bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Sumanene: A C3-Symmetric Fragment Structure of C60
Authors: Sakurai Hidehiro 
Published: February 2020

Bowl-shaped pi-conjugated compounds including partial structure of fullerenes, which are called "buckybowls", are of importance not only as model compounds of fullerenes but also as their own chemical and physical properties. Two pristine structure are known, C5v-symmetric corranulene and C3v-symmetric sumanane. One of the characteristic features of buclybowls is that they possess terminal C-H structure, which can be chemically transfered to the functional groups to control the chemical/physical structure of the bowls with ease. In particular, three benzylic positions of sumanene are highly expected to functionalize to other groups such as carbonyl group, which can tune the electrochemical character of the bowls. For example, sumanenetrione exhibits stepwise multi-electron reduction process. Cyclic voltammograms of the stepwise first and second one-electron reduction showed reversible waves with associated reduction potentials which were almost equivalent to those of C60.
(Invited) Long-Lived Charge Separated States Exclusively from the Triplet Excited States in Palladium Porphyrin-Fullerene Conjugates
Authors: D'Souza Francis , Obondi Christopher , Churchill Brittani , Lim Gary N. , Poddutoori Prashanth , van der Est Art 
Published: February 2020

Molecular engineering of donor-acceptor conjugates to control their photoinduced processes to yield the much desired long-lived charge separated states has been one of the major goals in artificial photosynthesis. The charge separated states of sufficient lifetime and stored energy are key in ultimately driving the photocatalytic processes of either light-to-electricity conversion or light-to-fuel production. In simple donor-acceptor dyads, charge separation from the singlet excited donor or acceptor due to rapid charge recombination process results in a short-lived charge separated state of singlet spin character. Utilization of high energy triplet sensitizers instead of the traditionally employed singlet sensitizers could be an elegant approach to generate long-lived charge separated states. The radical ion-pairs of triplet spin character charge recombine to the ground state slowly due to spin forbidden nature of the process. However, witnessing such a process purely from the triplet excited state without the interference of the singlet excited state and other competing photochemical events such as excitation energy transfer has been challenging to establish.
Here, we report our strategy to observe electron transfer exclusively from the triplet excited state of the donor in PdP-C60 dyads (see figure below). Using transient absorption spectral studies operating at different timescales and time-resolved electron paramagnetic resonance (TR-EPR) studies, photoinduced electron transfer from 1PdP* to C60 leading to the formation of PdP•+-C60
•- charge separated state of singlet spin character has been witnessed in 2 (instead of triplet-triplet energy transfer observed in 1
1) due to the close proximity of the donor and acceptor entities. In contrast, by lowering the energy of the [(TPA)3PdP]•+-C60
•- state owing to the presence of electron rich TPA entities (facile oxidation) compared to that of 3C60*, electron transfer from 3(TPA)3PdP* to C60 leading to [(TPA)3PdP]•+-C60
•- charge separated state of triplet spin character with lifetime in the microsecond range has been observed in 3 in polar solvents. Results of these findings and its significance will be highlighted.

C. Obondi, G. N. Lim, F. D’Souza, Triplet-Triplet Excitation Transfer in Palladium Porphyrin – Fullerene and Platinum Porphyrin – Fullerene Dyads’ J. Phys. Chem. C 2015, 119, 176-185.

Figure 1
(Invited) Decorating Nanocarbons with Perylenediimide Systems
Authors: Sastre-Santos Ángela , Pla Sara , Martin-Gomis Luis , Fernández-Lázaro Fernando 
Published: February 2020

Carbon-based nanostructured materials (fullerenes, carbon nanotubes or graphene, to name a few) are known to show electron-acceptor properties at the molecular scale, together with high values of electron mobilities in bulk. Thus, its implementation in active materials is an important issue in order to develop organic efficient full optoelectronic devices. One of the strategies employed in the improvement of the interesting optoelectronic properties of carbon nanostructures, is the doping, either in a covalent or a non-covalent way, with specially designed electron-donor/light harvesting moieties. These moieties act like light collectors, exciting themselves and promoting an electron to a higher energy state, which is rapidly deactivated through electron and/or energy transfer processes to the carbon-based nanostructure.
Here we present different strategies for the covalent and non-covalent functionalization of nanocarbon materials. In these examples, the decorating agents, specially designed perylenediimides[1-4] (Figure 1) and others, whose electronic character has been modulated through the introduction of different substituents, are successfully employed to improve the light absorption behaviour in the UV and NIR regions of the, in principle, unabsorbing carbon nanoforms, thus yielding hybrid materials with potential applicability like active layers in organic photovoltaic 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

Martín-Gomis, L.; Rotas, G.; Ohkubo, K.; Fernández-Lázaro, F.; Fukuzumi, S.; Tagmatarchis, N.; Sastre-Santos, Á. Nanoscale
2015, 7, 7437-7444..

Barrejón, M.; Pla, S.; Berlanga, I.; Gómez-Escalonilla, M. J.; Martín-Gomis, L.; Fierro, J. L.; Zhang, M.; Yudasaka, M.; Iijima, S.; Gobeze, H. B.; D’Souza, F.; Sastre-Santos, Á.; Langa, F. J. Mater.Chem. C.
2015, 3, 10215-10224.

Pla, S.; Niemi, M.; Martín-Gomis, L.; Fernández-Lázaro, F.; Lemmetyinen, H.; Tkachenko, N. V.; Sastre-Santos, Á. Phys.Chem. Chem. Phys. Accepted.

Martín-Gomis, L.; Karousis, N.; Petsalakis, I. D.; Ohkubo, K.; Fernández-Lázaro, F.; Tagmatarchis, N.; Fukuzumi, S.; Sastre-Santos Á. Submitted.

Figure 1.
Chemical structures of a) [60]Fullerene-Perylenediimide (C60-PDI, DB-1,7-Pyr-PDI-C60) and b) Double Wall Carbon Nanotube-Perylenedimide (DWCNT-PDI).

Figure 1
(Invited) Transition Metal Dichalcogenides: Growth and Characterization
Authors: Bartels Ludwig 
Published: February 2020

I will present the growth of transition metal dichalcogenides films (MoS2, MoSe2, WS2, WSe2, MoTe2) and their alloys via chemical vapor deposition and high vacuum techniques.[1] I will highlight the growth of the material on different substrate and the ensuing variation of properties before describing how post-growth processing allows chalcogen exchange towards local change of bandgap.[2] Deposition onto functional substrates - such as ferroelectrics - permits further local modification of the material properties toward device applications.[3]
[1] J. Mann, et al., Advanced Materials 26 1399 (2014).
[2] Q. Ma, et al., Acs Nano 8 4672 (2014).
[3] A. Nguyen, et al., Nano Lett 15 3364 (2015).
(Invited) Towards Large Scale Growth of Two-Dimensional Transition Metal Dichalcogenides
Authors: Grossman Jeffrey C , Ferralis Nicola 
Published: February 2020

Investigations of 2D materials have increased substantially, as they have been shown to exhibit a wide range of novel electronic properties. Transition metal dichalcogenides (TMDCs), depending on the polytype and number of d-electrons, can exhibit metallic, semi-metallic, and semiconducting behavior. In addition, enhancements to optical behavior, especially in the form of absorption, have been observed in these 2D materials. In contrast to the well-known 2D material graphene, the presence of a bandgap, as well as device performance on transistors fabricated using certain TDMCs, indicate that they could serve as possible successor materials to Si. The successful, industrial deployment of such materials however relies on the ability of large scale synthesis of high quality TMDCs.

Large scale, high quality growth of graphene has been enabled by successful application of vapor deposition techniques such as chemical vapor deposition (CVD). In extending the quest for high quality, large scale synthesis of 2D TMDCs, similar vapor deposition techniques have been explored, mainly CVD. Yet, high quality extended 2D TMDCs are still lacking.
Atomic Layer Deposition (ALD) can be instrumental to the production of large area, two-dimensional materials, and simultaneously offer superior alternatives to exfoliating methods. In this work we consider the transition metal dichalcogenide MoS2 – specifically its growth starting from an ALD route comprised of (tBuN)2(NMe2)2Mo and O3 to produce MoO3, followed by subsequent sulfurization steps to produce MoS2. Data from a variety of direct measurement techniques, including atomic force microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy, for determining the existence and optical properties of monolayer MoS2 will be presented.
(Nanocarbons Division SES Young Investigator Award) Making Graphene Resist Aggregation
Authors: Luo Jiayan 
Published: February 2020

Graphene-based sheets have stimulated great interest in many scientific disciplines and shown promise for wide potential applications. Among various ways of creating single atomic layer carbon sheets, a promising route for bulk production is to first chemically exfoliate graphite powders to graphene oxide (GO) sheets, followed by reduction to form chemically modified graphene (CMG). Due to the strong van der Waals attraction between graphene sheets, CMG tends to aggregate. The restacking of sheets is largely uncontrollable and irreversible, thus it reduces their processability and compromises properties such as accessible surface area. Strategies based on colloidal chemistry have been applied to keep CMG dispersed in solvents by introducing electrostatic repulsion to overcome the van der Waals attraction or adding spacers to increase the inter-sheet spacing. In this dissertation, two very different ideas that can prevent CMG aggregation without extensively modifying the material or introducing foreign spacer materials are introduced.
The van der Waals potential decreases with reduced overlapping area between sheets. For CMG, reducing the lateral dimension from micrometer to nanometer scale should greatly enhance their colloidal stability with additional advantages of increased charge density and decreased probability to interact. The enhanced colloidal stability of GO and CMG nanocolloids makes them especially promising for spectroscopy based bio-sensing applications.
For potential applications in a compact bulk solid form, the sheets were converted into paper-ball like structure using capillary compression in evaporating aerosol droplets. The crumpled graphene balls are stabilized by locally folded π-π stacked ridges, and do not unfold or collapse during common processing steps. They can tightly pack without greatly reducing the surface area. This form of graphene leads to scalable performance in energy storage. For example, planer sheets tend to aggregate and lose surface area. So their capacitive performance tends to decrease with increased loading level. But the crumpled balls can resist aggregation and retain high capacitance at high loading level. The crumpled graphene balls can be also used as expandable shells for wrapping lithium ion battery anode materials such as Si nanoparticles, which can accommodate their expansion/contraction without facture, and thus greatly improve the coulombic efficiency of the anode.
Synthesis and Characterization of Graphene Flakes to be Used in the Development of Electrodes for Li-Ion Batteries
Authors: Díaz Francisco , Campo Teresa , Cotto María , Márquez Francisco , Morant Carmen , Elizalde Eduardo 
Published: February 2020

One of the main problems in our society is the energy production and storage. Ion-Li batteries are commonly used as an alternative for energy production but have the disadvantages of a poor recharged cycles and the possibility of fire. Researches are done to develop efficient anodes and cathodes for batteries and one of the possible alternatives is the use of graphene. Due to its unique planar structure, transparency, mechanical strength, thermal properties, and electronic conductivity, graphene is a very promising material for nanoelectronic devices, sensors, energy-storage and/or transparent conducting electrodes applications. The exceptional properties of graphene are a consequence of the continuous network of hexagonally arranged sp2-bonded carbon atoms in a 2D-structure. Among the different synthesis processes to obtain graphene (i.e. chemical exfoliation, mechanical cleavage, epitaxial growth or chemical vapor deposition-CVD), the last one (CVD) is considered as the most promising procedure to obtain continuous graphene flakes, with very low level of defects. Although the presence of unwanted byproducts and structural damages is unavoidable, this method is one of the most suitable for large-scale and controllable synthesis of graphene. Commonly, the synthesis of graphene by CVD requires a copper or nickel sheet as substrate, and alcohols or methane as carbon source.
In this research, a CVD method, slightly modified with respect to the standard procedure, has been used to obtain graphene flakes (see Figure 1). Thus, a mixture of ethanol:N2:H2 was used to obtain a blue plasma at high temperature, responsible for the synthesis of graphene. A complete analysis of the as-synthesized graphene flakes has been performed using a combination of tools including scanning and transmission electron microscopies (SEM and TEM), Raman spectroscopy, X-ray photoemission spectroscopy (XPS), atomic force microscopy (AFM) and infrared spectroscopy (FT-IR).

Figure 1
Electrochemical Water Treatment Using Graphene, Graphene Foam and Graphene / Metal Oxide Composites
Authors: Roberts Edward , Sharif Farbod , Gagnon Luke 
Published: February 2020

Combining adsorption with electrochemical oxidation has been shown to be effective for the removal and oxidation of dissolved and dispersed organic contaminants from water, using a graphite flake adsorbent. In order to increase the adsorption capacity, we have investigated the use of graphene based adsorbents, which have high specific surface area combined with electrochemical activity. We have prepared and tested reduced graphene oxide (RGO), graphene foam and graphene metal oxide composite materials. RGO offer significantly higher adsorptive capacity than graphite flake. Similarly graphene foam was found to have a high adsorption capacity, although the adsorption kinetics were poor due to the slow diffusion of conatminants into the foam pores. A graphene foam would be more readily separated from the treated water and further work is planned to determine whether a flow through treatment process can be used to overcome the slow adsorption kinetics. However, during electrochemical oxidation, the structural integrity of the foam was compromised after only 1 or 2 cycles, presumably due to oxidation of the graphene. A graphene / iron oxide composite was preapred with ferromagnetic characteristics to enable separation from the treated water. The adsorption capcity was slightly reduced, but the electrochemcial regeneration performance was good. Oxidation of graphene remains a challenge, and work is ongoing to explore the use of graphene / titanium dioxide composites. The TiO2 will catalyse the organic oxidation and may also protect the graphene from oxidation.
Understanding the Binding Mechanism for Catalysis and Energy Storage
Authors: Liu Yuanyue , Wood Brandon , Lou Jun , Ajayan Pulickel M , Yakobson Boris I. , Goddard William A 
Published: February 2020

Many catalytic and energy-storing reactions occur through the binding of substances. Understanding the binding mechanism could help design better materials/devices. Using atomistic theory, we show that (i) the Li capacity of pristine graphene is lower than that of graphite, despite its higher surface area [1]; (ii) the binding between Li and C can be described by a ‘states-filling’ model [2]; (iii) This model is used to study the electrochemical hydrogen production, and leads to the discovery of a self-optimizing and highly-active metal dichalcogenide catalyst, whose extraordinary performance relies on the surface-activity, different from conventional Mo and W dichacogenides which have only edge active [3]; (iv) why graphite has a low capacity for Na while high capacities for other alkali-metals, an important question for the development of Na-ion batteries [4]. These progresses demonstrate the power of atomistic theory in aiding the understanding and designing materials.
[1] Y. Liu, V. I. Artyukhov, M. Liu, A. R. Harutyunyan, B. I. Yakobson, J. Phys. Chem. Lett.
2013, 4, 1737-1742.
[2] Y. Liu, Y. M. Wang, B. I. Yakobson, B. C. Wood, Phys. Rev. Lett.
2014, 113, 028304.
[3] Y. Liu, K. P. Hackenberg, J. Wu et al, submitted.
[4] Y. Liu, B. Merinov, W. A. Goddard, submitted.
(Invited) Conjugated Polymer Spherical Microcavities for Energy Conversion
Authors: Yamamoto Yohei 
Published: February 2020

Optical microcavities play an important role for the next-generation light technology. Recently, we succeeded in fabricating spherical microcavities from conjugated polymers (CPs) by simple self-assembly process and found that the microcavities show whispering gallery mode (WGM) resonant photoemission [1-4]. The CP-based microcavities are superior to conventional microcavities in points of simple fabrication process, function as both cavity and emitter, high photo-stability and optical gain, and potent use for electrically-driven WGM and lasers. In this presentation, we demonstrate the WGM-mediated intersphere light propagation and cascade-like energy conversion, in which the confined modes realize directional light energy transport between adjacent spheres and subsequent color conversion.
[1] T. Adachi et al., J. Am. Chem. Soc. 2013, 135, 870-876. [2] L. Tong et al., Polym. Chem. 2014, 5, 3583-3587. [3] K. Tabata et al., Sci. Rep.
2014, 4, 5902/1-5. [4] S. Kushida et al., Macromolecules
2015, 48, 3928-3933.
(Invited) Carbon Nanotube-Templated Synthesis of Covalent Porphyrin Network for Oxygen Reduction Reaction
Authors: Campidelli Stephane , Hijazi Ismail , Bourgeteau Tiphaine , Cornut Renaud , Morozan Adina , Jousselme Bruno 
Published: February 2020

The fabrication of functional hybrid materials that preserves and combines the properties of their building blocks is a central issue of nanosciences. Among the different classes of nanomaterials, carbon nanotubes are promising for electronics, catalysis and composite applications. Within the context of sustainable development and renewable energy, we and others envisioned the use of functionalized or doped carbon nanotubes in electrocatalytic systems.1
,
2 In such systems, the catalytic sites need to be supported on conducting materials. Carbon nanotubes, thanks to their electrical conductivity and their high surface area appear as the ideal material for that purpose.
In actual proton exchange membrane fuel cell devices (PEMFC), the reactions at the electrodes and in particular the reduction of oxygen is performed by platinum nanoparticles. The cost of platinum encourages the development of new catalysts based on non-noble metals. In nature, the reduction of oxygen is performed by iron porphyrins in the active center of enzymes. Thus bio-inspired catalysts based on cobalt or iron macrocycles have been extensively studied for oxygen reduction reaction (ORR).3
,
4

Here, we describe the formation of a covalent network of porphyrins around MWNTs. Our approach is based on adsorption of ethynylporphyrins followed by the dimerization of the triple bonds. The nanotube acts as a template for the formation of the polymeric layer. The nanotube hybrids were characterized and tested for the ORR in a series of electrochemical measurements in acidic conditions. Compared to similar systems in which monomeric porphyrins are simply physisorbed, the nanotube hybrib showed a higher activity, a higher current density, a lower overpotential and a four electrons reaction pathway.5

References
(1) Zhang, W.; Sherrell, P.; Minett, A. I.; Razal, J. M.; Chen, J. Energy Environ. Sci.
2010,
3, 1286-1293.
(2) Morozan, A.; Jousselme, B.; Palacin, S. Energy Environ. Sci.
2011,
4, 1238-1254.
(3) Zagal, J. H.; Griveau, S.; Silva, J. F.; Nyokong, T.; Bedioui, F. Coord. Chem. Rev.
2010,
254, 2755-2791.
(4) Morozan, A.; Campidelli, S.; Filoramo, A.; Jousselme, B.; Palacin, S. Carbon
2011,
49, 4839-4847.
(5) Hijazi, I.; Bourgeteau, T.; Cornut, R.; Morozan, A.; Filoramo, A.; Leroy, J.; Derycke, V.; Jousselme, B.; Campidelli, S. J. Am. Chem. Soc.
2014,
136, 6348-6354.

Figure 1
(Invited) Purification of a Non-Precious Metal Oxygen Reduction Catalyst to Reveal the Active Species
Authors: Gewirth Andrew A. , Varnell Jason A. , Tse Edmund C. M. 
Published: February 2020

Despite substantial efforts to understand the structure of the active site in Fe-based non-precious metal (NPM) catalysts for the oxygen reduction reaction (ORR) in fuel cells, the identification of the active species remains elusive, impeding progress towards the development of highly active and cost efficient catalysts. We report the isolation and identification of the active Fe species in an NPM catalyst using Cl2 and H2 treatments which decrease the heterogeneity of the catalyst. The Cl2 treatment decreases catalyst activity as shown by a negative shift in the ORR onset of ca. 170 mV. Subsequent treatment with H2 restores the initial activity of the catalyst. Mössbauer spectroscopy and X-ray absorption spectroscopy show many Fe species in the as-prepared catalyst while the catalyst after the Cl2 and H2 treatments contains only reduced Fe species encapsulated by C which are highly active for the ORR.