bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electropolymerization and Electrochemical Performance of Nickel Schiff Base Complexes on Reduced Graphene Oxide(RGO) Support for Supercapacitors
Authors: Deng Fuhai , Li Xinping , Wang YuDong , Li Jianling 
Published: February 2020

Supercapacitors have a high power capability and relatively large energy density compared to the conventional capacitors. Conducting polymers have been shown as promising electrode materials because of their high conductivity and fast redox activity. N,N_-ethylenebis(salicylideneaminato) nickel(II), (Ni(salen)), which is the archetype of Schiff base metal complexes, was easily synthesized onto the surface of reduced graphene oxide(RGO) by the route of linear potential sweep. Growth parameters such as the apparent surface coverage and the doping level were investigated to confirm the effects of supports on the Ni(salen) polymerization.SEM, TEM, Raman, and XPS analyses show that the poly(Ni(salen)/RGO composite prepared from this approach,at the same time it exhibited an excellent electrocapacitive performance with a high specific capacitance over 260 F g-1

Fig.1 (a) Polymerization Q varies with polymerization time at different voltages ; (b) GCD curves of MWCNTs and the composites at a current density of 1.0 mA cm2 under the voltage range of 0 V to 1.2 V.

Reference

1 Kim, M., Lee, C., & Jang, J. (2014). Fabrication of Highly Flexible, Scalable, and High‐Performance Supercapacitors Using Polyaniline/Reduced Graphene Oxide Film with Enhanced Electrical Conductivity and Crystallinity.Advanced Functional Materials, 24(17), 2489-2499.
2. Salanne, M., Rotenberg, B., Naoi, K., Kaneko, K., Taberna, P. L., Grey, C. P., ... & Simon, P. (2016). Efficient storage mechanisms for building better supercapacitors. Nature Energy, 1, 16070.

Acknowledgement

This work is financially supported by the National Natural Science Foundation of China (No. 51372021).

Figure 1
DFT Simulation of Edge Halogenated Graphene Nanosheets As an ORR Catalyst in Fuel Cells
Authors: Rodriguez Roberto , Humphrey Nicholas , Arias Gabriel , Goddard William A , Yu Ted H. 
Published: February 2020

Edge halogenated graphene-nanosheets1have recently been discovered to be a low cost Oxygen Reduction Reaction (ORR) catalysts for alkaline fuel cells. Better understanding of ORR on these catalysts is needed to understand:
i) why these doped catalysts form water in the preferred 4e-ORR mechanism over the peroxide formation found in undoped graphene.
ii) how to improve these catalysts, so that ORR can occur in the preferred acidic environment.
We used the PBE flavor density functional theory (DFT) with the SeqQUEST code2to calculate the binding energies, onset potential, and reaction barriers for ORR using either bromine, chlorine or iodine as the hetero-atom dopants on edge halogenated graphene-nanosheets. We examined both the zig-zag and armchair edges and find that the ORR intermediates bind to the zig-zag edges more strongly than the armchair. We find that the ORR intermediate species HOO does not bind to the basal plane. Thus, the ORR occurs on the graphene edges and not on the basal plane surface. We also find that the halide doped graphene zig-zag and armchair edges lead to a skewed geometry due to nonbonded interactions of the halogen with each other on the adjacent edge sites.
Although the ORR intermediate species bind more strongly on the zigzag edges, our results predict that ORR occurs in the armchair edges based on the predicted onset potential calculation that agree well with experiments (Cl: 0.95 V, Br: 0.70 V, I: 0.72 V). We used nudged elastic band (NEB) calculations in conjunction with the CANDLE water solvation method3 to predict the potential dependent barriers4of the ORR.
The dissociation of O2 in the second step of the ORR indicates that halogen doped graphene favor the 4e- pathway. In addition, the barrier to form –OH is much lower on the halide graphene edges than undoped graphene. Based on the calculated barriers, we conclude that iodine-doped graphene has the lowest thresholds water formation (0.56 eV at 0.72 V), which we find to be the rate determine step (RDS). This is in agreement with ORR activity of experimental results indicating iodine doped graphene performs better than bromine-doped, chlorine-doped, and undoped1.
References:
1. I. Y. Jeon, H. J. Choi, M. Choi, J. M. Seo, S. M. Jung, M. J. Kim, S. Zhang, L. Zhang, X. Zhenhai, L. Dai, N. Park and J. B. Baek, Scientific Reports 3(1810), 1-7 (2013).
2. P. Schultz, (SEQQUEST, Sandia National Laboratory).
3. R. Sundararaman and W. A. Goddard, J Chem Phys 142(6), 064107 (2015).
4. H. Xiao, T. Cheng, W. A. Goddard and R. Sundararaman, J Am Chem Soc 138 (2), 483-486 (2016).

Figure 1
Structural Identification of 11 of the 19 Isomers of the Opv Acceptor Bispcbm Via
13c NMR and UV-Vis Absorption Spectroscopy, and Cyclic Voltammetry, Coupled with DFT Simulations
Authors: Liu Tong , Misquitta Alston J. , Abrahams Isaac , Dennis John 
Published: February 2020

The as-produced isomer mixture of the organic photovoltaic acceptor material bisPCBM has recently been purified into 19 components by peak-recycling HPLC and their frontier orbitals have been characterised by UV-Vis absorption spectroscopy and cyclic voltammetry. OPV devices based on the purified isomers may now be made, but before meaningful conclusions can be made about why some isomers are better that others in these devices, we mush first know which particular isomer is used in which OPV device. Here we present the structural identification of more than half (11) of the 19 isomers by 13C NMR and UV-Vis spectroscopy.

Via UV-Vis spectroscopy the 19 isomers of bisPCBM were classified into 7 different groups, with each group containing 2 or 3 members. Each of the 7 groups corresponds to 1 of the 7 bond types identified by Hirsch (trans-1, trans-2, trans-3, trans-4, e, cis-3, cis-2). By examining the molecular structure of each of the 19 isomers, we conclude that 11 isomers have C1 symmetry, 3 isomers have Cs symmetry, 3 have C2 symmetry, 1 has C2h symmetry and 1 has C2v symmetry; and we have confirmed this prediction experimentally by 13C NMR spectroscopy. The two high-symmetry isomers, C2h and C2v, which correspond to the two polar isomers (where the two addends bridge the 1,9 and 52,60 bond of C60with the two addends having opposing relative orientations) correspond to the first and third HPLC fractions by retention time, respectively.
Unfortunately, the other isomers cannot be identified from the NMR spectra alone. However, as the UV-Vis spectra and 7 groups identified above reduce the uncertainty to no more than 3 isomers, when coupled with the symmetry identified from NMR spectra, some of the isomers may be confidently identified. For example, the 13th HPLC fraction belongs to the cis-2 group which contains one C
s and two C
1 isomers. The NMR spectra shows that this 13th fraction is the C
s isomer, which involves the 32,33 bond of C60. By this method, the other C
s and C
2isomers were also unambiguously confirmed.
The remaining unidentified isomers all have C
1 symmetry and cannot be further identified by this method. For these isomers, the HOMOs and HOMO-LUMO gaps were calculated by DFT and TD-DFT methods. By comparing the experimental and calculated results, some, but not all, the C
1 isomers were tentatively identified with reasonable confidence. For the remaining 8 C1 isomers the DFT calculations were not able to adequately distinguish, so the identification of these isomers will have to wait for single crystal analysis. A full description of the identification of the isomers will be presented in the meeting.
Purification and Frontier Orbital Characterisation of 19 Purified Isomers of the Opv Acceptor Bis[60]PCBM
Authors: Dennis John , Shi Wenda , Hou Xueyan , Liu Tong 
Published: February 2020

The as-produced isomer mixture of the organic photovoltaic device acceptor material bis-[60]PCBM has been purified into its constituents by peak-recycling HPLC, and those individual isomers were characterised by UV-Vis absorption spectroscopy and cyclic voltammetry.
A total of 19 isomers (from a potential total of 21isomers) were purified from the mixture to a standard exceeding 99.5% with respect to other isomers. Three different columns, silica, 5PYE and 5PBB, were used and tried on each isomer to achieve the highest purification efficiency. The UV-Vis spectra and cyclic voltammograms demonstrate that each of the isomers exhibit different electronic properties. Their HOMO, LUMO and HOMO-LUMO gaps range from, -5.673 to -5.402 eV, from -3.901 to -3.729 eV, and from 1.664 to 1.883 eV, respectively.
Based on comparisons with known UV-vis absorption spectra of analogous materials we conclude that there is correlation between HPLC retention time and the relative positions of the addends; in that generally the closer the addends are to each other the longer the retention time of the isomer, and vice versa. These comparisons have enables us to tentatively, assign each of the isomers to one of the 8 bond types identified by Hirsch and co-workers1,2 (Trans1, Trans2, Trans3, Trans4, equatorial, Cis3, Cis2 and Cis1), such that the identity of the isomers is reduced to being one of only 2 or 3 isomers.
The LUMO levels of the majority of the isomers are above that of the isomer mixture, and hence, OPV devices based on each of those isomers are predicted to have a V
OC higher than that of present devices based on the mixture (with the most promising isomer being 94 meV above that of the mixture and 188 meV above that of [60]PCBM).
Furthermore, with the removal of energetic and morphological disorder associated with the normal mixture of bis-[60]PCBM isomers, it is also predicted that OPV devices based on all of the isomers will have better charge carrier transport properties, and thereby potentially higher currents, than those based on the mixture.
Preliminary analysis of an unoptimized P3HT/bisPCBM device based on the isomer with the highest LUMO indicates an open circuit voltage that is 210 meV above that obtained from the PCBM-based analogous, which is very significant given that the target voltage for OPVs is about 1 V. In addition, time-of-flight conductivity measurements indicate that electron carrier mobility for this isomer is similar to that of PCBM. Optimisation of a is underway and in addition to the abovementioned purification and frontier orbital the findings, the results of the performance of optimised devices will be presented at the meeting.
(Invited) Organic Polymers for Thermoelectric Energy Conversion
Authors: Chabinyc Michael 
Published: February 2020

Semiconducting polymers have been proposed as potential materials for thermoelectric devices. While there have been significant advances in designing polymers for applications such as solar cells and thin film transistors, significantly less is understood about how to control their thermoelectric properties. The performance of thermoelectric materials is determined by their electrical conductivity, thermopower and thermal conductivity. Each of these properties is related to the carrier concentration in semiconducting materials and their electronic density of states. The electronic density of states is strongly modified by processing methods used to introduce dopants making it difficult to predict their electrical properties. We will discuss our efforts to understand how the electrical conductivity and thermopower of semiconducting polymers are interrelated using model polymer systems including poly(3-hexylthiophene) and a thienothiophene-basedpolymers, PBTTT. We find that changes in processing conditions can increase the electrical conductivity by >50x at the same apparent carrier concentration, while causing smaller changes in the thermopower. The increase in performance can be understood by the nanoscale connectivity between ordered domains and quantitated using synchrotron-based X-ray scattering methods. We will also present temperature-dependent transport measurements that further help to understand changes in performance. Prospects for the ultimate performance of polymer thermoelectrics will be discussed.
An Impedance Study on Porous Carbon/Lithium Titanate Composites for Li-Ion Battery
Authors: Deng Zhaofeng , Ho Ching-Kit , Li Chi-Ying Vanessa , Chan Kwong-Yu 
Published: February 2020

The electrode structure affects the charge-transfer process, electronic conduction, mass transport within pores, and therefore electrochemical performance of batteries 1. In this study, a hierarchical carbon network with hollow core and mesoporous shell (HCMS) 2,3 and activated carbon (AC) are employed as supports for Li4Ti5O12 (LTO) anode material. LTO/HCMS composite shows higher capacity than LTO/AC composite under high-rate and low-temperature conditions. In order to study the performance-structure relationship, electrochemical impedance spectroscopy (EIS) technique with transmission line model (TLM), together with material characterization, are utilized to study the electronic conduction process, mass transport within the pores and the charge-transfer process of LTO/C composites and carbon supports.
Fig. 1 TEM images of (a) HCMS and (b) AC carbon supports; (c) Nyquist plots (symbol), and plots (line) fitted with equivalent circuit model for symmetric HCMS/HCMS (○, solid line) and AC/AC (□, broken line) coin-cells in 1M LiPF6 in EC/EMC/DMC (1:1:1).

References

[1] N. Ogihara, S. Kawauchi, C. Okuda, Y. Itou, Y. Takeuchi, and Y. Ukyo, J. Electrochem. Soc., 159, A1034 (2012)
[2] F. Li, M. Morris, and K.Y. Chan, J. Mater. Chem., 21, 8880 (2011)
[3] C. Yang, C.Y.V. Li, F. Li, and K.Y. Chan, J. Electrochem. Soc., 160, H271 (2013)

Acknowledgements

This project is financially supported by Innovation and Technology Commission, Hong Kong (Project No.: ITS/076/11), HKU Seed Fund for Basic Research (Project No.: 201605159011), and University Development Fund for Clean Energy and Environment.

Figure 1
(Invited) New Glycofullerenes for Ebola Virus Infection
Authors: Ramos-Soriano Javier , Pérez Alfonso , Rodríguez-Pérez Laura , Illescas Beatriz , Rojo Javier , Delgado Rafael , Martín Nazario 
Published: February 2020

Multivalency is an important issue in the study of carbohydrate−protein interactions as well as for getting a better understanding of the virus infection processes. Thus, different chemical and bio-inspired scaffolds have been used in the literature in the search for new glycoconjugates bearing larger units of carbohydrates located in the appropriate spatial arrangement.
At the molecular level, there are a wide variety of examples where multivalency drastically enhances the interactions between biomolecules in comparison with the monovalent binding. The search for high-affinity ligands for the study and understanding of the mechanisms involved in multivalent interactions has yielded a wide variety of artificial glycoconjugates which include, among others, glycopolymers, glycodendrimers, and glyconanoparticles. Recently, we have shown that hexakis-adducts of [60]fullerene endowed with 12, 24 or 36 mannoses, act as strong inhibitors for DC-SIGN in an Ebola infection assay model.1 Furthermore, a drastic increase in the inhibition process to the subnanomolar scale has been observed when the size and mannoses´ number are increased in the tridecafullerenes endowed with 120 mannose units decorating the periphery of the molecule.2

In this work, we report the synthesis and study of novel carbon nanostructures and carbohydrates for the multivalent presentation in an artificial Ebola virus infection model. These new carbon nanoforms have been chemically modified by the covalent attachment of glycofullerenes using the CuAAC “click chemistry” approach as well as in the absence of Cu in order to prevent the unfavorable metal effect.3 The efficiency to block DC-SIGN mediated viral infection by an artificial Ebola virus has been tested in a cellular experimental assay finding that, these systems are potent inhibitors of viral infection.
References
1. a) J. Luczkowiak, A. Muñoz, M. Sánchez-Navarro, R. Ribeiro-Viana, A. Ginieis, B. M. Illescas, N. Martín, R. Delgado, J. Rojo, Biomacromolecules
2013, 14, 431-437; b) J.-F. Nierengarten, J. Iehl, V. Oerthel, M. Holler, B. M. Illescas, A. Muñoz, N. Martín, J. Rojo, M. Sánchez-Navarro, S. Cecioni, S. Vidal, K. Buffet, M. Durka, S. P. Vincent, Chem.
Commun.
2010, 46, 3860-3862; c) M. Sánchez-Navarro, A. Muñoz, B. M. Illescas, J. Rojo, N. Martín, Chem. Eur. J.
2011, 17, 766-769.
2. A. Muñoz, D. Sigwalt, B. M. Illescas, J. Luczkowiak, L. Rodríguez, I. Nierengarten, M. Holler, J.-S. Remy, K. Buffet, S. P. Vincent, J. Rojo, R. Delgado, J.-F. Nierengarten, N. Martín, Nat. Chem., 2016, 8, 50-57 - DOI: 10.1038/NCHEM.2387.
3. J. Ramos-Soriano, J. Juan Reina, A. Pérez-Sánchez, B. M. Illescas, J. Rojo, N. Martin, Chem. Commun., 2016, 52, 10544-10546 - DOI: 10.1039/C6CC05484F

Figure 1
(Invited) Single Carbon Nanotube Tracking Reveals Nanoscale Organization of the Extracellular Space in Live Brain Tissue
Authors: Cognet Laurent 
Published: February 2020

Sub-wavelength localizations of single molecules allows super-resolution imaging and a subtle probing of spatio temporal nano-environments in cells [1].
By using biocompatible luminescent single wall carbon nanotubes (SWCNTs) in the near-IR emission [2,3], here we show an approach to directly observe local structures and rheology of the extracellular space in a brain tissue using super-resolution imaging. Upon injection in live rat cerebroventricles [4], individual SWCNTs are followed for tens of minutes in acute slices as they diffuse inside the extracellular space. Because of the interplay between the nanotube geometry and the extracellular space local environment [5], we can extract information about the extracellular space dimension and local viscosity. We find a striking diversity of extracellular space dimensions down to 40 nm, and as well as of local viscosity values. Moreover, by chemically altering the brain extracellular matrix of the live animals before nanotube injection, we reveal that ECS rheology properties are affected, but that extracellular space alterations are local and inhomogeneous at nanoscale dimensions [6].

References

[1] Godin et al , Biophys. J, (2014).
[2] Gao, et al, Biomater. Sci.(2016).
[3] Danné et al submitted
[4] Varela et al Nat. Comm. (2016).
[5] Fakhri et al , Science(2010).
[6] Godin et al Nat. Nanotechnol. (2016).
Graphene Quantum Dots: Emerging Carbon Nanomaterials
Authors: Hadad Caroline , Gonzalez Dominguez Jose Miguel , Istif Akcan , Da Ros Tatiana 
Published: February 2020

Among the various carbon nanostructures, the graphene quantum dots represent an emerging 0D platform with very interesting properties for biological application. More specifically they are properly water-soluble, they can be decorated exploiting different chemical approaches and they possess intrinsic characteristics of fluorescence.
Herein, we report a new top-down strategy to prepare these structures, that has been recently explored and allows an almost quantitative conversion of the carbon source, and some preliminary biological results.
(Invited) Modification and Analysis of Carbon Based Structures By Metal Nanoparticulate Ions
Authors: Schultz John Albert , Hauge Robert , Adams W. Wade , Brinson Bruce E , Kim Nam Dong , McCully Michael , Lewis Ernest , Barbacci Damon , Balaban Carey , Muller Ludovic , Jackson Shelley , Woods Amina 
Published: February 2020

Our collaborative work to create and soft land ionized gas phase single crystalline metal nanoparticulate ions onto substrates was motivated by Robert Hauge’s wish to produce templates for carbon nanotube carpet growth. Ionwerks created a machine to do this but, as is often the case, funding was found first for alternative applications.
One such has been low energy (500 eV) injection of 8 nm silver nanoparticulate ions (AgNP-) into the near surface of bio-polymers. A uniform layer (70 e15 Ag atoms/cm2) of these implanted particles serve to assist the laser desorption of intact biomolecules from a brain tissue sample into the gas phase. Some of these desorbed molecules are ionized and can be transported into a mass spectrometer and uniquely identified by their exact mass to charge (m/z). By scanning a 50 micron focused laser across the surface of an AgNP implanted rat brain tissue sections, a complete mass spectrum can be acquired at each of several hundred thousand laser locations. Images of specific biomolecules can be derived from these spectra. Putative molecular biomarkers can then be identified by inter-comparing the numerous molecular images from each animal grouping within an animal study. Images from the same brain levels between injured (or diseased) and uninjured rats define histological micro domains in which elevated or decreased molecular ion intensities correlate with other measures of injury/disease state severity. Imaging of these biomarker ions is becoming useful in preclinical screening of drug candidates and should ultimately enter clinical settings.
The AgNP enhanced mass spectral imaging has been also applied to the surface analysis of synthetic polymers, fullerenes, and nanotubes.
A third application uses 30 keV, 15 nm AgNP ion impacts to form otherwise unattainable controlled nano-sized holes in graphene—especially “rebar” graphene. Alternatively, low energy soft landing at lower energy can form nanostructures upon the graphene which have implications for device formation.
However, before departure, Bob made it clear that we needed to get back to carpet growth and other ideas which he outlined in extensive and explicit discussions—mostly at outdoor cafes and coffee shops. His dictates and imprimatur remain.
(Invited) Functionalization and Environmental Dependent Emission Properties of Photoluminescent Defect States in Carbon Nanotubes
Authors: Doorn Stephen K. , He Xiaowei , Hartmann Nicolai F. , Gifford Brendan , Tretiak Sergei , Htoon Han , Bullad George , Olivier Jean-Hubert , Therien Michael J. 
Published: February 2020

Red-shifted emitting states in carbon nanotubes, introduced by chemically stable and tunable covalently-bound dopants,1,2 are gaining attention for their potential to boost photoluminescence quantum yields,1,2 add new functionality,3,4 and serve as single photon emitters.5 These sites present a rich array of new photophysics, with dependences on specific functionalization chemistry and environmental interactions. As examples, we will present low-T photoluminescence (PL) probes of defect-state electronic structure for sp
3 defects introduced by aryl functionalization and compare to quantum chemical theory and to earlier studies on oxygen-introduced defects.6 Environmental effects on both low-T spectroscopy and ensemble-level relaxation dynamics7 will also be presented. In particular, dielectric environment is found to significantly impact PL relaxation times in contrasting ways, enabling further understanding of relaxation mechanisms and how they relate to spectroscopic observables. Finally, control over chemical functionality and dielectric environment will be shown as routes for optimizing single photon emission behaviors, in agreement with earlier theoretical results.8

References

1. Ghosh, S. et al., Science, 330, 1656 (2010).
2. Piao, Y. et al., Nature Chem., 5, 840 (2013).
3. Kwon, H. et al., J. Phys. Chem. C, 119, 3733 (2015).
4. Akizuki, N. et al., Nature Comm., 6, 8920 (2015).
5. Ma, X. et al., Nature Nanotech., 10, 671 (2015).
6. Ma, X. et al., ACS Nano, 8, 10782 (2014).
7. Hartmann, N. et al., ACS Nano, 10, 8355 (2016).
8. Hartmann, N. et al., Nanoscale, 7, 20521 (2015).