bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Electrochemical Properties of Lepidocrocite Titanate- Graphene Heterostructures
Authors: Barim Gozde , Lin Jason , Doeff Marca M.
Published: July 2021

Layered titanates with lepidocrocite structure can be used as anodes for lithium, sodium or potassium batteries in conventional or flow cell configurations. Although they are attractive owing to their low cost, low toxicity, and high abundancy, their low conductivity and poor cycling performance are major hurdles for these materials. Here, we used a self-assembly approach to overcome electronic transport limitations and to build in the conductivity by incorporating a conductive component such as reduced graphene oxide (rGO) or into nitrogen doped graphene (NDG) in the van der Waals gaps to make 2D heterostructures.

In this presentation, solution-phase synthesis of K0.8[Ti1.73Li0.27]O4 (lepidocrocite titanate, LT) heterostructures with graphene is demonstrated. After synthesis by conventional solid-state routes, K0.8[Ti1.73Li0.27]O4 is proton exchanged and ion-exchanged with bulky cations, causing expansion of the structure, and exfoliated by mechanical shaking. Exfoliated layered titania sheets are self-assembled with either reduced graphene oxide (rGO) or dopamine into heterostructures through flocculation via counter cations (e.g. Mg2+, Na+) or in situ conversion of dopamine into nitrogen doped graphene (NDG), respectively. Both coagulated LT-rGO and LT-NDG heterostructures exhibit capacities which are more than two times higher than the capacities of pristine lepidocrocite titanate (K0.8[Ti1.73Li0.27]O4), and display good capacity retention after 50 cycles in sodium half-cells configurations.
(Invited) Environmental Impact of Carbon Nanotubes & Graphene and Related Materials (GRMs)
Authors: Flahaut Emmanuel , Evariste Lauris , Liné Clarisse , Mottier Antoine , Mouchet Florence , Barret Maialen , Pinelli Eric , Galibert Anne Marie , Soula Brigitte , Larue Camille , Gauthier Laury
Published: July 2021

Carbon nanomaterials (and especially carbon nanotubes) are often cited first when people are asked about "nanoparticles" in general. For some people, they represent a huge potential of applications due to their extraordinary properties (or more realistically because of their unique combination of different properties), while some others will mention first the (potential) related toxicity issues.

We will quickly review different aspects related to the potential environmental toxicity of carbon nanomaterials and will summarize our main results in this field. In particular, we have identified that the impact of carbon nanomaterials with very different morphologies ranging from zero-D (nanodiamonds) to 2D (few-layer graphene, graphene oxide) can be generalized when the metric used for the comparison of the data is the surface (m²/L) instead of the weight (g/L) [1]. We will illustrate in the specific case of graphene oxide how the modification of surface chemistry (reduction) can be used to significantly decrease the risk during handling and use, in the framework of a "safer(r) by design" strategy [2].

Finally, we will give a brief overview of our recent work on the impact of carbon nanotubes on plants grown in contaminated soils.

REFERENCES:

[1] A. Mottier, F. Mouchet, C. Laplanche, S. Cadarsi, L. Lagier, J-C. Arnault, H. Girard, V. Léon, E. Vazquez, C. Sarrieu, E. Pinelli, L. Gauthier, E. Flahaut, Nano Letters, 16 (6), (2016), 3514-3518, "Surface area of carbon nanoparticle: a dose-metric for a more realistic ecotoxicological assessment"

[2] L. Evariste, L. Lagier, P. Gonzalez, A. Mottier, F. Mouchet, S. Cadarsi, P. Lonchambon, G. Daffe, G. Chimowa, C. Sarrieu, A-M. Galibert, C. Matei Ghimbeu, E. Pinelli, E. Flahaut, L. Gauthier, Nanomaterials, 9, (2019), 584:1-16, "Thermal reduction of Graphene Oxide mitigates its in vivo genotoxicity toward Xenopus laevis tadpoles"
(Invited) Hybrid Van Der Waals Heterostructures: From Fundamentals to Applications
Authors: Orgiu Emanuele
Published: July 2021

2D materials are held together by weak interplanar van der Waals (vdW) interactions. The incorporation of molecules in such materials holds an immense potential to understand and modify the fundamental physical properties of the pristine materials while creatin new artificial materials. Whilst nature offers a finite number of 2D materials, an almost unlimited variety of molecules can be designed and synthesized with predictable functionalities. The possibilities offered by systems in which continuous molecular layers are interfaced with inorganic 2D materials to form hybrid organic/inorganic van der Waals heterostructures (H-vdWH) are emphasized. Similar to their inorganic counterpart, the hybrid structures have been exploited to suggest novel device architectures. Moreover, specific molecular groups can be employed to modify intrinsic properties and confer new capabilities to 2D materials. In particular, I will highlight how molecular self-assembly at the surface of 2D materials can be mastered to achieve precise control over position and density of (molecular) functional groups, paving the way for a new class of hybrid functional materials.

In particular, within such vdW heterostructures, currently assembled by mechanical superposition of different layers, periodic potentials naturally occur at the interface between the 2D materials. These potentials significantly modify the electronic structure of the individual 2D components within the stack and their alignment, thus offering the possibility to build up hybrid and novel materials with unique properties.

Also, I will show how the presence of ordered supramolecular assemblies bearing different functional groups can modify the pristine Shubnikov-De Haas oscillations occurring in graphene.

Finally, an example will be given of how a carefully designed H-vdWH could be used for sensing of different biomarkers.
(Invited) Carbon Dots – from Imaging to Green Energy Applications
Authors: Naccache Rafik
Published: July 2021

In recent years, nanomaterials, defined as materials < 100 nm in a single dimension, have garnered significant interest for the development of novel applications in the physical and life sciences. This is especially true for luminescent nanoparticles, which have been investigated for the development of sensors, imaging/diagnostic probes, display and solar cell applications. Recently, a relatively new class of luminescent nanomaterials, namely carbon dots, has come to light. Carbon dots, sometimes known as carbongenic dots, are carbon, oxygen, nitrogen and hydrogen containing materials with the first two elements typically accounting for ~90% of their elemental composition. Moreover, they are typically water dispersible and can be prepared from an abundant number of inexpensive sources including small molecules such as citric acid, amino acids and sugars. While they are small in size (typically 1-10 nm), they can offer a high quantum yield of emission, a process that is controlled through passivation of the surface with an organic reagent. Of particular interest are their optical properties, which can be tailored via careful selection of the starting precursors and the desired synthesis route resulting in the ability to generate fluorescence from the blue to the near infrared regions of the spectrum. In addition to their versatile optical properties, these carbon dots are generally known to have low cytotoxicity and good biocompatibility. Combined with their small size and versatile optical properties, developing carbon dots as a nanoplatform can be achieved as they lend themselves for integration in a myriad of applications most notably in bio-imaging and sensing. Our work focuses on achieving a fundamental understanding of the synthesis of carbon dots in order to control their size and achieve homogenous surface chemistry and optical properties. As they are fluorescent, we have investigated their development as bimodal imaging probes and exploited their temperature and pH dependent optical properties in order develop novel intracellular temperature and pH sensors. We can also endow them with chiral properties during synthesis opening up novel avenues for chiral sensing and antimicrobial applications. Finally, in recent developments, we have exploited their physico-chemical properties in green energy applications focusing on the production of biofuels.
(Invited) Optical Properties and Active Plasmon Excitations in Nanocrystals and 2D Materials
Authors: Henrard Luc
Published: July 2021

The control and tuning of the optical properties of materials and the localization of electromagnetic energy are long standing quests for scientists. Not only it allows to design new classes of adaptive devices such as smart windows but also to perform surface enhanced vibrational spectroscopies such a SERS. Behind all these applications, fundamental questions are still debated : what is the role of electron correlation in the optical response ? How to include to contribution of crystal field in the dielectric response of complex system ? How the local electro-magnetic field influence the optical absorption and the SERS activity ?

For metallic nanostructured systems, the optical properties are directly related to collective electronic excitation (plasmons) and they depend mainly on the composition, shape and size of the system. Doped semiconductors such as Indium Tin Oxide have been also shown to display active plasmon, i.e., optical excitations that can be controlled by an external stimulus such as static electric potential [1].

In 2D materials like graphene, the electrostatic doping is a commonly used to modify the optical response due to the low density of state at the Fermi energy. Moreover, topological corrugation, anisotropy [2], chemical doping [3] and electrostatic coupling in vanderwaals heterostructures plays very specific roles on the optical responses. Graphene nanodots and molecular PAH also supported plasmon excitation and electrochromic behavior.

In this presentation, based on numerical simulations, we analyze the optical properties of these compounds and we discuss the influence of electrostatic coupling and charging effects. We emphasized the role of the electron correlation and of the local field in classical, semi-empirical and ab-initio methods.

[1] A. Maho et al. Solar Energy Materials and Solar Cells 200 (2019) 110014

[2] B. Majerus et al. Phys. Rev. B 98 (2018) 125419

[3] F. Joucken et al. Phys. Rev. Mat. 3 (2019) 110301
(Invited) Defect Engineering in Plasma-Treated Graphene Films
Authors: Stafford Luc
Published: July 2021

Engineering of defects located in-grain or at grain boundary is central to the development of functional materials and nanomaterials. While there is a recent surge of interest in the formation, migration, and annihilation of defects during ion and plasma irradiation of bulk (3D) materials, the detailed behavior in low-dimensional materials remains most unexplored and especially difficult to assess experimentally. A new hyperspectral Raman imaging scheme providing high selectivity and diffraction-limited spatial resolution is here adapted to examine plasma-induced damage in a polycrystalline graphene film grown by chemical vapor deposition on copper substrates and then transferred on silicon substrates. For experiments realized in nominally pure argon plasmas at low pressure, spatially resolved Raman conducted before and after each plasma treatment shows that the defect generation in graphene films exposed to very low-energy (11 eV) ion bombardment follows a 0D defect curve, while the domain boundaries tend to develop as 1D defects. Surprisingly and contrary to common expectations of plasma-surface interactions, damage generation at grain boundaries is slower than within the grains. Inspired by recent modeling studies, this behavior can be ascribed to a lattice reconstruction mechanism occurring preferentially at domain boundaries and induced by preferential atom migration and adatom-vacancy recombination. Further studies were realized to compare the impact of different plasma environments promoting either positive argon ions, metastable argon species, or VUV-photons on the damage formation dynamics. While most of the defect formation is due to knock-on collisions by 11-eV argon ions, the combination with VUV-photon or metastable atom irradiation is found to have a very different impact. In the former, the photons are mainly thought to clean the films from PMMA residues due to graphene transfer from copper to silicon substrates. On the other hand, in conditions with both ion and metastable atom irradiation, the surface de-excitation of the latter seem to greatly enhance the self-healing of the grain boundaries due to an increase of the local energy deposition. Finally, these experiments were used as building blocks to examine the formation of chemically doped graphene film in such plasmas using argon mixed with either traces of N- or B-bearing gases. While preferential n-type doping was observed in graphene domains in nitrogen-containing plasmas, preferential p-type doping was observed at grain boundaries in boron-containing plasmas.
(Invited) Scanning Gate Imaging of Charge Transport in Graphene Nanodevices
Authors: Hackens Benoit
Published: July 2021

Quantum transport in nanodevices is usually probed thanks to measurements of the electrical resistance or conductance, which lack the spatial resolution necessary to probe local-scale electron behaviour. Here, we will discuss how to get real-space local information on peculiar quantum transport phenomena inside graphene constrictions. The results were obtained using low temperature scanning gate microscopy (SGM), which consists in mapping the electrical conductance of a device as an electrically-biased sharp metallic tip scans in its vicinity [1].

If the tip-induced perturbation is relatively small, SGM is an imaging technique giving access to the local density of states inside mesoscopic devices [2]. Here, we will focus on the regime of large tip-induced perturbation. This regime is particularly interesting in the case of graphene: depending on tip voltage and tip-sample distance, one can tune the shape, size, and smoothness of the moving scattering region associated with the tip, and eventually create a moving circular pn-junction within the device. We use this moving pn-junction to probe peculiar aspects of relativistic charge carrier dynamics within graphene devices: Klein tunnelling and current focusing and defocusing [3], Fabry-Pérot interferometry [4], signatures of whispering gallery modes [5] and tunneling between counterpropagating quantum Hall edge states [6]. This work unlocks new possibilities in the field of electron optics in graphene.

[1] M.A. Eriksson et al., Appl. Phys. Lett. 69, 671 (1996); M. Topinka et al., Science 289, 671 (2000).

[2] F. Martins et al., Phys. Rev. Lett. 99, 136807 (2007) ; M. Pala et al., Phys. Rev. B 77, 125310 (2008).

[3] B. Brun et al., Phys. Rev. B 100, 041401 (2019).

[4] B. Brun et al., 2D Materials, 7, 025037 (2020).

[5] B. Brun et al., submitted.

[6] N. Moreau et al., submitted.
(Invited) Alteration of the Electrical Transport in Carbon Nanotube Network Field-Effect Transistors Using Polymer Encapsulants and Gate Dielectrics
Authors: Lapointe Francois
Published: July 2021

Enriched semiconducting single-walled carbon nanotubes (SWCNTs) inks of high purity opens a wealth of possibilities for device fabrication using printing techniques and solution processes. [1] Logics, displays, sensors and large-scale integrated circuits [2] appear to be within reach. For those promises to concretize, a better control over parameters such as carrier type and mobility, operation power and device-to-device variability is needed. Beside the ambient effect (notably water and oxygen) on the transport of carbon nanotube network field-effect transistors (CNN-FETs), the nature of the surrounding materials (as a passivation layer or as a gate dielectric) appears to play a crucial role in determining the device's characteristics.

Firstly, we have tested a large number of polymeric materials as the bottom gate in three-terminal CNN-FETs. We have found that the transport characteristics parameters such as the threshold voltage and the hysteresis are affected by the chemical nature of the polymer. [3] Subjecting those CNN-FETs with various gate dielectrics to a series of volatile analytes, we observed drastically different responses which suggests the usefulness of polymer gate dielectric variations in cross-reactive sensors arrays.

Secondly, polymeric materials were used as an encapsulant over bottom gate CNN-FETs. [4] A smooth and continuous variation of the threshold voltage has been achieved by using a series of poly(styrene–co–2-vinyl pyridine) copolymers with different monomer ratios. A surface charge density measurement methodology has been developed to rationalize the threshold voltage variations upon encapsulation with various polymers. Finally, we explored the use of n-doping molecules blended with polymer encapsulants as an efficient way to obtain n-type transport characteristics. This strategy is further used in the implementation of simple p-n junctions showing a modest rectification.

References

[1] Bati, A. S. R. et al. Recent Advances in Applications of Sorted Single‐Walled Carbon Nanotubes. Adv. Funct. Mater.
29 1902273 (2019)

[2] Hills, G. et al. Modern Microprocessor Built from Complementary Carbon Nanotube Transistors. Nature
572 595–602 (2019)

[3] Lapointe, F. et al. Carbon Nanotube Transistors as Gas Sensors: Response Differentiation Using Polymer Gate Dielectrics. ACS Appl. Polym. Mater.
1 3269-3278 (2019)

[4] Lapointe, F. et al. Polymer Encapsulants for Threshold Voltage Control in Carbon Nanotube Transistors. ACS Appl. Mater. Interfaces
11 36027-36034 (2019)
(Invited) Shedding Light on the Growth Kinetics of Individual Carbon Nanotubes Using in Situ Optical Microscopy
Authors: Pimonov Vladimir , Tran Huy-Nam , Monniello Léonard , Michel Thierry , Vialla Rémy , Prévot Guillaume , Tahir Saïd , Jourdain Vincent
Published: July 2021

Growing single-walled carbon nanotubes (SWCNTs) with high selectivity for specific chiralities is a matter of intense research activity with important implications in the fields of electronic and optoelectronic devices. However, a fundamental understanding of the dependence of each growth step (nucleation, elongation, chirality change, termination) on the nanotube chirality is still missing to allow a rational design of highly selective growth methods. In this presentation, we will show how a newly developed method of optical imaging [1,2] allows the in situ observation of individual SWCNTs in real conditions of growth (i.e. at atmospheric pressure on a substrate) and with time resolution down to a few tens of ms. Based on these observations, we will report on the dependence of the growth kinetics (rate, lifetime) of individual SWCNTs on the growth conditions (temperature, carbon supply) and on the SWCNT chirality (diameter, chiral angle). We will also report a comprehensive method to model the optical spectra of individual SWCNTs on substrate obtained with the same polarization-based setup [2]. Importantly, this model includes the influence of the commonly used anti-reflection substrates (e.g. SiO2/Si), and of coherent and non-coherent depolarization by the optics. This model allows extracting both the real and imaginary parts of the nanotube susceptibility and improving the chirality assignment when coupled with complementary techniques such as Raman spectroscopy.

[1] Liu et al, Nature Nanotechnology (2013), 8, 917.

[2] Comprehensive model of the optical spectra of carbon nanotubes on a substrate by polarized microscopy, L. Monniello, H.-N. Tran, R. Vialla, G. Prévot, S. Tahir, T. Michel, V. Jourdain, Physical Review B (2019), 99, 115431.

Figure 1
(Invited) Towards Industrialization of Boron Nitride Nanotubes: Purification and Quality Assessment
Authors: Kingston Christopher
Published: July 2021

Boron nitride nanotubes (BNNTs) exhibit as impressive a range of properties as their isoelectronic carbon nanotube (CNT) cousins, and include unique features like substantially higher thermal stability, a wide band gap, transparency through the visible region and better biocompatibility.1 Historically, very low production volumes had prevented the science and technology of BNNTs from evolving at even a fraction of the pace of CNTs. We helped to addressed this limitation through the development of an industrially scalable plasma process for the manufacturing of BNNT,2,3 which can synthesize kilogram quantities of highly crystalline, small diameter few-walled BNNTs daily. The next hurdles on the path to fully exploiting the properties of BNNTs in applications are precise purity and quality control and assessment. In this talk I will present our recent advances in these areas. We have developed a large-scale purification process that raises the purity of as-produced BNNT above 90% in a single-step.4 The process relies on the use of pure or diluted chorine gas at elevated temperature. We have evaluated the process at various temperatures, up to 1050 °C, and have used a range of imaging and spectroscopic assessments to qualify the results. Quality (purity + defect density) assessment of bulk nanotube samples has been a pervasive challenge in the field of carbon nanotubes for more than 30 years. To help address this challenge for BNNTs, I will show how the specific and strong interfacial interaction between regiorandom poly(3-hexylthiophene) (rra-P3HT) and BNNTs leads to the emergence of structured absorption and emission bands that can be used to quantify the relative quality of BNNT samples.5-7

Augustine, T. Cheung, V. Gies, J. Boughton, M. Chen, Z. J. Jakubek, S. Walker, Y. Martinez-Rubi, B. Simard and S. Zou, Nanoscale Advances, 1, 1914-1923 (2019).

S. Kim, C. T. Kingston, A. Hrdina, M. B. Jakubinek, J. Guan, M. Plunkett and B. Simard, ACS Nano, 8, 6211-6220 (2014).

S. Kim, M. Couillard, H. Shin, M. Plunkett, D. Ruth, C. T. Kingston and B. Simard, ACS Nano,12, 884-893 (2018).

Cho, S. Walker, M. Plunkett, D. Ruth, R. Iannitto, Y. Martinez Rubi, K. S. Kim, C. M. Homenick, A. Brinkmann, M. Couillard, S. Dénommée, J. Guan, M. B. Jakubinek, Z. J. Jakubek, C. T. Kingston, and B. Simard, Chem. Mater., 32, 3911−3921 (2020).

Martinez-Rubi, Z. J. Jakubek, M. B. Jakubinek, K. S. Kim, F. Cheng, M. Couillard, C. Kingston and B. Simard, J. Phys. Chem., C, 119, 26605 (2015).

Martinez Rubi, Z. Jakubek, M. Chen, S. Zou, and B. Simard, ACS Applied Nano, 2, 2054-2063 (2019).

Z. J. Jakubek, M. Chen, Y. Martinez Rubi, B. Simard, and S. Zou, J. Phys. Chem. Lett., 11, 4179−4185 (2020).

Figure 1
Constant Phase Element Analysis of Ordered Carbon Electrodes Via Electrochemical Impedance Spectroscopy and Cyclic Voltammetry
Authors: Scisco Gibson Paul , Orazem Mark E. , Jones Kevin S. , Ziegler Kirk J.
Published: July 2021

Electrochemical double layer capacitors exhibit constant phase element (CPE) behavior in both their cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) response. Recently, Allagui et. al [Sci. Rep., vol. 7, September, p. 46828, 2017.] presented equations for finding CPE parameters from CV measurements. EIS data for porous electrodes exhibiting CPE behavior can be fit using the de Levie model. In this work, several ordered carbon electrodes of varying pore length were prepared by chemical vapor deposition (CVD) of carbon nanotubes (CNTs) within anodized aluminum oxide (AAO) templates. These electrodes were used to create supercapacitors with neat EMIM-BF4 ionic liquid electrolyte. CPE parameters Q and α were found for each device from both CV and EIS, and they are in good agreement between the two methods. However, the values of resistance, another fitting parameter in both models, vary drastically. The physical origin of these resistances is discussed. Additionally, the capacitance of the devices was calculated from both methods, using the Brug formula in the case of EIS. These capacitances disagree greatly, except for the thickest AAO templates (the longest pores). The devices in agreement also showed the lowest resistance values from CV. It is not apparent whether the agreement in capacitance is related to the pore dimensions or the extracted resistance values. {DISTRIBUTION STATEMENT A. Approved for public release; Distribution is unlimited 412TW-PA-20496]
(Invited) Water-soluble fullerenes (C60 and C70) with photoinduced ROS generation
Authors: Yamakoshi Yoko , Liosi Korinne , Solà Miquel , Mougel Victor
Published: July 2021

Three types of water-soluble fullerene derivatives were prepared from their Prato adducts by conjugation with PEG. One Prato derivative of C60 ([6,6]-addition) and two Prato derivatives of C70 (ab-[6,6] and cc-[6,6]-addition) with carboxylic acids were synthesized, purified and subjected to the amide-forming conjugation with amine-PEG to form corresponding C60- or C70-PEG conjugates (Figure (a)). All the conjugates showed photoinduced DNA cleavage by reactive oxygen species (ROS) formed by type II energy transfer pathway or type I electron transfer pathway (Figure (d)). The responsible ROS were measured by ESR spin-trapping methods using 4-oxo-TEMP (for singlet oxygen) and DEPMPO (for superoxide radical anion), and were shown to be significantly different in three materials (Figure (b)-(c)). To understand the mechanism of these differences, redox potentials of the precursor molecules were analyzed by cyclic voltammetry in order to determine the difference in electron transfer rates. The lifetimes of the triplet excited states were measured by laser-flash photolysis. Finally, calculations were performed to obtain rate constants for each step in the type I and II pathways. The data will be explained in detail.

Figure 1
(Invited) Endohedral Fullerene Hybrids: From Gold Nanoparticles to Graphene
Authors: Porfyrakis Kyriakos
Published: July 2021

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

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

Endohedral metallofullerenes continue to fascinate us with their versatility and attractive electronic properties.
(Invited) Novel Pyridine-functionalized Fullerene Derivatives toward the Efficient and Hysteresis-free Perovskite Solar Cells
Authors: Chen Muqing , Li Bairu , Jia Lingbo , Yang Shangfeng
Published: July 2021

Fullerene derivatives with strong electron-accepting abilities have been extensively used as electron transport layers (ETLs) of inverted (p–i–n) planar heterojunction perovskite solar cells (iPSCs); however the effect of the alkyl chains and a specific heteroatom site within the fullerene derivative on its electron transport properties has scarcely been studied. Herein,by employing pyridine carboxaldehydes bearing nitrogen sites within the pyridine moiety as a reactant, a series of novel pyridine-functionalized fullerene derivatives with variable nitrogen sites and alkyl chains length were synthesized facilely via a one-step 1, 3-dipolar cycloaddition reaction, and their molecular structures as well as molecular packing were unambiguously determined by X-ray single crystal diffraction. Despite that fullerene derivatives exhibit negligible difference in the molecular energy level and optical absorption, however, their electron transport properties are found to sensitively depend on the length of alkyl chains and nitrogen sites within the pyridine moiety. The C60-3-Py-based device shows the highest power conversion efficiency (PCE) of 17.57%. The discrepancy of the electron transport properties of fullerene derivatives is primarily due to the difference in the coordination interaction between the pyridine moiety and the Pb2+ ion of the MAPbI3 perovskite layer interaction between the pyridine moiety and the Pb2+ ion of the MAPbI3 perovskite layer.
(Invited) New Developments in Magnetic Properties of Endohedral Metallofullerenes
Authors: Popov Alexey A.
Published: July 2021

Encapsulation of magnetic species within robust molecular containers is a natural route towards stable and processable single molecule magnets (SMMs). Air-stability, thermal stability, ability to form thin molecular layers on different substrates are among the critical issues to be addressed. Chemical and thermal stability of fullerenes makes them perfectly suitable for this goal. Fullerenes can encapsulate up to four metal atoms within their inner space, and a number of lanthanide EMFs was found to show SMM behavior.1-5 Besides, EMF-SMMs can form monolayers by sublimation6 or by self-assembly from solution,7 and such monolayers retain their SMM properties on metallic substrates. In this contribution we will highlight recent developments in the field of lanthanide-EMFs with peculiar magnetic properties.

Spree, L.; Popov, A. A., Recent advances in single molecule magnetism of dysprosium-metallofullerenes. Dalton Trans.
2019,
48 (9), 2861-2871.

Liu, F.; Spree, L.; Krylov, D. S.; Velkos, G.; Avdoshenko, S. M.; Popov, A. A., Single-Electron Lanthanide-Lanthanide Bonds Inside Fullerenes toward Robust Redox-Active Molecular Magnets. Acc. Chem. Res.
2019,
52 (10), 2981-2993.

Liu, F.; Velkos, G.; Krylov, D. S.; Spree, L.; Zalibera, M.; Ray, R.; Samoylova, N. A.; Chen, C.-H.; Rosenkranz, M.; Schiemenz, S.; Ziegs, F.; Nenkov, K.; Kostanyan, A.; Greber, T.; Wolter, A. U. B.; Richter, M.; Büchner, B.; Avdoshenko, S. M.; Popov, A. A., Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal-metal bond. Nat. Commun.
2019,
10, 571.

Velkos, G.; Yang, W.; Yao, Y.-R.; Sudarkova, S. M.; Liu, X.; Büchner, B.; Avdoshenko, S. M.; Chen, N.; Popov, A. A., Shape-adaptive single-molecule magnetism and hysteresis up to 14 K in oxide clusterfullerenes Dy2O@C72 and Dy2O@C74 with fused pentagon pairs and flexible Dy–(μ2-O)–Dy angle. Chem. Sci.
2020,
11, 4766-4772.

Yang, W.; Velkos, G.; Liu, F.; Sudarkova, S. M.; Wang, Y.; Zhuang, J.; Zhang, H.; Li, X.; Zhang, X.; Büchner, B.; Avdoshenko, S. M.; Popov, A. A.; Chen, N., Single Molecule Magnetism with Strong Magnetic Anisotropy and Enhanced Dy∙∙∙Dy Coupling in Three Isomers of Dy-Oxide Clusterfullerene Dy2O@C82. Adv. Sci.
2019,
6 (20), 1901352.

Krylov, D. S.; Schimmel, S.; Dubrovin, V.; Liu, F.; Nguyen, T. T. N.; Spree, L.; Chen, C.-H.; Velkos, G.; Bulbucan, C.; Westerström, R.; Studniarek, M.; Dreiser, J.; Hess, C.; Büchner, B.; Avdoshenko, S. M.; Popov, A. A., Substrate-independent magnetic bistability in monolayers of single molecule magnet Dy2ScN@C80 on metals and insulator. Angew. Chem. Int. Ed.
2020,
59 (14), 5756-5764.

Chen, C.-H.; Spree, L.; Koutsouflakis, E.; Krylov, D. S.; Liu, F.; Brandenburg, A.; Velkos, G.; Schimmel, S.; Avdoshenko, S. M.; Fedorov, A.; Weschke, E.; Choueikani, F.; Ohresser, P.; Dreiser, J.; Büchner, B.; Popov, A. A., Magnetic hysteresis at 10 K in single molecule magnet self-assembled on gold. Adv. Sci.
2020, 202000777.
(Invited) Fullertubes: Isolation of Isomerically Purified and Pristine Samples
Authors: Koenig Ryan M , Franklin Hannah , Seeler Tiffany , Sedlaczek Angelina , Noble Cora , Ashcroft Chloe Annemarie , Stevenson Steven
Published: July 2021

Fullertube structures do indeed possess an elegant molecular architecture. Fullertubes also represent a new type of carbon allotrope that merges structural subunits of part fullerene and part nanotube. With fullerenyl endcaps and a nanotubyl belt region resembling a single layer of rolled graphene, fullertubes are highly anticipated to exhibit unique properties for use in multiple application areas (e.g., electronics, pharmaceuticals, etc). The first priority, however, is developing an approach to isolate large amounts of pristine, unfunctionalized samples of isomeric purity. This need for sample availability must be addressed before fundamental science and industrial research and development (R&D) can be effectively pursued. In this presentation, I will discuss separation strategies for purifying macroscopic quantities of isomerically purified fullertubes. We are making progress in expanding the fullertube length (i.e., increasing the aspect ratio) while maintaining a constant tubular diameter comparable to the diameter of C60. We will also discuss our latest results for chemically purifying new structural isomers of longer fullertubes......e.g., beyond C90-D5h(1) and C100-D5d(1) toward C120 isomers.
Theoretical Study of the Diels-Alder Dimerization of C30H10
Authors: Mendez Francisco , Richaud Arlette , López María J. , Mojica Martha , Alonso Julio A.
Published: July 2021

The development of new techniques for the synthesis of fullerenes is needed to reduce the production cost and the availability of those materials.[1-10] In this work we study, using the density functional theory (DFT) and the nudge elastic band (NEB) method, a route to obtain the C60 from two pentacyclopentacorannulene C30H10 fragments. The accessible precursor of C60, is a C60H20 molecule, which is a C60 fullerene wrapped by a double belt of twenty H atoms forming C-H bonds around the equatorial plane of C60 (the poles are occupied by the central pentagons of the two fragments). The proposed C60H20 molecule has a synthetic analogue reported by Boltalina et al.[11] Our theoretical justification for the dimerization of the C30H10 fragments supports the achievable synthetic route for the C60.[12]

References.

1.- Diederich, Y. Rubin, Angew. Chem. Int. Ed., 1992, 31, 1101.

2.- T. Scott, Angew. Chem. Int. Ed., 2004, 43, 4994.

3.- M. Tsefrikas, L. T. Scott, Chem. Rev., 2006, 106, 4868.

4.- Mojica, F., J. A. Alonso, J. Phys. Org. Chem., 2013, 26, 526.

5.- T. Scott, M. M. Boorum, B. J. McMahon, S. Hagen, J. Mack, J. Blank, H. Wegner, A. de Meijere, Science, 2002, 295, 1500.

6.- Otero, G. Biddau, C. Sánchez-Sánchez, R. Caillard, M. F. López, C. Rogero, F. J. Palomares, N. Cabello, M. A. Basanta, J. Ortega, J. Méndez, A. M. Echavarren, R. Pérez, B. Gómez-Lor, J. A. Martín-Gago, Nature, 2008, 454, 865.

7.- B. M. Ansems, L. T. Scott, J. Am. Chem. Soc., 2000, 122, 2719.

8.- H. F. Bunz, Y. Rubin, Y. Tobe, Chem. Soc. Rev., 1999, 28,107.

9.- L. Chapman, M. R. Engel, J. P. Springer, J. C. Clardy, J. Am. Chem. Soc., 1971, 93, 6696

10.- T. Scott, M. A. Petrukhina, Preface in Fragments of Fullerenes and Carbon Nanotubes: Designed Synthesis, Unusual Reactions and Coordination Chemistry; L. T. Scott, M. A. Petrukhina, Eds.; John Wiley & Sons Inc., Hoboken, New Jersey, 2012, pp. vii–x.

11.- V. Boltalina, V. Yu. Markov, P. A. Troshin, A. D. Darwish, J. M. Street, and R. Taylor, Angew. Chem. Int. Ed., 2001, 40, 787.

12.- A. Richaud, M. J. López, M. Mojica, J. A. Alonso, F. Méndez. RSC Adv., 2020, 10, 3689-3693. https://doi.org/10.1039/C9RA09804F.
Electrochemical Synthesis and Characterization of Ppy/Ni Composite Nanowires As Supercapacitor Electrode
Authors: Arya Sandeep , Verma Sonali , Mahajan Prerna , Khosla Ajit
Published: July 2021

The academic research and industrial manufacturing of supercapacitors have been rapidly going on since the first patent reported in 1957 and the applications of supercapacitor have been expanded in variety of fields [1]. Supercapacitors, have gained attention as power source for applications demanding quick energy supply. The increasing demand of wearable as well as portable electric devices requires systems with flexibility and wearable compatibility without sacrificing the performance. This requires the electrode to be durable under mechanical deformations, which grants the polymers with intrinsic advantages. Thus, polymers, either as substrate or active material have gained great attention. As for polymer based supercapacitor materials, some conducting polymers such as polypyrrole [2], polythiophene [3, 4] etc, are highly investigated. Moreover, electrode obtained from composites of these polymers with various materials, like CNTs [5], metal oxide [6] and other materials (such as Ni, Zn) modified the electrical conductivity as well as capacitance of the material. Further, the morphology of the electrode plays imperative role. Nanostructured electrodes like nanowires based electrodes [7] with enlarged surface area are reported for enhancing the performance. Here, PPy/Ni composite nanowires were synthesized electrochemically via using polycarbonate membrane as shown in Fig.1 and then investigated as supercapacitor electrode. Firstly, for the deposition of nanowires, an electrolyte composed of NaNO3, HNO3, pyrrole monomer and NiSO4.6H2O was prepared. The deposition was carried out at -0.65V for 1000s at room temperature. The obtained nanowires were first dried and then dichloromethane was used for dissolving the membrane. Further, SEM, XRD, CV, GCD etc characterizations were done to scrutinize the morphology, composition and electrochemical performance of the synthesized material.

Keywords: Nanowires, supercapacitor, polymers, electrochemical energy storage.

References:

[1] I. Shown, A. Ganguly, L.C. Chen, K.H. Chen, Energy Sci. Eng. 3 (2015) 2.

[2] M. Zhu, Y. Huang, Y. Huang, H. Li, Z. Wang, Z. Pei, Q. Xue, H. Geng, C. Zhi, Adv. Mater. 29 (2017) 1605137.

[3] S. Gnanakan, N. Murugananthem, A. Subramania, Polym. Adv. Technol. 22 (2011) 788.

[4] A. Laforgue, P. Simon, C. Sarrazin, J.-F. Fauvarque, J. Power Sources 80 (1999) 142.

[5] D. Antiohos, G. Folkes, P. Sherrell, S. Ashraf, G.G. Wallace, P. Aitchison, A.T. Harris, J. Chen, A.I. Minett, J. Mater. Chem. 21 (2011) 15987.

[6] Z. Yu, C. Li, D. Abbitt, J. Thomas, J. Mater. Chem. A 2 (2014) 10923.

[7] K. Wang, J. Huang, Z. Wei, J. Phys. Chem. C 114 (2010) 8062.

Figure 1
Understanding and Mitigating Mechanical Degradation in Li-S Batteries: Lithium Sulfide Particle Compressions and Additive Manufacturing of Lithium Sulfide-Carbon Composites
Authors: Saccone Max A. , Greer Julia R.
Published: July 2021

Li-S batteries are poised to outcompete Li-ion batteries in key sectors such as transportation and grid storage. Improving energy density and mitigating degradation in Li-S batteries could unlock immense impacts such as gigaton-order annual CO2 reduction. Well-designed electrolyte systems can mitigate the degradation mechanisms of electrolyte reactivity, polysulfide shuttling, and lithium dendrite growth. The most significant remaining degradation mechanism is mechanical failure and detachment of insulating Li2S from the conductive matrix in the cathode, causing irreversible capacity fade.

We measure the yet unknown material properties and deformation mechanisms of Li2S powders via in situ SEM mechanical experiments. Understanding these basic properties is a first step towards rational design of high energy density, long-cycling, and mechanically robust sulfur cathodes.

We also describe the development of a novel technique for additive manufacturing of Li2S composites to fabricate such rationally designed cathodes and demonstrate a 3D printed Li2S cathode with feature sizes 3x smaller than previously attainable via additive manufacturing methods for Li-S cathode materials . This work represents the most fundamental mechanical study of Li-S batteries to date and will pioneer a new design strategy for 3D-structured Li-S cathodes.

Figure 1
Achieving a Wider Window Potential in Aqueous Supercapacitors By an Artificial Interface
Authors: Olarte Marco , Menu Marie-Joelle , Simon Patrice , Gressier Marie , Taberna Pierre-Louis
Published: July 2021

Devices with high power density which can store energy with a fast rate charge-discharge, the supercapacitors are suitable in different applications where high power is needed. That because it stores charge by fast surface process, i.e. ion adsorption of an electrolyte into the electrochemical double layer at the electrode/electrolyte interface. Nevertheless, in order to extend their autonomy beyond few seconds, its energy density has to be increased. For this aspect, in recent years many teams around the world have set up different strategies as a combination of a carbon electrode with a faradic type electrode (battery electrode or pseudocapacitive) or through the development of new active materials, including the development of new electrolytes. The main significant achievements are more on the active material side. Even though some works have been successful in increasing the cell voltage, thanks to the use of new ionic liquids, they are still room for improvement regarding the increase of the cell voltage.

To address this point, we have targeted to obtain an aqueous-based high voltage supercapacitor. Our strategy consists in using an Artificial Interface (ai) by depositing an ionogel onto a carbon electrode, the ai is composed of an inorganic matrix and an ionic liquid, in order to form a passivation layer at the electrode/electrolyte interface; a better electrochemical and thermal stability of this interface is thus expected. The ai has got to be electronically insulating but ionic conductive, limiting or even preventing the transfer of electronic charge to the electrode / electrolyte interface.1,2

First things first, the study have been carried out on glassy carbon where AI has been deposited and the linear sweep voltammetry tests in an aqueous electrolyte based on EMI+ HSO4
- and H2SO4 indicate, in both cases, an increase in the potential window: the onset potential for water reduction is shifted toward more cathodic potentials. Going further, tests in the presence of a redox probe (Ferri-Ferro potassium cyanide) demonstrate the absence of electron transfer at the electrode/electrolyte interface. On the other hand, it appears, thanks to measurements carried out by electrochemical impedance spectroscopy, since within the ai is embedded EMI+ TFSI-, better ionic conduction is obtained when the electrolyte is made of EMI+ HSO4
-, sharing the same cation than the one of ai. As we will be showing, a better transference number is achieved for EMI+ cations than for H+.

Figure 1
(Invited) Unidirectional Epitaxy of TMD Monolayers on Sapphire
Authors: Zhu Haoyue , Choudhury Tanushree , Huet Benjamin , Bansal Anushka , McKnight Thomas V. , Trainor Nicholas , Redwing Joan
Published: July 2021

Wafer-scale synthesis of semiconducting transition metal dichalcogenide (TMDs) monolayers is of significant interest for device applications to circumvent size limitations associated with the use of exfoliated flakes. Promising results have been demonstrated for epitaxial films deposited by vapor phase techniques such as CVD and MOCVD. However, the three-fold symmetry of TMDs such as MoS2 and WSe2, results in two energetically equivalent domain alignments, often referred to as 0o and 60o domains, when grown on substrates such as c-plane sapphire and graphene. The oppositely oriented domains give rise to inversion domain boundaries (IDBs) upon coalescence which exhibit a metallic character and are generally undesirable. In this study, we demonstrate the epitaxial growth of unidirectional TMD monolayers on 2” diameter c-plane sapphire substrates with a significantly reduced density of inversion domains. Steps on the sapphire surface are shown to break the surface symmetry giving rise to a preferred domain orientation.

Metalorganic chemical vapor deposition (MOCVD) was used for the epitaxial growth of WSe2 and WS2 monolayers on c-plane sapphire in a cold-wall horizontal quartz-tube reactor. The as-received sapphire substrates, which are miscut ~0.2o toward <112 ̅0>, consist of steps with sub-1 nm step height separated by 50-70 nm wide terraces. A three-step nucleation-ripening-lateral growth process, carried out at temperatures ranging from 850oC to 1000oC, was used to achieve epitaxial films using W(CO)6, H2Se and H2S as precursors in a H2 carrier gas. Nucleation was observed to occur at the terrace edge and the growing domains align epitaxially with the underlying (0001) sapphire lattice. As a result of the nucleation process, the domains grow with a zig-zag edge facing the terrace edge which imparts a preferential direction to the domains. The percentage of domains with a preferred direction ranges from 75%-86% depending on MOCVD growth conditions. Continued lateral growth for times ranging from 10-30 minutes results in fully coalesced TMD monolayers that are epitaxially oriented on the sapphire, as assessed by in-plane x-ray diffraction, with a reduced density of inversion domain boundaries. The results demonstrate the important role of surface structure in nucleation and epitaxial growth of TMD monolayers.