bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Working Towards a Cost-effective Lithium-ion Battery Recycling Process
Authors: Polzin Bryant J. , Spangenberger Jeffrey , Gaines Linda
Published: February 2020

Lithium-ion batteries in electric and hybrid-electric vehicles are just now starting to reach their end-of-life. There are several options to address these end-of-life batteries, landfilling or recycling. Recycling is a desirable option because of the benefits it can bring, including reductions in life-cycle costs, reduced energy usage, lower environmental impacts, and decreased dependence on scarce or imported materials. The options available now for recycling of lithium-ion batteries are not optimal, so research and development (R&D) is needed to make economic processes available for use by the time large volumes of batteries from electric vehicles and other uses go out of service. By then these battery materials could be 20 year-old formulations with little residual value from its structure or contained elements. In particular, cathode formulations are evolving towards varied morphologies, emphasizing formulations that contain reduced quantities of cobalt (the valuable element sought in most current recycling operations), reducing the incentive for recycling with standard pyrometallurgical or hydrometallurgical methods.

Several key questions must be addressed by R&D. Most of these focus on the cathode, which is the most valuable form of material that can be recovered. How can the cathode get separated from the other cell components? Can they be recovered? How can optimum cathode function get restored? Can we separate one cathode type from another? Can we modify the cathode composition or morphology to update it for reuse? This presentation will provide a summary of Argonne’s work to create a feasible battery recycling system.
Preparation of N,F,B-Doped Carbon Materials for High-Performance Electric Double Layer Capacitors
Authors: Kim Dae Kyom , Piao Yuanzhe
Published: February 2020

The incorporating heteroatom species into carbon materials give opportunities for improving electrochemical properties. Single N-doping strategies are widely studied because of easy preparations and relative abundance in nature. However, facile synthetic methods of multiple-heteroatom-doped carbons are urgent for high-performance supercapacitors. In this study, we propose N,F,B-doped carbons for electric double layer capacitors derived from polyamic acid mixed with boric acid using pyrolysis process. Fluorinated polyamic acid is applied for a N,F-doping source and boric acid acts as a B-doping source. The synthesized carbon materials exhibit excellent electrochemical performances because of the synergetic effects of each N, F, and B atoms. The N and F atoms improve electronegativity property and also low doped B atoms improve redox reactivity in the carbon. The electrode is fabricated by direct pyrolysis process with carbon fabrics, which is an advantage for binder-free type electrodes and flexibility. The morphology and surface properties of the fabricated electrodes are studied by SEM, XPS, Raman, sheet resistance, and contact angle measurement. Furthermore, the flexible symmetric device with PVA-1M H2SO4 gel electrolyte fabricated from the N,F,B-doped carbon indicates a high volumetric capacitance and an energy density as well as mechanical stabilities under various deformations. These results are expected that the synthesized N,F,B-heteroatom-doped carbons offer great potentials as electrode materials for supercapacitor applications.
Study on a Novel Double-Layer Anode for Solid Oxide Fuel Cells Based on CO2 Dry Reforming of Methane
Authors: Wei Tong , Jia Lichao , Chen Bingxin , Li Ruizhu , Chi Bo , Pu Jian , Li Jian
Published: February 2020

Solid oxide fuel cell (SOFC) is an energy conversion device that converts chemical energy in fuels into electric energy directly with the advantages of high efficient, clean, and wide fuel adaptability. Most hydrocarbons such as natural gas, ethane and bio-oil can be used as fuels in SOFC. When a hydrocarbon fuel, such as methane (CH4), is directly used for IT-SOFCs without prereforming by adding oxygen, steam or carbon dioxide, it is electrochemically oxidized on the triple-phase boundaries (TPB) with a strong tendency of carbon deposition in the traditional Ni-based anode. In this paper, we introduce an extra internal reforming layer on the surface of anode-support. The layer of a LaCrO3 based perovskite with exsolved Ni nanoparticles catalyst (La0.6Sr0.2Cr0.85Ni0.15O3 showed high stability in reducing atmosphere and excellent catalytic performance. Based on this, two types of anode-supported cell are fabricated by tape casting, screen printing and sintering processes. The first one is a conventional anode supported cell with a configuration of Ni-GDC/GDC/GDC-LSCF (cell 1); and the other contains a reforming layer mixed with La0.6Sr0.2Cr0.85Ni0.15O3 and SDC which was a well coking resistant promoters (cell 2). When CH4–CO2 was used as the fuel, which was supposed to yield syngas with the H2–CO ratio close to unity, the polarization resistance of the cell 1 reach at 0.247 Ω cm2 whereas the value of cell 2 is 0.082Ω cm2 at 750 °C. These results implied that both the physical and the chemical properties of the TPB have been altered drastically during internal dry reforming since that Ni-based anode show poor catalytic performance in reforming and are prone to coking. Consequently, the maximum power density for cell 1 was 470 mW cm-2 and the cell suffered from degradations during a 1 h galvanostatic operation at 1 A cm-2. The performances of the cell 2 are significantly increased above the level of the cell 1, demonstrating a peak power density at 929 mW cm-2 at 750 °C and a stable cell voltage at 1 A cm-2 and 750 °C for 48 h. Carbon deposition in the anode region of the tested cell 2 is not detected, as the La0.6Sr0.2Cr0.85Ni0.15O3 is a more active and stable catalyst than the Ni-based anode-support for dry reforming. Finally we demonstrated the strong interaction between the exsolved nanoparticles and the substrate could prevent coking deposition and proposed a promising configuration of double-layer anode for solid oxide fuel cells with on-cell reforming.

Figure 1
Nanocomposites of Copper Sulphide and Graphene Oxide for High-Performance Supercapacitors
Authors: Singhal Rahul , Thorne David , Lemaire Peter , Martinez Xavier , Zequine Camila , Gupta Ram , Uhl David , Scanley Ellen , Broadbridge Christine
Published: February 2020

Supercapacitors or electrochemical capacitors are receiving greater interest because of their high-power density, long life, low maintenance, and safer operation. The low energy density of such devices needs to improve. In this work, copper sulfide (CuS), a cheap and environment-friendly compound, is used along with graphene oxide (GO) to provide high energy and power densities. CuS nanoparticles and its nanocomposites with GO was synthesized using a facile method for supercapacitor applications. For the synthesis of CuS, an appropriate amount of copper acetate was dissolved in a water-butanol solution for 30 minutes followed by the addition of thiourea. The final solution was then transferred into Teflon-lined stainless-steel autoclave and heated at 180oC for 24 hours. The resulting participate of CuS was recovered using a centrifuge, washed with DI water, and dried in air for 24 hours. A similar procedure was followed for the synthesis of CuS-GO nanocomposite with the addition of appropriate amount of GO in the water-butanol solution prior to the addition of copper acetate and thiourea.

Phase purity of the synthesized materials was determined by using X-ray diffraction (XRD) studies. XRD patterns of CuS showed the peaks at 2θ angle of 10.38o, 28.42o, 28.88o, 32.48o, 33.18o, 46.54o, 48.28o, and 59.68o corresponding to (100), (101), (102), (006), (110), (108), (116) planes, respectively, which indicates the covellite CuS hexagonal structure [1,2]. There were no additional peaks found in the XRD pattern of CuS-GO composite, confirming the phase purity of the synthesized materials. TEM images revealed nano-scale morphology of the synthesized particles. The particle size of CuS and CuS/GO composite were found as 95.11 nm, and 64.70 nm, respectively.

All the electrochemical measurements were conducted in standard three-electrode configuration, using a platinum wire as a counter electrode and Hg/HgO as a reference electrode. CuS and its composite with graphene oxide on nickel foam were used as working electrodes. All the electrochemical measurements were performed in 3M KOH solution. Electrochemical properties of the synthesized samples were investigated using cyclic voltammetry and galvanostatic charge-discharge studies. The specific capacitance was calculated from cyclic voltammogram, obtained at various scan rate between 10 - 300 mV/s. The specific capacitance of CuS and CuS-GO nanocomposite was found to be 400 and 600 F/g, respectively at a scan rate of 10 mV/s. The detailed results on synthesis, physical, and electrochemical characterization will be presented.

References:

[1] W. Xu, Y. Liang, Y. Su, S. Zhu, Z. Cui, X. Yang, A. Inoue, Q. Wei, C. Liang¸ Electrochim. Acta 211 (2016) 891–899.

[2] C. J. Raj, B. C. Kim, W. J. Cho, W. G. Lee, Y. Seo, K. H. Yu, J. Alloys and Comp. 586 (2014) 191–196.

Figure 1
Exploration of New Electrolyte Additive for Solid Electrolyte Interphase (SEI) Modification
Authors: Li Jingnan , Wu Bingbin , Lochala Joshua Andrew , Xiao Jie
Published: February 2020

Solid electrolyte interphase (SEI), which is generated from the decomposition of the electrolyte at low potentials, plays an important role in repeated reversible ion transport and thus dictates the cycle life of electrochemical cells. [1] A stable SEI layer effectively suppresses the continuous decomposition of the electrolyte and enhances the fast ion diffusion during cycling. [2] As a critical component of SEI, LiF could effectively inhibit electron tunneling and improve the quality of SEI formed on anode materials. A LiF-rich SEI layer is believed to improve the uniformity of the electrode surface morphology and reduce the uneven deposition of Li metal. [3] However, how to enrich the LiF component in SEI layers is challenging. In this work, a new electrolyte additive has been designed and synthesized to produce more inorganic LiF during SEI formation. The electrolyte additive has been applied to both Si and Li anodes to understand the SEI formation mechanism in the presence of the new additive.

References

Collins, J., Gourdin, G., Foster, M., & Qu, D. (2015). Carbon surface functionalities and SEI formation during Li intercalation. Carbon, 92, 193-244.

Zhang, S. S. (2006). A review on electrolyte additives for lithium-ion batteries. Journal of Power Sources, 162(2), 1379-1394.

Zhang, X. Q., Cheng, X. B., Chen, X., Yan, C., & Zhang, Q. (2017). Fluoroethylene carbonate additives to render uniform Li deposits in lithium metal batteries. Advanced Functional Materials, 27(10), 1605989.
Lead-Carbon Nanofiber Based ANODE for High Performance LI-ION Battery
Authors: Pham Hiep , Sarkar Susmita , Park Jonghyun
Published: February 2020

Lead-carbon (Pb-C) nanofibrous anodes for lithium-ion batteries were prepared via the electrospinning method. The use of lead-based anodes with high amounts of carbon has been shown to improve the cycling performance of batteries through increased capacity retention and electrical conductivity. This is attributed to the Pb-C accommodation to volume change during lithiation/de-lithiation upon cycling as well as suppressed formation of the unstable solid-electrolyte interphase layer. By preparing the anode via electrospinning, an increase in specific area and active material content can be achieved with significant improvement to the battery performance. In this report, significant enhancement of battery performance in terms of specific capacity and cyclability is made using the prepared Pb-C nanofiber anodes. The Pb-C nanofiber anode exhibits a high specific capacity of 637 mAh g-1 with excellent cycling performance.
Optimization of Design Parameters and Operating Conditions of Electrochemical Capacitors for High Energy and Power Performances
Authors: Ike Innocent Sunday , Sigalas Iakovos Jack , Iyuke Sunny E
Published: February 2020

Theoretical expressions for performance parameters of different electrochemical capacitors (ECs) were optimized by writing MATLAB scripts to solve them and also via MATLAB R2014a optimization tool box. Performance of different kind of ECs at given circumstances were compared through theoretical equations and simulation of various models subject to conditions of device components, using optimal coefficient associated to battery-kind material and constant associated to electrolyte material KBMopt and KEopt , as well as our symmetric electric double layer capacitor (EDLC) experimental data. Estimations of performance parameters were feasible and achievable once details of electrodes mass ratio, operating potential range ratio and specific capacitance of electrolyte are known. Performances of asymmetric EC with suitable electrode mass and operating potential range ratios using aqueous electrolytes, and that with suitable electrode mass and operating potential range ratios using organic electrolyte with appropriate operating potential range and specific capacitance were factors of 2.2 and 5.56, respectively, greater than those of symmetric EDLC and asymmetric EC using the same aqueous electrolyte, respectively. This enhancement came along with reduction in cell mass and volume. Also, storable and deliverable energies of asymmetric EC with suitable electrode mass and operating potential range ratios using proper organic electrolyte were factor of 12.9 greater than those of symmetric EDLC using aqueous electrolyte, with reduction in cell mass and volume. Storable energy, energy density and power density of asymmetric EDLC with suitable electrode mass and operating potential range ratios using proper organic electrolyte were factor of 5.56 higher than those of similar symmetric EDLC using aqueous electrolyte with reduction in cell mass and volume by a factor 1.77. Also, introduction of asymmetric EDLC with the same type of electrode, and suitable electrodes mass ratio, working potential range ratios and proper organic electrolyte enhanced performance of conventional symmetric EDLC using aqueous electrolyte with reduction in cell mass and volume. These results can obviously reduce number of experiments to determine optimum manufacturing state of EC, and also demonstrated that institution of asymmetric electrode and organic electrolyte was very successful in improving performance of EC with reduction in cell mass and volume. These results can as well be a guideline for design, fabrication and operation of electrochemical capacitor with outstanding storable energy, energy and power densities.

Key words: Electrodes symmetry; Modelling and simulation; Performance parameters; Electrolytes type; Working potential range; Asymmetric capacitors.
Advanced Reversible Long-Lasting Flexible Metal-Air Batteries Using Mn/Fe Hexaiminobenzene Metal-Organic Frameworks
Authors: Shinde Sambhaji S , Wagh Nayantara , Kim Dong-Hyung , Lee Jung-Ho
Published: February 2020

Fast growing “Internet of Things” has an ever-increasing demand for advanced batteries with high energy density, robustness, flexibility, and environmental benignity for emerging high-tech electronic technologies, electric vehicles, and smart grids. Herein, we demonstrate robust aqueous and flexible ZABs employing three-dimensional dual-linked hexaiminobenzene metal-organic frameworks (Mn/Fe-HIB-MOF) as redox-active robust bifunctional electrocatalysts with ultrahigh intrinsic electrical conductivity and atomically tuned multi-shelled hollow spheres. Superionic functionalized bio-cellulose nanofibrous, solid-state membrane electrolyte (64 mS∙cm−1) is also presented with outstanding flexibility and water retention. The well-defined quintet-shelled hollow sphere MOFs possess a hierarchical porous structure, excellent packing density with a surface area of (2,298 m2.g-1), and chemical stability contrasted to conventional MOFs. The Mn/Fe-HIB-MOFs exhibited superior bifunctional oxygen electrocatalytic activity (0.627 V) with half-wave potential (0.883 V) for oxygen reduction and overpotential (280 mV @10 mA∙cm−2) for oxygen evolution reactions, outperforming commercial Pt/C and RuO2. The liquid and flexible ZABs with the present constituents revealed the world-record breaking cycling stability of 1,000 h (6,000 cycles) and 600 h (3,600 cycles) with fast fading and exceptionally high rate capacity (10 and 25 mA cm-
2), respectively, reported to date for rechargeable ZABs. These promising results illustrate great perspectives for sustainable rechargeable ZABs in the modern industries of electric vehicles and wearable electronics.
Development of a New 3D Hybrid Nanostructured Carbon/MnO2 Framework By Automated Spray Coating and Electrodeposition As High Performance Electrode Material for Supercapacitor Applications
Authors: Pognon Grégory , Rogier Clemence , Galindo Christophe , Bondavalli Paolo , Aubert Pierre-Henri , Vancaeyzeele Cedric , Nguyen Tran Minh Giao
Published: February 2020

Nano-engineering of electrode through a versatile spray coating and subsequent electrochemical controlled modifications with metal oxide have been explorated toward a specific design of electroactive material targeting an increase energy densities in supercapacitors while maintaining high power densities. Exploiting pseudocapacitance and nanostructuration by combining transition metal oxides and nanostructured carbon materials in one electrode is considered as one of the best ways to achieve these performances.

In this study, carbon nanotubes/graphene/manganese dioxide nanostructured films were designed as supercapacitors electrodes. MnO2 is a well-known pseudocapacitive material used to increase the energy density allowing quite good cyclability of thousand cycles. The selected carbon nanomaterials generate high conductivity and their association is an efficient way to insure large surface area to maintain a high power density. The challenge is to assemble these materials into a nanostructured electrode with controlled homogeneity, morphology, and composition. Our approach consists in synthesizing MnO2 by anodic electrodeposition directly onto the conductive nanostructured carbon framework. The association of carbon nanotubes and graphene in a specific multi-layered organization by spray aim at creating a porosity controlled network in the electrodes with highly accessible and electroactive surface.

The carbon nanomaterials were deposited onto a current collector by dynamic automated spray gun deposition, an easily scalable, reproducible and industrially suitable method used for nanostructuration of thin films. Materials were characterized by SEM, XPS, microporosity analysis; their electrochemical behavior has been evaluated by cyclic voltammetry and impedance spectroscopy and their performances and cyclability by galvanostatic charge/discharge experiments. Results demonstrate that the capacitance can reach up to 190 F/g (110 F/cm3) for binder free electrodes thanks to a control of the MnO2 morphology, particle size and mass loading.
Three-Dimensional Modeling of Mediator-Enhanced Solid-State Supercapacitors
Authors: Zhou Xiangyang , Wang Yuchen , Qiao Xiaoyao , Zhang Chen , Mansour Azzam N.
Published: February 2020

One of the approaches to improve the specific energy of supercapacitors is to mix soluble or semi-soluble redox materials or “mediators” with electrolyte in electrode materials. The redox materials can undergo reversible electrochemical reactions at the interfaces between electronic conductor (carbon materials) and electrolyte phases thereby storing charges in the form of reduced and oxidized mediators. Often this kind of SCs are referred to “redox electrolyte SCs” or “mediator SCs”. A three-dimension model is established to simulate the transport process and electrochemical process of mediator-enhanced solid-state supercapacitors. The roles of mediators are studied in wide ranges of supercapacitor parameters, including concentration, conductivity, and diffusivity. The simulation results are validated using experimental data previously published. Specifically, the present study is aimed to analyze the roles of mediators in the so-called battery-like versus capacitor-like behaviors, the effect of release of free ions by mediators during charging, and the effect of mediator shuttling. The simulation results show that with mediators concentration greater than 0.2 mol L-1 and diffusivity greater than 3 × 10-12 m2 s-1 in electrodes, the charge/discharge behaviours are generally battery-like. However, at adiffusivity below 3 × 10-12 m2 s-1, the charge/discharge behaviours are generally capacitor-like. The simulation results clearly reveal that if free ions are given off by mediators during the charging process, the specific capacity of the supercapacitors can be extended. The simulation results also indicate that if the diffusivity of mediators in the separator membrane is below 10-12 m2 s-1, the self-discharge of the supercapacitor due to shuttling of the redox species between the electrodes is negligible. Thus, an operational mediator supercapacitor relies on a selective separator membrane and a high diffusivity in the composite electrodes.
Nanohydroxyapatite/Graphene Nanoribbons Nanocomposites for Bone Tissue Engineering Applications
Authors: Oliveira Francilio Carvalho , Carvalho Jancineide Oliveira , Viana Bartolomeu Cruz , Marciano Fernanda Roberta , Lobo Anderson Oliveira
Published: February 2020

It has been difficult to find bioactive compounds that can optimize bone repair therapy and adequate osseointegration for people with when people osteoporosis. The nano-hydroxyapatite (nHAp) / carbon nanotubes with graphene oxides (GNR) composites have emerged as promising materials/scaffolds for bone regeneration in phase its bioactivity and osseointegration properties. Herein, we evaluated the action of nHAp/GNR composites to promote bone regeneration using an osteoporotic model. First, three different nHAp/GNR composites (1, 2 and 3 wt% of GNR) were produced and characterized. For in
vivo analyses, 36 Wistar rats (var. Albinus, weighing 250 to 300 g, CEUA n.002/17) were used. Prior to implantation, osteoporosis was induced by oophorectomy in female rats. After 45 days, a tibial fracture was inflicted using a 4.0 mm Quest trephine drill. Then, the animals were separated into 6 sample groups at two different time periods 21 and 45 days. The lesions were filled with 3 mg of one of the above samples using a curette. After 21 or 45 days of implantation, the animals were euthanized for analysis. Histological, biochemical, and radiographic analyses (DIGORA method) were performed. The data were evaluated through ANOVA, Tukey tests, and Kolmogorov-Smirnov tests with statistically significant at p < 0.05. Both nHAp and GNR exhibited osteoconductive activity. However, the nHAp/GNR composites exhibited regenerative activity proportional to their concentration, following the order of 3% > 2% > 1% wt. Therefore, it can be inferred that all analyzed nanoparticles promoted bone regeneration in osteoporotic rats independent of analyzed time.
(Invited) Resonance Raman Spectroscopy Studies in 2D and 1D Nanocarbons
Authors: Souza Filho Antonio G G
Published: February 2020

Raman spectroscopy is a nondestructive tool widely used to characterize a variety of nanomaterials including the novel 2D and 1D systems such as graphene and MoS2, linear carbon chains, among others. Since electrons and phonons are specially coupled to each other due to the reduced dimensionality, this technique provides detailed information about the structure and electronic properties of theses layered systems thus allowing one to probe in the phonon spectra the numbers of layers and their interactions with the environment. Most of these 2D materials are on substrate and the understanding on how the substrate affects the physical properties of these atomic thickness layers is a key point for fully characterize the materials. In this regard, strain is an important variable to take into account because the adhesion of the layered materials depends on the nature of the substrate and a key question is how the strain is transferred from a given substrate to the 2D material, for instance.

The use of hydrostatic pressure has been an effective method modulate the interactions between the 2D materials with substrates and environment and Raman spectroscopy has been important for investigating these strained 2D nanomaterials because the Raman cross section of these low dimensional materials is very large.

In this talk, we discuss recent results obtained for high-pressure Raman studies of graphene (mono- and bilayer) and MoS2 (mono-, bi-, tri- and many layers) sitting on substrate. Depending on the pressure transmitting medium, the pressure-induced changes in the Raman modes frequency at different rates, which has been attributed to different strain transferred from the substrate to the 2D materials. In the case of MoS2, the behavior of Raman modes suggested that a biaxial stress is transmitted from substrate to the MoS2 layers by means of the substrate deformation due to pressure and the magnitude of such stress transfer is found to be dependent of the number of layers. We also discuss the effects of strain on the vibrational properties of linear carbon chains encapsulated in carbon nanotubes.
(Invited) Tuning the Electrocatalytic Activity of Fe Phthalocyanine Via Axial Ligation to Multiwalled Carbon Nanotubes and Via Ligand Substitution: Electrochemistry of l-Cysteine and l-Cystine
Authors: Zagal Jose H
Published: February 2020

Multiwalled carbon nanotubes (MWCNTs) are excellent platforms for the fabrication of active electrodes for electrocatalysis and electrochemical sensors [1], especially by chemical modification with molecules of known activity. We have studied the electrocatalytic activity of hybrid electrodes containing Fe-phthalocyanine (FePc) axially linked to carbon nanotubes and tested these electrodes for l-cysteine oxidation and l-cystine reduction. It is important to remark that the l-cysteine/l-cystine is a biological relevant redox couple that plays a very important role in many living systems. We have compared the electrocatalytic activity of pristine multi-walled carbon nanotubes and functionalized with –COOH, –NH2groups (MWCNT-p, MWCNT-c and MWCNT-a). These MWCNTs were chemically modified with iron phthalocyanine (FePc). These hybrid systems were characterized using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and AFM. The Fe(II)/(I) and Fe(III)/(II) redox processes of the surface confined FePc are slightly affected by the presence of MWCNTs. The activity for both reactions increases substantially by the presence of modified MWCNTs essentially by an area effect. However, when the currents are normalized by the amount of active sites estimated from the surface coverages of FePc, the activities plotted versus the redox potentials give volcano-shape curves. The data for l-cysteine oxidation fits well on a volcano correlation published previously [1] using several metal phthalocyanines and metal porphyrins (see Figure down below). This shows once more that a Mz+/M(z-1)+redox potential value does exist for which a maximum catalytic activity is observed and is an excellent reactivity descriptor for these complexes, as observed for other reactions. The reactivity trends do not change after the incorporation of FePc to MWCNTs with different chemical functionalities.

Acknowledgements The authors are grateful to Fondecyt Projects 1140199, 1181037, Nucleo Milenio RC 120001. Fondecyt Postdoctoral Project 3150271 and Conicyt Scholarships M.P.O. 21130168.Fondequit, EQN160036.

References

E. Banks, R. G. Compton, Analyst,131(2006) 15-21.

A. Gutierrez, J.F. Silva, F.J. Recio, S. Griveau, F. Bedioui, C.A. Caro, J.H. Zagal, Electrocatalysis, 5 (2014) 426–437.

Figure 1
(Invited) Electrochemical Reduction of [60]Fullerene-Fused Lactones to [60]Fullerene-Fused Ketones
Authors: Niu Chuang , Wang Guan-Wu
Published: February 2020

A highly efficient electrochemical reduction of [60]fullerene-fused lactones to [60]fullerene-fused ketones, a formal process of retro Baeyer–Villiger reaction, has been achieved for the first time. The electrochemically generated dianionic [60]fullerene-fused lactones can be transformed into [60]fullerene-fused ketones in the presence of acetic acid in high yields. Control experiments have been performed to elucidate the reaction mechanism.
(Invited) Open-Cage Fullerene C60 Derivatives Encapsulating a Paramagnetic Molecule
Authors: Murata Yasujiro
Published: February 2020

Organic electron spin systems have received much attention owing to their broad interests in medicine, quantum device, molecular magnetism, and etc. Fullerene C60 has an inner space which is suitable to accommodate a variety of small molecules. In this work, we constructed organic electron spin systems, O2@openC60 and NO@openC60, by encapsulation of the molecules inside an open-cage C60 derivative with high crystallinity and solubility. In the case of O2@openC60, the EPR signals were observed and the paramagnetic behaviour was demonstrated above 3 K without an antiferromagnetic transition.[1] In the case of NO@openC60, however, sharp 1H NMR signals were observed with remarkable paramagnetic shifts despite the encapsulation of the paramagnetic molecule. Although an NO molecule is known to be inactive in ESR measurements due to the intrinsic orbital angular momentum, the ESR signal of NO@openC60 was detected below 40 K owing to the symmetry breaking.[2]

[1] A Stable, Soluble, and Crystalline Supramolecular System with a Triplet Ground State

Futagoishi, T.; Aharen, T.; Kato, T.; Kato, A.; Ihara, T.; Tada, T.; Murata, M.; Wakamiya, A.; Kageyama, H.; Kanemitsu, Y.; Murata, Y. Angew. Chem. Int. Ed. 2017, 56, 4261-4265.

[2] Construction of a Metal-Free Electron Spin System by Encapsulation of an NO Molecule inside an Open-Cage Fullerene C60 Derivative

Hasegawa, S.; Hashikawa, Y.; Kato, T.; Murata, Y. Angew. Chem. Int. Ed. 2018, 57, 12804-12808.
(Invited) Photoinduced Charge Separation in Several Dyads Involving Fullerenes
Authors: Solà Miquel , Stasyuk Antony J. , Stasyuk Olga A. , Voityuk Alexander A.
Published: February 2020

Conversion of the sunlight into chemical energy is considered to be one of the most important and fundamental chemical reactions in nature. A broad variety of artificial photosynthetic systems based on dyads, triads and up to pentads involving electron donor and acceptor moieties have been designed and synthesized in order to investigate artificial photoinduced energy and electron transfer processes. In this work, we discuss a series of computational studies that involves the photoinduced charge separation in metal-cluster encapsulated triphenylamine-[80]fullerenes,[1]
in a transition-metal complex linked to a fullerene moiety,[2] in an all-fullerene hetero-dumbbell formed by two fullerene units, namely C60 as the electron acceptor component and endohedral Lu3N@C80 as the donor unit,[3] and in four akamptisomers of quinoxalinoporphyrin–[60]fullerene complex.[4]

References

[1] J. P. Martínez, M. Solà and A. A. Voityuk. Chem. Eur. J. 22 (2016) 17305.

[2] A. J. Stasyuk, O. A. Stasyuk, S. Filippone, N. Martín, M. Solà and A. A. Voityuk. Chem. Eur. J., 24 (2018) 13020.

[3] Manuscript in preparation

[4] A. J. Stasyuk, O. A. Stasyuk, M. Solà and A. A. Voityuk. Chem. Eur. J., 2019, ASAP, DOI: 10.1002/chem.201804999

Figure 1
(Invited) Reactivity of Endohedral Metallofullerene Anions
Authors: Li Fang-Fang
Published: February 2020

Anionic fullerenes are nucleophilic reagents that can be easily generated by either chemically or electrochemically reductive methods. Electrochemical reduction is more convenient than chemical reduction since it is easy to generate the desired anions by controlling the potential and the charge transferred to the fullerene cages. Anionic C60 and C70 have been extensively used as nucleophilic reagents for fullerene functionalizations. The results clearly show the potential importance of fullerene anions as reagents to prepare functionalized fullerenes which are difficult to prepare in other ways. It is worth noting that different fullerene anionic states can lead to different products even under the same reaction conditions as a result of their different nucleophilicities. The chemistry of anionic fullerenes is an important complement to that of neutral species. The reactivity of anionic empty fullerenes is reasonably well developed, while the corresponding endohedral metallofullerene anions remain relatively less explored. The electrosynthetic method has not been widely applied to EMFs, and the reactivities of anionic EMF species have not been extensively studied. This prompted us to study the reactivity of EMF anions.
(Invited) Prato Addition to M3n@C80(M = Y, Gd): Mono, Bis, and Higher Adducts
Authors: Semivrazhskaya Olesya , Safwan Aroua , Yamakoshi Yoko
Published: February 2020

Regiocontrol of mutiple fullerene derivatization is important for producing derivatives with specific functions. In previous reports,[1]it was found that bis 1,3-dipolar cycloaddition (Prato reaction) can proceed in a regioselective manner in the case of trimetallic nitride template endohedral metallofullerene, (TNT-EMFM3N@C80, M = Sc, Lu, Y, Gd), while less regioselectivity is usually observed in the case of C60. This is presumably due to the effect of the endohedral metal cluster inside the C80and – especially in case of bis-addition reaction – the position of second addition sites seem to be dependent on the ionic radii of the metal. In this study, we used a larger excess of the dipole in the Prato reaction of M3N@C80(M = Y, Gd). After a short reaction interval, sufficient amounts of tri and tetra adducts were obtained, in addition to the bis-adducts. Although the adducts were not single isomers (four tris-adducts and mono-tetra adduct), the reaction occurred in regioselective manners. All generated tris- and tetra-adducts of M3N@C80 (M = Y, Gd) were isolated by HPLC. The structures of the tris-and tetra-adducts of Y3N@C80were established by 1H and 13C NMR.

Reference:

[1]. Aroua, S.; Garcia-Borràs, M.; Bölter M. F.;, Osuna, S.*; Yamakoshi, Y.*: Endohedral Metal-Induced Regioselective Formation of Bis-Prato Adduct of Y3N@Ih-C80 and Gd3N@Ih-C80, J. Am. Chem. Soc.
2015, 137, 58-61; Cerón, M. R.; Izquierdo, M.; Garcia-Borràs, M.; Lee, S. S.; Stevenson, S.; Osuna, S.; Eshegoyen, L.: Bis-1,3-dipolar Cycloadditions on Endohedral Fullerenes M3N@Ih-C80 (M = Sc, Lu): Remarkable Endohedral-Cluster Regiochemical Control, J. Am. Chem. Soc.
2015, 137, 11775 – 11782.
(Invited) A Pophyrin-centered Fullerene Tetramer Containing N@C60
Authors: Porfyrakis Kyriakos
Published: February 2020

N@C60, single atomic nitrogen incarcerated within a C60 fullerene, has been proposed as a qubit architecture due to the remarkably long relaxation times of its p-electron spins (T1 = 0.375 ms, T2 = 0.25 ms). Versatile methodologies for the chemical functionalization of N@C60 and large-scale production (approx. 1015 qubits per hour) mark it as a promising alternative to today's predominantly inorganic QIP (quantum information processing) systems. For the N@C60 system to be realized as a viable QIP system, qubit–qubit interactions must be well characterized, controlled entanglement must be demonstrated and scalable arrays must be assembled. Qubit–qubit interactions were previously characterized by the measurement of the paramagnetic dipolar coupling strength between two units in an N@C60 dimer by continuous wave electron paramagnetic resonance (cw-EPR) spectroscopy. However, the interactions of arrays of more than two qubits are yet to be explored. In this talk, I will describe a tetraphenylporphyrin-centered N@C60-containing C60 tetramer, which provides a scaffold for the measurement of dipolar interactions in arrays of up to four qubits, and is the largest N@C60-containing C60 array synthesized to date. N@C60 compatible synthesis of this tetramer is the proof of concept that it can be used to characterize many-qubit interactions if the reaction is repeated with high purity N@C60.
(Invited) Uranium-Based Endohedral Fullerenes: Completely Unexpected and Unusual Cage Structures Dictated By the Tetracationic Lanthanide Metal Ion
Authors: Echegoyen Luis , Cai Wenting , Poblet Josep M. , Feng Lai , Morales-Martinez Roser , Rodriguez-Fortea Antonio , Chen Ning
Published: February 2020

For the first time, actinide endohedral metallofullerenes (EMFs) with non-IPR carbon cages, U@C80, Th@C80 and U@C76, were successfully synthesized and fully characterized by mass spectrometry, single crystal X-ray diffractometry, UV-vis-NIR, Raman and cyclic voltammetry. Crystallographic analysis revealed that the U@C80 and Th@C80 shared the same non-IPR cage of C
1(28324)-C80, and U@C76 was assigned to non-IPR U@C
1(17418)-C76. All of these cages are chiral and have never been reported before. DFT calculations show that the stabilization of these unique non-IPR fullerenes originates from a four electron transfer, a significant degree of covalency and the resulting strong host-guest interactions between the actinide ions and the fullerene cages.

We now have a complete family of U@C2n compounds, and this family will be presented and discussed in detail.
Characterizing the Morphology of the Different Grown Homo/Hetero TMD Structures By Controlling Parameters – a Multiscale Computational Approach
Authors: Kashyap Jatin , Ghatak Kamalika , Datta Dibakar
Published: February 2020

Transition Metal Dichalcogenides (TMDs) and their homo/heterostructures have demonstrated excellent mechanical, optical, and electrical properties, which make this family of materials promising candidates for various future applications. TMD films are now being produced mainly by Chemical Vapor Deposition(CVD) and Molecular Beam Epitaxy(MBE), where it was only mechanical exfoliation technique in the beginning. A major drawback of mechanical exfoliation technique was that it could not be used for the mass production of the TMD layer similar to the graphene. However, CVD & MBE synthesis techniques for TMDs are still in a very early stage of development, leading to a poor understanding of what impacts the growth mechanism and post-growth products. Furthermore, a fundamental understanding of what controls morphology over a range of parameters (temperature, pressure, metal: chalcogen flux ratio) is still lacking. The primary reason for the presence of these challenges in a higher degree of complexities than graphene or any other single planar film is that TMDs are multi-planar films, which increases the number of variables involved and ultimately decreasing the control over the growth process. To gain fundamental insight into the growth mechanism of TMDs, we performed Grand Canonical Monte Carlo(GCMC) simulation of growth process over varying substrates. Besides GCMC, we developed in-house Kinetic Monte Carlo (KMC) code to obtain further insights at the macro-domain taking into account spatial and temporal scales. Density Functional Theory (DFT) calculations provide input for the KMC modeling. We have mainly considered the Homo/Heterostructures of MoS2/WS2to establish the relation between different controlling parameters (i.e., temperature, pressure, flux ratios) and the resulting morphology along with defect concentration of underlying substrates. Our preliminary Monte Carlo study captures the formation of the MoS2on the perfect MoS2surface starting with the individual Mo and S flux. We find that the temperature plays a crucial role in governing growth mechanisms. Further investigation is on-going on the growth physics of MoS2and other TMDs (e.g., WS2) on pristine and defective substrates. Our modeling approach provides guidelines for the experimentalists for the optimal design of TMD bilayer growth.
Effect of Structural Properties on the Photoelectrochemical Performance of Transition Metal Dichalcogenides
Authors: Tóth Peter S. , Szabó Gábor , Janáky Csaba
Published: February 2020

Layered transition metal dichalcogenides (TMDCs) have become promising candidates for photoelectrochemical (PEC) studies from the 80’s. Both n- and p-type MoSe2, and WSe2 materials were studied in photoelectrocatalytic reactions using model redox couples and hydrogen evolution reaction. (1-2) Exfoliation of the bulk, layered crystals to single- and few-layered two-dimensional (2D) nanosheets leads to new physical phenomena, different from their bulk counterparts. (3) The electrochemical properties of 2D nanoflakes −which define the performance of these materials in energy-related applications− depends on their structural properties. These structural features include the number of layers, the basal/edge planes, and the defect density. (4-5) Therefore, to employ 2D nanosheets for energy conversion and storage we need to understand their fundamental PEC properties, using an approach with spatial resolution.

In our study, TMDCs samples, MoSe2, WSe2, and MoWSe2 nanosheets were mechanically exfoliated to get bulk, few-layered, and monolayer specimens. The number of layers, and defect density in the separated nanosheets were characterised by Raman spectroscopy and atomic force microscopy. Our recently developed custom-designed microdroplet cell-based photoelectrochemical approach was applied to identify the structural parts and to measure the PEC activity of the flakes (10-50 μm droplets in diameter). PEC measurements, including photovoltammetry, photocurrent transient analysis, and quantum efficiency were carried out to reveal the role of structural properties on the light harvesting, charge transport, and recombination properties of TMDCs. We have determined the band diagrams of these materials using bandgap values from PEC studies and work functions achieved from ambient pressure photoemission spectroscopy (APS) and surface photovoltage spectroscopy (SPS) measurements. Our photoelectrochemical microscopy technique also allowed to probe the PEC reactivity of novel member of 2D family, such as MoWSe2 mixed transition metal dichalcogenide. Finally, I demonstrate the use of model reversible redox species (K4[Fe(CN)6], (NH4)2[IrCl6]) to mimic photoelectrocatalytic processes.

(1) F. R. F. Fan, H. S. White, B. L. Wheeler, A. J. Bard; J. Am. Chem. Soc. 1980, 102, 5142-5148

(2) W. Kautek, H. Gerischer; Ber. Bunsenges. Phys. Chem. 1980, 84, 645-653

(3) K. S. Novoselov, D. Jiang, F. Schedin, T. J. Booth, V. V. Khotkevich, S. V. Morozov, A. K. Geim; PNAS, 2005, 102, 10451-10453

(4) P. S. Toth, A. T. Valota, M. Velický, I. A. Kinloch, K. S. Novoselov, E. W. Hill, R. A. W. Dryfe; Chem. Sci., 2014, 5, 582-589

(5) M. Velický, M. A. Bissett, C. R. Woods, P. S. Toth, T. Georgiou, I. A. Kinloch, K. S. Novoselov, R. A. W. Dryfe; Nano Lett., 2016, 16, 2023-2032
Tackling Electrons in Two-Dimensional Materials for Electronic and Energy Applications
Authors: Liu Yuanyue
Published: February 2020

Two-dimensional (2D) materials have shown great potential for many applications such as electrocatalysis and electronics. However, their developments are impeded by a number of significant challenges, many of which root in the 'problems of electrons'. On the physics side, the electrons/holes in current 2D semiconductors do not move fast enough under electric field (i.e. low mobility), impeding their use in high-performance electronics and optoelectronics. On the chemistry side, the current 2D electrocatalysts still suffer from relatively low activity/selectivity, hindering their use in efficient energy conversion. These challenges urge for an improved understanding of the electrons in 2D materials, and using these insights to design/discover 2D host materials with better performance.

Here I will discuss our recent progress in understanding the chemistry and physics of electrons in 2D materials for electronic and energy applications. Specifically, I will show (1) what limits the intrinsic carrier mobility of two dimensional metal dichalcogenides, and how to find high-mobility 2D semiconductors [1]; (2) the significant impact of charge on electrochemical reactions of 2D materials, which is often neglected in modeling their electrochemistry, and the implications for energy applications [2].

[1] D. Kim, J. Shi, Y. Liu, JACS, 2018, 140, 9127

[2] L. Cheng, Y. Liu, JACS, 2018 DOI: 10.1021/jacs.8b07871
Transition Metal Salts Additive as Antioxidant or Metal Oxide Decorator during Electrochemical Exfoliation of Graphite?
Authors: Ejigu Andinet , Fujisawa Kazunori , Spencer Ben F. , Wang Bin , Terrones Mauricio , Kinloch Ian A , Dryfe Robert AW
Published: February 2020

The preparation of graphene via electrochemical exfoliation in aqueous solution is considered very attractive in terms of cost, scalability and non-toxicity. However, the quality of graphene produced by this method is inferior to the material produced by methods such as mechanical exfoliation due to the functionalisation of carbon by reactive oxygen radical species derived from water oxidation.1 There is a need to alleviate the effect of these radicals in order to capitalize on the use of anodic electrochemical exfoliation in aqueous solution.

In this presentation, we will describe the use of a new approach, based on the unexpectedly versatile role of transition metal ions to produce high quality graphene via an anodic electrochemical exfoliation route, using sulfate as the intercalating anion.2 Notably, some of the transition metals (Co2+, Fe3+) acted as antioxidants, preventing surface oxidation of graphene, while others (Ru3+, Mn2+, Ir3+) acted as metal oxide decorators (Figure 1). The graphene obtained by electrochemical exfoliation of graphite in the presence of Co2+ is two orders of magnitude more conducting and defect free than the one obtained in the absence of cobalt ion. This Co-treated graphene found to be an excellent cathode material for Aluminum-based batteries in terms of performance and cycling stability. The use of other transition metal ions (Ru3+, Mn2+, Ir3+) in the electrolysis solution resulted in decoration of graphene with the oxide of that metal in a single stage simultaneous process. This process can also allow for producing graphene functionalised with hybrid metal oxides (G-RuO2-Mn3O4) in a one-pot single step process, which can be used as electrodes for supercapacitors (500 F g-1) and as an efficient electrocatalyst for water splitting.

References

1) K. Parvez, Z. S. Wu, R. J. Li, X. J. Liu, R. Graf, X. L. Feng, K. Mullen, J. Am. Chem. Soc.
2014, 136, 6083.

2) A. Ejigu, K. Fujisawa, B. F. Spencer, B. Wang, M. Terrones, I. A. Kinloch, R. A. W. Dryfe, Adv. Funct. Mater.
2018, 28, 1804357.

Figure 1
Engineered [60]Fullerene-Graphene Macroassemblies: Synthesis, Characterization and Applications
Authors: Cerón Maira R. , Zhan Cheng , Pham Tuan Anh , Campbell Patrick G. , Biener Juergen , Echegoyen Luis , Biener Monika M.
Published: February 2020

Graphene and fullerenes are carbon allotropes with unique electronic structures and related electrochemical properties that have opened the door to many promising applications in the field of energy storage and harvesting. Graphene combines high surface area with high electrical conductivity which makes it a promising supercapacitor and capacitive desalination material; fullerenes, on the other hand, are characterized by their high electron affinity which makes them interesting as electron acceptors, for example in photovoltaic solar cells. Lawrence Livermore National Laboratory has achieved a fundamental understanding of the synthesis, electrochemical properties and stability of engineered all-carbon [60]fullerene-graphene macro-assemblies for potential energy storage and harvesting applications. Specifically, we synthesized and tested five C60 monoadducts that allowed us to tailor the fullerene-graphene interaction.

Fig. 1:

Fullerene-grafted 3D graphene bulk material.

Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 17-ERD-017. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. IM Release Number LLNL-ABS-764285.

Figure 1