bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Fullerenes for Catalysis: C60 As Molecular Vector in Hydrogen Transfer Reactions
Authors: Martin Nazario , Filippone Salvatore , Vidal Sara , Marco-Martínez Juan 
Published: February 2020

Nowadays, a complete understanding of fullerenes chemical reactivity has been achieved and, in this regard, we have demonstrated that a full control in the stereoselective functionalization of fullerenes is also possible, by using different asymmetric metal- and organo-catalyzed processes.1 Furthermore, fullerenes and transition metals have given rise to a wide set of sophisticated metallo-fullerene hybrids.2 However, despite the rich chemistry developed “onto fullerenes”, the chemistry carried out “with fullerenes” has been almost neglected. Thus, an intriguing and still open question is whether fullerenes could be involved in promoting or catalysing chemical transformations and, in particular, if fullerene double bonds are suitable to act in transfer hydrogenation processes.
In order to address these questions, we have designed and prepared a fullerene hybrid where C60is endowed with a metal atom, such as Ir, that has shown to have a high activity in transfer hydrogenation reactions. Thus, a new hybrid iridium-fullerene has been synthesized in which the fullerene moiety, far from being innocent, plays a leading role as a multi-site carbon-based hydrogen transfer catalyst. [60]Fullerene, analogously to NAD(P)H, acts as a hydrogen borrowing molecule by the reversible uploading of hydrogen. The highly efficient reduction of ketones with isopropanol as hydrogen donor, or the N-alkylation of amines with alcohols catalyzed by iridium-fullerene represent the first examples of fullerenes as catalysts in chemical reactions.
References
1. a) Maroto, E. E.; Izquierdo, M.; Reboredo, S.; Marco-Martínez, J.; Filippone, S.; Martín, N. Acc. Chem. Res.
2014, 47, 2660. b) Filippone, S.; Maroto, E. E.; Martín-Domenech, A.; Suárez, M.; Martín, N. Nat. Chem.
2009, 1, 578; c) Maroto, E. E.; Mateos, J.; Garcia-Borràs, M.; Osuna, S.; Filippone, S.; Herranz, M. Á.; Murata, Y.; Solà, M.; Martín, N. J. Am. Chem. Soc.
2015, 137, 1190.
2. a) Lebedeva, M. A.; Chamberlain, T. W.; Khlobystov, A. N. Chem. Rev. 2015, 115 (20), 11301; (b) Matsuo, Y.; Nakamura, E. Chem. Rev.
2008, 108, 3016.

Figure 1
Backside Anti-Reflecting Absorbing Layer Microscopy for in Situ Graphene Imaging and Modification
Authors: Campidelli Stephane , Cornut Renaud , Derycke Vincent , Ausserré Dominique 
Published: February 2020

Two-dimensional nanomaterials and their association into 2-D heterostructures have been extensively studied for the last couple of years. Thus, the development of new, versatile, high-resolution visualization and placement techniques is highly desirable. It is well known that a single layer of graphene can be observed under optical microscopy on Si/SiO2 substrates because of interference effects when the thickness of silicon oxide is optimized.1,2However, differentiating monolayers from bilayers remains a challenge and advanced techniques like Raman mapping, Atomic Force or Scanning Electron Microscopy (AFM, SEM) are more suitable to observe monolayers of graphene. Raman mapping and AFM are relatively slow and SEM is operated in vacuum so that in all cases real-time experiments including chemical modifications are not accessible. Therefore, the development of techniques that combine the large scale and speed of SEM, the topological information of AFM and the simplicity optical microscopy may greatly facilitate the study of nanomaterials.
In our group, we are interested in particular forms of graphene derivatives which are graphene oxide (GO) and reduced graphene oxide (r-GO). While a single layer of graphene absorbs 2.3% of the incident light,3 graphene oxide monolayer exhibits a weaker light absorption that makes it almost impossible to distinguish on Si/SiO2 surface. In 2007, Ruoff and co-workers were able to observe directly GO flakes using confocal microscopy; they even obtained higher contrast for GO than for graphene on Si/SiO2. For that they optimized a substrate by depositing silicon nitride layers from 60 to 70 nm on silicon.4

Here we introduce a novel optical microscopy technique based on the use of Anti-Reflecting and Absorbing (ARA) layers yielding to ultra-high contrast reflection imaging of graphene monolayers in air or in water. We name this technique “Backside Absorbing Layer Microscopy” (BALM) and we illustrate its efficiency by in-situ imaging graphene oxide (see Figure) and its chemical modification.
Reference:
(1) Blake, P.; Hill, E. W.; Castro Neto, A. H.; Novoselov, K. S.; Jiang, D.; Yang, R.; Booth, T. J.; Geim, A. K. Appl. Phys. Lett.
2007,
91, 063124.
(2) Roddaro, S.; Pingue, P.; Piazza, V.; Pellegrini, V.; Beltram, F. Nano Lett.
2007,
7, 2707-2710.
(3) Nair, R. R.; Blake, P.; Grigorenko, A. N.; Novoselov, K. S.; Booth, T. J.; Stauber, T.; Peres, N. M. R.; Geim, A. K. Science
2008,
320, 1308.
(4) Jung, I.; Pelton, M.; Piner, R.; Dikin, D. A.; Stankovich, S.; Watchrotone, S.; Hausner, M.; Ruoff, R. S. Nano Lett.
2007,
7, 3569-3575.

Figure 1
(Invited) Bi-thermoelectricity in Fullerene-based Molecular Junctions
Authors: Agraït Nicolás , Rincón-García Laura , Evangeli Charalambos 
Published: February 2020

Using a modified scanning tunnelling microscope we measure simultaneously the thermopower and conductance of single-molecule junctions of fullerenes connected to gold electrodes. We find that in contrast with C60 (1) the endohedral fullerene Sc3N@C80 (2) forms jnctions in which the magnitude and sign of the thermopower depend strongly on the orientation of the molecule and on applied pressure. We demonstrate that the origin of this exceptional behavior is the presence of a sharp resonance near the Fermi level created by the Sc3N inside the fullerene cage, whose energetic location, and hence the thermopower, can be tuned by applying pressure. These results reveal that Sc3N@C80 is a bi-thermoelectric material, exhibiting both positive and negative thermopower, and provide an unambiguous demonstration of the importance of transport resonances in thermoelectric performance of organic materials.
(1) C. Evangeli et al, Nanoletters 2013, 13, 2141.
(2) L. Rincon-Garcia et al, Nature Materials 2015 doi:10.1038/nmat4487.

Figure 1
Shear Assisted Electrochemical Exfoliation of Graphite Tographene
Authors: Shinde Dhanraj 
Published: February 2020

The exfoliation characteristics of graphite as a function of applied anodic potential (1 to 10 V) in
combination with shear field (400 to 74000 s-1) has been studied in a custom-designed microfluidic
reactor. Systematic investigation by atomic force microscopy (AFM) indicates that at
higher potentials, thicker and more fragmented graphene sheets are obtained, while at potentials
as low as 1 V, pronounced exfoliation is triggered by the influence of shear. The shear-assisted
electrochemical exfoliation process yields large (~10 micron) graphene flakes with a high proportion of single, bi-layer,
and tri-layer graphene, and small ID/IG ratio (0.21 to 0.32). This method comprises intercalation of sulphate and hydroxyl ions followed by exfoliation using
shear induced by a flowing electrolyte. Our findings on the crucial role of hydrodynamics in
accentuating the exfoliation efficiency suggests a safer, greener and more automated method for
production of high quality graphene from graphite.

Figure 1
Controlled Growth of Graphene on Porous Silicon
Authors: Ge Daohan , Qian Dongliang , Chen Guanggui 
Published: February 2020

Graphene as the most thin, two-dimensional atomic crystal material, which is made of sp2 hybrid carbon atoms, has unique properties, such as mechanical stiffness, strength and elasticity, very high electrical and thermal conductivities. These unusual properties have caused the emergence of tantalizing potential applications, ranging from field effect transistors to chemical and biochemical sensors. On the other hand, As an important porous material, more and more attention has been paid for porous silicon produced by electrochemical etching due to its wide applications
In this work, we demonstrate a hybrid material combining graphene and porous silicon together and focus on the study of the properties of porous silicon based graphene materials. A series of porous silicon substrates with different pore sizes are fabricated through electrochemical etching by varying the current density. Then, graphene films are transferred to the porous silicon substrate. The effects of morphology and porosity of porous silicon on the properties of graphene have been investigated.
In our experiment, highly-doped n-type samples (0.01-0.02 Ωcm, 300 μm- thick, CZ-grown, (1 0 0)-oriented and polished) were used. A set of anodizing experiments were performed at different applied current densities (50-500 mA/cm2), and the anodizing solution was composed of 48% aqueous HF ,30wt.% aqueous H2O2 and 99.7vol.% ethanol in a variety of concentrations. Corrosion time is set to 5 min. Next, graphene is transferred to the surface of porous silicon substrate by the transferring process. Fig. 1a shows the top-view SEM picture of the pores covered with graphene. The porous silicon was fabricated by anodization for 5 min with current density of 150 mA/cm2. Micro-Raman spectrometer was used to confirm the quality of graphene. Fig. 1b shows the result of Raman measurement of the porous silicon based graphene. The G and 2D peaks locate at 1588 cm-1 and 2683 cm-1, respectively, demonstrating the graphene is well transferred to the porous silicon substrate with good quality.

Figure 1
Graphene and Graphene Oxide in Low Temperature Fuel Cells for Enhanced Performance.
Authors: Holmes Stuart Martin , Balakrishnan Prabhuraj 
Published: February 2020

Graphene, Reduced Graphene Oxide (RGO) and Graphene Oxide have been incorporated into PEM fuel cell Membrane Electrode Assemblies (MEA’s).
Graphene Oxide (GO) has been added to the MEA of a Direct Methanol Fuel Cell (DMFC) providing additional tortuosity and hence reduced methanol permeability, the optimisation of the GO loading has led to superior performance(up to 50% improvement in power density) when compared to a standard DMFC.
The addition of CVD graphene onto the MEA of a DMFC has demonstrated no change in proton conductivity but lower methanol permeability, supporting the hypothesis of CVD graphene as a proton conductor and again increasing the power density of the DMFC by up to 50%.
Chemical Functionalization of N-Doped Graphene
Authors: Langa Fernando , Gomez-Escalonilla María J. , Barrejon Myriam , Primo Ana , García Hermenegildo 
Published: February 2020

Due to its unique physical and chemical properties, graphene is currently considered an ideal material for applications in electronic devices,[1] however, the lack of a band gap limits its application in the semiconducting field. Breaking the symmetry of graphene through the introduction of electron donor or acceptor heteroatoms into the graphene lattice has been proposed as a mean to controllably shift the electronic bands of graphene.[2] In this regard, nitrogen doping has been intensively studied, due to the facile doping process and the effective modulation of the electronic properties while maintaining high electrical conductivity. Because of the electron-rich nature of nitrogen, it leads to n-type electronic doping and the Fermi level is shifted above the Dirac point,[3] modifying the band gap in the material. Doped graphene could also be modified by specific reactions at the dopant heteroatom through different routes, depending on the nucleophilic or electrophilic nature of the dopant element.[4] In the particular case of graphene doped with nitrogen, N atoms could act as anchoring sites for N-alkylation reactions.[5]
In this lecture we present recent advances carried out in our group, concerning the chemical modification of N-doped graphene with different electron donor and electron acceptor moieties, as well as the influence in the electronic properties of the starting material.

[1] Z. Yang, J. Ren, Z. Zhang, X. Chen, G. Guan, L. Qiu, Y. Zhang and H. Peng, Chem. Rev.,
2015, 115, 5159.
[2] H. Wang, T. Maiyalagan and X. Wang, ACS Catal.,
2012, 2, 781.
[3] M. Wu, C. Cao and J. Jiang, Nanotechnology, 2010, 21, 505202.
[4] S. Navalón, A. Dhakshinamoorthy, M. Álvaro and H. García, Chem. Rev., 2014, 114, 6179.
[5] M. Barrejón, A. Primo, M. J. Gómez-Escalonilla, José Luis G. Fierro, H. García and F. Langa, Chem. Commun., 2015, 51, 16916.
The P- and N- Doping of Graphene through Specific Plasma Processing
Authors: Narayanan Rajaram , Zaretski Aliaksandr , Lipomi Darren , Bandaru Prabhakar R 
Published: February 2020

The interfacial capacitance of graphene, the fundamental building block of carbon based high surface area electrodes, is limited by its quantum capacitance (CQ
).1,2 We will show that the CQ
of single-layer and few-layer graphene can be increased, e.g., through doping using specific plasma processing techniques. We will first show that the density of states and consequently the carrier concentration of graphene can be increased via argon based plasma processing.3 Subsequently, we will suggest ways to modulate the effective doping (both, p- and /n- type) through subjecting the graphenes to plasmas consisting of differently charged ions (Argon and Nitrogen). We will indicate extensive Raman spectroscopy and electrochemical characterization, to clearly elucidate the nature of plasma doping and its effect on the quantum capacitance.4 The implications of plasma processing to the resistance change and the power density of graphene based electrochemical capacitors will be indicated. The work is of considerable scientific and technological interest.5, in terms of evaluating the underlying charge storage mechanisms of graphene for potential use in energy storage devices.

References:

1. J. Xia, F. Chen, J. Li, and N. Tao, Nat. Nanotechnol., 4, 505–509 (2009).
2. H. Yamada and P. R. Bandaru, Appl. Phys. Lett., 102, 173113 (2013)
3. R. Narayanan et al., Nano Lett., 15, 3067–3072 (2015).
4. A.Das et al., Nat. Nanotechnol., 3, 210–215 (2008).
5. L. L. Zhang et al., Energy Environ. Sci., 5, 9618 (2012).
(Invited) Hybrid Organic/Inorganic Bismuth-Based Materials for Solution-Processed Thin-Film Photovoltaics
Authors: Fabian David M , Ardo Shane 
Published: February 2020

The lead–halide-based hybrid organic–inorganic perovskite material, methylammonium lead iodide (MAPbI3), has recently garnered increased attention among researchers worldwide as a promising photovoltaic material. As of 2015, perovskite photovoltaic devices have achieved laboratory efficiencies in excess of 20%. Many challenges regarding the stability and toxicity of the MAPbI3 material, however, remain at the forefront of current research. Due to the toxicity of lead and a purely fundamental interest in dicationic organic groups in place of monocationic MA+, less toxic dicationic bismuth–halide materials are the object of my research. The bismuth–iodide networks of the materials under investigation were hypothesized to form chains that extend in one dimension, whereas in MAPbI3 the lead–iodide network forms a lattice in three dimensions. If a small dicationic organic group is incorporated into the structure, however, it was hypothesized that the bismuth–iodide chains are in close enough proximity to each other to provide for long-range charge transport in three dimensions, similar to that observed in MAPbI3.
A library of dicationic bismuth–halide materials has been investigated to determine optimal dicationic groups based on film quality, optical band gap, and current density versus potential (J–E) characteristics. XRD data of dicationic bismuth–halide thin films have suggested larger average crystal grain size than MAPbI3 thin films and SEM images of dicationic bismuth–halide thin films have indicated greater surface coverage than MAPbI3 thin films. UV–Vis absorption spectra of dicationic bismuth–halide thin films have revealed onsets of light absorption in the range of 565 nm to 620 nm, which correspond to optical band gaps between 2.2 and 2.0 eV. J–E measurements have indicated that dicationic bismuth–halide photovoltaic devices exhibit a photovoltage of almost 400 mV (Fig. 1). Thermal stability tests suggest that dicationic bismuth–halide thin films are significantly more robust than MAPbI3 thin films. Large single crystals have been obtained for a dicationic bismuth–halide material, and single-crystal XRD data have indicated that the material formed binuclear clusters of Bi2I10
4-, with two dicationic organic groups and two H2O molecules associated with each binuclear cluster. To my knowledge, this represents the first report of a crystal structure of this material. Efficient photovoltaic devices featuring a dicationic bismuth–halide material may offer a more environmentally friendly, stable alternative to MAPbI3 photovoltaic devices that currently dominate emerging photovoltaic technology research.

Figure 1
(Invited) Cost-Effective Anthryl Dyes for Dye-Sensitized Cells Under Dim Light
Authors: Lin Ching-Yao 
Published: February 2020

A series of anthracene-based organic dyes were prepared via cost-effective synthetic procedures for dye-sensitized cell application. UV-visible and fluorescent spectra, electrochemical properties as well as photovoltaic performance of the dyes were studied. Under one sun (100 mW/cm2), the AN-3 small cell (area = 0.16 cm2) outperforms others in the series. Under a dim light condition, the AN-3 modules (area = 36 cm2, manufactured by TDP, Taiwan) showed PCE comparable to that of the Z907 modules. After optimizing the synthetic procedure, we found that AN-3 can be manufactured at a fairly low price.
Reference: J. Phys. Chem. C 2015, 119, 24282−24289

Figure 1
(Invited) Linear and Star-Shaped Phthalocyanine-Acceptor Systems
Authors: Sastre-Santos Angela , Follana Jorge , Molina Desiré , Blas-Ferrando Vicente M. , Ortiz Javier , León Martín M. , Fernández-Lázaro Fernando 
Published: February 2020

Linear and star-shaped molecules based on p-conjugated chromophores containing a polycyclic aromatic core, with the adequate HOMO LUMO energy orbitals, have generated significant interest for use in optoelectronic devies due to their properties of isotropic absorption and strong tendency to stack into quasi-1D columns, thus generating a preferred charge transporting pathway.[1]
The majority of organic semiconductors display hole-transporting properties (p-type), with the phthalocyanines (Pcs)[2] as one of the most representative families. Donor-acceptor systems formed by electron-rich groups conjugated with electron-poor moieties that can organize themselves into columns are good candidates to show ambipolar behavior. For this reason, the fussion of p-type phthalocyanines with some other n-transporting materials might give rise to different grade of conjugation between both systems affording potential candidates for ambipolar character. The synthesis of this type of systems has been scarcely described to date due to the difficulties to synthetize phthalocyanines with the adequate substituents for the condensation with acceptor moieties.
Herein, we will emphasize the progress in the chemistry of donor-acceptor conjugated Pcs-acceptor arrays (Figure 1)[3] with particular attention being focused on systems that exhibit attractive electronic, optical and electrochemical properties, thus allowing them to be considered as promising candidates for future applications such as NIR dyes, photovoltaic dyes, nonlinear optical materials and nano-electronic devices.

Acknowledgements. This work has been supported by the Spanish Ministerio de Economía y Competitividad, Generalitat Valenciana and the European FEDER funds (grants CTQ2011-26455, CTQ2014-55798-R, PROMETEO 2012/010 and ISIC/2012/008)

References:

(1) (a) Forrest, S. R. Nature, 2004, 428, 911. (b) Shirota, Y.; Kageyama. H. Chem. Rev. 2007, 107, 953.
(2) (a) de la Torre, G.; Claessens, C. G.; Torres, T. Chem. Commun. 2007, 2000. (b) Martin-Gomis, L.; Fernández-Lázaro, F.; Sastre-Santos, A. J. Mater. Chem. A 2014, 2 15672.
(3) (a) Blas-Ferrando, V. M.; Ortiz, J.; Campos, V.M.; Mas-Torrent, M.; Fernandez-Lázaro, F.; Sastre-Santos, Á.; submitted. (b) Follana-Berná, J, Inan, D.; Blas-Ferrando, V. M.; Gorczak, N.; Fernández-Lázaro, F.; Grozema, F.; Sastre-Santos, Á. in preparation.
Figure 1. Chemical structure of different conjugated phthalocyanine-acceptors arrays

Figure 1
(Invited) Self-Organization and Cross-Linking of Tetraazaporphyrin Derivatives
Authors: Eichhorn S. Holger , Abdulhamied Elmahdy , Ahmida Mohamed M , Kayal Himadri 
Published: February 2020

Despite the many advances in the design of porphyrin derivatives for Langmuir Blodgett (LB) films, the formation of compressible monolayers with a flat-on orientation of the macrocycle has remained elusive. Presented here is the synthesis of tetraazaporphyrins (TAPs) that contain different types of functional groups to enhance their amphiphilic properties and stabilize their face-on orientation at the air-water interface. Some of these compounds also display self-organization in their bulk phase. The new design of these TAPs combines several structural features of TAPs we previously reported, which contain eight identical side-chains with terminal carboxylic acid, azide, and acetylene groups.1,2 Attachement of both carboxylic acid and azide or acetylene groups generated TAPs that form stable Langmuir and LB monolayers with flat-on orientation of the macrocycle. We also succeeded in cross-linking these Langmuir and LB monolayers via cycloaddition of azide and acetylene groups (click chemistry) in the presence Cu catalyst and thermally.
1. M. M. Ahmida, S. Dufour, Hui–Sheng Li, H. Kayal, R. Schmidt, C. E. DeWolf and S. H. Eichhorn, 2013, Soft Matter (9,3) 811-9, DOI:10.1039/c2sm27064a.
2. Himadri Kayal, M. M. Ahmida, S. Dufour, H. Taing, and S. H. Eichhorn, 2013, J. Mater. Chem. C, (1,42) 7064-7072, DOI: 10.1039/C3TC31588F.