bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase Diagram Approach to Study Acid and Water Uptake of Polybenzimidazole -Type Membranes for Fuel Cells
Authors: Bertasi Federico , Conti Fosca , Wacker Jurgen , Lehnert Werner , Korte Carsten , Di Noto Vito
Published: February 2020

Polybenzimidazole (PBI) membranes doped with phosphoric acid are the most commonly used materials for high-temperature polymer electrolyte fuel cells. Despite this fact, the thermodynamics of the adsorption process over the completely accessible doping range is still a hot topic and only little is known on the chemical equilibria of the species inside the membrane as a function of the composition of the ternary system PBI - H3PO4 - H2O. This includes details on the condensation equilibria, leading to the formation of diphosphoric acid and higher homologues species and on the proton transfer processes, i.e. on the dominant conduction mechanisms. As a first step to understand the thermodynamic equilibria in the ternary system PBI - H3PO4 - H2O the phase diagrams for two different polymers, uncross-linked poly(2,2’-(m-phenylene)-5,5’-bibenzimidazole) (m-PBI) and a cross-linked commercial PBI derivate (Fumapem AM-55), were evaluated from own and from experimental data found in literature. In this study, miscibility gaps are identified and equilibrium lines separating one- and two-phase fields in the diagrams are estimated. In conclusion, we present new evidences on the interactions between H3PO4 and polymer chains, the polycondensation equilibria of H3PO4 and the implications on proton conductivity.

References:

[1] Uptake of protic electrolytes by polybenzimidazole-type polymers – adsorption isotherm and electrolyte/polymer interactions 

C. Korte, F. Conti, J. Wackerl, P. Damms, A. Majerus, W. Lehnert J. Appl. Electrochem., 2015, 45, 857-871

[2] A vibrational spectroscopic and DFT study of poly(2,5-benzimidazole) (ABPBI) –phosphoric acid interactions in HT-PEFC membranes

G. A. Giffin, F. Conti, S. Lavina, A. Majerus, G. Pace, C. Korte, W. Lehnert, V. Di Noto Int. J. Hydrogen Energy, 2014, 39, 2776-2784

[3] Carbon NMR investigation of the polybenzimidazole-dimethylacetamide interactions in membranes for fuel cells.

F. Conti, S. Willbold, S. Mammi, C. Korte, W. Lehnert, D. Stolten, New J. Chem., 2013, 37, 152-156.

[4] Thermogravimetric and Spectroscopic Investigation of the Interaction between Polybenzimidazole and Phosphoric Acid

A. Majerus, F. Conti, C. Korte, W. Lehnert, D. Stolten ECS Trans., 2012, 50(2), 1155-1165.

[5] Raman study of the interactions polybenzimidazole – phosphoric acid in membranes for fuel cells

F. Conti, A. Majerus, V. Di Noto, C. Korte, W. Lehnert, D. Stolten Phys. Chem. Chem. Phys., 2012, 14, 10022-10026.
Electrode Mapping; Effects of Porosity and Thickness on NMC Full Cells
Authors: Freigang Alexander
Published: February 2020

While performance of a lithium ion battery is primarily determined by the materials used within, the cell design variables also play a significant role.  Parameters such as electrode thickness and porosity can influence overall cell energy density, power/rate performance, and lifetime.   Ideally, a cell design needs to include the effects from all relevant design variables and the interactions between these parameters. For example, increasing the electrode loading is a very effective method to improve overall cell energy density as decreasing the number of layers in the cell will improve the ratio of active/inactive components.  However, the thicker electrodes can result in poorer rate or power performance.  Porosity of the electrodes is also a key variable affecting both energy and power performance. 

Cell based models are effective tools to estimate overall cell energy density as the electrode loading and porosity varies.  However, these models are less adequate to predict power or rate effects as the electrode parameters are changed.  Capacity and power fade during cycling are not well described by current models or calculations.   Therefore, experimental evaluation of a wide range of electrode designs is necessary to appreciate the complex variable space of electrode composition, loading, and porosity.

In this poster, we will show the effects of cathode formulation, thickness, and porosity on key performance metrics for automotive applications.  Results from these experiments were used to identify benefits and limits of high loading electrode designs in high energy and power automotive cells. The data were also inputted into automotive pack models to predict effects on system level performance.  Furthermore the importance of a holistic approach to bridge the gap between lab scale experiments and a full scale application is discussed.
Annealing Effect on ORR Activity of Carbon Black-Based Electrocatalysts
Authors: Asih Wentika Putri Kusuma , Oktaviano Haryo Satriya , Waki Keiko
Published: February 2020

Non-precious metal electrocatalysts for ORR have been regarded as one of promising candidates for cutting the cost of fuel cell. It has been early considered that combination of transition metals, nitrogen doping together with carbon as support material is essential to have outstanding performance of this class of electrocatalyst.1 It is reported that in alkaline condition, combination of cobalt oxides (CoOx) nanocrystal-carbon nanotubes could also exhibit a high ORR activity.2 However, not only utilizing a large amount of transition metal oxides (~12-20 at. % Co) but also the annealing process in NH3 atmosphere are undesirable in the application. On the other hand, recently, it is reported that annealing in the inert atmosphere could also affect the ORR activity for carbon-based catalysts3. However, the understanding of the annealing effect in the inert atmosphere is still limited. Here, we showed that even by annealing the oxidized carbon black (CB) in Ar atmosphere at 900 oC and containing less amount of CoOx, we could achieve high ORR activity in 0.1 M KOH, suggesting that annealing process is essential to enhance the catalytic activity.

As precursor, we used raw CB from Tokai Carbon Co. Ltd (Tokablack #5500). To oxidize CB, raw CB was purified by using acid treatment as reported elsewhere3 and followed by solid-stated oxidation using CoOx as carbon oxidation catalyst. At first, purified CB was impregnated with 10 wt. % (~2.2 at. % Co), followed with heat treatment under Ar atmosphere at 300 °C for 3 hours and finalized by annealing in air at 230 °C for 25 minutes. Afterward, CoOx was removed by acid washing in 2M sulfuric acid, resulting in oxidized CB. To study the effect of annealing and removing the functional groups, samples were later treated at 900 oC in Ar atmosphere. Effect of the annealing toward ORR activity is shown in Fig. 1. It can be seen that without annealing in the Ar at 900 oC, oxidized CB showed lower reduction current than the annealed one. This suggests the important role of annealing to the enhancement of ORR activity. Annealing effect in the different temperatures together with the role of CoOx-oxidation catalysts on the ORR activity will be further discussed through the detailed characterization of the samples (e.g. RRDE, XPS, TPD and TEM) in the presentation.

References

[1] H. Tang, H. Yin, J. Wang, N. Yang, D. Wang and Z. Tang, Angew. Chem. Int. Ed., 52, 5585 (2013)

[2] Y. Liang, H. Wang, P. Diao, W. Chang, G. Hong, Y. Li, M. Gong, L. Xie, J. Zhou, J. Wang, T. Z. Regier, F. Wei, and H. Dai, J. Am. Chem. Soc., 134, 15849 (2012)

[3] K. Waki, R. A. Wong, H. S. Oktaviano, T. Fujio, T. Nagai, K. Kimoto, and K. Yamada, Energy Environ. Sci., 7, 1950 (2014)

Figure 1
Hybrid Electrolytes Composed of Garnet-Structured Inorganic Electrolyte and Polymer Binder for Lithium-Ion Battery with Enhanced Safety
Authors: Jung Yun-Chae , Kim Seul-Ki , Han Man-Seok , Kim Duck-Hyun , Shin Woo-Cheol , Ue Makoto , Kim Dong-Won
Published: February 2020

Lithium-ion batteries (LIBs) have been extended their application from mobile devices to large-sized battery market such as electric vehicles and energy storage system.[1] Recently, safety issues have become a significant concern for full utilization of these batteries especially in large capacity applications. However, organic liquid electrolytes used in LIBs are problematic due to their high flammability and solvent leakage. In this respect, many Li-ion conducting electrolyte materials for improving battery safety have been investigated as alternative electrolytes for lithium-ion batteries. Among these electrolytes, solid inorganic electrolytes present potential advantages, such as absence of electrolyte leakage, high electrochemical stability, non-flammability, high thermal stability and absence of problems relating to vaporization of organic solvents.[2] However, sheet manufacturing using thin-film technologies for making large-scale lithium-ion batteries, is considered to be very difficult. In addition, a lack of flexibility results in poor interfacial contacts between inorganic solid electrolyte and solid electrodes in the cell during charge and discharge cycling. In this work, we prepared the flexible hybrid electrolytes composed of lithium lanthanum zirconium oxide (Li7La3Zr2O12) as a Li+-conducting solid electrolyte and poly(vinylidene fluoride-co-hexafluoropropylene) as a polymer binder, and their characteristics and electrochemical properties were investigated. The hybrid electrolyte was employed to assemble lithium-ion battery composed of graphite negative electrode and LiCoO2 positive electrode.

References

1.  J. B. Goodenough, and Y. Kim, Chem. Mater. 22 (2010) 587.

2.  J. W. Fergus, J. Power Sources 195 (2010) 4554.
Nano Perovskite SmFeO3 as an Electrode Material for Symmetrical Solid Oxide Fuel Cells
Authors: Fan Weiwei , Sun Zhu , Wang Junkai , Zhou Jun , Wu Kai , Cheng Yonghong
Published: February 2020

The nano SmFeO3-δ
(SFO) perovskite oxide was synthesized by citric-acid method and assessed in regard to its possible use as an electrode material for symmetrical solid oxide fuel cells. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) confirmed that the SFO oxide prepared by this method had a single orthorhombic phase belonging to the Pnma (62) space group. Size of SFO nanoparticles, investigated by scanning electron microscope (SEM), was in the range of 200–400 nm. Analysis of electrical conductivity revealed that SFO was a p-type semiconductor. SFO had a good chemical compability with yttria stabilized zirconia (YSZ) electrolyte and showed no phase separation both in air and 5% H2/N2 atmospheres after calcination of 20 h at 850 °C. The SFO cathode and anode showed the lowest charge transfer resistances at 800 °C, 1.03 and 1.28 Ω cm2, respectively. Moreover, the SFO|YSZ|SFO symmetrical cell demonstrated performance with an open circuit potential of 0.96 V and peak power density of 6.85 mW cm-2 at 800 °C using humidified H2 as the fuel, respectively.
Templated Non Precious Cathode Catalysts Prepared By Transition Metal and Chitosan for Oxygen Reduction Reaction in Alkaline Electrolyte
Authors: Qiao Jinli
Published: February 2020

The oxygen reduction reaction (ORR) is an important energy conversion reaction, especially for fuel cells1 and metal–air batteries.2 Pt-based materials are widely recognized as superior ORR electrocatalysts , hindering this technology's commercialization because of their expensive and scarce nature;3 in addition, these catalysts are not sufficiently stable and exhibit unsatisfactory catalytic activity towards the oxygen reduction reaction (ORR). Certain types of N-containing transition metal catalysts have showed high activity for oxygen reduction in alkaline media,4 however, compared to Pt-based catalysts for practical application in fuel cells, both the ORR activity and stability of these catalysts have to be significantly improved.5,6

 It is believed that the high surface area, high porosity and proper pore structure of catalyst usually lead to high catalytic activity for the ORR. Template method has drawn great attention to obtain the specified morphology and predetermined microstructure.7,8  In this paper, we choose template method to synthetize polyporous non precious metal catalysts. Nanoscale SiO2 was employed as sacrificial supports to create pores, while chitosan (CTS) as source of N and C.

The CTS-Fe catalysts were prepared by homogeneously dispersion of metal and CTS precursors onto the surface of SiO2. SiO2 was etched by 5M NaOH after dried at 85 oC for 48h, then the resultant powder was pyrolized in an N2 atmosphere at 800oC for 1h. The vacated SiO2 particles lead to creation of pore. The final powder was washed to be neutral by purified water and then dried overnight. Meanwhile, samples pyrolized in an N2 atmosphere respectively at 700oC, 900oC for 1h were prepared by the same procedure. Base on this method, we prepared CTS-Fe catalysts respectively at 700oC, 800oC, 900oC,with high porosity. The kinetics and electrocatalytic activity on the M-PEI catalysts have been measured using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and rotating disk electrode (RDE). All these tests were carried out in a glass cell consisting of a three-electrode system in 0.1M KOH at the ambient solution temperature.

References

1. B. C. Steele and A. Heinzel, Nature
, 2001, 414, 345.

2. E. M. Erickson, M. S. Thorum, R. Vasic, N. S. Marinkovic, A. I. Frenkel, A. A. Gewirth and R. G. Nuzzo, J. Am. Chem. Soc., 2012, 134, 197.

3. M. Arenz, K. J. Mayrhofer, V. Stamenkovic, B. B. Blizanac, T. Tomoyuki, P. N. Ross and N. M. Markovic, J. Am. Chem. Soc., 2005, 127, 6819.

4. J.L. Qiao, L. Xu, L. Ding, L. Zhang, R. Baker, X. F. Dai, J. J. Zhang, Applied Catalysis B: Environmental
125, 197 (2012).

5. Y. Yang, Z. Shi, S. Holdcroft, Macromolecules
37 1678 (2004).

6. R.W. Kopitake, C.A. Linkours, H.R. Anderson, G.L. Nelson, J. Electrochem Soc
147, 1677 (2000).

7. K. Kamegawa, H. Yoshida. Carbon
35, 631(1997).

8. R. Ryoo, S.H. Joo, M. Kruk, M. Jaroniec. Adv. Mater.
13, 677(2001).

Figure 1
The Influence of Electrolyte Composition on the Electrochemical Properties of Li-Sulfur Dioxide Batteries
Authors: Yang Tae Hyeon , Yang Hye Jeong , Kang Ji Hoon , Kim Seok , Jung Yongju
Published: February 2020

Primary lithium-sulfur dioxide (Li-SO2) batteries composed of a carbon cathode, a lithium anode and an organic electrolyte containing sulfur dioxide (SO2) in an organic solvent were presented in the late 1960s and are mainly used in defense applications.1 Recently, rechargeable Li-SO2 batteries with high energy density have been demonstrated.2-3 The technological breakthrough came from innovative electrolyte systems and nanostructured carbon cathodes. In general, a highly conductive liquid inorganic electrolyte such as LiAlCl4×xSO2 has been used.

To date, however, the influence of the electrolyte composition on the electrode reaction of SO2 has not been explored. In this study, the electrochemical properties of Li-SO2 rechargeable batteries are examined in various electrolyte solutions. In addition, the relation between carbon loading and SO2 utilization is intensively investigated.

Acknoledgments

This study was supported by the Energy Efficiency and Resources Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), the financial resources granted from the Ministry of Trade, Industry and Energy, Republic of Korea (No. 20132020000260).

References

1. W. F. Meyers, B. Bell, J. W. Simmons, U.S. Patent 3,423,242 (1969).

2. G. Jeong, H. Kim, J. H. Park, J. Jeon, X. Jin, J. Song, B.–R. Kim, M.-S. Park, J. M. Kim and Y.-J. Kim, Energy Environ. Sci., 8 (2015) 3173.

3. H.-D. Lim, H. Park, H. Kim, J. Kim, B. Lee, Y. Bae, H. Gwon and K. Kang, Angew. Chem., 127 (2015) 9799.
Noble Metal Nitride X Catalyst for H2-Br2 Redox Flow Batteries
Authors: Doan Huong , Alsudairi Amel , Ghoshal Shraboni , Bates Michael , Jia Qingying , Mukerjee Sanjeev
Published: February 2020

Renewable energy such as wind and solar has grown exponentially resulting in a high demand for low-cost, modular and scalable energy storage. Redox Flow Batteries (RFBs) offer improved flexibility in energy capacity and power density for grid-scale energy as compared to NaS & Li-ion batteries which are currently in-use. In particular, H2-Br2 RFBs are known for their low-cost components such as electrolyte (HBr) and electrodes (Br-/Br2). However, the hydrogen electrode of H2-Br2 flow cells suffers from well-known stability issues as a result of halide adsorption on the catalyst surface and Pt dissolution. The shortcomings occur due to Br2 cross-over. Finding a catalyst that could overcome this would be a significant milestone in addressing energy needs. Northeastern University Center for Renewable Energy Technology (NUCRET) synthesized and tested several Pt & Ir nitride catalyst. These catalyst materials were screened for hydrogen evolution reaction and hydrogen oxidation reaction (HER-HOR) activity via a rotating disk electrode (RDE) cell. RDE studies of pure Ir/C and Pt/C catalysts showed that the Ir-component and Pt- component are active for both HER & HOR. However, Ir or Pt catalysts alone are not stable under stability testing conditions which involve high-voltage cycling or exposure to Br2.  NUCRET successfully synthesized 40 wt% Pt-Ir-Nx/C sample that exhibited i0 well above the 0.6 A/ mg target.  This Pt-Ir-Nx/C catalyst, along with commercial Pt-Ir/C and Pt/C, were also subjected to stability testing in 1M HBr with 1mM Br2 The Pt-Ir-N/C sample exhibited increased stability compared to the commercial Pt-Ir/C and Pt/C catalysts. Cyclic Voltammetry (CV) results suggest that the Pt-Ir-Nx/C sample suffered ~50% loss in HER/HOR activity (Figure 1 right). In addition, Pt-Ir-Nx/C sample lost about 30% of electrochemical active surface area (ECSA) (Figure 1 left), compared to 70% Pt-Ir/C and 100% Pt/C standard loss.  This presentation will attempt to analyze the results from the point of view of the effect of nitrogen functionalization as distinct from other factors such as particle size, etc.  Use of in situ synchrotron XAS spectroscopy and Raman in conjunction with electrochemical data both from single cell as well as RDE will be presented.  

Acknowledgement

The authors gratefully acknowledge the financial support from Arpa-e, Department of Energy under grant no DE-AR0000262, lead by TVN systems, Kansas.

Figure 1
A Convenient and Versatile Method to Control the Electrode Microstructure Toward High-Energy Lithium-Ion Batteries
Authors: Zhao Hui , Yuca Neslihan , Yang Qing , Liu Gao
Published: February 2020

Control over porous electrode microstructure is critical for the continued improvement of lithium ion batteries. This paper describes a convenient and economical method for controlling electrode porosity, thereby enhancing material loading and stabilizing the cycling performance of lithium ion electrodes. We demonstrates an areal capacity of ~4 mAh/cm2 at a C/10 rate (0.51 mA/cm2) and an areal capacity of 3 mAh/cm2 at a C/3 rate (1.7 mA/cm2), one of the highest material loadings reported for a Si-based anode at such a high cycling rate. X-ray microtomography confirmed the improved porous architecture of the Si-based electrode. The method developed here is expected to be compatible with the state-of-the-art lithium ion battery industrial fabrication processes, and therefore holds great promise as a practical technique for boosting the electrochemical performance of lithium ion batteries without changing material systems.
Intermetallic Li-Anode Systems: Cu-Li-Sn
Authors: Fuertauer Siegfried , Beutl Alexander , Li Dajian , Cupid Damian Marlon , Flandorfer Hans
Published: February 2020

In addition to alternative modifications of carbon and organic composite materials, intermetallic alloys are promising candidates for new anode materials for lithium ion batteries (LIBs) because of the significantly increased theoretic capacities when compared to conventionally used graphite. However, the drastic volume changes during lithiation of pure metals such as Al or Sn lead to degradation of particle-to-particle contacts, resulting in very low cyclic stabilities. One of the various concepts to solve this problem is to use intermetallic alloys as new anode materials. For example, Cu6Sn5 and Cu3Sn are promising anode materials because Cu does not form intermetallic compounds with Li. A (Cu)-alloy matrix would act to buffer the strain induced by volume changes and simultaneously ensure electrical contact between lithiated regions.

Advanced materials design by computational methods rely significantly on experimentally determined thermodynamic and phase diagram data of the material systems to be able to simulate the electrochemical behaviour of new lithium ion batteries. Therefore comprehensive experimental investigations applying various methods like PXRD and SC-XRD studies, thermal analysis, and drop calorimetry were performed to gain a full understanding of the Cu-Li-Sn alloy system. The outcome of our comprehensive experimental work includes 4 isothermal sections, 8 isopleths, a liquidus projection and a reaction scheme as well as mixing and formation enthalpies. In addition, six new ternary intermetallic compounds could be found and their structure was described. Based on these results, the equilibrium lithiation reactions of Cu-Sn alloys could be proposed for the first time.

In this presentation we would like to briefly report about the special features and designs of our experimental methods. Subsequently, selected experimental results on Cu-Li-Sn will be shown and discussed. Our comprehensive experimental data together with literature data will lead to a very well founded CALPHAD assessment as an input for computational materials design.

  This work has been funded by the FWF under the project I559-N19 and by the DFG under the projects FL-730/1-2 and CU 203/ 1-2, all within the DFG priority project SPP 1473 “WeNDeLIB”.
The Electrochemical Behavior As an Indicator Test for the Graphitic Property of the Carbonaceous Anode Materials in Lithium-Ion Batteries
Authors: Elsayed Aly Mohamed Sayed Sofy
Published: February 2020

The graphitic nature of carbonaceous materials allows its application as anode material for lithium ion batteries (LIBs) as it governs. The graphitic nature of carbonaceous materials manages the distribution of the intercalated Li+ ions and where could be hosted to form the lithiated graphitic compound LixCn. In this work, a series of graphite oxides (GOs) were synthesized following the Hummer method, followed by a hydrothermal reduction. The reduced graphite oxides (RGOs) were elementally, physically and electrochemically investigated. The electrochemical behavior for each RGO as anode material for LIB was studied using the cyclic voltammogram (CV). The interlayer distance d002
for each RGO was correlated with the slope and the length of the anodic voltage plateau region for each RGO. The length of the anodic voltage plateau regions and their slopes change inversely and sequentially with d002
. This relation secures a new application for the electrochemical properties of the graphitic material, which could be used as a rapid test to estimate the interlayer distance d002
in-between the adjacent graphene layers.
Spinel Decorated Aligned Carbon Nanotube Arrays As Supercapacitor Electrodes
Authors: Oguntoye Moses , Pesika Noshir
Published: February 2020

Accompanying the need for green energy generation is a need for energy storage systems since most green energy sources like solar and wind are intermittent. In recent times, much research focus has been placed on providing more durable and higher capacity energy storage devices like supercapacitors, which has led to the design of better electrode materials for these supercapacitors. Graphitic carbon nanotubes have been tipped as superior materials for making supercapacitors because of their unique electrical properties and pore structure. They are inert, lightweight, have high electrical conductivity, high thermal stability and very high surface areas especially when aligned. As a result, they are very suitable as electrode templates because thin nanosheets or nanoparticles can be embedded within them in a high surface area configuration without excessively sacrificing ion accessibility and electrical conductivity. We report the use of aligned carbon nanotubes as supercapacitor electrode templates and highlight their superiority, as a result of a better ordered pore structure, to entangled or collapsed carbon nanotubes for electrode applications. Specifically, we use Ni-Co mixed oxide and Co-Mn mixed oxide spinels characterized using EDX and XRD as electroactive materials. These spinels have been chosen because of their relatively high electrical conductivity and are optimized for relative metal ratios. Different methods of electrochemical deposition were also explored to achieve uniform coating. However, one challenge associated with using aligned carbon nanotube templates is the resistance between the current collector and the nanotubes. It is well known that an insulating alumina layer is necessary for the sustained and efficient growth of self-aligned nanotubes. In trying to overcome this challenge, we added a molybdenum layer to reduce the resistive effect of the alumina layer. Another challenge is the capillarity induced collapse of the nanotube forest between electrodeposition and annealing during the preparation of the electrode. Our approach to solving this involved the use of a new universally applicable method: specifically supercritical drying to preserve pore structure and prevent forest collapse during annealing after electrodeposition on self-aligned carbon nanotube forests. We highlight the effects each of these processes on the eventual capacitive performance of the prepared electrodes.
(Invited) Prisitine C60 and C70 fullerenes As Electron Transport Materials for Perovskite Solar Cells
Authors: Delgado Juan Luis
Published: February 2020

The photovoltaic community is currently experiencing the revolution of the solar cells based on perovskite materials. Since the first reports based on a solid hole-transporting layer appeared, a great variety of organic molecules have been employed as electron or hole-selective contacts in regular and/or inverted perovskite-based solar cells (PSCs) (Figure 1 A and C, respectively). Fullerene and their derivatives are playing a very important role as electron-selective contact (ESC) in inverted solar cells as well as in self-assembled monolayers of fullerene derivatives on TiO2 in regular devices. Moreover, the interest of fullerenes in PSCs has been increased by the recent report of Snaith’s group, which describes the successful incorporation of [60]fullerene instead of the usual TiO2 as ESC in regular PSCs architectures (Figure 1B).

In the present comunication, careful photovoltaic studies following a well-described experimental protocol have been carried out with PSC fabricated with [70]fullerene,  [60]fullerene and [60]fullerene derivatives as Electron Transport Material in regular perovskite solar cell architecture, in order to study their suitability as ETM for PSC. The obtained results indicate that the use of these materials as ET materials in PSC allow the obtention of highly efficient devices (≥10%), due to the introduction of the "fullerene saturation approach".

Figure 1
(Invited) Synthesis and Photoswitching Tunability of GHz Dielectric Property at e-Polarizable [60]Fullerosomic Surface of Hybrid Core-Shell Nanoparticles
Authors: Chiang Long , Wang Min , Yu Tzuyang , Tan Loon-Seng , Urbas Augustine
Published: February 2020

We fabricated highly magnetic γ-FeOx@AuNP core-shell nanoparticles with deposition of fullerosome array of C60(>DPAF-C9) at the outer shell. It formed a configuration of three-layered core-shell (γ-FeOx@AuNP)@[C60(>DPAF-C9)]n
1. These surface-stabilized soluble NPs were found to be capable of photoinducing surface plasmonic resonance (SPR) effect in the inner Au layer by white LED light and subsequently transfer the accumulated PR energy at the interface to the outer, partially bilayered 1-derived fullerosome membrane layer in a near-field (~1.5 nm). The phenomena led to large amplification of dielectric properties associated with the photoswitching effect and the new unusual phenomenon of delayed photoinduced capacitor-like (i.e. electric polarization) behavior at the frequency range of 0.5‒4.0 GHz. The effect may be suitable for designing photoresponsive dielectric-switchable nanomaterial toward applications of GHz frequency devices.
(Invited) Controlled Assembly of C60 Using Supramolecular Scaffolds
Authors: Fukushima Takanori
Published: February 2020

Spontaneous molecular assembly in solution usually proceeds under thermodynamic control and thus provides a reliable approach to creating materials with high positional and/or orientational order of the constituent molecules.  If supramolecular building blocks could be purposely designed, one may control the alignment of functional molecular units so that the resulting assembly can take full advantage of the inherent properties of the functional units.  This presentation will focus on the controlled assembly of C60 using several supramolecular building blocks.  When C60 is attached to a particular type of hexabenzocoronene capable of forming a nanotubular assembly, a coaxial nanotube results, where the wall consists of hole-transporting hexabenzocoronene arrays, while inner and outer surfaces are covered by an electron-transporting monolayer of C60 [1].  We have also shown that an amphiphilic design of an oligothiophene-C60 dyad provides a rational strategy for tailoring bicontinuous electron donor and acceptor arrays [2].  We recently found that a tripodal triptycene self-assembles into a 2D hexagonal structure by nested packing. The interpenetration of the triptycene part may suppress structural fluctuation, thus enabling the formation of organic films with a remarkably long-range structural order [3].  Using this tripodal triptycene as a supramolecular building block, a C60 unit can be assembled into a two-dimensional sheet-like structure.  The synthesis and properties of these materials with controlled C60assemblies will be discussed.

References: [1] Y. Yamamoto, G. Zhang, W. Jin, T. Fukushima, N. Ishii, A. Saeki, S. Seki, S. Tagawa, T. Minari, K. Tsukagoshi, T. Aida, Proc. Natl. Acad. Sci. U.S.A.
2009, 106, 21051–21056.  [2] W.-S. Li, Y. Yamamoto, T. Fukushima, A. Saeki, S. Seki, S. Tagawa, H. Masunaga, S. Sasaki, M. Takata, T. Aida, J. Am. Chem. Soc.
2008, 130, 8886­–8887.  [3] N. Seiki, Y. Shoji, T. Kajitani, F. Ishiwari, A. Kosaka, T. Hikima, M. Takata, T. Someya, T. Fukushima, Science
2015, 348, 1122–1126.
(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
(Invited) Helical Polymer Wrapped C70-Fluorene Triadds As Ultrafast Nonlinear Photoresponsive Materials
Authors: Wang Min , Jeon Seaho , Tan Loon-Seng , Cooper Thomas , Chiang Long
Published: February 2020

We applied a novel molecular wrapping approach to fullerenyl hybrid triads to minimize solid aggregation in coating thin-film applications. Several C60-(antenna)x and C70-(antenna)x analogous compounds having branched hybrid triads C60(>DPAF-C18)(>CPAF-C2M) and C70(>DPAF-C2)(>CPAF-C2M) nanostructures, for example, were applied in the study. The structural design was intended to facilitate the ultrafast fs intramolecular energy-transfer from photoexcited antenna to the C60> cage moiety upon two-photon pumping at either 780 or 980 nm, respectively, for broadband nonlinear optical applications. 2PA characteristics at multiple NIR wavelengths provided support for their suitability in uses that includes the 2PA ability of two antenna, DPAF (700‒850 nm) and CPAF (850‒1100 nm), and the fullerene cage at shorter wavelengths (600‒700 nm). The phenomena can be enhanced by the helical polymer wrapping technique.
(Invited) The Effect of Degradation on the Wetting Properties of Exfoliated Black Phosphorus
Authors: Favron Alexandre , Moraille Patricia , Gaufrès Étienne , Phaneuf Anne-Laurence , Lévesque Pierre , Francoeur Sebastien , Leonelli Richard , Martel Richard
Published: February 2020

Thin layers of black phosphorus attract a growing interest in electronics and optoelectronics for their bidimensional properties (2D) giving raised to high mobility and tunable direct band gap. Thin films are however unstable in air and synthesis of high quality samples consisting of pristine few-layered materials remains challenging, as a result. We recently established that a combination of oxygen, light and moisture provides the conditions leading to a photo-oxidation of the layers. In controlled conditions, the kinetic of the reaction is well captured by a redox model, but the evolution is less clear in normal humidity conditions where water can simply accumulate at the surface and forms droplets. In the present study, we investigate the wetting properties of thin black phosphorous films and its evolution during degradation using FastScan atomic force microscopy in different humidity conditions. From a statistical analysis of the bubbles formed, the wettability is found to decrease with layer thickness. This difference in surface tension between thinner and thicker layers is ascribed to an accumulation of phosphoric acid in the bubbles, which reveals increasing degradation rates with decreasing layer thickness. From our analysis and a simple rate equation model, it is found that: i) A threshold humidity is necessary for water condensation; ii) The photo-oxidation occurs on single bubble sites; iii) Black phosphorus layers immersed in water slowly thickens and crumbles anisotropically due to water etching during degradation.
Insight into the Nanoscale Mechanism of Exceptional H2O Transport in Graphene Oxide Membrane
Authors: Ban Shuai
Published: February 2020

Realistic models of graphene oxide membrane were developed and validated to interpret the exceptional water permeation in association with XPS, TG-DSC and DVS measurements. With respect of the GO oxidization level, surface distributions of functionality agglomerates were analyzed in line with TEM observations, and 3 types of interlayer domains in slit pores of GO membranes were identified. It was found H2O occupancy strictly follows the hydrophilicity degrees of as-defined domains upon GO hydration. Calculated sorption enthalpies and isotherms are in good agreement with experimental data, and the results indicate the dominant role of Coulomb interaction. GO expansion shows a transition from the interstratification of H2O monolayer to the accumulation of H2O multilayers at the interlayer distance of 0.8 nm. The evolution of both hydrogen bonds and H2O diffusivities suggests the existence of 3 types of H2O species with different binding states and molecular mobilities. The computed H2O permeability on the basis of sorption-diffusion theory supports the exceptional H2O transport capacity in GO membrane.
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.