bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigations on Mechanisms of Ionic Transport and Phase Transition in Insertion Electrode Materials for Lithium/Sodium-Ion Batteries
Authors: Huang Xuejie , Sun Yang , Lu Xia , Pan Huilin , Zhao Liang , Hu Yong-Sheng , Gu Lin , Li Hong , Chen Liquan , Xiao Ruijuan
Published: February 2020

Insertion electrode materials are included in the majority of ambient-temperature Li/Na-ion batteries, which attract increasing attention in energy storage. Being a commercialized cathode material of Li ion battery, olivine LiFePO4 has undergone intensive research. Previously, the two-phase separation mechanism upon charging was well accepted, while recent experimental results indicates a more subtle atomic structure, lithium-staging, exists upon charging. We show that, through first-principles calculations, the observed lithium-staging configuration in partially delithiated LiFePO4is a kinetically controlled thermodynamically metastable state. Our results shed light on the interactions between electron and ion and hence may have general implications for investigating the ionic transport in other strongly correlated mixed conductor materials. [1]

Spinel Li4Ti5O12 is well-known as a “zero-strain” anode for lithium-ion batteries. We found that it can also accommodate sodium ions, displaying an average storage voltage of 0.91V vs. Na+/Na. Through combined density functional theory calculations and scanning transmission electron microscope imaging techniques, a three-phase separation reaction, which has never been seen in any insertion electrode materials for lithium- or sodium-ion batteries, is confirmed in the sodiation process of Li4Ti5O12. Furthermore, interfacial structure is clearly resolved at an atomic scale in electrochemically sodiated Li4Ti5O12for the first time via the advanced electron microscopy. [2]

Acknowledge:

This work was supported by funding from the “863” Project (2009AA033101), “973” Projects (2013CB934002,2009CB220104)

Reference:

[1] Yang Sun, Xia Lu, Ruijuan Xiao, Hong Li, and Xuejie Huang. Chem. Mater. 24 (2012) 4693.

[2] Yang Sun, Liang Zhao, Huilin Pan, Xia Lu, Lin Gu, Yong-Sheng Hu, Hong Li, Michel Armand, Yuichi Ikuhara, Liquan Chen and Xuejie Huang. Nat. Commun. 4 (2013) 1870
Rotational Dynamics and Li+ Transport Pathways in [PF6][P1,2,2,4]
Authors: Carignano Marcelo A. , Serra Pablo
Published: February 2020

Diethyl(methyl)(isobutyl)phosphonium hexafluorophosphate, [PF6][P1,2,2,4], is an organic ionic plastic crystal with potential uses as a solid electrolyte in Li-ion cells. Using molecular dynamics simulations we perform an exhaustive study of this material at temperatures spanning from 175 K to 500 K. The simulations predict the stability of the crystalline phase for temperatures lower than 197 K where a transition to a semi-plastic phase with rotations of the PF6 anion is observed. At 280 K the larger cations start to undergo jump-like rotations. A transition to a fully plastic phase is observed at 340 K, and melting occurs at 450 K. We have also studied the most favorable pathways for a single Li ion to move in the bulk of the material at each one of the different phases. Overall the results agree with previously reported experimental data and the simulations provide exquisite details on the atomistic rotational dynamics. Nevertheless, the simulations also reveal the shortcomings of current force fields to describe material properties in an extended temperature range and highlight the needs for further theoretical efforts in order to achieve predictive power in general systems.
Measurement and Characterization of Li-Ion Battery Single Particles
Authors: Miller Dean J
Published: February 2020

One of the challenges in correlating Li-ion battery performance with structure is the fact that most measurements provide average properties that are difficult to correlate with local microstructure. We approach this challenge by electrochemical cycling of single particles upon which detailed characterization can be carried out before and after various periods of cycling. The electrochemical cycling of single particles shows the same characteristic signatures as those observed in measurement of coin cells, confirming the validity of these measurements to global behavior. By using a measurement platform compatible with a variety of microstructural characterization approaches, we are able to characterize single particles at various points in cycling, providing an improved opportunity to correlate changes in structure with changes in electrochemical performance. This presentation will detail our approach and the insights gained from these correlated measurements.

*Research sponsored by the U.S. DOE, Office of Science and by the U.S. DOE, EERE – Vehicle Technologies Program, under contract DE-AC02-06CH11357. The Electron Microscopy Center is supported by the Office of Science.
Density Functional Tight Binding Study on Solid Electrolyte Interface of Lithium Sulfur Battery
Authors: Hur Kahyun
Published: February 2020

One of the most promising cathode materials for lithium batteries is sulfur, abundant in nature and an undesirable impurity in petroleum. It is thus very cheap. Lithium sulfur batteries, i.e. lithium batteries with a sulfur cathode, have potentially high electric capacity but so far only very poor cyclability. For practical use of lithium sulfur batteries, the poor cyclability should be overcome. However, chemical reactions at lithium and sulfur interface are barely known thus hampering the progress in this field. In particular, theoretical and simulation studies on lithium-sulfur solid electrolyte interface (SEI) at the atomic scale are highly demanding in order to accurately understand interactions between lithium and sulfur. Density functional tight binding (DFTB) approach is based on density functional theory but much more efficient thus enabling simulations of large-scale molecular systems and their long-time dynamics. One of the most severe drawbacks of DFTB approaches is lack of available parameters for lithium batteries. Here we have developed DFTB parameters for SEI of lithium sulfur batteries including electrolytes and performed long-time molecular dynamics simulations to understand kinetics of lithium insertion into sulfur electrodes. Chemical interactions of lithium electrolytes and sulfur electrodes are demonstrated and further compared with more accurate DFT calculations at a smaller system.
On Various Hydrocarbon Ion Conducting Membranes for a Vanadium Redox Flow Battery
Authors: Lee Mi-Soon , Choi Young-Woo , Jeon Jae-Deok , Nahm KeeSuk
Published: February 2020

Several types of ion conducting membranes such as cation exchange membrane, anion exchange membrane, and amphoteric membrane with low vanadium co-ion crossover were evaluated for a vanadium redox flow battery. Three kinds of polymer electrolytes consisting of caion exchangable or anion exchangable or aphoteric functionals were introduced into porous hydrocarbon substrates and crosslink-polymerized by radical polymerization in this work.  The thickness of the prepared membranes was controlled between 20 and 25 micrometers to extremely lower membrane resistances. Finally, film-like polymer electrolyte membranes were prepared. To compare membrane property a cast type of caion exchange membrane was also prepared. The prepared four different types of pore-filling membranes and a cast membrane were examined to compare vanadium co-ion crossover through the membranes. Also, the physico-chemical properties of the prepared membranes such as swelling behavior, membrane area resistance were investigated to apply for charge-discharge performance in correlation with the electrolyte composition.

Figure 1
Study on the Electrochemical Characteristics of Multiwalled CNTs Decorated By Various Oxygen Functional Groups (Non-Aqueous and Aqueous based Electrolytes)
Authors: Oktaviano Haryo Satriya , Wajima Mikiya , Waki Keiko
Published: February 2020

Functionalized nano carbon have been reported as promising cathode materials for Li ion battery (LIB).[1-2] Unlike the conventional Li intercalation into host material, the Li storage mechanism on this materials was thought to be the Faradaic reaction between surface functional groups and Li, C=O + Li+ + e- = C-O-Li.[1-2] Introducing functional groups on  few walled carbon nanotubes (CNTs) by acid treatment resulted in Li storage capacity up to 120 mAh/g.[2] However, the origin of which functional groups is responsible for such reaction still elusive. A better understanding on the electrochemical characteristics of functionalized nano carbon is not only important for LIB storage but also aqueous based electrochemical systems.

It is known that there are two major dominant surface groups present on functionalized CNTs; they are carboxyl and carbonyls.[3] To be able to study the electrochemical characteristics of different oxygen functional groups, controlling the type of surface groups on CNTs is obligatory. Here, different kind of functional groups are introduced onto multiwalled CNTs (VGCFX) by varying different oxidizing agent, such as reflux under inorganic acid solution or reacting with organic acid (i.e. citric acid). Furthermore, by annealing at certain temperatures, we also could selectively attain the functional groups present on the surface of CNTs. The electrochemical studies of oxygen functional groups are carried out in non-aqueous (organic) and aqueous based electrolytes, to obtain comprehensive knowledge on the functional groups reactivity.

On the other hand, X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) are extensively used to examine the type and amount of surface groups. Fig. 1 shows the C1s XPS spectra of two of different samples, they are acid treated CNTs (HA) and citric acid treated HA (HA-CA). Briefly, acid treated CNTs was derived from refluxing pristine CNTs in the mixture of H2SO4/HNO3, while citric acid treatment was conducted by mixing the HA with citric acid, followed by annealing in air at 300 oC. It can be seen from XPS scan, that HA-CA has an appeared peak relating to the carboxyl group (288.9 eV) than HA. This suggests that citric acid treatment is plausible to introduce carboxyl groups on the surface of multiwalled CNTs. The roles of the oxygen functional groups play in the electrochemical characteristics will be discussed in the presentation.

References

[1] S. W. Lee, N. Yabuuchi, B. M. Gallant, S. Chen, B. S. Kim, P. T. Hammond, and Y. S. Horn, Nature Nanotechnology, 5, 531 (2010)

[2] S. W. Lee, B. M. Gallant, Y. Lee, N. Yoshida, D. Y. Kim, Y. Yamada, S. Noda, A. Yamada, and Y. S. Horn, Energy Environ. Sci., 5, 5437 (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
Electroless Deposition Assisted CuO/Carbon Fiber Nanohybrids for Fiber Supercapacitors
Authors: Park Hun , Noh Seung Hyun , Kim Young Beom , Han Tae Hee
Published: February 2020

A rapid growth in wearable technology is accelerating the advent of next generation of wearable electronics, which will become even more wearable and functional. Before this advance, however, the development of one-dimensional (1-D) flexible energy storage devices which can be woven into textile forms favorable to direct integration with wearable electronics is essential. To this end, many researchers have extensively studied fiber-type supercapacitors because when compared to batteries, supercapacitors exhibit higher power density, longer cycle life, and better safety. Inspite of these merits of supercapacitors, a scalable and facile synthetic route for fabrication of 1-D electrodes is still limited. In addition, low energy density of supercapacitors must be overcome for their practical use. In this work, we used carbon fibers as both a current collector and template for electroless deposition of copper. After thermal treatment, the carbon fibers were continuously coated with multifaceted copper oxide, leading to increase of the surface area. Moreover, with the aid of pseudo-capacitive behavior of copper oxide, the energy density of our fiber-type supercapacitor was highly improved, compared to carbon fibers only. Our approach offers a scalable, robust synthetic pathway to prepare CuO/carbon fiber composites for supercapacitor electrodes via electroless deposition.
Modeling the Thermal Behavior of a Lithium-Ion Battery Module for Hybrid Electric Vehicle Applications
Authors: Koo Boram , Yi Jaeshin , Shin Chee Burm
Published: February 2020

The lithium-ion battery (LIB) is a preferred power source for hybrid electric vehicle (HEV) applications due to its outstanding characteristics such as high energy density, modular scalability, long cycle life, and low self-discharge rate among others. In a battery module for HEV applications, an uneven temperature distribution in the module can be created depending on the operating conditions and the types of thermal management. Uneven temperature distribution in a module could cause an electrical imbalance and thus lead to the lower performance and shorter life of battery. It is, therefore, important to calculate accurately the uneven temperature distribution in a battery module in order to achieve the optimum performance and long life of the battery module.

In this work, a modeling is performed to investigate the effect of the operating condition on the thermal behavior of an LIB module. The thermal conductivities of the various compartments of a battery cell are estimated based on the equivalent network of parallel/series thermal resistances of the battery components. The heat generation rate in an LIB cell is calculated by using the modeling results of the potential and current density distribution of a battery cell. The temperature distributions in the LIB module obtained from the modeling are in good agreement with the experimental measurement.

The battery module consisting of 8 prismatic pouch-type LIB cells modeled in this work is shown in Fig. 1. In Fig. 2, the temperature distributions of the LIB cells within the module at a few cross sections along the y direction are shown at the discharge time of 960 s with the discharge rate of 3C for natural convection cooling. The temperatures of the two cells located at the bottom and top of the module are lower than those of the other cells.

Figure 1
Surface Chemistry, Charge Transfer, and Transport in La0.1Sr0.9TiO3-Alpha-Based Solid Oxide Fuel Cell Anodes: Modeling and Experimental Study
Authors: Yurkiv Vitaliy , Constantin Guillaume , Hornes Aitor , Gondolini Angela , Mercadelli Elisa , Sanson Alessandra , Dessemond Laurent , Costa Rémi
Published: February 2020

Ni/YSZ composite materials have shown the tremendous success over past years for application as SOFC anodes. One of the biggest advantages of Ni/YSZ SOFC anode is its ability of direct utilization of various fuel types, i.e. H2/H2O, CO/CO2 and hydrocarbons. It is, however, well known that operation of those anodes upon various fuels could cause various types of cell degradation. Therefore, the replacement of Ni cermet with alternative ceramic materials is essential to develop long-term operating SOFC technology.

In the present contribution, we combine modeling and experimental study of electrochemical hydrogen oxidation at an alternative perovskite based mixed-conducting SOFC anode. Composite electrodes were produced by conventional wet ceramic processing (screen printing – spraying) and sintering on YSZ electrolytes (La0.1Sr0.9TiO3-α-Ce1-xGdxO2-α | YSZ) with different compositions and microstructure, and were electrochemically characterized using symmetrical button-cells configuration. An elementary kinetic model was developed and applied to explore the performance of LST based SOFC anode. A detailed multi‐step heterogeneous chemical and electrochemical reaction mechanism was established taking into account transport of ions in all ionic phases, and gas transport in channel and porous media. It was found that heterogeneous chemistry at LST surface has capacitive behavior that alters the impedance spectra. In addition, surface charge-transfer reaction, which describes partial oxygen ionization, caused impedance feature and is rate-limiting at high temperature. The gas transport in the supply chamber (gas conversion) is significant only at moderate temperatures.
Mechanical and Dielectric Relaxation in 8 Mol% YSZ
Authors: Gao Peipei , Radovic Miladin , Brankovic Goran , Brankovic Zorica
Published: February 2020

8 mol% Yittria Stabilized Zirconia (8YSZ) with high ionic conductivity is currently essential material for highly-efficient and environmentally-friendly energy technologies, such as solid oxide fuel cells (SOFCs). Mechanical properties, as well as electrochemical properties, of 8YSZ are of great importance for reliability and durability of SOFCs which work under harsh environment including high temperature, mechanical stress, electrical field, oxidizing/reducing environment, etc. In this study, mechanical behavior of 8YSZ was studied by cycling compression testing and Dynamic Mechanical Analysis (DMA) in the 25 – 600°C temperature range. Both testing methods demonstrate significant frequency dependent mechanical losses in the 50 – 500°C temperature range that can be attributed to anelastic reorientation of oxygen vacancy – dopant clusters. In addition, electrical polarization and impedance spectroscopy were carried on in the same temperature range, and the results are compared to the results of mechanical spectroscopy. Underplaying mechanisms for electro-mechanical coupling in 8YSZ were discussed in more details in this paper.
High Energy Density Aqueous Metal Hydride-Air Batteries
Authors: Bugga Ratnakumar V , Kindler A. , Valdez Thomas I , Tan Hongjin , Weadock Nick , Fultz Brent , Uddin Jasim , Addison Dan
Published: February 2020

Li-ion batteries exhibit poor abuse tolerance which necessitate complex charge management electronics, elaborate thermal management and adequate mechanical reinforcements, which result in reduced system-level energy densities and higher battery costs.  These constraints make the aqueous systems more appealing, especially if their energy densities can be further improved.  In this context, we are developing low cost and safe (aqueous) rechargeable metal-hydride / air batteries with high energy densities (200 Wh/kg and 400 Wh/l at cell level) and long cycle life for electric vehicle applications under an ARPA-E sponsored program.  Our effort is focused on developing: i) new metal hydride alloys with higher hydrogen absorption capacities, ii) stable electro-catalysts for bifunctional oxygen electrode or suitable dual-electrodes for oxygen reduction/oxidation, iii) Stable hydroxyl membranes for improved cell durability and easier water management, and iv) New cathode designs with dispersed catalysts over nanostructured frameworks.

For the metal hydride anodes, the desired performance parameters include: i) High hydrogen absorption of > 1.5 w% in the gas phase with low absorption pressures (below 2 bar) and desorption temperatures (ambient), ii) High electrochemical capacity of 400 mAh/g, iii) Low corrosion rate and long cycle life (> 1000 cycles) and iv) fast electrode kinetics to operate at  > C/3 rate. We initially focused on AB5 alloys, supplied by BASF (e.g., La10.5Ce4.3Pr0.5Nd1.4Ni64.3Co5.0Al6.0Mn4.6Cu3.4)1 to establish the baseline for MH-air cells.    In parallel, we have started developing metal hydride alloys of V-based BCC Alloys, specifically quaternary alloys of Ti-V-Ni-Cr, which reportedly have a maximum discharge capacity of 450 mAh/g with 90% capacity retention over 30 cycles.2 For the metal hydride air cells, we have been focusing on both the options of bifunctional air cathode as well as dual-electrode configuration, i.e., with an auxiliary electrode to support the oxygen evolution reaction (OER).   Our initial studies for the bifunctional air cathode are based on thin-film noble metal catalysts, dispersed on nanostructures. For the dual electrode configuration, we are examining low-cost commercial electrodes based on manganese oxide catalysts for oxygen reduction, and Ni-based electrodes for OER. In either case, we have been able to demonstrate good cycling characteristics in laboratory MH-air test cells.  In addition, we performed fundamental studies on the MH anodes as well as air cathodes, using the Differential Electrochemical Mass Spectroscopy (DEMS) technique (developed at Liox with swage-lock test cells coupled with mass spectrometer), to understand the gaseous environments within a MH-air cell.

Young et al., J. of Alloys and Compounds 509 (2011) 4896.

Inoue et al., Electrochimica Acta (2012), 59, 23-31
Rechargeable Seawater Battery
Authors: Kim Youngsik
Published: February 2020

This study demonstrates the feasibility of a rechargeable sweater battery that use seawater and its contents of chemicals as the anode and cathode materials for the first time. Na-ions were harvested from the seawater by charging the battery, and the harvested Na-ions were discharged with water (or oxygen dissolved in the seawater) as oxidants to produce an electricity. Seawater provided both chemicals of the anode (Na metal) and cathode (O2) materials for the proposed battery, and it is rechargeable. From the discharge voltage (~2.9 V) and charge voltage (~4.0 V) at the first cycle, ~73% of the voltage efficiency was observed. When the seawater battery was built by using a hard carbon as the anode and NASICON as the solid electrolyte, a good cycle life performance was observed up to 40 cycles.
Battery Metrics and Real-World Automotive Target Modelling
Authors: Karulkar Mohan
Published: February 2020

Long term PHEV and EV targets, provided by USABC, highlight the need for batteries with both higher energy and higher power.[1]  These mid- and long-range goals provide standardized targets for assessing future battery technology, and are developed with the vehicle in mind. Consequently, they include pack-level and cell-level targets.

Conversely, much of the work performed on early-stage technology focuses on one specific component, like the anode or cathode. Half-cell configurations are typically used with Lithium metal, and not a real-world counter electrode. Also, experiments are usually carried out in research cells (coin, Swagelok, etc) which carry high weight and volume overhead in exchange for stability and reproducibility with small electrodes. Thus, extrapolating the experimental performance of a material in a research setting to compare with a cell-level target is difficult.

To address this gap, an automotive target modelling tool has been developed and demonstrated on several candidate systems.[2] The model allows comparison of early-stage materials with real-world automotive targets from USABC, including energy density, power density, specific energy, and specific power (Figure 1).  It also allows the proposal of hypothetical scenarios to identify the most promising areas of development, as well as potential showstoppers (Figure 2). 

An in-depth discussion of Ford’s Carbon-Silicon composite anode research will be discussed in the context of automotive target modelling, as will several other battery systems.  A discussion on metrics in general will also be presented, as well as the development of a systematic material assessment protocol and “early assessment targets.” 

Figure 1: Automotive target modelling for several investigated C-Si systems, for Specific Power.

Figure 2: Using Automotive target modelling to assess hypothetical scenarios and identify cases where all targets can be met.

[1] United States Advanced Battery Consortium, USABC Goals for Advanced Batteries for EVs (2013).

[2] M. Karulkar, R. Blaser, R. Kudla, J. Power Sources, 273, 1194-1201 (2015).

Figure 1
Effect of Contaminants on the Performance of a PEMFC
Authors: Tavakoli Bahareh , Weidner John W.
Published: February 2020

The overall cost and performance of proton exchange membrane fuel cells (PEMFCs) are an issue of tradeoffs, and the optimal design depends on the application. For example, avoiding degradation via contamination by using expensive materials increases the initial cost to produce the system, but it can extend life and improve the overall performance. This may be desirable where reliability is paramount. In contrast, using less expensive materials reduces the initial cost, but at the expense of the life-time cost of the system and reduced performance.

During this study, a systematic and collaborative investigation was conducted to understand, characterize, and quantify the degradation mechanisms due to contaminants that arise from components that make up the fuel-cell system. Initially, the key contaminants that leach out of commercial assembly-aid materials were identified and screened for their detrimental effect on fuel-cell component performance (e.g. catalyst activity, membrane conductivity). Then, model compounds were selected and in-depth parametric studies were performed. In total, four model compounds in the assembly aid materials have been selected to study the degradation mechanisms, and the impact to PEMFC performance and durability of each compound was evaluated by in-situ infusion tests and in-situ membrane resistance tests. The results from these parametric studies were then used to develop mathematical models to quantify the performance loss and recovery of the fuel cell.
(Invited) Morphological Control and Kinetics Characterization for Perovskite Solar Cells
Authors: Diau Eric Wei-Guang
Published: February 2020

The development of all solid-state thin-film solar cells has reached a new milestone when the devices made of organometallic lead halide perovskite materials were reported with power conversion efficiency (PCE) exceeding 19 %. The key issue to make a device with a great photovoltaic performance for perovskite solar cells is to control the film morphology of perovskite under different experimental conditions. In this lecture, I will demonstrate how the film morphology of perovskite can be controlled via varied synthetic approaches. Typical n-type device has a structural configuration FTO/TiOx/TiO2/CH3NH3PbI3/Spiro-OMeTAD/Au whereas that of a p-type device is configured as ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Al. For n-type devices, varied mesoporous TiO2 nanostructures were applied to show the morphological effect of the scaffold on the device performance with a mesoscopic heterojuction; for p-type devices, varied additives were applied to control the formation morphology of the perovskite nanocrystals with a planar heterojunction. Photo-induced absorption (PIA) spectra and nanosecond transient absorption (ns-TAS) kinetics were also performed to understand the electron-hole recombination rates responsible for the corresponding device performances. Measurements of power dependence on emission intensities vs excitation power densities were also performed and an Auger-type energy transfer model was utilized to rationalize the observed relaxation dynamics.
(Invited) Photophysics of Hybrid Semiconductor Nanostructure in Photocatalytic Hydrogen Generation Applications
Authors: Kuno Masaru
Published: February 2020

Semiconductor nanostructures possess a number of applications in solar energy conversion.  This includes using colloidal quantum dots in solar cells and, more recently, using analogous nanostructures such as nanowires (NWs) in photocatalytic applications.  Here we describe recent work to understand the photocatalytic response of solution-synthesized CdSe NWs within the context of hydrogen generation.  Various CdSe NW-based systems such as core/shell structures and hybrid metal nanoparticle/semiconductor NW hybrid systems have been studied.  In all cases, femtosecond transient differential absorption spectroscopy has been used to reveal relevant carrier relaxation processes in these materials as well as the flow of charges across the different heterointerfaces that are present.  By correlating these transient absorption results to results from accompanying hydrogen generation efficiency measurements, we have, in turn, rationalized the response of these materials, clarifying the role that different heterojunctions play in establishing both charge separation and hydrogen generation efficiencies.
(Invited) Plasmon-Induced Artificial Photosynthesis
Authors: Misawa Hiroaki
Published: February 2020

We have demonstrated plasmonic photocurrent generation from visible to near-infrared wavelengths without deteriorating photoelectric conversion using electrodes in which gold nanorods are elaborately arrayed on the surface of a TiO2 single crystal.1-3 We have also reported the stoichiometric evolution of oxygen via water oxidation by irradiating the plasmon-enhanced photocurrent generation system with near-infrared light.4-6 In the present study, we developed a plasmon-assisted water splitting system that operates under irradiation by visible light; the system is based on the use of two sides of the same strontium titanate (SrTiO3) single crystal substrate.7 The water splitting system contains two solution chambers to separate hydrogen (H2) and oxygen (O2), respectively. To promote water splitting, a chemical bias was applied by pH values regulations of those chambers. The quantity of H2 evolved from the surface of platinum, which was used as a reduction co-catalyst, was twice of O2 evolved from an Au nanostructured surface. Thus, the stoichiometric evolution of H2 and O2 was clearly demonstrated. The hydrogen evolution action spectrum closely corresponds to the localized surface plasmon resonance spectrum, indicating that the plasmon-assisted charge separation at the Au/SrTiO3 interface promotes water oxidation and the subsequent reduction of a proton on the backside of the SrTiO3substrate. We have elucidated furthermore that the chemical bias is dramatically reduced by plasmonic effects, which indicate the possibility of constructing an artificial photosynthesis system with low energy consumption.

According to the analogous method of the water splitting system, we have successfully constructed the artificial-photosynthesis system which produces the ammonia by a photofixation of a nitrogen molecule based on visible light irradiation.8Unlike the water splitting system, ruthenium is used as a co-catalyst instead of a platinum for the ammonia synthesis, and not a solution system but a gas system is used to reduce nitrogen gas. The action spectrum of the apparent quantum efficiency of ammonia evolution showed good agreement with the plasmon resonance spectrum. Therefore, we succeeded in photoelectrochemical synthesis of ammonia by the visible light irradiation through the plasmon-induced charge separation.

References:

Y. Nishijima, K. Ueno, Y. Yokota, K. Murakoshi, H. Misawa, J. Phys. Chem. Lett.
2010, 1, 2031-2036.

S. Gao, K. Ueno, H. Misawa, Accounts. Chem. Res., 2011, 44, 251-260.

X. Shi, K. Ueno, T. Oshikiri, H. Misawa, J. Phys. Chem. C,
2013
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117, 24733-24739.

Y. Nishijima, K. Ueno, Y. Kotake, K. Murakoshi, H. Inoue, H. Misawa, J. Phys. Chem. Lett.,
2012, 3, 1248-1252.

X. Shi, K. Ueno, N. Takabayashi, H. Misawa, J. Phys. Chem. C,
2013, 117, 2494-2499.

K. Ueno, H. Misawa, NPG Asia Mater., 2013, 5, e61.

Y. Zhong, K. Ueno, Y. Mori, X. Shi, T. Oshikiri, K. Murakoshi, H. Inoue, H. Misawa, Angew. Chem. Int. Ed., 2014, 53, 10350-10354.

T. Oshikiri, K. Ueno, H. Misawa, Angew. Chem. Int. Ed., 2014, 53, 9802-9805.
Porphyrin Derivatives in Transistors and Nano/Micro Sized Coordination Polymers
Authors: Lee Suk Joong
Published: February 2020

Recently, the charge-transport phenomena of organic conjugated materials have been intensively investigated because of the potential applications in electronics and optoelectronics. Among them, organic field-effect transistors (OFETs) fabricated from either thin films or well-defined single crystals (SCs) as charge-transporting layers are one of the most promising electronic devices. In particular, the unique anisotropic arrangement of organic semiconducting molecules owing to their strong intermolecular interactions is expected to have a significant influence on the OFET performance, because the larger overlap of pi-orbitals between neighboring molecules may increase the bandwidth and facilitate charge-transport. In this regards, porphyrin is one of the most important p-conjugated planar molecules and they have often been employed in OFETs, organic phototransistors (OPTs), and organic photovoltaics (OPVs). A deeper understanding of such systems has hardly been achieved because of the lack of information on the molecular packing and intermolecular arrangement (which are closely related to the OFET performance), since most porphyrin-based OFET devices are based on thin films or polycrystalline objects prepared by spin-coating or vacuum-deposition processes and showing relatively poor device performances because of the limitation in use of pi-conjugation. For a high degree of crystallinity with an excellent determinacy as well as a high corresponding device performance, the extension of pi-orbitals and the location of conjugative substituents on the porphyrin core may play major roles. Therefore, I like to present a series of new pi-extended porphyrin derivatives and their OFET devices performances along with films and single-crystals.

In addition, I like to introduce the rational synthesis of porphyrin based unique structures with a variety of morphologies obtained from the manipulation of secondary substituents (i.e., substituents that are not directly bonded to the porphyrin ring) and the introduction of various metals to engender van der Waals interactions beyond the immediate porphyrin ring and metal meditated coordination bondings. So, I like to introduce porous coordination polymer particles assembled by a simple synthetic manipulation and their applications in heterogeneous catalysis.
Phthalocyanine Based Anti-Corrosive Materials
Authors: Gokceoren Argun T , Arsalanoglu Yasin , Kaplan Ekrem
Published: February 2020

Nanofibers possess exclusive physical, chemical, and electronic properties. Although different methods are known [1-2], electrospinning has been used with an increasing impact because of the ease of proceeding and the use of a wide range of polymeric materials [3–4] in the production of nanofibers. This electrostatic technique consists by the propulsion of a polymer solution trough an electrostatic field created by a high voltage applied syringe and an oppositely charged collector where the fibrins are formed. The applied electrical field, the collector distance, and the assets of the polymer solution had an immense effect on physical and morphological properties of the fiber such as the diameter, the surface area per unit mass and the pore size [5].

Because of the thermal, chemical and optical stability and the formation of an aligned crystalline film phthalocyanine derivatives have found applications as photovoltaic cells, solar cells, sensor electrodes, drug release systems, gas detectors and electroactive devices [6-9].

In this work, Metal free phthalocyanine grafted polypyrrole and cobalt metallated phthalocyanine grafted polypyrrole nanofibers were successfully collected onto Staineless Steel SAE 1020 (UNS G10200) by means of electrospinning technique. The anti-corrosion performance of the final system has been evaluated in 3 wt.% NaCl solution by means of Electrochemical Impedance Spectroscopy (EIS) and Tafel measurements. Different methods were used to characterize the obtained fibers. Fourier-transform infrared spectroscopy, Scanning electron microscope and polarized optical microscope were used for their morphological characterization, while electrical behaviors of the nanofibers were characterized by direct current and electrochemical impedance spectroscopy measurements.

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[4] Joo J., Park K.T., Kim B.H., Kim M.S., Lee S. Y., Jeong C. K., Lee J. K., Park D. H., Yi W. K., Lee S. H., Ryu, K. S. Synth Met 2003; 135; 7-13.

[5] Chronakis I.S., Grapenson S., Jakob A. Polymer 2006; 47; 1597–1603.

[6] Li Y., Lu P., Yan X., Jin L., Peng Z. RSC Adv 2013; 3; 545-558.

[7] Lu H.-L., Syu W.-J., Nishiyama N., Kataoka K., Lai P.-S. Journal of Controlled Release 2011;155;458–464.

[8] Jeong S.I., Jun I.D., Choi M.J., Nho Y.C., Lee Y.M., Shin H. Macromol Biosc 2008;8;627–637.

[9] Mugadza T., Nyokong T. Synthetic Metals 2010;160; 2089–2098.
Electrochemical Investigation of the Corrosion Behavior and Galvanic Compatibility Between Microchannel Tubes and Fins of an Aluminum Automotive Condenser
Authors: Pech-Canul Maximo A. , Echeverría Marbella , Pech-Canul Martin I. , Aguilar-Cordero Julio C. , Gorocica-Diaz Jorge A. , Arana-Guillén René , Puch-Bleis José
Published: February 2020

The condenser of air-conditioning unit for automotive application is an aluminum heat exchanger with three main components: the headers, microchannel tubes and fins. It is normally installed in the neighborhood of the front grill, so it is subjected to external corrosion. Of main concern is the possibility of tube perforation, leading to coolant leaking. One way to improve the corrosion resistance of the condenser is to protect the outside of the microchannel tubes with a sprayed zinc coating. The standard test for corrosion of automotive heat exchangers is saltwater acetic acid test (SWAAT) which is intended to reproduce lifetime performance. With the aim of satisfying recent demands in the industry for higher SWAAT performance, a condenser prototype was developed in this study using flat tubes made with a 1000 series alloy spray-coated with zinc and  fins made with 3003 series alloy with a double clad of 4343 alloy. The condenser prototype was brazed in a controlled atmosphere industrial furnace, using the Nocolok® flux brazing process. External corrosion was simulated by immersion, in SWAAT solution, of small samples cut from the tube/fin panel, taking care to seal the ends of the tubes with epoxy resin. Results of potentiodynamic polarization and electrochemical impedance spectroscopy were compared to those for individual components (uncouple tube and fin) and indicated that the electrochemical behavior is dominated by the fins. The pitting corrosion resistance of the condenser is afforded by the zinc diffusion layer on the tubes and this effect was investigated with cross-sectional corrosion potential profiles and potentiodynamic determination of the pitting potential. Galvanic compatibility between the tube and fins was evaluated with zero resistance ammetry (ZRA) and showed that there is an evolution in galvanic corrosion as zinc in the diffusion layer gets depleted. Furthermore, the localized corrosion behavior at the tube-fin joint was investigated with scanning electrochemical microscopy (SECM) and scanning vibrating electrode (SVET).
Multifunction Nanostructured Coatings
Authors: Ferreira Mario G. S. , Tedim Joao , Zheludkevich Mikhail L.
Published: February 2020

The active corrosion protection of metallic substrates can be achieved by addition of corrosion inhibitors to protective coatings. However, direct mixing of an inhibitor with coating formulations can lead to important drawbacks decreasing barrier properties of the coating and diminishing activity of the inhibitor. Also, soluble inhibitors can cause phenomena like osmotic blistering or be leached out spontaneously to the environment, which limits long-term performance and is environmentally pernicious. To overcome this problem and have controlled release of inhibitor different strategies of inhibitors storage in nanocontainers have been developed in order to produce smart self-healing coatings.

In this work novel protective nanostructured coatings with self-healing ability are presented. This effect is obtained on the basis of nanocontainers that release entrapped corrosion inhibitors in response to local pH changes or presence of corrosive species. The development of new nanocontainers for organic and inorganic corrosion inhibitors achieved is described, especially the most promising from industrial point of view, based on Layered Double Hydroxides (LDH). The combination of different of these nanocontainers in the same coating system has proved to be effective to accomplish further functions as antifouling and sensing.
Corrosion Effects of Electrolytic Biocomposites Coated Magnesium on Endolithial Cell Viability
Authors: Yen Shiow Kang , Lin Ruei Cheng , Wang Ming Jia
Published: February 2020

Though the degradable magnesium alloy used to construct an absorbable stent could be another candidate, its poor corrosion resistance is relatively a serious impediment against wider applications of magnesium alloy[1]. In this study, the coatings of zirconia (ZrO2) bottom layer and calcium phosphate (CaP) top layer are carried out on pure magnesium specimens by electrolytic deposition and subsequent annealing, leading to the corrosion current density reduced from 13.3 to 3.86 μA/cm2 derived by potentiodynamic polarization tests in artificial blood plasma at 37 °C. Furthermore, calcium phosphate (CaP), gelatin (Gel) and heparin (Hep) are co-deposited on post CaP/ZrO2 coated specimens in order to fabricate the heparin sustaining release system for promoting the hemocompatibility of magnesium. Heparin loaded composite coatings are analyzed by X-Ray diffractometry (XRD), field emission scanning electron microscope (FESEM), focused ion beam  (FIB) system, toluidine blue colorimetric assay, UV-visible spectrometer, and indirect endothelial cell viability tests. The drug content increases from 243.56±55.18 μg/cm2 for single layer (CaP-Hep) to 484.19±19.26 μg/cm2 for multilayer (CaP-Gel-Hep/CaP-Hep/CaP/ZrO2) and the sustaining release of the latter lasting for more than 28 days compared with that of the former for 1 day in PBS solution. The cell viability, related to Mg2+ ions in medium extracts which are still toxic to endothelial cells at high concentrations, is 63 % for the uncoated, 97 % for the ZrO2 coated, and 110 % for the CaP/ZrO2 and CaP-Gel-Hep/CaP-Hep/CaP/ZrO2 coated specimens compared with 100 % for the negative control. All results indicate that ZrO2 coated, CaP/ZrO2 coated, and CaP-Gel-Hep/CaP-Hep/CaP/ZrO2coated magnesium specimens are potential for biodegradable cardiovascular stents.

Acknowlegement

The authors are grateful for the support of this research by the National Science Council,Republic of China (Taiwan) under contract No. NSC 102-2221-E-005-027-MY3.

[1]M.J. Wang, C.F. Li, S.K. Yen, Electrolytic MgO/ZrO2 duplex-layer coating on AZ91D magnesium alloy for corrosion resistance, Corrosion Science, 76 (2013) 142-153.
Effects of High-Energy Electro-Pulsing Treatment on Microstructure and Corrosion Behavior of Ti-6Al-4V Alloy
Authors: Ye Xiaoxin , Tang Guoyi
Published: February 2020

The effect of electro-pulsing treatment (EPT) on the microstructure and corrosion behavior of cold-rolled Ti-6Al-4V alloy strips is investigated in this paper. It’s found that anti-corrosion property of titanium alloys is greatly improved with the help of EPT, which is demonstrated by the polarization test and surface observation with the beneficial effect of refining microstructure and forming a protective anatase-TiO2 film on the materials surface. The rapid recrystallization process and oxide formation of the titanium alloy strip under EPT are attributed to the enhancement of nucleation rate, atomic diffusion and oxygen migration resulting from the coupling of the thermal and athermal effects. It’s a novel viewing angle of relationship among the electropulsing process, microstructure and corrosion behavior, which is facilitated in the future research and application of biomedical titanium alloys.
Gold/ Polypyrrole Multilayer Electrode for Biochip Applications
Authors: Ofek Almog Rakefet , Sverdlov Yelena , Vernick Sefi , Shacham-Diamand Yosi
Published: February 2020

Novel gold/ polypyrrole/ gold electrodes for biochip applications are presented.  The electrodes demonstrated better conductivity than polypyrrole electrodes and better sensitivity than conventional gold electrodes. We describe the device fabrication and the electrical properties of the electrodes.  Polypyrrole was deposited by electrochemical polymerization, and a thin top gold layer was electro-deposited on the Polypyrrole.

A study of the nucleation and growth of the top gold using high resolution scanning electron microscope is presented. Under stagnant conditions a significant electro-crystallization was observed. Electrochemical characterization essential for future bio-sensing application was demonstrated.  The electrochemical behavior of the metal/Ppy/metal electrodes was tested by CV and impedance spectroscopy. The novel electrode system was tested for their application as whole cell biosensors using substrate - enzyme interaction by product electrochemical activity. We studied the response of the new electrode in biological solutions (PBS).

We found that depositing Ppy on thin metal seed layer dramatically increases the measured current of the electrodes, as compared to Au electrode. This effect was also demonstrated by CV measurements as well as in amperometric detection of alkaline-phosphatase enzymatic activity using biological chips. This high current produces noise that interferes with the proper operation.  However, when sufficient metal is electrodeposited on the Ppy, the behavior of the electrode becomes similar to that of a metal electrode, as demonstrated by CV and by amperometric detection of enzymatic activity. The CV curve has the same characteristics as that of the planar gold electrode, with a considerably higher current peak (Ip).

The modified Au/Ppy/Au electrode yielded an improved signal, compared with that from a flat gold electrode. The electrodeposition of Ppy followed by Au, on the surface of the biochip’s Au seed layer, affected the electrocrystallization of the Au particles on the Ppy (Fig 1) resulting in a high surface area. This electrode can serve as a highly sensitive, high surface area and flexible sensor for biological species.

Figure 1
Study on Thermal Stability of Ag-Coated Cu Powders Fabricated By Electrochemical Methods
Authors: Seo Nali , Zhuo Kai , Park Yu-Seon , Park Jeong-Hwan , Roh Yung-Seok , Chung Chan-Hwa
Published: February 2020

The conductive paste market is growing with many uses and development in solar cells, touch panels, and other display devices. Those conductive pastes contain the Ag powders as a metal filler to maintain its high electrical conductivity. Recently, as the price and consumption of Ag has been precipitously increased, there are many efforts to use alternative materials.

One of the ways to reduce the paste cost is adoption of core-shell structured metal fillers with putting the inexpensive Cu in the core. By coating the Ag on Cu powders, the low electrical resistance has been maintained even at higher temperatures in air. The key technique in this process is the way how to achieve uniform Ag coating on Cu, which prevents the Cu powders from oxidation and sustains its conductivity.

In our work, galvanic displacement reaction by being based on difference of potential and electroless plating method supplied the electrons from reducing agent are used to coat Ag on Cu powder. The Ag has been formed on Cu powders using electrochemical method that coats uniform metal thickness on material surfaces using those electrochemical methods.

We report Ag shell which has been coated various contents (silver 15wt.%, 30wt.%, 40wt.%) and  analyze thermal stability of the powders using FE-SEM (Field Emission Scanning Electron Microscope, JSM-7000F, JEOL, Japan), EDS (Energy Dispersive Spectroscopy, EDAX, U.S.A.), ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometer, Optima-4300 DV, PerkinElmer, U.S.A.), XRD (X-ray Diffraction, D8 ADVANCE, Bruker corporation, Germany), and CP (Cross-section Polishing, IB-09020CP, JEOL, Japan).

Keywords: Core-shell, Silver-coated copper, Galvanic displacement reaction, Electroless plating method, Thermal stability

Figure 1