bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) New Aqueous Two-Phase Systems for Sorting DNA-Wrapped SWCNTs
Authors: Lyu Min , Yang Juan , Li Yan , Zheng Ming
Published: February 2020

Previous studies have shown that polymer-polymer aqueous two-phase systems are very effective for DNA-wrapped SWCNTs sorting. Here we report that polymer-salt systems are also very effective. In some of the new aqueous polymer-salt two-phase systems, we can easily obtain pure SWCNTs of certain chirality from the top phase by just one-step extraction. By continuously changing the composition of the system, certain SWCNTs can also be purified from the bottom phase without using extra modulating agent. Since the polymer-salt system contains only one kind of polymer, it can greatly increase the flexibility in designing sorting processes to meet the application needs of sorted SWCNTs.
(Invited) Self-Aligned Short-Channel Heterojunction Diodes and Transistors Based on Carbon Nanotubes and Related Nanoelectronic Materials
Authors: Hersam Mark C.
Published: February 2020

Parallel self-aligned fabrication methods in modern silicon-based microelectronics have enabled sub-lithographic registration between processing steps, ultimately facilitating substantial advances in circuit complexity over the past few decades. In contrast, while carbon nanotubes and related nanoelectronic materials have shown significant potential for digital and analog electronics due to their high mobilities, ultrathin geometry, and broad range of permutations in van der Waals (vdW) heterojunctions, devices based on vdW nanoelectronic materials have not fully exploited parallel self-aligned fabrication. Here, introduce a self-aligned processing methodology that enables the realization of field-effect transistors with channel lengths below 150 nm with minimal short-channel effects and improved current saturation, as demonstrated with semiconducting carbon nanotubes and monolayer MoS2. In vdW heterojunctions, this self-aligned approach allows dual-gate electrostatic control of the carrier density in both of the constituent semiconductors while concurrently achieving independent gate control of the short-channel series transistors. Since this self-aligned methodology is compatible with a diverse range of nanoelectronic materials and can be implemented in parallel via large-area lithographic processes without sacrificing lateral spatial resolution, it is likely to impact a wide range of vdW heterojunction devices.
(Invited) Biological Imaging Using up-Conversion Photoluminescence of Carbon Nanotubes
Authors: Miyauchi Yuhei
Published: February 2020

Single-walled carbon nanotubes (SWNTs) have been considered as nearly ideal luminescent probes for deep-tissue bioimaging because of their photoluminescence in near-infrared range known as the second optical window of biological tissues [1]. Moreover, efficient phonon-assisted up-conversion photoluminescence (UCPL) in SWNTs, for which the excitation light wavelength can be longer than the emission one, has recently been discovered [2, 3]. The UCPL phenomena enable SWNTs excited at wavelengths longer than ~1050-1200 nm to emit PL shorter than 1000 nm in which standard Si-based detectors have finite sensitivity. The availability of the UCPL thus potentially enhances the usefulness of SWNTs as luminescent probes in their bioimaging applications. We will report our recent progress in whole-body imaging of living mice with negligible autofluorescence using UCPL of SWNTs. We will also discuss application of the UCPL phenomena of SWNTs for near-infrared optical thermometry.

[1] K. Welsher, Z. Liu, S. P. Sherlock, J. T. Robinson, Z. Chen, D. Daranciang, and H. Dai, Nat. Nanotechnol. 4, 773 (2009). [2] N. Akizuki, S. Aota, S. Mouri, K. Matsuda, and Y. Miyauchi, Nat. Commun. 6, 8920 (2015). [3] S. Aota, N. Akizuki, S. Mouri, K. Matsuda, and Y. Miyauchi, Appl. Phys. Express 9, 045103 (2016).

Part of this study was supported by the Research Foundation for Opto-Science and Technology, the Nakatani Foundation, and by JSPS KAKENHI Grant Number JP15H05408.
(Invited) Variance Spectroscopy Studies of Single-Walled Carbon Nanotube Aggregation
Authors: Sanchez Stephen R. , Bachilo Sergei M. , Weisman R. Bruce
Published: February 2020

Understanding aggregation in samples of dispersed, well-individualized single-walled carbon nanotubes (SWCNTs) is important for many basic studies and applications. We will describe a study that uses the recently developed technique of variance spectroscopy to monitor aggregation kinetics of SWCNTs in aqueous surfactant dispersions. Unlike other techniques used to investigate colloidal dispersions, variance spectroscopy resolves individual subpopulations in mixed samples based on their distinct fluorescence signatures. Following the addition of NaCl coagulant to unsorted SWCNT dispersions, we monitored changes in the independent particle concentrations of six semiconducting (n,m) species. These data were supplemented by time-resolved measurements of fluorescence intensity, which showed pseudo-first order kinetics that was independent of SWCNT structure and was attributed to quenching by energy transfer to metallic SWCNTs. The decreases in particle concentration directly revealed aggregation. They were found to fit reasonably well to a second-order rate law with some dependence on structure at higher salt concentrations. Finally, covariance analysis was applied to the variance data to monitor correlated spectral fluctuations arising from specific heteroaggregates. Those results showed equivalent associations between different semiconducting SWCNT species during salt-induced aggregation.
(Invited) Interfacial Functionalization of Carbon Nanostructures: From Effective Charge Propagation and Storage to Enhancement of Electrocatalytic and Bioelectrocatalytic Properties
Authors: Kulesza Pawel J
Published: February 2020

Of particular interest to the preparation of advanced materials is synthesis and characterization of carbon nanostructures (e.g. nanotubes) and noble metal nanoparticles, their stabilization (e.g. through self-assembly), as well as organization into two-dimensional arrays and controlled fabrication (e.g. through the sequential attraction) into three-dimensional network films. They can form nanosized materials with well-defined composition, structure and thickness. The interfaces can be also highly functionalized, and they can exhibit specific catalytic or unique electronic, charge storage, optical and sensing properties. We explore here the ability of inorganic structures to stabilize and derivatize metal and carbon nanostructures. Among inorganic systems, polyoxometallates of molybdenum and tungsten are attractive since they can not only adsorb irreversibly on solid surfaces but also exhibit reversible stepwise multielectron transfer reactions. The concept of the layer-by-layer formation of hybrid (organic-inorganic) assemblies composed of anionic polyoxometallate-protected carbon nanotubes (or metal nanoparticles) and ultra-thin films of positively charged conducting polymers (e.g. such as polyaniline or PEDOT) will be described and discussed here. The resulting novel composite materials have been fabricated as thin or moderately thick (µm level) films on electrode surfaces. As evidenced from STM and scanning electron microscopy, their morphology is still granular but the structure is fairly dense. Further, they are characterized by fast dynamics of charge propagation. Obviously, this research is of importance to the construction of effectively operating charge storage devices (capacitors), charge mediators (e.g. in bioelectrochemistry), molecular electronic systems and electrocatalysis. In the latter case, polyoxometallates can also be applied to stabilize and link Pt-Ru, Pt-Sn and various alloyed Pt-based nanoparticles. It is apparent from diagnostic cyclic voltammetric, rotating disk voltammetric and chronoamperometric measurements that such systems exhibit attractive properties towards electroreduction of oxygen or oxidation of alcohols (ethanol, methanol). Here, it is possible that addition of polytungstate or molybdate clusters to ruthenium or tin hydroxo species at the catalytic interface results in activating effect on dispersed platinum particles. An alternate explanation may involve a possibility of electronic effects and/or different morphologies of the catalytic films in the presence and absence of polyoxometallate.
(Invited) Development of Nanostructured Mesoporous Carbon As a Support and Catalyst for Fuel Cell Application
Authors: Pak Chanho , Lee Bong Ho , Lee Ji Yeon , Lee Seung Woo , Kim Do Hyung , You Dae Jong , Kim JI Man
Published: February 2020

In recent years, polymer electrolyte fuel cells (PEFC) using hydrogen and methanol as fuel, respectively, have been attracting interest because the application areas of PEFC is expanding in the fuel cell electric vehicle, household fuel cell and portable fuel cell [1,2]. In this fuel cells, electricity is directly generated by electrochemical reactions such as hydrogen and methanol oxidation reaction at the fuel electrode and oxygen reduction reaction(ORR) at the air electrode, thus providing a high electrical efficiency and environmentally friendly. To carry out such an electrochemical reaction in the electrode, the supported catalyst on which the active precious metal is dispersed with high dispersion is essential [1,2]. That is, the supported catalyst is usually composed of a support and catalytically active elements such as Pt, Pd, Ru. In general, carbon materials having a high electrical conductivity, a large specific surface area, and a high chemical stability is applied as a support for an electrochemical catalyst [2]. Among the nanostructured carbon materials, the ordered mesoporous carbon (OMC), which have a large surface area and very well-connected the mesopores has been developed as a novel support for the fuel cell applications [3,4]. In this presentation, I would like to explain the brief history of the development of OMC support by authors for the PEFC such as direct methanol fuel cell and proton exchange membrane fuel cell. For example, Pt supported on the S-containing OMC(S-OMC) showed a higher thermal stability compared to the carbon black and pure OMC due to the strong metal-support interaction [5]. In addition, composite support between OMC and SiC for enhancing the catalytic stability of Pt toward the ORR will be presented as a recent example [6]. The composite supports are prepared by changing the temperature for the carbonization process during the nano-template method [6]. The SiC contents in the composite support were increased by increasing the temperatures. The Pt catalyst supported on the composite support showed excellent activity stability for ORR compared to the Pt particles on the pristine OMC and commercial Pt/C catalyst.

[1] Y.-J. Wang, N. Zhao, B. Fang, H. Li, X. T. Bi, and H. Wang, Chem. Rev.,115, 3433 (2015).

[2] C. Wang, S. Wang, L. Peng, J. Zhang, Z. Shao, J. Huang, C. Sun, M. Ouyang, and X. He, Energies, 9, 603 (2016).

[3] A. Eftekhari and Z. Fan, Mater. Chem. Front., 1, Advance Article (2017).

[4] H. Chang, S. H. Joo, and C. Pak, J. Mater. Chem. 17, 3078 (2007).

[5] H. I. Lee, S. H. Joo, J. H. Kim, D. J. You, J. M. Kim, J.-N. Park, H. Chang, and C. Pak, J. Mater. Chem., 19, 5934 (2009).

[6] D. J. You, X. Jin, J. H. Kim, S.-A. Jin, S. Lee, K. H. Choi, W. J. Baek, C. Pak, and J. M. Kim, Int. J. Hydrogen Energy, 40, 12352 (2015).
(Invited) Transport of Ions Along the Exterior of Single-Walled Carbon Nanotubes
Authors: Kim Yun-Tae , Lee Chang Young
Published: February 2020

Single-walled carbon nanotube is a tubular nanomaterial having atomically smooth surface, and potentially serves as a highly efficient molecular conduit. Recent studies on utilizing carbon nanotube as a molecular conduit have largely focused on the transport through the interior of the material. The exterior of carbon nanotubes, however, has been overlooked by the carbon nanotube community. Mapping the distribution of charges and elements along individual nanotubes, we found that the exterior of single-walled carbon nanotubes is an ion channel that preferentially carries cations under an electric field. Repeating the measurements on a covalently functionalized nanotube suggests that cation-π interaction plays an important role in achieving such cation-preference during transport. The exterior transport of ions leads to formation of salt crystals that amplify Raman scattering of the nanotube itself and molecular species within the crystals.
First-Principles Study on the Gese Monolayer As an Anode Material for Alkali Metal Ion Batteries
Authors: Sannyal Arindam , Jang Joonkyung
Published: February 2020

Rechargeable Li-ion batteries (LIBs) are extensively utilized for sustainable and renewable energy storage,1 but the high cost and low abundance of lithium have prompted the quest for alternative energy storage systems such as Na and K ion batteries.2 An enhanced gravimetric energy density and a high diffusion rate of carrier ions are important aspects to consider in development of alkali metal ion batteries. Recently, 2D layered materials have emerged as anode materials for batteries.1 Among them, the Group IV monochalcogenides are proposed as anode materials in the forms of nano-crystals3 and sheets.4 Herein, by using the density functional theory calculation, we show that the GeSe monolayer can be an anode material for Na and K ion batteries. The calculations of the phonon dispersion and formation energy prove that the GeSe monolayer is a structurally and thermodynamically stable material which can be experimentally exfoliated from its bulk counterpart.5 The GeSe monolayer shows adsorption energies of 1.92, 1.22 and 1.32 eV, respectively, for Li, Na and K ions. Upon electrodeposition of an alkali metal ion, substantial charge transfers from the metal atom to the GeSe monolayer and the semiconducting GeSe monolayer turns into a metallic state. The GeSe monolayer gives an anisotropic diffusion of the metal ions with moderate/low energy barriers on GeSe (0.29, 0.11 and 0.10 eV along zigzag, respectively, for Li, Na and K) which ensures fast charge and discharge rates. The low average voltages suggest that the GeSe monolayer is a suitable anode for alkali metal ion batteries. The GeSe monolayer yields a capacity of nearly half (177 mAh g-1) of the commercial graphite anode. On the other hand, the theoretical capacities of Na and K ions are calculated to be 707 and 353 mAh g-1, respectively, which are larger than that of typical 2D anode materials.

Reference:

H. R. Jiang, W. S., M. Liu, L. Wei, M. C. Wu and T. S. Zhao, Boron phosphide monolayer as a potential anode material for alkali metal-based batteries. J. Mater. Chem. A
2017,
5 (2), 672-679.

Joshi, R. P. O., B.; Barone, V.; Peralta, J. E., Hexagonal BC3 : Robust Electrode Material for Li, Na, and K Ion Batteries. J. Phys. Chem. Lett.
2015,
6 (14), 2728-2732.

Im, H. S. L., Y. R.; Cho, Y. J.; Park, J.; Cha, E. H.; Kang, H. S., Germanium and Tin Selenide Nanocrystals for High-Capacity Lithium Ion Batteries: Comparative Phase Conversion of Germanium and Tin. J. Phys. Chem. C
2014,
118 (38), 21884-21888.

Ramasamy, P. K., D.; Lim, D.-H.; Ra, H.-S.; Lee, J.-S., Solution synthesis of GeS and GeSe nanosheets for high-sensitivity photodetectors. J. Mater. Chem. C
2016,
4 (3), 479-485.

Karmakar, S. C., C.; Datta, A., Two-Dimensional Group IV Monochalcogenides: Anode Materials for Li-Ion Batteries. J. Phys. Chem. C
2016,
120 (27), 14522-14530.
Hybrid Nitrogen-Incorporated Reduced Graphene Oxide-Branched Carbon Nanotubes Architectures for Lithium Ion Battery Anode
Authors: Park Ho Seok , Kang Yingbo
Published: February 2020

The growth of carbon nanotubes (CNTs) on three-dimensional nitrogen doped reduced graphene oxide (NG) and formation of nitrogen-incorporated reduced graphene oxide/iron oxide (CNT/NG-Fe) by in-situ formation of iron oxide has been successfully realized via microwave synthesis using NG and iron precursor. The morphology and structure of the CNT/NG-Fe are characterized by ﬁeld emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Raman. Compared with the RGO, the CNTs can be easily grown on the NG due to the good conductivity introduced by the presence of pyrrolic and pyridinic centers. As shown in the electrochemical performances, the discharge capacity of the 3D CNT/NG-Fe is 1208 mAh g-1 at 50 mA g-1 which is greater than 890 and 820 mAh g-1 of the CNT/G-Fe and NG. After 130 cycles at 100 mA g-1, the capacity gradually increases to 1020 mAh g-1 with the Coulombic efficiency of > 98.5 %. The enhanced capacity, rate capability and cyclic stability of the CNT/NG-Fe can be attributed to doping effect of N-configuration and unique hierarchical structure consisting of the dense CNT branches on 3D macroporous continuity.
Actinide Nitride Clusterfullerene: Synthesis, Isolation and Spectroscopic Characterization of U2N@C80
Authors: Li Xiaomeng , Zhang Xingxing , Chen Ning
Published: February 2020

All the nitride clusterfullerenes discovered so far adopted a trimetallic nitride template. Here, we report that an unprecedented nitride cluster endohedral fullerene with only two metal atoms in the cluster, U2N@C80, has been successfully synthesized by a modified arc-discharge method and isolated by a multistage HPLC process. Mass spectroscopy, UV-vis-NIR absorption spectrometry and Raman spectroscopy were employed to investigate its structure and some intriguing properties have been revealed. The UV-vis-NIR absorption spectrum of U2N@C80 in CS2 is featured with two weak absorption peaks at 446nm and 680 nm. Compared with previously reported M3N@I
h(7)-C80 (M= Tm, Gd, Y, Er, Dy) fullerenes, their overall absorption spectra, characteristic absorption peaks and optical band gaps are almost identical, providing evidence for a probable six-electron transfer from the interior cluster to the exterior fullerene cage. In addition, the features of the low energy Raman spectrum of U2N@C80 also show similarities to those of fullerenes with I
h-C80 cage, which agree well with the UV-vis-NIR absorption study. However, in the range of 100-200 cm‒1, the peaks of the stretching metal-cage mode is observed at 119,135 cm‒1, which shows great difference from those of lanthanide endohedral fullerenes, M3N@I
h(7)-C80 (M=Tm, Gd, Y, Er, Dy), indicating a quite different metal-to-cage interaction between the inner cluster and the I
h(7)-C80 cage from that of the lanthanide nitride endohedral fullerenes.
(Invited) Mediating Reductive Charge Shift Reactions in Electron Transport Chains
Authors: Guldi Dirk M.
Published: February 2020

We report the synthesis of a full-fledged family of covalent electron donor-acceptor1-acceptor2 conjugates and their charge-transfer characterization by means of advanced photophysical assays. Both Zn(II)Porphyrins and Zn(II)Phthalocyanines were linked to different electron-transport chains of pairs of electron accepting C60 and C70 fullerenes. In this way, a fine-tuned redox gradient is established to power a unidirectional, long-range charge transport from the excited-state electron donor via a transient C60
•- towards C70
•-. This strategy helps minimize energy losses in the reductive, short-range charge shift from C60 to C70. At the forefront of our investigations are excited-state dynamics deduced from femtosecond transient absorption spectroscopic measurements and subsequent computational deconvolution of the transient absorption spectra. These provide evidence for cascades of short-range charge-transfer processes, including reductive charge shift reactions between the two electron-accepting fullerenes, and for kinetics that are influenced by the nature and length of the respective spacer. Of key importance is the postulate of a mediating state in the charge-shift reaction at weak electronic couplings. Our results point to an intimate relationship between triplet-triplet energy transfer and charge transfer.
(Invited) Intermediates Captured By C60 in Combustion
Authors: Xie Su-Yuan , Zhang Qianyan , Deng Shun-Liu
Published: February 2020

Although derivatives of fullerenes are prevalent in the fullerene-producing flame, chemistry of these derivatives has rarely been discussed in previous literatures. Here we show a series of nascent intermediates that are on-line produced in the flame of acetylene-benzene-oxygen and in situ captured by C60 for clarifying the growth of carbon clusters. Based on MS, NMR, IR, UV/Vis analyses as well as single-crystal diffraction, in combination with DFT calculations, the intermediates captured by C60 are identified. The present work exemplifies the capture of possible intermediates by C60 from the flame, and thus provides insight into the mechanism responsible for the formation of fullerene.
(Invited) Highly Stabilized Perovskite Solar Cells By Li-Ion-Containing Fullerene Salt As Both Dopant and Anti-Oxidant
Authors: Matsuo Yutaka , Jeon Il , Ueno Hiroshi
Published: February 2020

Lead halide perovskite solar cells (PSCs) have drawn great attention as the promising solar energy source in recent years. Their certified power conversion efficiencies (PCEs) now reach more than 20%. Despite high PCE, low stability of PSCs has been the most serious drawback, which is in dire need of resolution. It has been found that light, oxygen, and water are the origins of the perovskite layer degradation. In particular, dopants used for 2,2’,7,7’-tetrakis(N,N-di-p-methoxyphenylamine)-9,9’-spirobi-fluorene (spiro-MeOTAD) hole-transporting material are attributed for the low stability, due to their hygroscopic nature. Replacement of liquid electrolyte by spiro-MeOTAD was a breakthrough at the initial stage of PSC development, improving PCE substantially, owing to well-aligned energy band and amorphous nature of spiro-MeOTAD. However, because spiro-MeOTAD intrinsically has low mobility, a dopant must be present to improve the conductivity. Lithium bis(trifluoromethanesulfonyl)imide salt (Li+TFSI−) has been widely used as the p-dopant for spiro-MeOTAD. Li+TFSI− does not directly oxidize spiro-MeOTAD, but instead, promotes the oxidation of spiro-MeOTAD by oxygen at the presence of light or thermal excitation. Because doping spiro-MeOTAD with Li+TFSI− requires oxygen, it is difficult to control the amount of spiro-MeOTAD oxidation; the formation of oxidized spiro-MeOTAD has been shown to be reversible during device operation depending on ambient conditions and the sweep direction of current−voltage (J
−V) measurement. Also, a number of factors, including light intensity, the concentrations of lithium ions and oxygen, has been shown to the amount of oxidized spiro-MeOTAD. Uncontrolled oxidized spiro-MeOTAD is unpredictable and leads to inconsistent reproducibility and instability of PSCs. In addition to this, as mentioned above, Li+ salt is extremely hygroscopic and induces moisture-based degradation of PSCs.

In this work, lithium-ion-encapsulated [60]fullerene bis(trifluoromethanesulfonyl)imide salt ([Li+@C60]TFSI−) was used in PSCs instead of Li+TFSI− as a solution aforementioned problems. C60 encapsulating Li+ changed the hydrophilic alkali salt to a hydrophobic species. Also, spiro-MeOTAD mixed with [Li+@C60]TFSI−produced cationic salt spiro-MeOTAD●+TFSI− and neutral Li+@C60
●− by electron transfer from spiro-MeOTAD to Li+@C60. While spiro-MeOTAD●+TFSI−functioned as an effective hole transporting material Li+@C60
●− functioned as an antioxidant, reacting with any intruding oxygen and moisture. spiro-MeOTAD●+TFSI− required no chemical additives nor oxidation as it was technically pre-oxidized spiro-MeOTAD. By preventing unnecessary oxidation in the device system, [Li+@C60]TFSI−-used devices showed approximately 10 times higher stability than the conventional Li+TFSI−-used devices.

Figure 1
(Invited) Inverted Planar Perovskite Solar Cells Using Coordination Fullerene Polymers As Acceptor Layer
Authors: Winkler Krzysztof , Gradzka Emilia , Wysocka-Zolopa Monika , Enachescu Marius , Moise Calin , Pumnea Alex
Published: February 2020

Perovskite solar cells can be composed of thin film of perovskite donor and fullerene derivative acceptor sandwiched between a PEDOT:PSS coated ITO positive electrode and a low work function metal negative electrode. So far, [6,6]-phenyl-C61-butrilic acid methyl ester (PC60BM) and its corresponding C70 derivative (PC70BM) have been dominantly used as the acceptors in these solar cells.1 Fullerenes and fullerene derivatives can be incorporated into polymeric structure with transition metal atoms (Pd, Pt) or metal complexes units (-Ir(CO)2-, -Rh(CF3CO2)2-, -Ni[P(CH3)3]-).2 They can be formed under chemical and electrochemical conditions. Coordination polymers of fullerene and palladium, C60Pdx (x = 1-3), have been investigated most intensively. The chemical synthesis of this material is carried out in benzene solution containing fullerene and zero-valent palladium complex as precursors for polymerization process. The same procedure has been applied for the formation of coordination polymers of fullerene derivatives, PC60BM and PC70BM. These polymers formed regularly sized spherical particles with diameter of about 120 nm (Fig. 1). They also exhibit electrochemical activity in the potential range of fullerene cage reduction (Fig. 2). Electron transfer on the polymeric backbone results in the significant increase of the conductivity of the polymeric material.3 Coordination polymers containing PC60BM and PC70BM can be used as an acceptor layer in perovskite solar cells. We anticipate an improvement in power conversion efficiency and stability of the devices in comparison to the solar cells based on tin crystalline films of PC60BM and PC70BM.

Meng, L.; You, J.; Guo, T.F.; Yang, Y. Chem. Res.
2016, 49, 155-165.

Balch, A.L.; Winkler, K. Chem. Rev.
2016, 116, 3812-3882.

Gradzka, E.; Wysocka-Zolopa, M.; Winkler, K. Phys. Chem. C
2014, 118, 14061-14072.

Figure 1
(Invited) Structural Identification of 19 Purified Isomers of Opv Acceptor Material Bis[60]PCBM
Authors: Liu Tong , Abrahams Isaac , Dennis John
Published: February 2020

The molecular structures of 19 purified isomers of bis-phenyl-C62-butyric acid methyl ester (“bis[60]PCBM”) were identified by a combination of 13C NMR and UV-Vis absorption spectroscopy, and HPLC retention time analysis. The 13C NMR spectra indicated the symmetry of each isomer. It also showed that all 19 isomers are dicyclopropa-fullerenes (none are homo-fullerenes). This is because the fullerene bridgehead for both addends are sp
3 hybridized; resonating between 75 and 85 ppm. According to UV-Vis spectroscopy, the 19 isomers were classified into 7 groups - each corresponding to one of the 7 bond types identified by Hirsch and co-workers (trans-1, trans-2, trans-3, trans-4, e, cis-3, cis-2).

All 58 nominal molecular structures of Bis[60]PCBM were accounted for by isolating the first addend as bridging fullerenes carbon 1 and 9 by default, after which the 2nd addend may to one of the 29 remaining double bonds on C60 with two orientations relative to that of the 1st addend. However, symmetry reduced this number to 36 physically distinguishable isomers. Many of these isomers have enantiomers, and hence cannot be spectroscopically distinguished; which reduces the number of effective isomers to 22. If these, 3 are not expected to form owing to steric hindrance because each of these three isomers involve the cis-1 bond whereby the bulky addends would be attached to two adjacent double bonds on the same 6-membered ring on C60.

There were 7 isomers with C1 molecular point group symmetry, 4 with CS, 6 with C2, 1 with C2v and 1 with C2h symmetry. The C2h, C2v, and all 5 non-equatorial C1 molecular structures were unambiguously assigned to their respective HPLC fractions. For the other 12 isomers, the 13C NMR and UV-Vis spectra placed them in 6 groups of two same-symmetry isomers. Based on the widely spaced HPLC retention times of the two isomers within each of these 6 groups, and the empirical inverse correlation between retention time and addend spacing, each molecular structure was assigned to its corresponding HPLC fraction.

The information presented will enable those who follow and produce photovoltaic devices based purified isomers to know which specific isomer is being employed in their devices, develop a deeper understanding of morphological order/disorder within the acceptor phase, and thereby draw meaningful conclusions on why some isomers perform better than others.
(Invited) High Efficient Tumor Therapeutic Technique Based on Water Soluble Metallofullerene Derivatives
Authors: Wang Chunru
Published: February 2020

For a long time, researchers have been puzzled of the therapy of malignant tumors and the current therapeutic strategies are always accompanied by toxicity or side effects. Making use of the irregular vascularization with abnormal leakiness of the tumor vessels, gadofullerene nanoparticles functionalized with amino acid (specially β-alanine, abbreviated as GF-Ala), circulate in the blood and then accumulate at the tumor site through the enhanced permeation and retention (EPR) effect. Due to the involvement of β-alanine onto the fullerene cage improving the uniformity of size distribution, magnetic properties and the affinity with proteins, GF-Ala nanoparticles assisted by radiofrequency have exhibited a higher antitumor activity than multihydroxylated gadolinium endohedral metallofullerenes (GF-OH) nanoparticlesour recently reported. We speculate the superior properties of GF-Ala nanoparticles result in a stronger interaction with radiofrequency and long blood circulation time, which would influence the nanoparticles to destruction of tumor vasculature. Long-term toxicity evaluation show GF-Ala nanoparticles could be eliminated from the mice after several days and no obvious toxicity was found to the main organs. All these results suggest GF-Ala is valuable to develop into a potential anticancer drug with high-efficacy and low-toxicity

Reference
s

Zhou Y.; Deng, R.J.; Zhen, M.M.; Li, J.; Guan, M.R.; Jia, W.; Li, X.; Zhang, Y.; Yu, T., Zou, T.J.; Lu, Z.G.; Guo, J.; Sun, L.; Shu, C.Y.; Wang, C.R. Biomaterials, 2017, 133, 107

Zhen, M.M.; Shu, C.Y.; Li, J.; Zhang, G.Q.; Wang, T.S.; Luo, Y.; Zou, T.J.; Deng, R.J.; Fang, F.; Lei, H.; Wang, C.R.; Bai, C.L.. Science China-Materials, 2015, 58, 799
(Invited) What Can Electrochemistry Learn from Chess?
Authors: Dawson-Elli Neal , Mitra Kishalay , Subramanian Venkat R.
Published: February 2020

Batteries are complex electrochemical devices whose short-term and long-term operational lives are highly dependent on their construction, materials, and use cases. Models have been developed and used to improve the performance of batteries by providing different material design, model based control and model based battery management systems1,2.

In recent literature, data science techniques have been used to accomplish a variety of tasks related to representing simulated data for control or estimation purposes2,3,4
. Data science techniques have also been used to approximate optimal solutions to computationally difficult problems, such as the traveling salesman problem5. Rather than create a surrogate model to use with a typical optimization scheme, we will examine framing the problem as a parameter ‘correction’ endeavor. By doing so, it may be possible to retain all of the information present in a time series of error and leverage this information to very quickly go from a poor initial guess to a viable solution, after which time iterative optimization schemes can take over. The effectiveness of this approach (both in terms of efficiency and robustness) will be compared with the standard approaches. This method is inspired by DeepChess, a comparative deep neural network structure which plays successfully against world-class chess algorithms4.

Acknowledgments

The authors thank the United States Department of Energy (DOE) for the financial support for this work though the Advanced Research Projects Agency – Energy (ARPA-E) award #DEAR0000275, as well as the Clean Energy Institute (CEI) through the DIRECT program at the University of Washington. Part of the research has been supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U. S. Department of Energy through the Advanced Battery Materials Research (BMR) Program (Battery500 Consortium)

References

Y. Dai, and V. Srinivasan,. J. Electrochem. Soc., 163, A406 (2016).

N. Dawson-Elli, S. B. Lee, M. Pathak, K. Mitra, and V. R. Subramanian, “Data Science Approaches for Electrochemical Engineers: An Introduction through Surrogate Model Development for Lithium-Ion Batteries,” J. Electrochem. Soc., vol. 165, no. 2, pp. A1–A15, Jan. 2018.

D. A. C. Beck, J. M. Carothers, V. R. Subramanian, and J. Pfaendtner, “Data science: Accelerating innovation and discovery in chemical engineering,” AIChE J., vol. 62, no. 5, pp. 1402–1416, May 2016.

Blake R. Hough, author. Jim Pfaendtner, degree supervisor. 2016 Thesis (Ph. D.)--University of Washington,2016.

B. La Maire and V. Mladenov, “Comparison of Neural Networks for Solving the Travelling Salesman Problem,” in 11th Symposium on Neural Network Applications in Electrical Engineering,NEUREL 2012 - Proceedings, 2012.

E. David, N. S. Netanyahu, and L. Wolf, “DeepChess: End-to-End Deep Neural Network for Automatic Learning in Chess,” arXiv:1711.09667 [cs, stat], vol. 9887, pp. 88–96, 2016.
(Invited) Interface Modification for Efficient Charge Transfer in Perovskite Solar Cells
Authors: Murakami Takurou N
Published: February 2020

Power conversion efficiencies of the perovskite solar cells (PSCs) are drastically increased in this 5 years. PSCs without a mesoporous TiO2 layer, planar-type cells, commonly obtained poorer cell performance as compared to cells with a porous TiO2 layer, owing to inefficient electron transfer from the perovskite layer to the compact TiO2 layer in the former case. The matching of the conduction band edge (CBE) levels of perovskite and the compact TiO2 layer is thus essential for enhancing solar cell performance. In this work, we discussed about the interface between perovskite and electron transport layer (ETL) to improve the performance of the PSCs with adjustment of the CBE levels for reducing the energy loss at the material interfaces in the PSCs. The CBE levels were evaluated with the electrochemical methods.

The chemical bath treatment with TiCl4 (TiCl4 treatment) for the compact TiO2 layer to increase the performance of PSC has been reported. The effect of the TiCl4 treatment was considered as the cause of the wettability increases of the precursor solution of the perovskite on TiO2 compact layer and the efficient charge transport from perovskite layer to TiO2 layer. However, TiCl4 treatment may change the CBE potentials. The adjustment of the CBE potentials will be important issue to obtain the low barrier potentials for electron transfer from perovskite to TiO2 compact layers. To study the effect of the TiCl4 treatment on the CBE potentials, we prepared the electrochemical cells with the iodide and tri-iodide redox electrolyte and treated substrate with TiCl4 aqueous solution and the relation between open circuit voltages (
V
oc) and the electron density in TiO2 layer of the cells were measured with the charge extraction methods. The V
oc as the quasi CBE potential was negatively shifted with the TiCl4 treatment but positively shifted with heating after TiCl4 treatment. We compared the PSCs performance as the different heating temperature at 150 °C, 300 °C, and 450 °C of the TiCl4 treated compact TiO2 layers. The Voc was decreased and the short circuit current was increased with increasing the temperature. The highest PCE was obtained with the heating at 300 °C.
Electrodeposited ZnO-Based, Organic-Dye Sensitized Solar Cells: Advantages and Limitations
Authors: Canto Aguilar Esdras Josué , Rodríguez Pérez Manuel Jesús , García Rodríguez Rodrigo , De Denko Alexandra T. , Osterloh Frank E. , Oskam Gerko
Published: February 2020

The dye-sensitized solar cell (DSSC) is one of the most promising third generation photovoltaic technologies, which nowadays shows conversion efficiencies as high as 14 %. The attractive qualities of DSSCs include promising efficiencies, but also the low cost projected for their large-scale production for niche applications, in particular, for semi-transparent windows and indoor lighting conditions. This implies the optimization of all processing steps and components used, and a better understanding of the mechanisms of generation and loss of electrons involved in the solar cell functioning. Based on these observations, we have selected ZnO as the electron transporting material, not only for its much better electrical properties (when comparing with the commonly used TiO2), but also for the simple synthesis methods by which it can be obtained, such as electrodeposition (a low temperature an scalable technique), which offers to move toward the fabrication of more economically profitable devices. Hence, part of this work presents a detailed study on the effect of the bath composition, additives and deposition conditions used on the morphological and structural features of materials electrodeposited from ZnCl2 and Zn(NO3)2 solutions.

The combination of this material with organic dyes with high absorption coefficient in the solar spectrum regime, promise an increase in cell current and voltage. For that reason, we have prepared solar cells with nanostructured, mesoporous ZnO films electrodeposited from an optimized aqueous ZnCl2 solution, an organic fluorenyl-thiophene dye (OD-8) as sensitizer, and an electrolyte solution with either the I-/I3
- or the [Co(2,2'-bipyridyl)3]2+/3+ redox couple. An improvement in efficiency may be expected, related to the more positive redox potential of the [Co(2,2'-bipyridyl)3]2+/3+ couple and faster dye regeneration kinetics, but this can only be achieved if the recombination rate at the semiconductor/electrolyte interface is sufficiently slow. Hence, we have evaluated the effect of CDCA (chenodeoxycholic acid) as coabsorbent in the dye solution, with the purpose to diminish the amount of uncovered area of the electrode surface, in order to minimize recombination. We use I-V curves in combination with intensity-modulated photovoltage spectroscopy, charge extraction measurements, and surface photovoltage spectroscopy to gain insight in the factors involved into the photochemical charge separation in ZnO-based organic-DSSCs.
Additively Manufactured Electrochemical Plating Enclosures
Authors: Thorpe Adam J , Arrington Christian L. , Pillars Jamin R.
Published: February 2020

Additively manufactured plating enclosures can be used as a cheap alternative to traditional plating tanks and fixturing, which can reduce the volume of chemistry required, allow for complex fluid dynamics across the part surface, and offer the possibility of augmenting and tuning the thermal gradients and electrical fields surrounding the part. Selective tank geometries allow for electrodes that can be integrated or conformally shaped onto the enclosure. By allowing for such diverse electrode geometries, these enclosures create the possibility of near-uniform electric fields for complex parts, unique electrical contact mechanisms that can be integrated into the enclosure itself, as well as accurate and minimally invasive part fittings to maintain part alignment during the plating process.

Several commercially-available thermoplastics and photopolymers were analyzed for compatibility with a variety of chemistries commonly used in the electrodeposition processes. Preliminary testing and analysis of custom polymer plating enclosures was performed to demonstrate process viability. Parylene coatings can further increase the chemical resistance of the enclosure, leading to a wider range of chemistries which the custom polymer enclosures are resistant to. Further, polymer metallization and evaporation techniques offer the possibility of directly incorporating electrodes into the fixture itself, as well as for creating thermal contacts with external heat sources.

Together, these techniques create the possibility of creating more uniform parts and coatings, while reducing chemical waste, material and equipment cost, and development time for laboratory-scale electroplating processes.

Supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.
An Analysis of Transient Impedance-like Diagnostic Signals in Batteries
Authors: Teo Linnette , Pathak Manan , Kolluri Suryanarayana , Dawson-Elli Neal , Schwartz Daniel T. , Subramanian Venkat R.
Published: February 2020

Electrochemical impedance spectroscopy (EIS) is an established technique for monitoring and testing of electrochemical systems, including batteries. Parameters related to electrochemical phenomena such as charge-transfer kinetics and mass transport can be estimated from the impedance response over a range of frequencies1.

The classical description for impedance of an electrochemical system, subjected to a periodic input perturbation, depends upon achieving a steady periodic output state2. However, there may be value in analyzing the joint time-frequency response of a dynamic impedance-like output signal under conditions that are not steady periodic3. For example, it has been shown that using a dynamic impedance-like response allows parameter estimation to be carried out in shorter times than waiting for a steady periodic state to be reached4. This may be particularly valuable for accessing low frequency (slow) phenomena such as thermodynamic and diffusion effects. As a result, dynamic impedance-like signals may be a valuable tool for real time diagnostics of battery degradation processes.

The objective of this study is to develop time and frequency dependent solutions for existing battery models to further investigate the full dynamic response of the system. Devan et al. has performed transient voltage analysis for a porous electrode model5 and short-time current density response for an intercalation particle model4. A comparison to the steady periodic response for parameter estimation and the choice of optimum frequencies for measurements will be explored. While the analysis will begin with a simple physics-based model, the goal is to develop a fast and efficient tool for porous electrode 2D models. In particular, the focus will be on the gain in estimating parameters with specific confidence intervals, and mechanism validation from using the transient data compared to steady state models.

References

Yu, B. N. Popov, J. A. Ritter, and R. E. White, Journal of The Electrochemical Society,
146, 8 (1999).

Ceder, M. Doyle, P. Arora, and Y. Fuentes, MRS Bulletin, 27, 619–623 (2002).

Doyle and J. Newman, in Tutorials in Electrochemical Engineering—Mathematical Modeling, edited by R.F. Savinell, J.M. Fenton, A.C. West, S.L. Scanlon, and J. Weidner (The Electrochemical Society, Seattle, 1999) p. 144.

Devan and R. E. White, Journal of The Electrochemical Society, 154(2007).

Devan, V. R. Subramanian, and R. E. White, Journal of The Electrochemical Society, 152 (2005).
Development of High Temperature Operation SiC Power Module
Authors: Sato Shinji , Kato Fumiki , Tanisawa Hidekazu , Koui Kenichi , Watanabe Kinuyo , Murakami Yoshinori , Sato Hiroshi , Yamaguchi Hiroshi
Published: February 2020

We have developed a Silicon Carbide (SiC) power module that can operate at high temperatures up to 250 °C. Figure 1 shows the overview of the developed power module. The withstand voltage of the power module is 1200 V, two SiC - MOSFETs are built in, and it is a circuit composition of one phase of the power inverter. The two-layer SiC-Active Metal Brazed Copper(AMC) not only reduces the area of the power module but also reduces circuit inductance. In addition, this power module has a built-in snubber circuit that reduces the switching surge voltage of the SiC-MOSFET during high-speed switching.

Generally, when the power module is operated at a high temperature, the reliability such as occurrence of lowering of the main bonding strength of the power module is significantly reduced due to thermal deformation. In this power module, the main components of the module are joined using eutectic solder with a solidus line above 350 °C. Copper-tungsten (CuW) was selected as the base plate material. Since the Coefficient of Thermal Expansion (CTE) values of CuW and SiN - AMC are close, it is possible to reduce the stress applied to these joints when the temperature changes. In addition, CuW has excellent thermal conductivity and heat capacity and suppresses heat generation of SiC-MOSFET.

To evaluate the performance of this module, a switching test at 100 A was performed at 250 °C. The switching waveform is shown in Fig.2. The turn-off switching time tf was about 10 ns, and the switching surge voltage at that time was about 150 V. The turn-off switching waveform was almost the same from room temperature to 250 °C. As a result, it was shown that this power module can operate at 250 °C and the built-in snubber circuit works effectively at all temperatures.

Acknowledgement

This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), "Next-generation power electronics / Consistent R&D of next-generation SiC power electronics" (funding agency: NEDO).

Figure 1
The Influence of Electrode Width and Sealing Method on Leakage Pressure of Microfluidic Electrochemical Devices
Authors: González-Gallardo Carlos Luis , Casanova-Moreno Jannu Ricardo
Published: February 2020

Polydimethylsiloxane (PDMS) has been one of the most actively developed polymers for microfluidics, which irreversibly seals on silicon-based surfaces (e.g., glass) after it is exposed to air plasma. The problem lies in its use in the fabrication of microfluidic electrochemical cells. The metal electrodes (e.g. gold) are inert to the plasma, which causes leakage in the PDMS-gold interface of the cell, affecting the data obtained in electrochemical detection experiments. In recent years, advances have been made in sealing methods of PDMS-glass and PDMS-gold interfaces, using a peptide bond by the reaction of a carboxylic acid and an amine, for the fabrication of microfluidic devices. In this work we have studied the effect of the variation of the width of gold electrodes in the sealing of the PDMS-gold interfaces of the electrochemical cells. It was observed that, using the plasma method, at a width of 3 μm, the system supported leakage pressures of 105 kPa, decreasing to 19 kPa at a width of 700 μm. The influence of the width of the electrode on the leakage pressure can be due to the fact that around the electrode there is a stronger bonding force and, the smaller the width of the electrode, the greater the pressure needed to deform the PDMS. Leakage pressure measurements on chips sealed with the carboxyl-amine method are planned. It is expected that the carboxyl-amine method will support higher pressures than the plasma method at large electrode widths due to the higher adhesion forces between the PDMS-gold interfaces in this method. At small widths, the plasma method is expected to be superior.

Figure 1