bluuebunny/crossref_metadata_2025 huggingface dataset:
Electropolymerization of Thiophene in a Bis(fluorosulfonyl)Amide Based Phosphonium Ionic Liquid
Authors: Nishihata Keiichi , Tsunashima Katsuhiko , Ono Yasushi , Matsumiya Masahiko
Published: February 2020

Room-temperature ionic liquids (RTILs) have been regarded as potential electrolytic media for electropolymerization processes.1 Many kinds of RTILs have been investigated for the electropolymerizations. For example, we have reported that a bis(fluorosulfonyl)amide (FSA) anion based imidazolium ionic liquid promoted the electropolymerization reaction of pyrrole and the anion doping into the polymerized film, improving the conductivity of the film.2 We also have applied the phosphonium based RTILs to the electropolymerization of pyrrole, investigating the influence of the phosphonium RTILs on the polymerized film properties.3 However, electrosynthesis of polythiophene in phosphonium RTILs has not been examined. In this work, we report the electropolymerization of thiophene in triethylpentylphosphonium FSA (P2225-FSA) and the effect of the phosphonium RTIL on the polythiophene film properties.

P2225-FSA was prepared according to the procedure we have previously reported,4 and dried under high vacuum at 80°C for 6 h before use. The electropolymerization of thiophene in P2225-FSA was carried out by cyclic voltammetry (CV) method using a three-electrode cell equipped with a working electrode of platinum or transparent glass electrode and an IL-based Ag/Ag+ reference electrode.

Fig. 1 showed the cyclic voltammograms for the electropolymerization of thiophene in P2225-FSA. It was found that an irreversible oxidation peak was observed and maintained even when the cycle was repeated, forming the polythiophene film on the electrode surface. It is noted that the peak current at 2.2 V vs Ag/Ag+ was enhanced by cycling, which seems likely to be attributed to the efficient anion doping into the polymerized film grown on the working electrode surface. Fig. 2 depicted a SEM image of the polythiophene film grown in P2225-FSA. A uniform surface of the film grown in P2225-FSA was observed when compared to that in an organic solvent based electrolyte, which is closely similar to the result previously found in the electropolymerization of pyrrole. The electrochemical activity and thermal stability of the polythiophene film obtained will be discussed.

References

1. K. Sekiguchi, et al, J. Electroanal. Chem.
1, 557 (2003).

2. K. Tsunashima, et al, ECS Electrochem. Lett., 3, G1 (2014).

3. K. Honma, et al, Abstracts of the Electrochemical Society of Japan
82nd Spring Meeting, PS27 (2015).

4. K. Tsunashima, et al, Electrochem. Commun., 13, 178 (2011).

Figure 1
Development of Miniaturized Nongassing Electroosmotic Pump for the Drug Delivery
Authors: Zhu Enhua , Shin Woonsup
Published: February 2020

Electroosmotic pumps are the simplest among all the pumps, consisting of two electrodes separated by a porous membrane. Most use Pt electrodes and operate at high voltages, electrolyzing water. Because evolved gas bubbles adhere and block parts of the electrodes and the membrane, steady pumping rates are difficult to sustain, and if it pumping in the closed system, the oxygen and hydrogen will mix together and it’s not safe. The use of electrochemical reaction such as Ag/Ag2O to operate the pump non-gassing with higher efficiency. It has simple structure, battery operable, flow rate is linear to voltage and to area of the pump. The pump is now curretly used to develop drug pumps such as insulin patch pump and implantable morphine pump.
2D Metal Carbide(Ti3C2Tx) Electrochemical Capacitors in Ionic Liquids
Authors: Alhabeb Mohamed , Van Aken Katherine L , Anasori Babak , Gogotsi Yury
Published: February 2020

Two dimesional (2D) metal carbides, known as MXenes,have attracted interest in energy storage applications due to their unique properties[1-3]. Pseudocapacitors are types of electrochemical capacitors in which energy is stored via surface redox reactions mechanism.

Here, we studied free standing films of titanium carbide MXene (Ti3C2) as pseudocapacitor electrodes in inoinc liquids (ILs) electrolytes. In comparison to aqueous electrolytes, the use of ILs enables us to increase the operating voltage window of MXene based electrodes and leads to high energy density. This study opens new door for MXene based electrodes in applications that requires high energy density.

References:

1. Naguib, M., et al., Two
‐Dimensional Nanocrystals Produced by Exfoliation of Ti3AlC2. Advanced Materials, 2011. 23(37): p. 4248-4253.

2. Lukatskaya, M.R., et al., Cation intercalation and high volumetric capacitance of two-dimensional titanium carbide. Science, 2013. 341(6153): p. 1502-5.

3. Ghidiu, M., et al., Conductive two-dimensional titanium carbide/clay/'with high volumetric capacitance. Nature, 2014. 516(7529): p. 78-81.
Nanoparticle Dynamics in Room Temperature Ionic Liquids
Authors: Tanner Eden E L , Batchelor-McAuley Christopher , Compton Richard G
Published: February 2020

Nanoparticle dynamics in Room Temperature Ionic Liquids (RTILs) is an underexplored field, despite high interest in RTILs in nanoparticle synthesis, the modification of electrodes and as catalysts. The solvent environment of a RTIL provides a high ionic strength medium in which to understand nanoparticle dynamics and the role of the capping agent in electron transfer to the nanoparticle.

Oxidation of silver nanoparticles capped with poly(ethylene) glycol in 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim BF4) is reported for the first time (J. Phys. Chem. C, 2015,
119 (32), 18808-18815). The oxidation of the nanoparticles shows a time dependency, suggesting that the nanoparticles assemble at the electrode surface and time allows the polymer coating to undergo an unwrapping process before the silver core is accessible for electron transfer with the electrode (‘polymer-gated’).

The addition of chloride, commonly present as an impurity in RTILs, allows 'nano-impacts', where by the nanoparticle travels to the electrode surface via Brownian motion before undergoing electron transfer as it makes contact with the electrode, to be observed novelly in a RTIL. (J. Phys. Chem. C, 2016, 120 (3), pp 1959–1965). The presence of the chloride allows the nanoparticles to undergo oxidation to silver chloride, which does not require rearrangement of the polymer.

Finally, the importance of the capping agent, and its control over the mechanism of oxidation, has been established (Chem. Eur. J, 2016, doi:10.1002/chem.201505117). Examining nanoparticles capped with 2000, 6000, and 10,000 MW poly(ethylene) glycol reveals a shift in the mechanism of silver oxidation (from nano-impact to polymer gated).
Peroxidase-Enhanced Photocatalytic Activity of Au-Cu2O Core-Shell Nanocrystals
Authors: Kuo Ming-Yu
Published: February 2020

As the talented motif of two-component systems, core-shell nanocrystals with multi-functional chemical properties have attracted ever-increasing interests. Among the different material combinations, Au-based core-shell nanocrystals are particularly appealing since the protected, nano-sized Au can perform a myriad of catalytic reactions, e.g. peroxidase enzyme mimics. On the other hand, utilization of Au can benefit semiconductor nanostructures for various photocatalytic applications. The introduced Au may function as charge separation enhancer for semiconductor, which improves the carrier utilization efficiency to promote photocatalysis. In this work, Au-Cu2O core-shell nanocrystals were synthesized and used for unique peroxidase-assisted photocatalytic applications. By virtue of the peroxidase-like property of nano-sized Au, Au-Cu2O can catalyze hydrogen peroxide to generate OH radicals for participation in photocatalytic reactions. On the other hand, due to the relative band alignment, introduction of Au can enhance the charge separation of Cu2O, therefore improving the overall photocatalytic activity. The peroxidase-enhanced photocatalytic properties of Au-Cu2O nanocrystals were evaluated by using methyl orange as the test pollutant. The results showed that Au-Cu2O surpassed pure Au and pure Cu2O in methyl orange degradation under light illumination. This superiority was ascribed to the functionality synergy between the remarkable peroxidase activity of Au and the pronounced charge separation of Au-Cu2O. This work delivers a new photocatalyst configuration by exploiting the multi-functionalities of nanosized Au for environmental and energy science applications.
Enhanced Thermoelectric Properties in One-Dimensional Mg/Ge Nanostructures
Authors: Lin Hsieh-Chang , Jiang Ming-Xun , Hsin Cheng-Lun , Chang Jeng-Kuei , Lee Sheng-Wei
Published: February 2020

High figure-of-merit (ZT) thermoelectric (TE) materials that efficiently convert heat into electricity have attracted great attention for providing a promising solution to sustainable energy technology. For a high performance TE material, the concurrent of low thermal conductivity (κ) and high electrical conductivity (σ) is essential since ZT increases linearly with σ and is inversely proportional to κ. Nanostructuring TE materials that effectively reduces lattice conductivity in conjunction with no apparent influence on electrical properties, has been recognized as the most effective approach for increasing the ZT. Therefore, it has been demonstrated that one-dimensional nanostructures could reduce the κ by hindering the carrier transport and phonon scattering, thereby leading to the enhancement of ZT. Mg2X-based (where X can be Si, Ge, Sn, or Pb) compounds are cost-effective and eco-friendly candidates for commercial applications in mid-temperature thermoelectric power generation. More importantly, these material systems have the advantage of integrating with existing Si-based integrated circuits. Recently, bulk state of Mg2Ge with ZT=0.3 at 700K has been reported. In this study, we utilize electrospinning method combining with thin-film deposition technique to fabricate one-dimensional Mg/Ge nanostructures with different composition ratios. We also fabricate suspended micro-fabricated devices for measuring thermal and electrical transport in these one-dimensional Mg/Ge nanostructures. It was found that the (Mg2Ge+Ge) sample has the highest ZT value of 0.45 at 600K among all one-dimensional Mg/Ge nanostructures. This ZT enhancement can be attributed to the lower κ, which results from the enhanced phonon scattering in one-dimensional nanostructures.
Electrochemical Detection of Low-Concentration Ammonia Gas on Miniaturised Electrodes in Room Temperature Ionic Liquids
Authors: Hussain Ghulam , Silvester Debbie S.
Published: February 2020

The detection of ammonia (NH3) gas at low concentrations is of great importance due to its use in a wide range of industries e.g. the oil and gas industry, fertilizer industry, refrigeration industry1 and due to its high toxicity. Concentrations as low as 500 ppm can be lethal, and the current (USA) Occupational Health and Safety Permissible Exposure Limit (OSHA PEL) is 25 ppm in the gas phase. There are commercially available electrochemical gas sensors to monitor ammonia, mostly based on amperometric gas sensors (AGSs). However one problem with AGSs is that their solvent/electrolyte combinations are typically water/sulphuric acid, and can dry-up quickly, thus making the lifetime of these sensors very limited. Room Temperature Ionic Liquids (RTILs) have been attracting a great attention as replacement electrolytes in AGSs2 due to their unique physical properties such as wide electrochemical windows, high intrinsic conductivity, low volatility and negligible vapor pressure, high chemical and thermal stability and their ability to dissolve a wide range of compounds. Importantly, they do not evaporate when exposed to a high gas flow, and can function in hot and dry environments. In our work, we are investigating commercially available thin-film metal electrode surfaces as new sensing surfaces, consisting of three electrodes that are incorporated onto a small area on an inert substrate. Their small size means that only a few microliters RTIL solvent needed, and the small amount of inert metal required (e.g. platinum) minimizes the overall cost of the sensor. Four different techniques will be employed for ammonia oxidation: linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV), and potential-step chronoamperometry (PSC) over the concentration range of 10-100 ppm NH3. The results on commercially available Pt thin-film electrodes, screen-printed electrodes, and microarray thin-film electrodes will be compared to “ideal” Pt microdisk electrodes. Calibration curves (current vs. concentration) for all voltammetric techniques on all four surfaces will be presented, showing excellent linearity with increased concentrations of NH3. The limits of detection found on all four surfaces for all four techniques are in the range of ca. 2-5 ppm, much lower than minimum exposure limit (25 ppm) for NH3. These results are highly encouraging and suggest that RTILs and low-cost miniaturised electrodes can be combined in sensor devices to detect ammonia gas at low ppm concentrations.

References:

(1) Stetter, J. R.; Li, J. Chemical Reviews
2008, 108, 352-366.

(2) Buzzeo, M. C.; Hardacre, C.; Compton, R. G. Analytical Chemistry
2004, 76, 4583-4588.
Visual Detection of Denatured Ferritin via Plasmonic Gold Nanoparticle Exposure through an Aminosilane
Authors: Farrell Monique , Reaume R. , Franklins D. , Jenrette Erin , Flowers Jasmin , Pradhan Aswini K
Published: February 2020

When administered to a patient, the presence of denatured proteins within a therapeutic drug product can induce a series of adverse effects ranging from mild irritation, immunogenicity, anaphylaxis, or instant death. Current methods to detect protein degradation are complicated and expensive due to costly instrumentation, reagents and technician processing time. Therefore this paper exploits plasmonic nanoparticles to create a platform for visual biosensing of denatured proteins that is fast, low cost, sensitive and user friendly. In this study artificially heat stressed ferritin and gold nanoparticles are exposed to 3-aminopropyl triethoxysilane. Upon degradation of the protein, systematic blue shifts were observed in the absorbance spectra of the gold nanoparticle/ferritin and aminosilane solution. The blue shifts in absorbance translate visually into a detectable color transition from a blue color to a purple hue. The extent of ferritin degradation was quantified using Raman spectroscopy. The mode of degradation was confirmed using dynamic light scattering and was attributed to aggregation of the ferritin due to accelerated heat stress. We have demonstrated a proof of concept which describes a system to visually detect ferritin from horse spleen that has experienced various levels of degradation.

Keywords: Biosensor, Gold nanoparticles, Denatured Protein, Visual Detection, Ferritin, Degraded Protein

Figure 1
Mesoporous Materials
Authors: Dam Duc Tai , Lee Jong-Min
Published: February 2020

Over the last decade, due to increasing environmental pollution and depletion of fossil fuels, considerable effort has been devoted to the development of clean and sustainable sources of energy. On top of that, latest technological advancements in market of hybrid electric vehicles and electronic devices lead to a need of alternative energy storage/conversion systems with higher powers and energy densities. As a result, electrochemical energy systems are grasping more attention as alternative energy sources.

In our research, we combined methods to obtain mesoporous materials which can be used as electrode material of supercapacitor with very high specific capacitance. We will discuss the influence of electrodeposition parameters such as deposition potentials, deposition temperatures and deposition time on the electrochemical capacitor behavior.

Acknowledgements Funding support for the research from Singapore Maritime Institute Maritime Sustainability (MSA) R&D Programme is gratefully acknowledged.
III-V Semiconductors for Solar Vanadium Redox Flow Battery
Authors: Wang Peng , Parkinson Bruce A
Published: February 2020

The intermittent nature of renewable energy from wind and solar sources requires effective energy storage systems. Even though solar energy storage can be realized in the form of hydrogen gas by photoelectrochemical reaction, hydrogen is a very low-density gas requiring high-end technology for storage and transport. The low quantum yield is also far below commercialized value, which makes it difficult for large-scale application. The vanadium redox flow battery(VRB) is a true redox flow battery, which combines electrochemical conversion and storage via reduction and oxidation reactions of vanadium redox couples, V(II)/V(III) in the negative half-cell and V(IV)/V(V) in the positive half-cell.1-3 With the same active vanadium species in both electrolytes, it overcomes cross contamination problem. Due to its low cost, high capacity, high charge-discharge efficiency, and long life cycles, VRB has attracted extensive research focus.

The solar VRB allows photoelectrodes to convert solar energy into electrochemical energy and direct storage of energy in positive and negative electrolyte containing V(IV)/V(V) and V(II)/V(III) redox couples, respectively. Gallium phosphide with a band gap of 2.26 eV, meets the requirement of optimal solar energy conversion efficiency in photoelectrochemical or photoelectrolysis cells.4 Our work demonstrated that photoredox reactions of vanadium electrolyte occurred on gallium phosphide under sunlight, indicating the promising use of gallium phosphide as photoactive electrodes for solar VRB. A thin amorphous TiO2 layer deposited on top of gallium phosphide by atomic layer deposition(ALD) was found beneficial to improve the long-term stability of gallium phosphide in an acidic medium, as well as facilitate electron/hole transfer on semiconductor/electrolyte interface. Thus, solar VRB would offer a promising approach for solar energy harvest, conversion and storage.

(1) Sum, E.; Skyllas-Kazacos, M. Journal of Power Sources 1985, 15, 179–190.

(2) Skyllas Kazacos, M.; Kazacos, G.; Poon, G.; Verseema, H. International Journal of Energy Research 2010, 34, 182–189.

(3) Noack, J.; Roznyatovskaya, N.; Herr, T.; Fischer, P. Angewandte Chemie International Edition 2015, 54, 9776–9809.

(4) Standing, A.; Assali, S.; Gao, L.; Verheijen, M. A.; van Dam, D.; Cui, Y.; Notten, P. H. L.; Haverkort, J. E. M.; Bakkers, E. P. A. M. Nature Communication 2015, 6, 7824.
Fundamental Aspects of Large-Scale Energy Storage System Safety
Authors: Hewson John , Ferreira Summer , Lamb Joshua , Orendorff Christopher J , Chalamala Babu
Published: February 2020

As the scale of energy storage systems increases, safety considerations grow commensurately with the amount of stored energy. The authors summarize a recent review of safety and reliability findings for battery storage and identify R&D gaps, particularly as batteries are scaled into system level hardware. While there have been a number of studies addressing failure of rechargeable batteries in portable computing and consumer electronics, with a small number of studies on electric vehicle battery systems, in the case of stationary batteries for grid energy storage, very little information exists on the fundamental aspects of safety. The aim of this review is to focus on the R&D needs that will allow the community to build on prior knowledge to address issues of abuse and safety for larger, grid scale energy storage systems. The primary focus of the review will be on the underlying materials science, electrochemical processes, and thermal kinetics that can lead to major safety events. Importantly, consideration will be given to identifying cell and system level interactions, how such interactions manifest into catastrophic failures, and the need to develop mitigation strategies.

To date, the safety of energy storage systems has been looked at almost exclusively through the narrow lens of cell level failures. While a greater understanding of cell level failures has been critical to the success of rechargeable batteries in consumer electronics, the complexity associated with the scale of energy in grid energy storage applications necessitates consideration of a wider range of system level issues related to power electronics, to power conditioning systems and to fire suppression of large energy storage systems and the surrounding physical infrastructure. Furthermore, the kinetic behavior of cell-level failure must take into account the probability of propagation and thermal runaway that is not indicated in smaller batteries of the same chemistry. We will first provide a summary on the status of current research and outline the immediate and longer term R&D needs to advance the fundamental safety and reliability needs of the grid energy storage industry.
The Effect of Contact Resistance during Nail Penetration of Commercial Automotive Lithium-Ion Cells
Authors: Abaza Ahmed
Published: February 2020

Nail penetration is an abuse test that is part of most automotive safety test standards, e.g. the Society of Automotive Engineers’ SAE J2464. The main purpose of nail penetration is to test how batteries can withstand two failure mechanisms; internal short circuits and physical damage such as in the case of road accidents.

In this research, nails with varying diameters and materials were used to carry out penetration tests on commercial 15 Ah automotive Lithium-ion pouch cells. The voltage and temperature profiles of the cells during penetration were recorded. The data shows significant variability between tests with the same experimental conditions (nail properties, ambient temperature and cell type). It is proposed that the variability is due to the varying way the nail interacts with the penetrated layers of the cell. Therefore, the contact resistance between the bilayers of the cell and the nail varies between each test.

Contact resistance cannot be readily measured in nail penetration tests. In order to understand if the contact resistance is indeed the source of variability, an external short-circuit experiment has been conducted. Different shunt resistors were used to model and represent the contact resistance and this is presented.
Non-Isothermal Electrochemical Model for Low Temperature Operation of Linca Battery
Authors: Basu Suman , Hariharan Krishnan S , Kolake Subramanyya Mayya , Song Taewon
Published: February 2020

Failure of Li-ion battery at low temperature continues to be one of the bottlenecks towards large scale commercialization of electric vehicles. Due to its high energy density, nickel-cobalt-aluminum (NCA) has gained favor as cathode material. However, not much has been reported about that low temperature performance of these cathodes. Experimental results showed that at low temperature (≤273K), the discharge voltage show effects of additional physical processes. A standard pseudo two-dimensional (P2D) electrochemical model may not be enough to adequately capture these behavior1.

At low temperature, Li-ion cells may exhibit Li-plating at anode, pseudo-capacitance at the electrode surfaces and sharp voltage drop due to increased electrolyte transport resistance, leading to cell failure. On the other hand voltage recovery due to self-heating has also been reported. Similar mechanisms have been implemented in Li-ion cells with NCM chemistry operating at low temperature2. Li-plating during charging at low temperature result in increased voltage during discharge as Li-plated over anode offer zero potential. When discharged at high rate and low temperature, the voltage shows sharp drop followed by a recovery and finally a gradual drop up to the cut off voltage. Heat generation, inherent to the high discharge rate, causes self-heating of the cell which in turn reduces the transport resistances and resulting in eventual voltage recovery. These mechanisms have been implemented over the base electrochemical-thermal model1 and validated against experiments (Fig.1). 

References:

S. Basu et al., J. Power Sources 283 (2015) 132-150

Y. Ji, Y. Zhang, C-Y. Wang, J. Electrochem. Soc., 160 (4) A636-A649 (2013)

Figure 1
3D Imaging and in-Operando X-Ray Tomography Study of Lithiation Induced Delamination and Cracking of Si Based Anodes for Lithium Ion Batteries
Authors: Tariq Farid , Yufit Vladimir , Kareh Kristina , Lee Pui-kit , Yu Dennis Y.W. , Eastwood David S , Lee Peter D , Biton Moshiel , Merla Yu , Peled Emanuel , Golodnitsky Diana , Brandon Nigel P.
Published: February 2020

It is becoming increasingly important to meet rising demands for energy storage, supply and portability. An ability to directly image and manufacture electrochemical devices such as batteries, in 3D, at high resolutions will help address these demands. The influence of microstructure on electrode behaviour can be tracked through 3D imaging, ultimately enabling intelligently designed electrodes to be printed or additively manufactured.

Tomographic techniques allow for direct 3D imaging and characterisation of complex multi-phase microstructures which are inadequately described in 2D. The performance of battery electrodes is dependent on their inherent nano/micro scale structures where important reactions occur. Microstructural differences in mechanical, electrochemical or transport behaviour at fine length scales ultimately influences cell and pack level performance. Additionally, during processing or operation, microstructural evolution may degrade electrochemical performance.

Here we utilise X-ray tomographic techniques to probe in 3D, silicon based battery structures at high resolutions. The advanced 3D quantification of complex electrode shapes, structures and morphology facilitates a detailed understanding of cell level behaviour. Furthermore, we directly image and track in-operando interfacial and microstructural changes during operation and dynamic failure (Figure 1). In doing so this provides important insights for future electrode design, enabling performance optimised structures to be created and understanding the sources of performance degradation.

Figure 1
Carbonized Nanocellulose Sustainably Boosts the Performance of Activated Carbon in Ionic Liquid Supercapacitors
Authors: Li Zhi , Liu Jun , Thundat Thomas George
Published: February 2020

Carbonized cellulose nanofibrils (CNF) have been employed to improve the rate performance of activated carbon (AC) traditionally used in supercapacitors. Because of the large amount of surface functionalities, CNF form strongly interconnected composite with AC, which turns into a free-standing carbon nanofibers/AC film after carbonization. In the film, the carbon nanofibers are ‘welded’ on AC particles and integrate them into one piece of carbon. The interaction between AC and carbon nanofibers, originating from the strong AC-nanocellulose affinity, is much stronger than the traditional physically mixed AC/nanocarbon composite and also significantly reduces the contact resistance in the composite. Conductive atomic force microscope (C-AFM) analysis reveals that the network of carbonized CNF possesses markedly better electron transport efficiency than the AC particles. When tested as supercapacitor electrode at commercial level mass loading, the composite film exhibits 2 times slower capacitance fading at high current and 3 times higher maximum power density than the bare AC. In addition, using the nanocellulose, which is derived from renewable resources, increases the total electrode cost only by a small margin, thereby making the composite a competitive electrode material for electricity storage on a large scale.
Vertically Stacked Bilayer CuCo2O4/MnCo2O4
heterostructures on Functionalized Graphite Paper for High-Performance Electrochemical Capacitors
Authors: Liu Shude , Hui Kwan San , Hui Kwun Nam
Published: February 2020

Cobaltite system with spinel structures is a promising cathode material for next-generation high-performance electrochemical capacitor because of its high stability in electrochemistry. However, increasing the mass loading of active materials without sacrificing the geometry of the nanostructures remains a challenge. In this study, we propose vertically stacked bilayer spinel heterostructures constructed from hierarchical CuCo2O4/MnCo2O4 on graphite paper as highly capable supercapacitor electrode. A two-step hydrothermal method with post annealing treatment is used in the preparation of heterostructures. CuCo2O4/MnCo2O4
electrode delivers remarkable specific capacitance of 1434 F g−1 at 0.5 A g−
1, considerable high-rate capability (810 F g−1 at 15 A g−1), and an excellent cycling stability maintaining 81.4% at 10 A g−
1 after 5000 cycles. An electrochemical capacitor device operating at 1.6 V is constructed using CuCo2O4/MnCo2O4
and graphene as positive and negative electrodes, respectively. The device shows high energy density of 42.1 Wh kg−1 at a power density of 400 W kg−1, as well as good cycling stability (88.4% retention after 10000 cycles). The stacking concept of heteronanostructures can potentially enrich the electrochemical performance of metal oxides for next-generation electrochemical capacitors.

Figure 1
In-Situ TEM Analysis of Ink-Jet Printed MnO2-Graphene for Supercapacitor Electrodes
Authors: McKeon Lorcan , Long Edmund , Coelho João , Zhang Chuanfang , Park Sang Hoon , Coull Richard , Shmelov Aleksey , Nicolosi Valeria
Published: February 2020

Supercapacitors composed of nano-layered material electrodes represent a new generation of energy storage technology. Understanding and analyzing the mechanism of how the electrode material changes and degrades during the charge and discharge process is fundamental to maximizing the efficiency of supercapacitors.

The primary objective of this body of work was to develop a method whereby the electrode-electrolyte interface of a supercapacitor could be analyzed by real time in-situ TEM imaging during the charge-discharge process. This experimental approach combines advanced microscopy techniques and electrochemical testing. This approach is in the preliminary stages of experimental development, with very few major published works exploring the specific use of this technique. First, an effective method for repeatable deposition of our layered electrode material was developed, using inkjet printing methods. Our selected active material, MnO2-Graphene nanoflakes suspended in Isopropanol was used as our material ink for printing. This suspension was printed onto a specialized electrochemistry TEM chip, featuring Au electrodes and a transparent SiN2 window for TEM viewing. A low concentration dispersion of 0.5 mg mL-1 was first used to optimize the printing process and to find the printing parameters that minimized the spreading of the printed line. Having fully optimized the printing process, a high concentration 10 mg mL-1 suspension of MnO2-Graphene was used to deposit the working electrodes of our micro electrochemical cell.

This cell was tested with a range of potential windows and multiple material deposition thicknesses. In most potential ranges, responses from the active material were difficult to observe due to the noise created by the inherent double layer capacitance of the Au electrode. Higher amounts of deposited material produced slightly higher responses but were for the most part unobservable above the aforementioned noise. These high layer depositions were also electron opaque. During in-situ TEM CV testing of these cells, prominent dendritic growth outward from our electrodes were observed.

Higher CV responses ex-situ could be achieved with higher amounts of deposited active material, overcoming the noise generated by the Au-electrolyte reactions. For in-situ tests, morphological changes could be observed with lower amounts of material, so that the individual flakes of the Solid-Electrolyte interface can be resolved via TEM analysis.
Supercapacitive Properties of the Electrodeposited Layered Electrodes of Ruthenium Oxide and Polyaniline
Authors: Kim Kwang Man , Lee Young-Gi , Kim Jumi , Kim Ju Young , Ko Jang Myoun
Published: February 2020

Layered electrodes of electrodeposited RuO2 (eRuO2) and polyaniline (ePAn) are prepared on a platinum substrate to yield ePAn-on-eRuO2 and eRuO2-on-ePAn electrodes and their supercapacitive properties are investigated. The eRuO2 electrode forms a compact stratified structure with nearly flat surfaces by electrodeposition from a RuCl3×3H2O-based solution, whereas the ePAn electrode forms densely connected particles or particle aggregates by the electrodeposition from aniline solution. In the scan rate range of 20-1000 mV s-1, specific capacitance (810-575 F g-1) of ePAn-on-eRuO2 electrode is superior by the higher probability to occur redox reaction and proton diffusion due to particulate surface and inner pores of the upper layer (ePAn), respectively. In contrast, the eRuO2-on-ePAn electrode loses the specific capacity (680-550 F g-1) but achieves higher capacity retention ratio (81%) by flat compact surface of the upper layer (eRuO2).

Fig. Schematic diagrams of (a) eRuO2, (b) ePAn, (c) ePAn-on-eRuO2, and (d) eRuO2-on-ePAn electrodes.

Figure 1
Hybrid Composite Electrodes for Supercapasitors Prepared By Simple Routes
Authors: Mokkelbost Tommy , Hanetho Sidsel Meli , Barnett Alejandro Oyarce , Tolchard Julian Richard , Svensson Ann Mari , Montemor Fatima
Published: February 2020

Supercapacitors, which can store energy by a combination of electrostatic (double layer capacitance) and electrochemical (pseudocapacitance) storage of electrical energy, are an important energy storage device applicable for a variety of uses and technologies, especially in applications which requires rapid charge/discharge cycles and several thousands of cycles, e.g. short term energy storage and high power delivery. The asymmetric electrode configuration which allows for the use of aqueous electrolytes are a promising route to low-cost and environmentally friendly supercapacitors without compromising power and energy density.

Here we present a novel approach based on easy synthesis methods to prepare hybrid electrode materials consisting of mixed transition metal oxides for the redox contribution together with carbonaceous materials contributing to the double layer response. The synthesis methods used are possible to scale up and results in nanosized, high surface area hybrid electrode materials. Three different methods have been selected resulting in significant different morphologies and characteristics. The electrode materials have been characterized by standard physical techniques, e.g. SEM, TEM, EDX and XRD. To prepare final electrode materials, inks using PTFE, ketjen black and H2O/isopropanol, was spray coated on carbon paper with a loading of approximately 1 mg/cm2. The electrodes were tested for electrochemical performance as capacitors, by use of techniques such as cyclic voltammetry and charge and discharge curves, as a function of electrode composition, time and type of aqueous based electrolyte, and compared with hybrid electrodes fabricated by e.g. electrodeposition methods.

Preliminary results have shown that it is possible to produced hybrid materials through cheap and flexible processes in aqueous electrolytes.
Controllable Growth and Ultrasensitive Molecule Detection of Large-Area Doped Graphene
Authors: Lyu Ruitao
Published: February 2020

Substitutional doping with heteroatoms is a very efficient way to tailor the electrical and chemical properties of graphene. Due to the size limitation, the most adjacent neighbors of carbon in the Periodic Table of the Elements, i.e. boron and nitrogen, are the best choice for achieving substitutional doping due to their similar sizes when compared to carbon. Accordingly, both experimental and theoretical research on N-doped graphene have been extensively carried out so far. However, the experimental reports on large-area Si-doped and B-doped graphene sheets are still quite few up to now. In this contribution, we summarize our recent progress on controllable synthesis of centimeter size, high-crystallinity doped graphene sheets. Their excellent sensing properties are demonstrated by using gaseous (e.g. NO2, NH3)1 and liquid molecules (e.g. crystal violet, rhodamine B and methylene blue)2 as probes. Our results will open up new avenues for developing high-performance sensors able to detect trace amount of molecules. In addition, other new fascinating properties can be exploited based on as-synthesized large-area doped graphene sheets.

References

1. Lv, R. et al. Ultrasensitive gas detection of large-area boron-doped graphene. PNAS
112, 14527-14532 (2015).

2. Lv, R. et al. Large-Area Si-Doped Graphene: Controllable Synthesis and Enhanced Molecular Sensing. Adv. Mater.
26, 7593-7599 (2014).
Macroscale Superlubricity Enabled By Ensembles of Graphene on Diamond Nanoscrolls
Authors: Sankaranarayanan Subramanian K. R. S.
Published: February 2020

The power of modern supercomputers together with the availability of highly scalable atomistic simulation codes have begun to revolutionize the modeling and computational analysis of materials. An enticing illustration of the same comes from our recent work where large-scale molecular dynamics (MD) simulations performed on Argonne’s supercomputer Mira closely coupled with experimentation led to a breakthrough in the field of tribology.1 An elusive phenomenon termed “Macroscale superlubricity” which refers to an extremely low friction state was shown to originate from an intriguing nanomechanical phenomenon: graphene patches wrap around nm sized diamond particles to form nanoscrolls that have significantly reduced contact area to an underlying surface. Atomistic simulations elucidated the overall mechanism and explained the mesoscopic link between the nanoscale mechanics and macroscale experimental observations. Given our recent success with nano-lubricants1, we will focus on accurately capturing ensemble effects across tribological interfaces using some representative lubricant materials (2-D materials, nanoparticles) and their combinations for different types of environments and operating conditions. This talk also will include brief discussion on our ongoing efforts towards development of a new class of force fields to enable high-fidelity large scale dynamical and statistical simulations of tribo-interfaces, properties and functionalities of new lubricants, as well as pathways and mechanisms of their in operando synthesis and assembly.

References:

Berman et al. Science, 348, 6239, 1118 (2015)
RCC Inspired Synthesis of Graphene - Carbon Nanotube Hybrid for Use in Flexible Electronics
Authors: M S Brahma Teja , B Siva Kumar
Published: February 2020

Graphene with its unique electronic and structural qualities has become an important material for use in various devices as a substrate for catalyst loading. Graphene hybrids have emerged as a new platform for various applications such as flexible photovoltaics and other flexible electronics. Key features for a material to be used include stability, rigidity, flexibility and conductivity. A self assembled hybrid of Graphene and CNTs just like laying Reinforced Concrete Cement, is envisaged to be the an ideal substrate. Also in view of growing industrial demands, a scalable method has been developed to obtain the conducting films.

Figure 1
Improved Performance in Flexible Organic Solarcells Via Optimization of Highly Transparent Silvergrid/Graphene Electrodes
Authors: Seo Jung Hwa , Walker Bright
Published: February 2020

Organic solar cells (OSCs) were fabricated on polyethylene terephthalate (PET) substrates using hybrid silver grid/graphene films as transparent conducting electrodes and the effect of the silver grid dimensions was characterized. OSCs fabricated using optimized grid dimensions of 200 mm X 200 mm X 50 nm X 2 mm (length X width X height X linewidth) on PET substrates exhibited two times the power conversion efficiency of control devices using graphene only.
Graphene Oxide Layers for a Long-Term Stable Electrochromism
Authors: Kim Tae-Ho , Choi Ki In , Kim Hyeri , Oh Seong Hyeon , Koo Jaseung , Nah Yoon-Chae
Published: February 2020

In general, organic electrochromic materials have shown a poor long-term stability during the electrochemical reactions, which is mainly due to the weak mechanical properties of the mateials in orgnanic electrolytes. There have been several approaches to enhance the stability of electrochromic polymers. As one of the effective methods, incorporation of graphene oxide (GO) into the polymers has been introduced to solve the stability issue because GO has known to significantly improve the physical properties of polymers having a good compatibility with them. A poly(3-hexyl thiophene) (P3HT) is one of the important electrochromic polymers showing color changes between red and pale blue during electrochemical reactions. However, a poor life time of P3HT is deemed a main obstacle to utilize it as an aictive layer in commercial applications such as displays or smart windows. In this study, we prepare the electrochromic P3HT layer modified with GO and discuss the electrochromic properties of the composites. In order to construct the composites, the GO protective layer which has been modified by octadecylamine (ODA) is transferred on spin-coated P3HT layer by using Langmuir-Schaefer technique. The GO-ODA protective layer shows a high coverage with closed packed molecules and a good compatibility with P3HT layer. Furthermore, it is observed that the P3HT modified by GO-ODA protective layer shows a superior long-term stability compared to pristine P3HT layer during electrochromic reactions.
Spectroscopic Analysis of Nitrogen-Doped Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared By Coaxial Arc Plasma Deposition
Authors: Gima Hiroki , Zkria Abdelrahman , Yoshitake Tsuyoshi
Published: February 2020

Ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) is a new candidate carbon semiconductor applicable to electrical devices. It has been investigated that nitrogen-doping for diamond is ineffective for realizing n-type conduction at room temperature, because nitrogen form a deep donor level of 1.7 eV below the bottom of a conduction band in diamond. For a-C:H, n-type conduction is realized by nitrogen doping, however it is difficult for the carrier density to be controlled widely. On the other hand, it has been reported that nitrogen doping is effective for UNCD/a-C:H prepared by chemical vapor deposition (CVD) and pulsed laser deposition (PLD)1), 2), the doping mechanism for UNCD/a-C:H seems to differ from those for diamond and a-C:H. In this study, UNCD/a-C:H films were prepared by coaxial arc plasma deposition (CAPD) with nitrogen atmosphere and the effects of the nitrogen doping on the UNCD crystallite formation were structurally investigated. X-ray photoemission spectra (XPS), which were measured with MgKα line, of the UNCD/a-C:H films prepared at different inflow ratio of nitrogen and hydrogen (IN/H
). N1s peaks strengthened with an increase in the IN/H
, which evidently indicates that the nitrogen content in the film increased with the IN/H
. The nitrogen contents of the films deposited at IN/H
of 0.25, 0.5, 1.0 and 1.5 were estimated to be 3, 5, 6 and 8 at. %, respectively. Near-edge X-ray absorption fine structure (NEXAFS), spectral shape of the nitrogen-doped films different from the undoped film were obtained. By increasing the doping amount, the intensity of the π*C=N increased, while the intensity of the σ*C-C is decreased. Which refers to strengthen in sp2 bonds and weaken in sp3 bonds. Furthermore, increasing the electrical conductivity by increasing the nitrogen-doping amount can be ascribed to contribute of sp2bonds. The details will be reported at the conference.

1) Dai, et al.: Phys. Rev. B 71, 075421 (2005).

2) T. Yoshitake, et al.: Jpn. J. Appl. Phys 49, 015503 (2010).
Defect Structures of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared By Physical Vapor Deposition
Authors: Katamune Yuki , Takeichi Satoshi , Al Riyami Sausan , Yoshitake Tsuyoshi
Published: February 2020

Ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were prepared by coaxial arc plasma deposition (CAPD), which is categorized as a physical vapor deposition technique, while the preparations are mainly conducted by chemical vapor deposition using a hydrocarbon carbon source gas. There have been few reports on defect structures in UNCD/a-C:H films thus far. In this study, the defect structures of UNCD/a-C:H films prepared by CAPD were investigated. Electron spin resonance measurements implied that there are a large number of dangling bonds in the films as defects. The optical absorption spectra exhibited additional optical gaps in diamond band gap due to disordered structures induced by dangling bonds and sp2- and sp3-bonded carbon atoms. The temperature dependence of the electrical conductivity indicated that the transport of carriers can be explained by a variable hopping theory, which might occur via defect states, similarly to the films prepared by conventional CVD.
Galvanic Corrosion Studies of Aluminum Coupled to Non-Passivating and Passivating Alloys
Authors: Quiambao Kathleen
Published: February 2020

Research has been conducted to study the corrosion behavior of galvanic couples in order to develop a thorough understanding of the galvanic corrosion of aluminum (i.e., 6061-T6 Al) in atmospheric environments when it is coupled to more noble non-passivating metals (i.e., silver and copper), passivating metals (i.e., Ti-6Al-4V and 316 stainless steel), and non-passivating active metals (i.e., mild steel and Mg AZ31B). The couples were subjected to atmospheric exposure in marine, volcanic, and rainforest environments, as well as the chloride-containing GM 9540 accelerated corrosion test. The purpose of the research project is to obtain a scientific understanding of the galvanic corrosion mechanisms and quantitative metrics for aluminum so that the data can be used to predict the effects of galvanic corrosion in multiple component systems. The determination of overall corrosion damage during atmospheric exposure is complicated because non-passivating, noble metals (e.g., Cu and Ag) can contaminate the aluminum surface and change the local-action corrosion rates; whereas, passivating metals (e.g., 316 stainless steel and Ti-6Al-4V) are less likely to contaminate the Al surface. In this experiment, corrosion rate was determined by measuring galvanic corrosion currents and total corrosion was measured via mass-loss data. The differing corrosion rates between each atmospheric condition can be attributed to environmental parameters such as specimen temperature, time of wetness, chloride deposition, acid rain, etc. Potentiodynamic polarization experiments were also conducted to study the mechanisms of galvanic corrosion for the couples described above.