electrochemical properties of the battery. There has been less emphasis on understanding chemical properties of the surface of the electrode and the chemistry that occurs at the electrode/electrolyte interface. Moving forward to develop new battery systems, gaining an understanding of the surface chemistry of battery materials is critical to improving performance.

The objective of this work is to highlight the need for surface analytical techniques and methodologies to fully characterize and improve battery materials. In this work, the surface chemistry of electrodes and electrolytes were analyzed using both X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). These are powerful tools to identify slight changes to the surface chemistry of battery materials with respect to factors such as electrode and electrolyte formulation, cycling conditions, air exposure, contamination, and sample replication.
Kerr Gated Raman Spectroscopy to Investigate Lithium-Ion Battery Interfaces
Authors: Hardwick Laurence J. , Cabo-Fernandez Laura , Kostecki Robert , Sazanovich Igor
Published: February 2020

Fluorescent species are formed during cycling of lithium ion batteries as a result of electrolyte decomposition due to the instability of the non-aqueous electrolytes and side reactions that occur at the electrode surface. The increase in the background fluorescence due to the presence of these components makes it harder to analyse data due to the spectroscopic overlap of Raman scattering and fluorescence. In this talk we will demonstrate that Kerr gate Raman is an effective technique for the isolation of the scattering effect from the fluorescence enabling the collection of the Raman spectra of Li-ion electrolyte materials, without the interference of the fluorescence component.

In particular we will present proof-of-concept experiments that the background fluorescence emission in the scattering spectrum of LiPF6 as salt and in the conventional battery electrolyte with ethylene carbonate: dimethyl carbonate solvents can be minimised or suppress by Kerr gated Raman. It was possible to detect degradation products resulting from the decomposition of LiPF6, which has not previously been observed by Raman scattering due to the fluorescence emission. It was also possible to investigate the reactivity of LiPF6 against decomposition in the electrolyte is slower than as with the pure salt.
(Invited) In-Situ Measurements of Stress Evolution in Composite Sulfur Cathodes
Authors: Pharr Matt , Zhang Yuwei , Luo Yuting , Fincher Cole , Banerjee Sarbajit
Published: February 2020

Owing to its enormous capacity, sulfur has emerged as a promising cathode material. Recent studies have identified and begun to mitigate a number of key electrochemical issues in sulfur-based cathodes, including poor conductivity and polysulfide dissolution/shuttling. However, the mechanics of lithiation/de-lithiation of sulfur are much more complicated than in other systems due to solid-to-liquid, liquid-to-liquid, and liquid-to-solid phase transformations, and thus remain poorly understood. To this end, this talk will discuss our recent measurements of the evolution of stresses in composite sulfur-carbon cathodes during electrochemical cycling, performed using an in-situ substrate curvature technique. This mechanical behavior is connected to electrochemical and structural evolution via combined scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction during cycling. Overall, these studies provide fundamental insight into the practical design of mechanically robust sulfur cathodes, thereby paving the way toward realizing new high-capacity systems.
(Invited) Molecular-Level Understanding of Ion Intercalation Mechanisms in Aluminum and Zinc Battery Electrodes Revealed By Solid-State NMR Spectroscopy
Authors: Messinger Robert J. , Jadhav Ankur , Hawkins Brendan E. , Xu Jeffrey
Published: February 2020

Solid-state nuclear magnetic resonance (NMR) spectroscopy is a powerful and quantitative characterization tool that can elucidate the local chemical, structural, and electronic changes that battery materials undergo upon electrochemical cycling. However, to date no solid-state NMR experiments have been reported that directly probe multivalent aluminum or zinc cations within intercalation electrodes, in part due to their challenging quadrupolar nature and in part due to the small number of structures that reversibly intercalate multivalent ions. Here, multi-nuclear solid-state magic-angle-spinning (MAS) experiments will be presented on rechargeable aluminum and zinc intercalation electrodes for the first time, revealing insights into their ion intercalation and charge transfer mechanisms. For aluminum or zinc batteries using the thio-Chevrel Mo6S8 and seleno-Chevrel Mo6Se8 as cathode materials, solid-state 27Al and 67Zn NMR experiments establish quantitatively the relative populations of intercalated aluminum or zinc cations in different local environments as a function of state-of-charge. For the seleno-chevrel electrodes, solid-state 77Se NMR experiments reveal the effects of aluminum- and zinc-ion intercalation on the local electronic structures of the Mo6Se8 frameworks. For comparison, aluminum-graphite batteries will also be analyzed, where solid-state 27Al NMR measurements yield insights into the local environments of monovalent chloroaluminate anions after intercalation into natural graphite. Opportunities and challenges will be discussed regarding the application of NMR spectroscopy to aluminum and zinc battery materials. Overall, the solid-state NMR and electrochemical results pave the way towards a better understanding of material design principles aimed at realizing multivalent intercalation electrodes with enhanced electrochemical properties.
Depth-Dependent Surface Analyses of 15% Vanadium Modified Lithium Iron Silicate
Authors: Zhang Ying , Wei Xuexia , Luo Xiaoying , Cheng Xuan
Published: February 2020

The unmodified and nominal 15% vanadium modified carbon coated lithium iron silicates (Li2FeSiO4/C) were prepared through a sol-gel precursor and solid-state reaction route. The microstructures and interfacial behaviors were examined and compared. In an effort to characterize whether the vanadium substitution took place, the chemical states and depth profiles of elements on the as-prepared nominal 15% vanadium modified Li2FeSiO4/C were studied by X-ray photoelectron spectroscopy (XPS) at the surface (0 nm), 50, 100, and 150 nm underneath the surface. It was found that the main crystal phase varied from monoclinic P21 to orthogonal Pmn21, while the nanoparticle surfaces were surrounded by amorphous carbon coating with the thickness of approximately 50 nm upon vanadium modification. Furthermore, the simultaneous presences of multivalent iron (Fe) and vanadium (V) ions were confirmed.
Probing Signatures of Thermal Metastability in Lithium-Ion Batteries
Authors: Mistry Aashutosh N , Perumaram Rangarajan Sobana , Mukherjee Partha P.
Published: February 2020

With advances in battery technology, lithium-ion cells have continued to grow in energy density. This scale-up in electrochemistry implicitly fosters coupled thermal effects and a higher propensity for undesired thermal events. Such thermal metastability is directly related to self-heating behavior, however, the understanding of which in conventional calorimeter testing is limited to specific thermal operation. In this work, we present an in operando approach to characterize thermal signatures based on ambient test data (without a calorimeter). Thermal metastability of Li-ion cells is especially examined in the context of electrochemical fatigue (i.e., cycling), electrochemical abuse (i.e., external short) and thermal extremes (e.g., low temperature).
Electrical Resistance Response of Reduced Graphene Oxide - Aramid Nanofiber Films to Bending-Induced Strain
Authors: Loufakis Dimitrios , Boyd James G. , Lutkenhaus Jodie L. , Lagoudas Dimitris
Published: February 2020

Structural energy storage is a field associated with the combination of important functions such as structural reliability, energy storage, and energy delivery. The combination of said functions ensures savings in the overall volume and mass of the system. Reduced graphene oxide (rGO) and aramid nanofibers (ANF) composite film electrodes were developed for the purpose of structural energy storage. Graphene is studied due to its remarkable mechanical properties, electrical conductivity and electrochemical surface area. Furthermore, Kevlar® aramid nanofibers enhance the structural properties of the composite due to their excellent mechanical properties. However, external strains are expected on the composite film due to its structural function, and the response of the electrical properties to external strain needs to be evaluated. In this work, the change in electrical resistance was measured under bending-induced strain, using a home-built instrument that allows for accurate strain measurements using image analysis. We show that the resistance of the film decreases under bending via a mechanism we called “mechanical annealing.” This mechanism may be the effect of improved stacking of rGO sheets. The degree of mechanical annealing was also correlated to the amount of bending strain, as well as the amount of ANF loading. Our results demonstrate an improvement, rather than deterioration of the electrical resistance of rGO/ANF composite films under strain, making them suitable for structural energy storage applications.
Electrochemically Engineered Graphite for Supercapacitor Application
Authors: Tamgadge Rupesh M , Shukla Anupam
Published: February 2020

Supercapacitors are also known as electrochemical capacitors (ECs) attracted considerable attention because of properties like high power density, rapid charge-discharge rate (few seconds), long cycle life (>100000 cycles) and low maintenance cost. These properties make EC an excellent candidate for applications like hybrid electric vehicles, frequency regulations in smart grids etc. However, designing freestanding binder-free electrodes with superior mechanical strength and suitable capacitance is still in the development stage. Graphene, a 2D form of carbon is one of the best candidates for supercapacitor electrode material, because of its properties, like, high surface area (~2630 m2 g-1), high intrinsic electrical conductivity, and chemical stability. Restacking and aggregation of graphene sheets during electrode fabrication process leads to ineffective use of its high surface area. Vertically oriented graphene (VOG) sheets on a conductive substrate can be a useful electrode for supercapacitor application. Exposed graphene sheets on the surface of graphite, increases the surface area of the electrode by order of magnitude and reduces the contact resistance since graphene sheets remain attached to the substrate. Here, we demonstrate an electrochemical approach for engineering graphite surface in such a way that we can directly grow vertically oriented graphene on the graphite substrate itself. Electrochemical exfoliation process increases interlayer spacing causing more and easy access to the surface area by electrolyte ions, thus reducing diffusion resistance. Anodization of graphite in 1 M H2SO4 leads to the growth of VOGs on a graphite substrate. Exfoliated graphite (EG) not only act as a current collector but also stores enough charges in the interlayer spaces. EG shows excellent capacitive performance in 1 M sodium sulphate electrolyte. The capacitance of graphite, 0.05 F cm-2 increases to 0.75 F cm-2 (scan rate of 5 mV s-1) in case of EG.
(Invited) Thermoelectric properties of Fermi-level tuned and Aligned Single Wall Carbon Nanotubes
Authors: Yanagi Kazuhiro
Published: February 2020

Single wall carbon nanotubes (SWCNTs) are one-dimensional materials with sharp van Hove singularities. Preparation of SWCNTs with a selected electronic structure, fabrication of their aligned thin films[1] and tuning their Fermi level allow us to reveal unique phenomena, which cannot be observed or correctly understood in conventional SWCNT random network thin films. For example, we observed anomalously large optical absorption for perpendicular polarization to the tube axis in highly doped aligned SWCNTs, which is related to intersubband transition plasmon phenomena in SWCNTs.[2] Here in this talk, we would like to discuss the thermoelectric phenomena in fermi level tuned and aligned SWCNTs.

In our society, a large amount of heat at relatively low temperature, which is emitted from factories, houses, human bodies, and so on, is left unused. Development of high-performance flexible thermoelectric devices is crucial to efficiently convert such unused waste heat into electric power. Understanding of relationships between electrical conductivity, Seebeck coefficient, and thermal conductivity in thin films of flexible materials and tuning of these parameters is crucial to improve the performance. Since the seminal study by Hicks and Dresselhaus,[3] the thermoelectric properties of low dimensional materials have been intensively studied, but it still has been of great importance to experimentally clarify how the one dimensional electronic structures can influence and enhance its thermoelectric properties, although there are several important theoretical predictions for enhancement of thermoelectric properties in one-dimensional electronic systems.[3,4] SWCNTs are a model of one-dimensional flexible materials, and will play important roles for realization of high-performance flexible thermoelectric devices.

Previously, we revealed how the location of Fermi-level influences the thermoelectric properties of semiconducting SWCNTs with diameter of 1.4 nm using electrolyte gating approaches.[5] However, in the previous study, the purity of chirality was not enough to clarify the intrinsic characteristics of semiconducting SWCNTs. In this talk, we will discuss the relationships between electronic structures, Fermi-level and thermoelectric properties using single chirality SWCNTs. In addition, we will discuss how the thermoelectric properties and conductivities exhibit isotropic or an-isotropic properties in aligned SWCNT thin films.[6]

Acknowledgment: K.Y. acknowledges support by JST CREST through Grant Number JPMJCR17I5, Japan
(Invited) Functional Design of Nanoscale Carbon for Active and Durable Electrocatalyst
Authors: Park Subin , Ahn Chi-Yeong , Yoo Ji Mun , Sung Yung-Eun
Published: February 2020

Previously, carbon was regarded as a support material for nanoparticle utilization in electrocatalysis fields, however various physicochemical tenability via doping, functionalization and morphology engineering opens its functional role in various electrocatalytic applications. Furthermore, carbon materials are highly accentuated as a promising alternative to state-of-art systems based on precious metals due to its cost-effectiveness and natural abundance. In this talk, we discuss simple and straightforward approach to prepare carbon-shell-protected nanoparticles (NPs) that have both high catalytic activity and long-term durability for electrochemical energy applications. A single-step thermal treatment of polydopamine-coated NPs leads to the formation of thin-layer carbon shell, providing physical and chemical protections preventing nanoparticle degradation. Moreover, carbon shell can successfully protect chemical properties of NPs during electrochemical operation condition, verifying superior stability. Finally, we also suggest several promising strategies to enhance utilization of porous nanostructure for electrocatalysis, focusing on pore structure engineering and bridging functional links between electrochemical performance and its pore structure.
Graphene/Poly(3,4-ethylenedioxythiophene): Polystyrenesulfonate Hybrid Electrodes for All Solid-State Flexible Supercapacitors
Authors: Cherusseri Jayesh , Sambath Kumar Kowsik , Thomas Jayan
Published: February 2020

Recent developments in the field of flexible and wearable electronic devices necessitate wearable supercapacitor technologies to power them. Electrode nanostructuring is a viable strategy to prepare high performance supercapacitor electrodes. Carbon nanomaterials such as carbon nanotubes, carbon nanopetals, graphene, etc are invariably used as supercapacitor electrodes due to their salient features such as good electronic conductivity, low density, large surface area to volume ratio, good chemical and electrochemical stabilities, high capacitance, bendability, etc. Herein, we report the development of all-solid-state flexible supercapacitor using graphene (Gr)/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) hybrid electrodes. The Gr/PEDOT:PSS hybrid electrodes are prepared by electrochemical deposition followed by dip-coating procedures. The morphology and texture of the Gr/PEDOT:PSS hybrids are examined by scanning electron microscopy and atomic force microscopy. The structure of the hybrids is determined by X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. The surface chemical analysis is performed using X-ray photoelectron spectroscopy. The Gr/PEDOT:PSS hybrid electrodes are tested by electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge-discharge measurements. The all-solid-state Gr/PEDOT:PSS hybrid supercapacitor exhibits excellent electrochemical performance with high flexibility and is a potential candidate to integrate with textile fabrics for application in wearable electronic devices.
(Invited) Computational Electrochemistry of Carbon Materials for Energy Storage
Authors: Jang Seung Soon
Published: February 2020

Through first-principles computational methods, the general electrochemistry of carbon materials is presented for potential applications. In developing a systematic approach for electrochemical properties, various structures of carbon materials including quinone derivatives, conjugated carbon molecules, and DNA are investigated. As one of the key insights into electrochemistry, reduction potentials are pursued, via density functional theory (DFT) modeling with PBE0/6-31G**+ calculations. Furthermore, given that solvents are often involved in electrochemical applications, the extent of their interactions with carbon materials is considered using PBF calculations. Results are analyzed using machine learning. From this study, new insights are offered on the relationship between structures and properties in carbon materials through DFT, achieving a full understanding of its electrochemistry for design of new materials.
(Invited) Holey Graphene Electrode Architectures
Authors: Lin Yi , Connell John W.
Published: February 2020

Graphene is an atomically thick sheet consisting of a graphitic carbon network with excellent mechanical strength, electrical and thermal conductivity, and chemical stability. Holey graphene is a structural derivative of graphene with arrays of through-thickness holes across the lateral surface of the nanosheet. The presence of holes not only has minimal detrimental effect to the graphene properties, but also leads to enhanced performance in applications such as electronics, sensors, and energy storage. For example, the holes allow more facile cross-plane ion transport than intact graphene, making holey graphene an ideal electrode material for electrochemical energy storage. The presentation will focus on another property of holey graphene that may greatly extend its application space; the ability to be compression molded into robust articles or architectures under solvent-free conditions without the need for parasitic binders. The unique dry compressibility of holey graphene has enabled facile fabrication of high mass loading, high performance electrodes for supercapacitors and high-energy battery systems such as lithium-oxygen and lithium-sulfur batteries. In addition, the versatility of the dry compression process has enabled facile tuning of homogeneous and composite electrode architectures to further improve the device performance.
Biomass Based Porous Carbons As Promising Composite Cathodes for Lithium Sulfur Battery
Authors: Arie Arenst Andreas , Kristianto Hans , Lee Joong Kee
Published: February 2020

The lithium sulfur battery is the one of the promising alternative rechargeable battery system to replace the conventional lithium ion battery system. It has a high capacity and energy density of 1,675 mA h g−1 and 2,500 Wh kg−1, respectively. The energy density is about five times higher compared to lithium ion batteries. Furthermore, sulfur is cheap, naturally abundant and safe . One of the main constraints is related to the poor electrical conductivity of sulfur which needs addition of high amount of conductive carbon, Another main problem is the high solubility of the intermediate polysulfides in the organic solvent electrolytes during discharge/charge process. Dissolved polysulfide components are moving back and forward between Li Anodes and Sulfur Cathodes, causing a rapid capacity loss and a low coulombic efficiency. The common approach to solve the problem was using the concept of sulfur encapsulation in the porous carbon structure. This strategy is the most popular study for cathodes in lithium sulfur battery in the last few years. It has been shown to solve the problems of low conductivity and dissolution of polysulfides simultaneously. As the results, the electrochemical performance of sulfur cathodes has been improved due the better electronic conductivity and the inhibation of polysulfide dissoltion. In this current works, biomass based porous carbons have been synthesized by using chemical activation of tropical salacca fruit peel with potassium carbonate and used as sulfur cathode component for lithium-sulfur batteries. The motivation was to obtain carbon with specific morphology and structures used for the application in composite sulfur cathodes for lithium sulfur battery. As shown by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption isotherms, the porous carbon material has microporous-mesoporous structures with honeycomb morphology. Composite sulfur cathode has shown a large initial discharge capacity of 802 mAh g−1 at current density of 0.1 C , which remained stable during 50 charge-discharge cycles . This stable and reversible cycleability of this composite cathode has been contributed by a unique combination of micro and mesoporosity, as well assurface functional groups, which could allow the retention of the intermediate polysulfides within the carbon porous structures, without enormous dissolution in the electrolyte.
Ni Wrapped-Carbon Nanofiber Based Anode for High Areal Capacity for Li-Ion Battery
Authors: Plateau Tazdik Patwary , Sarkar Susmita , Pham Hiep , Park Jonghyun
Published: February 2020

A thick layer of self-supported electrode showing simultaneous high specific capacity and areal capacity is developed by wrapping nickel on the carbon nanofibers (CNFs) via an electrospinning technique. This superior property is established by enhancing the interconnection among the nanofibers. Polyvinylpyrrolidone (PVP), polyacrylonitrile (PAN), and nickel acetate are used to fabricate the nanofibers. Carbonization assists inter-bonded morphologies in nanofibers and PVP helps to bind the nanofibers during carbonization process. Thus well bonded CNFs wrapped by Nickel show better specific and areal capacity. Different percentages of nickel in the nanofibers show a variation in the battery performance. The optimized nickel wrapped CNFs based anode represents a favorable porous nanostructure and large mass loading, which exhibits an areal capacity as high as 7.04 mAh/cm2 and excellent cycling stability.
Near-Infrared Confocal Imaging of Single-Walled Carbon Nanotube Uptake in Bacterial Cells
Authors: Antonucci Alessandra , Schuergers Nils , Zubkovs Vitalijs , Boghossian Ardemis Anoush
Published: February 2020

The distinctive properties of single-walled carbon nanotubes (SWCNTs) have inspired the development of innovative applications in the field of cell nanobiotechnology. Most studies to date have focused on eukaryotic cells capable of internalizing SWCNTs functionalized with a variety of non-covalent wrappings. However, the effect of SWCNT functionalization on transport across the thick cell wall of prokaryotes remains unexplored. In this study, we explore the uptake of SWCNTs in Gram-negative cyanobacteria and demonstrate selective internalization of SWCNTs decorated with charged protein wrappings. The functionalized SWCNTs are shown to traverse the outer cell wall of both filamentous and unicellular strains of cyanobacteria, independent of whether the strain is naturally competent for DNA uptake, with adsorption and internalization rate constants of kads = (9.08 ± 0.16) x 10-8 s-1 and kin = (1.466 ± 0.011) x 10-4 s-1, respectively. A custom-built, spinning disc confocal microscope was used for the first time to directly image near-infrared (NIR) SWCNT fluorescence within cells, revealing a highly inhomogeneous distribution of SWCNTs that is otherwise overlooked using conventional NIR widefield imaging. The nanobionic cells show sustained photosynthetic activity and growth, offering a powerful avenue for engineering photosynthetic organisms with augmented and even inherited nanobionic capabilities.
(Invited) Biomedical Applications of Metal Nanoparticle-Decorated Carbon Nanostructures
Authors: Star Alexander
Published: February 2020

Carbon nanotubes and graphene are highly sensitive to changes in the local chemical environment and serve as an ideal platform for the fabrication of label-free nanoelectronic sensors. We recently employed a series of metal nanoparticle functionalized carbon nanotube devices as cross-sensitive sensor arrays, demonstrating electronic “tongue” functions and ability to analyze different cell types. By combining analysis of sensor device characteristics with supervised machine learning algorithms, we have successfully discriminated among different analytes and accurately discerned the presence of specific analytes in the complex mixtures.

Carbon nanostructures can also be used as nano-carriers for applications in medical therapeutics. To this end, we developed cup-shaped carbon nanostructures, which have an elliptical hollow space that can be corked by gold nanoparticles at the opening. To illustrate the potential of corked nanocups as drug delivery systems, loading with common fluorescent dyes, as well as chemotherapeutic drugs, was performed. By using Raman spectroscopy, we were able to demonstrate the loading and release of the cargo in biochemical model systems and tumor-associated cells. We recently demonstrated in vivo systemic nanodelivery of paclitaxel loaded gold nanoparticle-corked nanocups inhibited melanoma growth in mice with 25-30% of treated animals being tumor free after 2-3 weeks.

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(Invited) Biocompatible Doped Graphene Quantum Dots Enabling Visible/Near-Infrared Imaging, Drug Delivery and Cancer Detection
Authors: Naumov Anton V , Campbell Elizabeth , Hasan Md Tanvir , Gonzalez-Rodriguez Roberto , Akkaraju Giridhar R.
Published: February 2020

Despite significant advances of nanomedicine, the issues of biocompatibility, accumulation-derived toxicity and the lack of sensing and in vivo imaging capabilities hamper the translation of many nanocarriers into clinic. To address these needs we develop and test the feasibility of new nitrogen, sulfur or metal-doped graphene quantum dots (GQDs) as fully biocompatible multifunctional platforms enabling theranostic image-guided approaches both in vitro and in vivo. These GQDs scalably produced in one-step synthesis from a single biocompatible carbon-rich precursor form 3-5 nm few-layer structures functionalized with oxygen-containing groups, however, showing high crystallinity and lattice spacing indicative of a graphitic platform. They are water-soluble, show no cytotoxicity at high concentrations of 1 mg/mL, and demonstrate substantial degradation at 36h in biological environments as verified by TEM imaging. Due to their small sizes, GQDs exhibit efficient internalization maximized at 12 h followed by further degradation/excretion and enable active agent delivery. Their intrinsic fluorescence in blue/green with up to 62% quantum yield and near-infrared allows for multicolor in vitro imaging on its own or in combination with other fluorophores and offers the potential capabilities for in vivo near-IR fluorescence tracking. Additionally, several GQD types exhibit pH-dependent fluorescence response that is successfully utilized as a sensing mechanism for acidic extracellular environments of cancer cells. It allows for deterministic, ratiometric discrimination between cancerous (HeLa and MCF-7 cell) and healthy (HEK-293 cell) environments with substantial spectral peak intensity ratios of 1.6 to 8 in healthy versus cancer cells. Such spectral technique, less prone to quenching discrepancies, provides a useful tool for pH-sensing of microenvironments. These results suggest fully biocompatible doped GQDs as multifunctional candidates for in vitro delivery of active agents, multicolor visible/near-IR fluorescence imaging, and pH-sensing of cancerous environments.
Intracellular Imaging and Thermal Sensing Using Fluorescent Carbon Dots
Authors: Macairan Jun-Ray , Naccache Rafik
Published: February 2020

In recent years, nanomaterials (defined as materials < 100 nm in a single dimension) have garnered a significant interest for the development of novel applications in the physical and life sciences. One such class of nanomaterials are carbon dots, a relatively new member in the carbon allotrope family, which possesses versatile optical properties rendering it attractive for sensing, catalysis, bioimaging and drug delivery applications, to name a few. These ultra-small nanoparticles, primarily comprised of carbon, oxygen, nitrogen and hydrogen have been touted to possess low toxicity, tunable fluorescence, low photo-blinking. Here, we have synthesized carbon dots via a bottom-up microwave method, using simple organic precursors including glutathione and formamide. We investigate the effect of reaction time and temperature in tailoring the optical properties of the dots to achieve high fluorescence quantum yields. Moreover, our systematic approach allows us to glean insights into the mechanism of formation of the carbon dots. These dots also show dual fluorescence in the blue and red regions of the spectrum, which we use to image HeLa cancer cells. Moreover, the blue and red fluorescence present a different response to a change in the environment temperature and we exploit this phenomenon to develop an intracellular ratiometric approach for sensing temperature inside living cells.
Understanding Corona Exchange Dynamics on Single-Walled Carbon Nanotubes with Multiplexed Fluorescence Monitoring
Authors: Pinals Rebecca L , Yang Darwin , Cao Wendy , Landry Markita P
Published: February 2020

Adsorption of polymers on single-walled carbon nanotubes (SWCNTs) has enabled developments in molecular sensing, in vivo imaging, gene and drug delivery, and chirality sorting applications. Noncovalent functionalization offers a modification route that preserves the pristine atomic structure, thus retaining the intrinsic near-infrared fluorescence of the SWCNTs for sensing or imaging functions, and offers a reversible binding mode for cargo delivery or chirality separation processes. However, noncovalent adsorption is an inherently dynamic process, where exchange occurs between molecules in the bulk solution and molecules on the surface, into what is known as the ‘corona phase’. In the case of polymers on SWCNTs, the nature, strength, and kinetics of both the polymer binding and unbinding processes are important contributors to the success of polymer-SWCNT based technologies. Understanding this binding process is especially important for intended uses of functionalized SWCNTs in biological environments, where native biomolecules compete with the original polymer to occupy the SWCNT surface. Binding of proteins and other biomolecules to the SWCNT not only disrupts the intended functionality of the nanoparticle, but further leads to potentially adverse biocompatibility outcomes.

We present an assay to study the process of corona exchange dynamics between solution-phase and corona-phase polymers on SWCNTs. Real-time tracking of polymer and protein adsorption and desorption events are conducted with systematic variation of the molecular entities and solution conditions. This assay exploits the quenching property of fluorophores in close proximity to the SWCNT surface to monitor ligand binding and unbinding events. Binding profiles are thus extracted from the experimental assay and used to inform a kinetic model of the system. This study encompasses exchange of SWCNT-adsorbed ssDNA and either ssDNA, surfactant, or protein added to the bulk solution with multiplexed fluorescence tracking of all entities. Moreover, the kinetics of these binding profiles are validated against an orthogonal and more ubiquitously-used platform monitoring solvatochromic shifting of the near-infrared SWCNT spectrum as a proxy for SWCNT corona perturbations (Beyene et al., Nano Letters, 2018; Heller et al., PNAS, 2011; Jena et al., ACS Appl. Mater. Interfaces, 2017). The work presented herein develops an understanding of the fundamental corona exchange mechanism, contextualizes the nature of the ligand exchange process versus SWCNT solvatochromic shifting, and provides insight into performance of these designed SWCNT-based systems in biologically relevant, protein-rich conditions.