bluuebunny/crossref_metadata_2025_split huggingface dataset:
(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) 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.
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.
Modulating Conductivity in Paintable Films from Solvent-Exfoliated Inks of 2D MoS2 and Bi2te3
Authors: O'Dwyer Colm 
Published: July 2021

Research on two-dimensional (2D) layered materials such as graphene,(1) transition metal dichalcogenides (TMDs), carbide and carbonitride relatives called MXenes,(2) has progressed beyond discovery to a wide range of uses. (3,4) In all applications where electronic transport is important, 2D materials, their assemblies, deposition, homo- and hetero-interfaces, layered networks, and composite with polymers, strongly influence the nature of conductivity and consequently the type of electrode or device. Photonics and optoelectronic investigations (5,6) are also sensitive to engineering of 2D materials and their composites, while energy storage and thermoelectric applications using 2D materials must take into account ion accessibility and thermal conductivity, respectively, in addition to electrical conductivity.
Exfoliation of parent bulk crystals to give 2D and few-layer MoS2 (7,8) and Bi2Te3 dispersions in solvents may also be promising functional inks. Whether thixotropic or dilatant, inks from particle dispersions are the basis of many printing and coating technologies.(9,10) Incorporating new functionality using 2D materials with standard processing has potential for interesting applications.
Here, we developed inks using high concentrations of exfoliated MoS2 and Bi2Te3 2D layer suspensions that can be painted as uniform films on substrates (11,12). Conductivity is controlled at material-level by high quality exfoliated 2D sheets, and in the case of Bi2Te3 we examined the influence of a PEG400 binder additive to the ink. We discuss the nature of in-plane electronic conductivity in painted films from both of these 2D material inks, and summarize measurements that show how conductivity is altered by the painting direction and aspect ratio of coated films.

References

(1) A. K. Geim, Science, 324, 1530 (2009).
(2) B. Anasori, M. R. Lukatskaya, and Y. Gogotsi, Nat. Rev. Mater., 2, 16098
(2017).
(3) V. Nicolosi, M. Chhowalla, M. G. Kanatzidis, M. S. Strano, and J. N. Coleman,

Science, 340, 1226419 (2013).
(4) C. O’Dwyer, L. Walsh, F. Gity, S. Bhattacharjee, and P. K. Hurley, Electrochem.

Soc. Interface, 27, 53 (2018).
(5) L. Britnell et al., Science, 340, 1311 (2013).
(6) F. Xia, H. Wang, D. Xiao, M. Dubey, and A. Ramasubramaniam, Nat. Photon., 8,
899 (2014).
(7) E. Carroll, D. Buckley, D. Mc Nulty, and C. O’Dwyer, ECS J. Solid State Sci. Technol.
9 093015 (2020).
(8) V. Sánchez, E. Benavente, V. Lavayen, C. O’Dwyer, C. M. S. Torres, G. González, and M. A. S. Ana, Appl. Surf. Sci. 252, 7941 (2006).
(9) E. B. Secor, B. Y. Ahn, T. Z. Gao, J. A. Lewis, and M. C. Hersam, Adv. Mater., 27,
6683 (2015).
(10) D. McManus et al., Nat. Nanotechnol., 12, 343 (2017).
(11) E. Carroll, D. Buckley, V. Mogili, D. McNulty, M. S. Moreno, C. Glynn, G. Collins, J. D. Holmes, K. M. Razeeb, C. O’Dwyer, Chem. Mater.
29, 7390-7400 (2017).
(12) E. Carroll, D. P. Buckley, G. Collins, J. D. Holmes, K. M. Razeeb, and C. O'Dwyer, ECS Trans.
64, 1 (2015).
Exfoliated Silicate Nanosheets As Novel Near-Infrared Fluorophores for (Bio)Photonics
Authors: Selvaggio Gabriele , Weitzel Milan , Oleksiievets Nazar , Oswald Tabea Anne , Nissler Robert , Mey Ingo , Karius Volker , Enderlein Jörg , Tsukanov Roman , Kruss Sebastian 
Published: July 2021

The near-infrared (NIR) region of the electromagnetic spectrum presents optimal characteristics for imaging of complex (biological) samples: this is mainly due to reduced light scattering, absorption, phototoxicity and autofluorescence. However, despite their clear potential over commonly employed visible fluorophores, only few NIR fluorescent materials are known so far, and even less are suitable for biomedical applications. For this reason, it is of great interest to search for novel materials that can enrich the so far poor library of NIR fluorophores.
We exfoliated a class of layered silicates: Egyptian Blue (CaCuSi4O10, EB), Han Blue (BaCuSi4O10, HB) and Han Purple (BaCuSi2O6, HP). These pigments fluoresce in the NIR (λ
emi ≈ 920-950 nm) with a long excited state lifetime (τ ≈ 10-100 µs). By milling, tip sonication and several centrifugation steps, small and monodisperse 2D nanosheets (NS) could be exfoliated. Most interestingly, the intense NIR fluorescence emission of the bulk counterparts is retained. In comparison to state-of-the-art fluorophores, EB-NS show no bleaching while displaying outstanding fluorescence intensity. Such qualities of EB-NS enabled us to inject them into systems of biological relevance such as developing Drosophila embryos, and perform in vivo single-particle tracking and microrheology measurements. Furthermore, it is possible to successfully detect EB-NS in plants. [1] In general, all the above mentioned three silicate NS prove bright enough to be imaged through several cm of tissue phantoms, which demonstrates the potential for (bio)photonics. Finally, we used the microsecond fluorescence lifetimes of EB-NS, HB-NS and HP-NS for micro- and macroscopic fluorescence lifetime imaging (FLIM). The results show that lifetime engineering of these silicate nanostructures is possible and can be used for lifetime-encoded imaging. [2]
In summary, we present a new exfoliation route that yields NIR fluorescent nanosheets of high promise as novel NIR fluorophores for bioimaging and photonics.
Literature:
[1] G. Selvaggio et al., Nat. Commun. 2020, 11, 1495.
[2] G. Selvaggio et al., in preparation.
(Invited) Nanopatterned Perovskite Films for High Performance Photo-Electronics
Authors: Park Cheolmin , Jeong Beomjin , Han Hyowon 
Published: July 2021

Ordered nanostructured crystals of thin perovskites films are of great interest to researchers because of the dimensional-dependence of their photoelectronic properties for developing the perovskites with novel properties [1]. In this presentation, both top-down and bottom-up approaches for fabricating nanostructured perovskite films are demonstrated. First, a variety of micro/nanopatterns of a perovskite film are fabricated by either micro/nano-imprinting or transfer-printing a thin spin-coated precursor film in soft-gel state with a topographically pre-patterned polymer mold, followed by thermal treatment for complete conversion of the precursor film to a perovskite one [2]. Second, we also demonstrate a simple and robust route, involving the controlled crystallization of the perovskites templated with a self-assembled block copolymer (BCP), for fabricating nanopatterned perovskite films with various shapes and nanodomain sizes [3]. When the precursor ion solution of a perovskite and poly(styrene)-block-poly(2-vinylpyridine) (PS-b-P2VP) was spin-coated on the substrate, a nanostructured BCP was developed by microphase separation. Spontaneous crystallization of the precursor ions preferentially coordinated with the P2VP domains yielded ordered nanocrystals with various nanostructures. The nanopatterned perovskites showed significantly enhanced photoluminescence (PL) with high resistance to both humidity and heat due to geometrically confining crystals in and passivation with the P2VP chains. Finally, we demonstrate that the perovskite crystals are more precisely controlled by the combination of the BCP self-assembly with top-down nanoimprinting.
References:
[1] B. Jeong, C. Park et al. Adv. Mater. 32, 2000597 (2020)
[2] B. Jeong, C. Park et al. ACS NANO 14, 2, 1645 (2020)
[3] H. Han, C. Park et al. Adv. Funct. Mater. 29, 1808193 (2019)