bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Vertically Aligned Carbon Nanotube Arrays from Premade Bimetallic Aluminum-Iron Oxide Nanoparticles Monolayer
Authors: Hoque Md Abdul , Nawarathne Chaminda P , Alvarez Noe T
Published: September 2023

Abstract: Carbon Nanotubes (CNTs) are excellent materials because of their unique physical and chemical properties. Though catalyst nanoparticles preparation from thin film catalysts are common but premade catalysts nanoparticles in liquid phase has control over the size and composition which control the diameter and length of CNTs. Here, we report the synthesis of vertically aligned (VA) CNTs on metal oxide substrates including silicon oxide and stainless-steel using aluminum-iron oxides Al2O3-Fe2O3 nanoparticles monolayer. Oleic acid functionalized Al2O3-Fe2O3 nanoparticles were assembled onto metal oxide substrate as a monolayer using 11-phousnoundecanoic acid (PNDA) linker molecule where phosphonate group bind to the substrate and terminal carboxylic group of PNDA bind to the surface of bimetallic oxide catalysts. Homogenous catalyst nanoparticles distribution from monolayer assembly can reduce the aggregation of catalyst particles which can increases the catalyst lifetime during CNTs growth. Synthesis of VA-CNTs require Al2O3 catalyst support on substrate surface, but our bimetallic Al2O3-Fe2O3 nanoparticles contain both catalyst support (Al2O3) and catalyst (Fe) in the same particle. The successful VA-CNTs synthesis were achieved by chemical vapor deposition (CVD) process using acetylene as carbon precursor in atmospheric pressure. We envision that our catalyst preparation for VA-CNTs growth can be a cost-efficient method for large scale synthesis of CNTs. Further, the VA-CNTs growth on conductive stainless-steel substrate can facilitate the electrochemical application of this hybrid materials for biomolecule sensing and heavy metals detection.
(Invited) Kinetics of SWCNT Coating Displacement By ssDNA Depends on SWCNT Structure
Authors: Lei Kunhua , Bachilo Sergei M. , Weisman R. Bruce
Published: September 2023

Non-covalent hybrids formed by suspending single-wall carbon nanotubes (SWCNTs) in single-stranded DNA (ssDNA) present novel phenomena and suggest potential applications in biomedicine and nanotube sorting. Although the structures of these hybrids have been simulated using molecular dynamics calculations, much more experimental research is needed to understand their properties. In this study, selective interactions between SWCNTs and ssDNA are probed by measuring the kinetics by which ssDNA displaces SDS (sodium dodecyl sulfate) coatings on the nanotube surfaces. We used samples initially suspended in a low concentration of SDS to allow the coating displacement to occur and to suppress formation of free SDS micelles. The displacement process was monitored by time-dependent measurements of SWCNT fluorescence intensities and wavelengths. Our experiments showed very smooth decreases in fluorescence intensity and red-shifts in fluorescence wavelengths during the displacement process. Through a series of measurements, we found that ssDNA sequences with repeated guanine (G) and thymine (T) bases showed systematic patterns in the coating displacement kinetics. One result is that SDS displacement depends strongly on oligo length, with (GT)3 showing an initial rate constant 500 times greater than that of (GT)20. For shorter oligos in the (GT)
n
series, we observe an inverse dependence of initial rate constant on SWCNT diameter, with SDS displacement from (6,5) more than twice as fast as from (8,7). However, this diameter dependence is not present for (GT)
n
oligos with n greater than 6. We also find a distinct and systematic dependence of initial rate constant on nanotube chiral angle for (GT)5 and (GT)6. This effect gives a factor of ~3 difference between (9,1) and (6,5) despite their identical diameters. We empirically find these initial rate constants to vary as (SWCNT diameter)-4(cos 3θ)-y with y = -1/2 for (GT)5 and -1 for (GT)6. In addition, the full displacement kinetic traces are well fitted by double exponential kinetics, with rate constants and amplitudes dependent on SWCNT diameter. A two-step kinetic model for the displacement process will be presented to account for these findings.
Advanced Data Analytics and Organic Color Centers for Diagnostic Applications
Authors: Kim Mijin , Gwynne Declan , Randall Ewelina , Goerzen Dana , Keblish Erin Elizabeth , Heller Daniel A.
Published: September 2023

Biofluids, most notably serum, contain many molecules that together may help to define the physiological state of a person. A grand challenge is to use serum to identify a clinical state with a high degree of certainty. Rather than attempting to accomplish biomarker development on a one-to-one recognition basis, it may be more effective to determine a whole clinical state via perception-based platforms due to recent achievements in sensor technologies and computational algorithms. In this talk, we present the development of carbon nanotube-based nanosensor arrays wherein the optical responses of the nanotubes were used to train machine learning models. We introduce the optical and chemical diversity of nanosensor array using molecular masking effects of DNA-wrapping and covalent functionalization of fluorescent quantum defects on nanotube surface. Machine learning can be employed to process the complex spectral responses of nanosensors and recognize spectroscopic fingerprints of certain clinical states from serum. We will discuss how these methods can complement and improve conventional diagnostic assays.
DNA-Surfactant Exchange and Quantifying Interactions of Pure (n,m) Single-Enantiomer SWCNTs Towards Biohybrid Self-Assembly
Authors: Barnes Benjamin , Fagan Jeffrey , Zheng Ming
Published: September 2023

Self-assembled biohybrid nanostructures made from single-wall carbon nanotubes (SWCNTs) and DNA are a promising model system for studying fundamental photo physics phenomena, and have significant potential as building blocks for applications such as biosensing and photovoltaics devices. Precise control of SWCNT bandgap and length in these biohybrid assemblies is highly desirable, but scalable production of such samples often benefits from processing in aqueous polymer and surfactant solutions that are then typically incompatible with DNA-directed assembly. DNA exchange is a promising route for replacing surfactants with self-assembling DNA sequences after these purification steps. Unfortunately, despite advances, DNA exchange remains a challenging technique with limitations due to uncontrolled aggregation and low yields. In this work we focus on improving the process for several well-defined SWCNT samples that are both single chirality and single enantiomer refined through aqueous two-phase separation as well as length sorted to a narrow distribution. With these, we demonstrate improvements in DNA exchange in both yield and control of the aggregation state by modifying DNA exchange processing parameters. We also show that the exchanged DNA-wrapped SWCNTs can be linked together by the addition of a complementary DNA bridge to form self-assembled biohybrid nanostructures for energy transfer studies. We use analytical ultracentrifugation and absorbance and photoluminescence spectroscopies to measure and quantify changes in as these biohybrid structures self-assemble. These developments pave the way for high yield assembly of precise biohybrid nanostructures for energy transfer studies and open potential applications in photovoltaics and biosensing.
Carbon Nanotube-Based Sensors for Intelligent Packaging
Authors: Sharif Niloufar , Boghossian Ardemis Anoush
Published: September 2023

Aim:

The aim of this project is to develop a gas-phase optical sensor for oxygen detection in intelligent packaging. The optical sensor will be based on near-infrared light that can penetrate through visibly opaque materials, including plastics, paper, and cardboard. An automated near-infrared camera will be used to precisely and quickly inform the user of any change in the integrity of packages that are vacuum-sealed or atmospherically modified.

Method:

The optical sensor is based on near-infrared fluorescence that is emitted from carbon nanotubes (CNTs). CNTs exhibit a sensitive and photostable fluorescence that is well suited for sensing applications. The CNTs are wrapped by one of two types of DNA, AT(15) and GT(15), through sonication. These wrappings control the responsivity of the CNTs to different gases while also solubilizing them for further processing. The resulting solutions are then drop-casted into a film. We subsequently investigate the response of the film in the presence of the target gas, oxygen, at different concentrations. Finally, we evaluate the selectivity of the sensor in the presence other gases including carbon dioxide, ethylene, and ammonia.

Results:

Our results reveal that the fluorescence intensity of the AT(15) and GT(15)-wrapped CNTs quenches upon the exposure of oxygen. Interestingly, we observe that the different CNT chiralities respond distinctly to the presence of oxygen. In particular, whereas some chiralities undergo an irreversible loss in fluorescence after several oxygen exposure cycles, the (8,6) chirality demonstrates stability over multiple cycles for both AT(15) and GT(15)-wrapped CNTs. Finally, our results show a concentration-dependent and selective response of both the AT(15)- or GT(15)-wrapped CNT sensors to the oxygen, as we observed no significant response to the other studied gases.

Conclusion:

We developed an optical, gas-phase sensor based on CNT fluorescence for intelligent food packaging. The sensor is selective to oxygen and demonstrates reversibility over multiple oxygen exposure cycles. These sensors can be used to monitor the integrity of packages that are vacuum-sealed or otherwise atmospherically modified. This technology can thus provide consumers and manufactures a means of preventing early spoilage and ensuring food quality.
(Invited) Stochasticity in the Number of Quantum Defects in Fluorescent Carbon Nanotubes
Authors: Kruss Sebastian
Published: September 2023

Single wall carbon nanotubes (SWCNTs) display chirality dependent near infrared (NIR) fluorescence. Their optoelectronic properties can be further tuned by incorporating quantum defects/organic color centers (OCC) via reactions with diazonium salts. The absolute number of defects per SWCNT determines the properties but is not exactly known. Measuring it is complicated because typical SWCNT samples contain multiple chiralities, that congest the spectra and prevents to distinguish defects from different chiralities. Aqueous two-phase extraction (APTE) is a powerful technique to isolate specific chiralities. Here, we show that quantum defects do not affect APTE, which indicates that the chemical potential is not substantially affected and pinpoints to low numbers of defects. The purity of (6,5)-SWCNTs allows us to image the NIR fluorescence contributions (E11 below 1050 nm, and E11
* above 1050 nm) on the single SWCNT level and defect incorporation itself on the single molecule level. Interestingly, one observes a stochastic distribution of the numbers of defects, which can be explained by a Poisson distribution. We find a mean number of defects of 0-3 per SWCNT. These results indicate the large variance between ensemble and single particle picture. In summary, we show that single quantum defects can be counted by NIR imaging and that stochasticity plays a crucial role for their optical properties.
(Invited) Playing with the Weakest Supramolecular Interactions in a 3D Crystalline Hexakis[60]Fullerene Induces Control over Hydrogenation Selectivity
Authors: Fernandez-Bartolome Estefania , Gamonal Arturo , Santos Jose , Sañudo Eva Carolina , Martín Nazario , Costa Jose
Published: September 2023

Weak forces can play an essential role in chemical reactions1. Controlling such subtle forces in reorganization processes by applying thermal or chemical stimuli represents a novel synthetic strategy and one of the main targets in supramolecular chemistry2. Actually, to separate the different supramolecular contributions to the stability of the 3D assemblies is still a major challenge. Therefore, a clear differentiation of these contributions would help in understanding the intrinsic nature as well as the chemical reactivity of supramolecular ensembles. In the present work, a controlled reorganization of an hexakis[60]fullerene-based molecular compound purely governed by the weakest van der Waals interactions known, i.e. the dihydrogen interaction – usually called sticky fingers – is illustrated3. This pre-reorganization of the hexakis[60]fullerene under mild conditions allows a further selective hydrogenation of the crystalline material via hydrazine vapors exposure. This unique two-step transformation process is monitored by single-crystal to single-crystal diffraction (SCSC) which allows the direct observation of the molecular movements in the lattice and the subsequent solid–gas hydrogenation reaction4.

Y. Inokuma, M. Kawano, M. Fujita, Nat. Chem. 2011, 3, 349 – 358.

J. Echeverria, G. Aullon, D. Danovich, S. Shaik, S. Alvarez, Nat. Chem. 2011, 3, 323 – 330.

Estefania Fernandez-Bartolome et all, Angew. Chem. 2019, 8, 2332-2337.

Estefania Fernandez-Bartolome et all, Chem. Science. 2021, 12, 25, 8682-8688.

Figure 1
(Invited) 2D-2D Heterostructures Beyond Van Der Waals
Authors: Perez Emilio M
Published: September 2023

We will describe the covalent grafting of 2H-MoS2 flakes on graphene monolayers embedded in field-effect transistors.[1] A bifunctional molecule was used that features a maleimide and a diazonium functional group, known to connect to sulfide- and carbon-based materials, respectively. MoS2 flakes were first exfoliated, functionalized by reaction with the maleimide moieties, then anchored to graphene through the diazonium groups. This approach enabled the simultaneous functionalization of several devices. The electronic properties of the resulting heterostructure are shown to be dominated by the MoS2–graphene molecular interface.

We will also discuss the journey that has led to these results, including the development of a “click” chemistry reaction for transition metal-dichalcogenides,[2-4] and insights into the covalent patterning of graphene.[5-8]

References:

[1] M. Vázquez Sulleiro, A. Develioglu, R. Quirós-Ovies, L. Martín-Pérez, N. Martín Sabanés, M. L. Gonzalez-Juarez, I. J. Gómez, M. Vera-Hidalgo, V. Sebastián, J. Santamaría, E. Burzurí, E. M. Pérez, “Fabrication of devices featuring covalently linked MoS2–graphene heterostructures.” Nat. Chem. 2022, 14, 695-700.

[2] M. Vera-Hidalgo, E. Giovanelli, C. Navio, E. M. Pérez, “Mild Covalent Functionalization of Transition Metal Dichalcogenides with Maleimides: a “click” reaction for 2H-MoS2 and WS2”, J. Am. Chem. Soc. 2019, 141, 3767-3771.

[3] R. Quirós-Ovies, M. Vázquez Sulleiro, M. Vera-Hidalgo, J. Prieto, I. J. Gómez, V. Sebastián, J. Santamaría, E. M. Pérez, “Controlled Covalent Functionalization of 2 H-MoS2 with Molecular or Polymeric Adlayers” Chem. Eur. J. 2020, 26, 6629-6634.

[4] M. Vázquez Sulleiro, R. Quirós-Ovies, M. Vera-Hidalgo, I. J. Gómez, V. Sebastián, J. Santamaría, E. M. Pérez, “Covalent cross-linking of 2H-MoS2 nanosheets”, Chem. Eur. J. 2021, 27, 2993.

[5] J J Navarro, S Leret, F Calleja, D Stradi, A Black, R Bernardo-Gavito, M Garnica, D Granados, A L Vazquez de Parga, E M Pérez, and R Miranda, “Organic covalent patterning of nanostructured graphene with selectivity at the atomic level”, Nano Lett. 2016, 16, 355-361.

[6] J. J. Navarro, F. Calleja, R. Miranda, E. M. Pérez, A. L. Vázquez de Parga, “High yielding and extremely site-selective covalent functionalization of graphene”, Chem. Commun. 2017, 53, 10418-10421.

[7] A. Naranjo, N. Martín Sabanés, M. Vázquez Sulleiro, E. M. Pérez “Microemulsions for the Covalent Patterning of Graphene.” Chem. Commun. 2022, 58, 7813-7816.

Figure 1
(Invited) Carbon Nano-Onions: Potassium Intercalation and Reductive Covalent Functionalization
Authors: Abellán Gonzalo , Pérez-Ojeda Rodríguez Maria Eugenia
Published: September 2023

Functionalization of carbon nanomaterials is a promising approach to controllably engineer the band gap structure, create novel architectures, and manipulate the interfacial characteristics of graphene and carbon nanotubes, increasing their processability.[1,2]

Herein we report the synthesis of covalently functionalized carbon nano-onions (CNOs) via a reductive approach using unprecedented alkali-metal CNO intercalation compounds. For the first time, an in situ Raman study of the controlled intercalation process with potassium has been carried out revealing a Fano resonance in highly doped CNOs. The intercalation was further confirmed by electron energy loss spectroscopy and X-ray diffraction. Moreover, the experimental results have been rationalized with DFT calculations. Covalently functionalized CNO derivatives were synthesized by using phenyl iodide and n-hexyl iodide as electrophiles in model nucleophilic substitution reactions. The functionalized CNOs were exhaustively characterized by statistical Raman spectroscopy, thermogravimetric analysis coupled with gas chromatography and mass spectrometry, dynamic light scattering, UV–vis, and ATR-FTIR spectroscopies. This work provides important insights into the understanding of the basic principles of reductive CNOs functionalization and will pave the way for the use of CNOs in a wide range of potential applications, such as energy storage, photovoltaics, or molecular electronics.[3]

[1] Abellán, G.; Schirowski, M.; Edelthalhammer, K. F.; Fickert, M.; Werbach, K.; Peterlik, H.; Hauke, F.; Hirsch, A. J. Am. Chem. Soc.
2017, 139, 5175.

[2] Schirowski, M.; Abellán, G.; Nuin, E.; Pampel, J.; Dolle, C.; Wedler, V.; Fellinger, T. P.; Spiecker, E.; Hauke, F.; Hirsch, A. J. Am. Chem. Soc.
2018, 140, 3352.

[3] M. E. Pérez-Ojeda, E. Castro, C. Kröckel, M. A. Lucherelli, U. Ludacka, J. Kotakoski, K. Werbach, H. Peterlik, M. Melle-Franco, J. C. Chacón-Torres, F. Hauke, L. Echegoyen, A. Hirsch, G. Abellán, J. Am. Chem. Soc.
2021, 143, 18997.

Figure 1
(Invited) Computational Modelling of Super-Reduced Polyoxometalates for Energy Storage
Authors: Poblet Josep M.
Published: September 2023

It is well know that polyoxometalates can be reduced at relatively potentials and can act as reservoir of electrons. Very recently, it has been reported that polyoxometalates clusters like Li6[P2W18O62] can achieve very high proton–electron storage capacities in aqueous solution. DFT calculations in combination with classical MD and CPMD simulations were able to substantiate that the physical properties of classical polyoxotungstates, like those of the prototypical Dawson anion [P2W18O62]6-, strongly depend on the presence of collective forces associated to POM concentration, pH and countercation nature. At low POM concentration and neutral pH only four electrons are reversibly incorporated to the POM. However, in acidic media, the POM framework begins to protonate after the third electron reduction. The salt concentration is also very relevant, since it favours the POM aggregation, which induces an additional stabilization of molecular orbitals. These and another features of reduced polyoxometales will be discussed in the present communication.
(Invited) Recent Advances in Subphthalocyanines
Authors: Gomez-Gomez Marta , Lopez-Serrano Elisa , Labella Jorge , Lavarda Giulia , Hernandez-Lopez Leyre , Azizi Kobra , Bottari Giovanni , Ince Mine , Lobo Checa Jorge , Guldi Dirk Michael , Torres Tomas
Published: September 2023

Subphthalocyanines (SubPcs) [1] are well-known cone-shaped chromophores consisting of three 1,3-diiminoisoindole units assembled around a boron atom. As a result of their 14 pi-electron aromatic core and their tetrahedral geometry, SubPcs exhibit outstanding physical and optoelectronic properties (e.g., strong dipole moment, excellent light absorption in the 550-650 nm, rich redox features, and excellent charge transport capabilities), that have been skilfully used in variety of applied fields, such as molecular photovoltaics, among others. SubPcs were used by us as non-fullerene acceptors in bulk heterojunctions (BHJ) solar cells. On the other hand as part of our systematic investigation in the preparation and study of novel SubPc-based D–A systems, we have used 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) as partner for SubPcs. Moreover, in the case of unsymmetrically substituted SubPcs (i.e., prepared by cyclotrimerization of a phthalonitrile with no C2v symmetry), they present inherent chirality and the corresponding couple of enantiomers can be isolated [2]. Columnar aggregates based on chiral SubPcs have been also prepared, giving rise to ferroelectric self-assembled molecular materials showing both rectifying and switchable conductivity. These chromophores have been incorporated in multicomponent systems showing a panchromatic response and allowing the tuning and controlling intramolecular FÖRSTER Resonance Energy Transfer for Singlet Fission.

[1] G. Lavarda, J. Labella, M. V. Martinez-Diaz, M. S. Rodriguez Morgade, A. Osuka, T. Torres, “Recent advances in subphthalocyanines and related subporphyrinoids” Chem. Soc. Rev. 2022, 51, 9482-9619.

[2] J. Labella, G. Lavarda, L. Hernández-López, F.Aguilar-Galindo, S.Díaz-Tendero, J. Lobo-Checa, T. Torres “Preparation, Supramolecular Organization, and On-Surface Reactivity of Enantiopure Subphthalocyanines: From Bulk to 2D-Polymerization” J. Am. Chem. Soc. 2022, 144, 16579-16587.
(Invited) Tether-Directed Regioselective Synthesis of Bispyrazolinofullerenes
Authors: Caballero Ruben , de la Cruz Pilar , Langa Fernando
Published: September 2023

The problematic regioselective synthesis of fullerene bisadducts was finely solved by Diederich with the introduction of the tether-directed functionalization.[1] Since then, many other examples have been described, most of them using double Bingel addition or Diels-Alder cycloaddition reactions. Surprisingly, although 1,3-dipolar cycloaddition reactions are the most popular procedure for functionalization of C60, the use of this reaction for regioselective synthesis of fullerene bisadducts.

Here we present our results of selective synthesis of trans-3 or e-bispirazolinofullerenes using bisnitrilimine tethered by di-tertbutylsilylbis(trifluoromethanesulfonate) group [3][4]. Further rupture of the silyl ester group allows the preparation of new derivatives for selected applications.

[1] L.Isaacs, R.F.Haldimann,F.Diederich,Angew.Chem.Int.Ed.Engl.1994,33,2339.

[2] F. Diederich, R. Kessinger. Acc. Chem. Res. 1999, 32, 537.

[3] V. Cuesta, M. Urbani, P. de la Cruz, L. Welte, J.F. Nierengarten, F. Langa, Chem. Comm. 2016, 52, 13205

[4] R. Caballero, M. Barrejón, J. Cerdá, J. Aragó, S. Seetharaman, P. de la Cruz, E. Ortí, F. D’Souza, F. Langa. J. Am. Chem. Soc. 2021, 143, 11199.

Figure 1
(Invited) Towards Understanding the Competition of Electron and Energy Transfer in Nanographene
Authors: Guldi Dirk Michael
Published: September 2023

Graphene has captured the imagination of researchers around the world due to its groundbreaking chemical and physical properties. Opening a band gap in graphene must be achieved without, however, compromising its exceptional properties as they are of paramount importance for its use in electronic devices. Notable is the fact that the band gap design in graphene is typically carried out by either chemical or physical methodologies. Chemical modification of graphene is mostly centered around “top-down” or “bottom-up” approaches. The earlier alters, nevertheless, the graphene lattice and, as a consequence, poorly defined structures emerge. The latter by means of, for example, organic synthesis offers a wide palette of tools to control sizes as well as geometries of the resulting “molecular” nanographenes with atomic precision. It allows the fabrication of uniform and well-defined molecular structures. Such “molecular” nanographenes are compelling choices for “on demand” molecular electronics, photovoltaic applications, hydrogen storage, and sensing. In recent years, two main strategies have been developed to fabricate “molecular” nanographenes of defined chemical structures. It is, on one hand, oxidative cyclodehydrogenation of custom-made polycyclic aromatic hydrocarbons (PAHs) and, on the other hand, on-surface cyclodehydrogenation, which enabled the preparation of atomically precise “molecular” nanographenes. To this end, the 13 fused-benzene rings of hexa-peri-hexabenzocoronene (HBC), which are arranged in a 2D disk-shaped fashion, render HBCs the smallest “molecular” nanographenes.
(Invited) Crystallographic Characterization of U@C2
n
(2n = 82−86): Insights about Metal-Cage Interactions for Mono-Metallofullerenes
Authors: Yao Yang-Rong , Echegoyen Luis
Published: September 2023

Endohedral mono-metallofullerenes are the prototypes to understand the fundamental nature and the unique interactions between the encapsulated metals and the fullerene cages. Recently, we succeeded in the synthesis, isolation, and characterization of four new U-based mono-metallofullerenes, including U@Cs
(6)-C82, U@C
2(8)-C84, U@Cs
(15)-C84, and U@C
1(12)-C86. Furthermore, a new finding concerning the metal positions inside the cages reveals that the encapsulated metal ions are always located on symmetry planes of the fullerene cages, as long as the fullerene cages possess mirror planes. Symmetrical patterns, such as indacene, sumanene, and phenalene, and charge transfer are found to determine the metal positions inside the fullerene cages. DFT calculations support that the metal-fullerene motif interaction determines the stability of the metal position. In fullerenes containing symmetry planes, the metal prefers to occupy a symmetrical arrangement with respect to the interacting motifs, which share one of their symmetry planes with the fullerene. This finding provides new insights into the nature of metal-cage interactions and gives new guidelines for structural determinations using crystallographic and theoretical methods.
(Invited) Exohedral Functionalization in Actinide Mono-Metallofullerenes: Computations Are Able to Explain Experiments
Authors: Rodriguez-Fortea Antonio , Abella Laura , Torrens Daniel , Poblet Josep M.
Published: September 2023

Since the isolation of the first endohedral metallofullerene La@C82,1 intensive research has been devoted to this family of compounds that encapsulate metal atoms or clusters in their inner void space.2 Recently, the first metallofullerene containing an actinide, Th@C82, was isolated and characterized.3 Other mono-actinidofullerenes as non-IPR U@C80, Th@C80 and U@C76; or IPR U@C82, U@C84, U@C86, Th@C80 and Th@C82 have been also characterized.4 In mono-actinidofullerenes, the actinide tends to have oxidation state +4, which involves an important metal-cage interaction with significant covalent contributions. This feature makes them different from lanthanofullerenes, where the metal is usually with oxidation state +3. Consequently, the electronic structure, properties as well as reactivity of actinidofullerenes are expected to be different compared to their lanthanide counterparts. We here analyze with computations at DFT level the exohedral functionalization of mono-actinidofullerenes for some typical addition and radical reactions, being able to explain their characteristic regioselectivity.

References

Chai, Y.; Cuo, T.; Jin, C.; Haufler, R. E.; Felipe Chibante, L. P.; Fure, J.; Wang, L.; Alford, J. M.; Smalley, R. E. J. Phys. Chem.
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Popov, A. A.; Yang, S.; Dunsch, L. Chem. Rev.
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Wang, Y.; Morales-Martínez, R.; Zhang, X.; Yang, W.; Wang, Y.; Rodriguez-Fortea, A.; Poblet, J. M.; Feng, L.; Wang, S.; Chen, N. J
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2017, 139, 5110-5116.

a) Cai, W.; Abella, L.; Zhuang, J.; Zhang, X.; Feng, L.; Wang, Y.; Morales-Martínez, R.; Esper, R.; Boero, M.; Metta-Magaña, A.; Rodriguez-Fortea, A.; Poblet, J. M.; Echegoyen, L.; Chen, N. J. Am. Chem. Soc.
2018, 140, 18039-18050; b) Yao, Y.-R.; Roselló, Y.; Ma, L.; Puente Santiago, A. R.; Metta-Magaña, A.; Chen, N.; Rodriguez-Fortea, A.; Poblet, J. M.; Echegoyen, L. J. Am. Chem. Soc.
2021, 143, 15309-15318; c) Yan, Y.; Morales-Martinez, R.; Zhuang, J.; Yao, Y.-R.; Li, X.; Poblet, J. M.; Rodriguez-Fortea, A.; Chen, N. Chem. Commun.
2021, 57, 6624-6627; d) Meng, Q.; Morales-Martínez, R.; Zhuang, J.; Yao, Y.-R.; Wang, Y.; Feng, L.; Poblet, J. M.; Rodriguez-Fortea, A.; Chen, N. Inorg. Chem.
2021, 60, 11496-11502.
Fabrication of Graphene Optical Devices for Endoscope Calibration
Authors: Medeiros Jacilene Martins , Rufino Fernando César , Fernandes Leonardo Araújo , Diniz Jose Alexandre , Cirino Giuseppe Antônio , Montagnoli Arlindo Neto
Published: September 2023

Endoscopic devices used in the clinical examination of pathologies such as glottic tumors can record real-time images of the vocal cords during vibration. Quantitative analysis of the glottic surface requires the metric system to obtain the absolute dimensions of the larynx in a series of acquired images. However, so far, there is no effectively automated and stable calibration method for clinical use. Therefore, most metrics used by professionals are invasive and subjective. Thus, this study reports the microfabrication of a diffractive optical element (DOE) that could potentially quantify cancer cells from the glottic surface of patients. It has been observed that the image of the glottis seen through an endoscope is shaped by its geometric properties and by the shading of color and brightness. Therefore, tumor location and size can be quantified by overlaying the DOE metric with light spots on images that include the glottic region. DOE was developed from processes used in the fabrication of integrated circuits and MEMS, already quite mature. To obtain high-quality images from optical reconstruction of the glottis, the use of graphene monolayers grown by chemical vapor deposition (CVD) on copper (Cu) foil was investigated. This was transferred to a glass substrate by wet method (Fishing method) and the etching steps of the Cu substrate were carried out. In this method, polymethylmethacrylate (PMMA) was used as the supporting polymer through the spinner. Two lithographs were made under the glass substrate with different approaches (using a Karl Suss MJB3 mask aligner system with a maximum resolution of 1 µm). The first, which preceded the thin-film transfer, aimed to delineate the graphene transfer area using an aluminum (Al) deposition technique by sputtering. The second lithography, linked to oxygen Ashing plasma corrosion, made it possible to study the modulation of a microrelief containing parallel and serpentine patterns, of amplitude and phase, spaced from 1 to 10 μm. An optical system containing an EOD and a Fourier lens was attached to the endoscope end to project a laser line parallel to the vocal cords. Image processing methods automatically identify pixels in the image data that belong to the projected laser line. Thus, the detection of the diffractive pattern was based on segmentation of endoscopic images centered on Sobel filtering and on the method with active boundary regions of the watershed. These use successively robust temporal and spatial characteristics of the laser lines projected onto the endoscopic image sequence. In short, the combination of laser projection device and image processing allows calibration of endoscopic images and can provide quantitative metric data for tumors on the surface of the vocal cords. Therefore, the proposed calibration method can be considered a powerful tool to aid in the prognosis of laryngeal pathologies.

Figure 1
Effect of Incorporating Graphene Oxide in ZnO and Study of the Thermistor Applications of ZnO-RGO Film
Authors: Olumurewa Kayode Oladele , Eleruja Marcus Adebola
Published: September 2023

This research reported the effect of incorporating graphene oxide in the hybrid of ZnO and investigated the thermistor applications. ZnO-RGO were synthesized by the hydrothermal method and spin coated on glass to obtain the thin film. The SEM micrograph of ZnO-RGO showed mini ZnO nanorods decorated and formed on the RGO sheet. The adherence of the nanorods were improved as the loading mass of GO increased in the composite. ZnO-RGO had thermal sensing response of 3.1 respectively at 573K and showed improved electrical conductivity as temperature increased. ZnO sensors logged a negative temperature coefficient (NTC) value of 0.00236 /K and a sensitivity value of 0.01392 Ω/ K while ZnO-RGO had a NTC value of 0.00248139 /K (which is higher than values obtained in literature for silver and palladium based graphene composites) and a sensitivity value of 0.00769 Ω/ K. A value of 0.0561eV was obtained for the activation energy of ZnO sensor while 0.0615 eV was obtained for ZnO-RGO. This research has confirmed that incorporating GO in ZnO increased the activation energy of ZnO-RGO thermistor, and consequently increased the thermal sensing response thus resulting in improved thermal sensing properties of ZnO. With an improved NTC, sensor response and activation energy, ZnO-RGO can replace Pd based RGO and Ag nanoparticles based RGO as thermistors.
Thickness-Controlled Synthesis of Uniform Hexagonal Boron Nitride Films on Metal Alloys by Chemical Vapor Deposition
Authors: Park Ji Hoon , Liu Hongwei , Hennighausen Zachariah , Zhang Kenan , Kong Jing
Published: September 2023

Two-dimensional (2D) multilayer hexagonal boron nitride (hBN) is a superior substrate for other 2D materials due to its insulating property, atomic-scale smoothness, and absence of dangling bonds, enhancing electrical or optical properties in high-performance 2D material-based devices. In most fabrication processes for 2D heterostructure devices, thick hBN flakes exfoliated from bulk have been used because of their high quality and simplicity in the process. However, exfoliated hBN flakes are limited in size and thickness control, impeding scale-up production for industrialization. Therefore, new synthesis strategies are required to overcome the drawback of the exfoliation method. In this work, we investigated the synthesis of large-area, multilayer hBN via atmospheric pressure chemical vapor deposition using single crystalline metal and single crystal alloy substrates. The synthesized results are characterized by optical microscopy, scanning electron microscopy, Raman spectroscopy, atomic force microscopy, etc. These studies provide a more comprehensive understanding of the growth mechanism of hexagonal boron nitride.
(Invited) Energy Level Alignment and Hot Carrier Extraction in Monolayer Semiconductor Photoelectrochemical Cells
Authors: Sambur Justin
Published: September 2023

The fundamental problem that limits the solar energy conversion efficiency of conventional semiconductors such as Si is that all absorbed photon energy above the band gap is lost as heat. The critical question that our research addresses is: Can we avoid energy losses in semiconductors? Hot-carrier systems that avoid such losses have tremendous potential in photovoltaics and solar fuels production, with theoretical efficiencies of 66% (well above the detailed-balance limit of 33%). Ultrathin 2D semiconductors such as monolayer (ML) MoS2 and WSe2 have unique physical and photophysical properties that could make hot-carrier energy conversion possible. The specific knowledge gap in the field is how the energy levels of 2D semiconductors move with applied potential and/or illumination, making the driving force for charge transfer (DG
0´) unclear. Since DG
0´ governs the hot-carrier extraction rate (k
ET), understanding how and why DG
0´ changes under solar fuel generation conditions is critical to controlling k
ET relative to the cooling rate. Absence of this critical information is limiting our ability to perform hot-carrier photochemistry. Our research team has employed photocurrent spectroscopy, steady-state absorption spectroscopy, and in situ femtosecond transient absorption spectroscopy as a function of applied potential to characterize underlying steps in a ML MoS2 photoelectrochemical cell. The rich data set informs us on the timescales for hot-carrier generation/cooling and exciton formation/recombination, as well as the magnitudes of changes in exciton energy levels, exciton binding energies, and the electronic band gap. These findings open the possibility of tuning the hot-carrier extraction rate relative to the cooling rate to ultimately utilize hot-carriers for solar energy conversion applications.
(Invited) Electrical Control in the Chemical Vapor Deposition Synthesis of Graphene and Related Materials
Authors: Kong Jing
Published: September 2023

Chemical vapor deposition (CVD) is widely used for the efficient growth of low dimensional materials. Typically, the synthesis parameters such as gas flow rate, temperature, pressure etc. are being optimized in order to achieve desirable results such as high-quality materials. Up to now, gas phase electro-chemical reactions have not been widely considered in CVD. In this talk, our explorations of using applied voltages to control the CVD synthesis results will be presented. We have found that applying an electric field between the copper substrate and a counter electrode has significant impacts on the growth of graphene. Electrochemical effect and ionic collision effect are observed in different conditions. Switching electric field can also be used to twist the chirality of carbon nanotubes. It is anticipated that electrical control during CVD synthesis could open up new ways to assist the synthesis of low dimensional materials in the future.
Decatungstate Photocatalyzed Acylation of 2D Transition Metal Dichalcogenides
Authors: Sideri Ioanna K. , Canton-Vitoria Ruben , Tagmatarchis Nikos
Published: September 2023

2D Transition metal dichalcogenides (TMDs) and their unique chemistry have flourished in the recent years owing to their pertinence in a broad series of front-row applications including electronic, opto-epectronic and energy storage /harvest devices for the semiconductors,1, 2 while also catalysis and photo /electrothermal applications for the metallic phases.3 Since their ability to protagonist in such applications is dependent on their chemical structure and processing, a great deal of research effort has been focused on TMDs’ functionalization. The nucleophilic nature of the metallic phase is responsible for the uneven flourish, regarding covalent functionalization, in favor of the metallic phase vs the semiconducting. In parallel, the main inspiration for such chemical transformations on 2D TMDs has been organic chemistry. However, until now there is no report based on a catalytic protocol for the covalent functionalization of TMDs. Following our previous report on the catalytic transformation of single walled carbon nanotubes,4 we herein present the decatungstate-photocatalyzed acylation of 2H-MoS2 and 2H-MoSe2, employing aliphatic and aromatic aldehydes (Figure 1). The successful protocol is accompanied by detailed optimization and spectroscopic characterization. The availability of the various aldehydes as means to realize chemical modifications of choice on the surface of 2H phase of TMDs and the mild reaction conditions protocol, shape an ideal methodology to advance the chemistry of 2D TMDs bringing them one step closer to industry applications.

References

[1] W. Choi, N. Choudhary, G. H. Han, J. Park, D. Akinwande, Y. H. Lee, Mater. Today 2017, 20, 3, 116-130.

[2] C. Stangel, E. Nikoli, N. Tagmatarchis, Adv. Energy Sustainability Res. 2022, 2200097.

[3] X. Yin, C. S. Tang, Y. Zheng, J. Gao, J. Wu, H. Zhang, M. Chhowalla, W. Chen, A. T. S. Wee, Chem. Soc. Rev., 2021, 50, 10087-10115.

[4] R. Canton-Vitoria, M. Quintana, N. G. Malliaros, N. Tagmatarchis, Adv. Mater. Interfaces 2022, 2201575.

Figure 1
Intercalation and Functionalization in 2D Materials
Authors: Cha Judy J
Published: September 2023

The large surface areas and interlayer gaps of 2D materials enable surface functionalization and intercalation as effective post-synthesis design knobs to tune the properties of 2D materials using ions, atoms, and organic molecules. For complete engineering control, detailed understanding of the interactions between the 2D materials and the molecules adsorbed on 2D materials surface or between the 2D materials and the intercalants is necessary.

I will first discuss surface functionalization to tune the electrical properties of 2D materials. We developed an experimental approach to quantitatively measure the doping powers of organic electron donors (OEDs) to monolayer MoS2. Using novel and previously studied OEDs, we demonstrate experimentally that the measured doping power is a sensitive function of molecule’s reduction potential, size, surface coverage, and orientation to 2D materials [1, 2].

I will then discuss electrochemical intercalation into 2D materials to induce novel phases that were previously undetected and to study heterointerface effects on the intercalation induced phase transition [3, 4]. We discover new structural phases in Td-WTe2 and T’-MoTe2 with lithium intercalation and these new phases are semiconducting even though the initial WTe2 and MoTe2 are semimetallic and lithium ions donate electrons to the host materials. In the lithium intercalation-induced phase transition from the 2H to 1T’ phase of MoS2, we show that the nucleation of the 1T’ phase proceeds via heterogeneous nucleation where the nature of heterointerface dictates the thermodynamics of the phase transition. For these studies, multi-modal, in-situ probes were necessary to track the changes in the structure-property relation of the layered materials as a function of intercalation.

[1] Advanced Electronic Materials 7, 2000873 (2021).

[2] Nano Letters 22, p.4501 (2022).

[3] ACS Applied Materials & Interfaces 13, p.10603-10611 (2021).

[4] Advanced Materials 34, 2200861 (2022).
(Invited) Nanoscale Mapping of Electrochemical and Photoelectrochemical Processes on 2D Layered Materials by SECM
Authors: Bo Tianyu , Jia Rui , Wilder Logan , Ghoshal Debjit , Miller-Link Elisa , Mirkin Michael
Published: September 2023

Electrocatalytic and photo(electro)catalytic activities of 2D materials are highly heterogeneous with different active sites, e.g., structural defects and facet edges, contributing to the overall current. Scanning electrochemical microscopy (SECM) and related techniques have been extensively used for localized measurements of electrocatalytic activity; however, the progress is hindered by the difficulty in pinpointing the active sites, particularly when their size is on the atomic scale. We have recently reported the use of SECM for nanoscale imaging of electrocatalytic reactions at 2D materials and photoelectrochemical processes at semiconductor surfaces. In this paper, we present new approaches to surface reactivity mapping, including electrochemical and photoelectrochemical tunneling experiments at monolayers and nm-thick exfoliated flakes of MoS2.
(Invited) Two-Dimensional Neuromorphic Computing Materials and Devices
Authors: Hersam Mark C
Published: September 2023

The exponentially improving performance of digital computers has recently slowed due to the speed and power consumption issues resulting from the von Neumann bottleneck. In contrast, neuromorphic computing aims to circumvent these limitations by spatially co-locating logic and memory. Beyond reducing power consumption, neuromorphic devices provide efficient architectures for image recognition, machine learning, and artificial intelligence [1]. This talk will explore how two-dimensional (2D) nanoelectronic materials enable gate-tunable neuromorphic devices [2]. For example, by utilizing self-aligned, atomically thin heterojunctions, dual-gated Gaussian transistors have been realized, which show tunable anti-ambipolarity for artificial neurons, competitive learning, spiking circuits, and mixed-kernel support vector machines [3]. In addition, field-driven defect motion in polycrystalline monolayer MoS2 enables gate-tunable memristive phenomena that serve as the basis of hybrid memristor/transistor devices (i.e., 'memtransistors' [4]) that concurrently provide logic and data storage functions [5]. The planar geometry of memtransistors further allows multiple contacts and dual gating that mimic the behavior of biological systems such as heterosynaptic responses [6]. Moreover, control over polycrystalline grain structure enhances the tunability of potentiation and depression, which enables unsupervised continuous learning in spiking neural networks [7]. Overall, this work introduces foundational circuit elements for neuromorphic computing by utilizing the unique quantum characteristics of 2D nanoelectronic materials [8].

[1] V. K. Sangwan, et al., Nature Nanotechnology,
15, 517 (2020).

[2] M. E. Beck, et al., ACS Nano, 14, 6498 (2020).

[3] M. E. Beck, et al., Nature Communications, 11, 1565 (2020).

[4] V. K. Sangwan, et al., Nature, 554, 500 (2018).

[5] X. Yan, et al., Advanced Materials, 34, 2108025 (2022).

[6] H.-S. Lee, et al., Advanced Functional Materials, 30, 2003683 (2020).

[7] J. Yuan, et al., Nano Letters, 21, 6432 (2021).

[8] X. Liu, et al., Nature Reviews Materials, 4, 669 (2019).
Defect Engineering in Large Area Epitaxial Monolayer MoS2 for Optoelectronics and Beyond
Authors: Ghoshal Debjit , Miller-Link Elisa , van de Lagemaat Jao
Published: September 2023

Monolayers of transition metal dichalcogenides (TMDCs), due to their tunable properties, have shown immense promise in applications such as optoelectronics, flexible electronics, spintronics and energy harvesting. Defect engineering has emerged as a facile tool to tune the properties of monolayer TMDCs making them more potent for these applications. While a high propensity of defects is useful for certain applications like catalysis, many other applications benefit from low defect densities. Thus, understanding the nature of these defects as well as finding quick throughput techniques to characterize them have become critical. Additionally, although several efforts have focused on creation/healing of defects, these processes are still premature and not well understood. In this talk, we will discuss defect engineering in large area epitaxial monolayer MoS2 thin films. We will outline in-situ approaches for fabrication/healing of defects. We will also demonstrate a quick throughput technique to characterize defect densities in these thin films. We envision the ability to modulate defect densities (create/heal) in a controllable fashion in these materials can open-up an additional knob to tune the opto-electronic properties of these materials thus making them more marketable for applications in opto-electronics, photonics, energy harvesting and beyond.
Electronic and Vibrational Properties of Episulfide-Graphene Materials
Authors: Haddad Elie , Sprocq Simon , Schue Leonard , Pimonov Vladimir , Dolle Mickael , Martel Richard , Rochefort Alain
Published: September 2023

Our group has investigated the stability of sulfur adatoms on graphene obtained by a direct reaction of highly oriented pyrolytic graphite (HOPG) with elemental sulfur. With the help of density functional theory (DFT) calculations, we have developed different models of the structure and evaluated the electronic and vibrational properties of synthesized graphene-sulfur (GS) materials. Our structural models are based on sulfur atoms covalently attached to graphene. The DFT electronic structure calculations support the formation of a strong and stable sulfur bonding to graphene and give a chemical composition in good agreement with the experimental proportion of sulfur to carbon. In addition, ab-initio molecular dynamics simulations allow us to confirm the stability on S-G bonds. The vibrational modes calculated with DFT support the vibrational signatures of the GS materials observed using Raman spectroscopy.