bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Study of PtCo/MNC and PtCo/Rgo As Anodic Electrocatalysts for Methanol Electro-Oxidation in Acid Medium
Authors: Macias Ferrer David , Melo Banda J. Aaron , Silva Rodrigo Rebeca , Verde Gómez J. Ysmael , Páramo García Ulises , Del Ángel Vicente Paz , Lam Maldonado Mayda
Published: February 2020

PtCo/MNC and PtCo/rGO as anodic electrocatalysts (20 wt% Pt loading) have been synthesized by non-sequential co-impregnation method and chemical reduction route using citric acid and Ar-H2 static atmosphere. Micro-/nano-structured carbon (MNC) sample was synthesized via nanocasting process with anhydrous pyrolysis at 800 °C using SBA-15 as hard template and refined sugar as carbon source. SBA-15 was prepared via sol gel using pluronic P-123 as surfactant. GO was prepared via Hummers modified method. The prepared materials were characterized by means of N2 physisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and high resolution transmission electron microscopy (HRTEM). The performance of PtCo/MNC for methanol oxidation reaction (MOR) was measured by cyclic voltammetry (CV), chronoamperometry (CA). The electrochemical characterization techniques revealed that the mass activity of PtCo/MNC, PtCo/rGO and the commercial electrocatalyst PtRu/C at 20 cycles were 473, 322 and 300 mA/mgPt respectively as well as the carbon monoxide tolerance index ICO for these catalysts were 1.38, 1.56 and 0.93 respectively. PtCo/rGO exhibit better electrocatalytic performance, electrochemical stability and best resistance to carbonaceous intermediates species for the electro-oxidation of methanol.
Metal-Organic Framework Derived Carbonaceous Materials As Superior Electrode Catalysts for Quantum Dot Sensitized Solar Cells
Authors: Li Yan , Zhao Lianjing , Zhao Leilei
Published: February 2020

An efficient electrocatalyst for the reduction of polysulfide electrolyte is vital to the construction of quantum dot sensitized solar cells (QDSCs). Carbonaceous materials would be the promising candidates for the fabrication of counter electrodes (CEs) on account of the competitive prices, good conductivity and corrosion inertness for the reduction of polysulfide electrolyte. Metal-organic frameworks (MOFs), especially N-rich zeolitic imidazolate frameworks (ZIFs), recently have been considered to be versatile precursors/sacrificial templates for the preparation of various homogeneous hetero-doping mesoporous carbons with predetermined functionalities.

In view of the abundant doped active sites and inherent larger surface area of ZIF derived carbon materials, we prepared Co,N-bidoped carbon nanomaterials simply via the pyrolysis of bimetallic (Zn and Co) ZIFs. In light of the inherent characteristics of heteroatom doped carbons and the benign catalytic performance of Cu nanoparticles (NPs), the N-C@Cu composites with 2-4 nm Cu NPs uniformly distributing in mesoporous N doped carbons prepared by carbonization of ZIF-8 were also synthesized. The obtained Co,N-bidoped and N-C@Cu composites were utilized as electrocatalysts to develop CEs for QDSCs. The CEs based on both Co,N-bidoped and N-C@Cu composites exhibit superior catalytic activity for polysulfide reduction in QDSCs, resulting in a low charge transfer resistance at the interface of CE/electrolyte, an improved fill factor (FF) and a high short circuit current density (J
sc). The outstanding performances of the CEs can be ascribed to the uniform distributed catalytic active sites, large hydrophilic surface area, and good conductivity. When Co,N-bidoped carbons deposited on fluorine doped tin oxide (FTO) glass were used as CEs, an impressive power conversion efficiency of 9.12% (V
oc = 0.635 V, J
sc = 26.15 mA·cm-
2, FF = 0.549) under one sun illumination with 100 mW·cm-
2 intensity was observed on QDSCs using Zn-Cu-In-Se QDs as sensitizers. Under the same conditions, the optimized N-C@Cu based QDSCs present a promising power conversion efficiency of 9.23%, significantly superior to those of pristine N-C/FTO (7.20%) and Cu2S/FTO (8.89%) CE based QDSCs. Consequently, there is a good chance to fabricate QDSCs of high efficiency with the CE catalysts derived from MOFs.
Rheological Properties of Dense Suspensions of Thermo-Responsive Microgel Mixtures Undergoing Colloidal Gelation
Authors: Minami Saori , Watanabe Takumi , Suzuki Daisuke , Urayama Kenji
Published: February 2020

Dense suspensions of thermo-responsive poly(N-isopropyl acrylamide) (N) microgels exhibit a characteristic temperature (T)-dependent viscoelasticity at characteristic temperature (T
c) due to T-induced changes in the type of interparticle interaction as well as the volume fraction of microgels[1]. In the range of T < T
c
N, where the swollen microgels with repulsive interparticle interactions are densely packed, the equilibrium modulus (G) decreases upon heating due entirely to the packing effect, i.e., a reduction in the volume fraction of the microgels (φ). At T > T
c
N where the attractive interparticle interactions between dehydrated and hydrophobic microgels emerge, the suspensions show solid-like elastic properties due to the network-like flocculation of the shrunken microgels (colloidal gelation), even when φ becomes considerably lower than the threshold for randomly close packing. The T-dependence of G shows minimum at a characteristic temperature (T
B; T
B > T
c
N) due to the competition between the repulsive interparticle interactions from the packing effect and electrostatic force, and the attractive interactions from the hydrophobicity.

The present study focuses on the mixtures of thermo-responsive N and poly(N-isopropyl methacrylamide) (NM) microgels with different volume transition temperatures (T
c
N = 31oC and T
c
NM = 39 oC, respectively)[2]. The temperature T
B in N/NM mixture suspensions shifts to a higher value with a decrease in N content in the mixtures (X
N), accompanied by a discontinuous-like change at a specific value of X
N. We analyze the T-dependent viscoelasticity of the mixture suspensions with various X
N on the basis of the volume fractions of the total microgels (φ
m) as well as the hydrophobic microgels (Φ
m
a). This analysis indicates that (1) the crossover of the φ
m dependence of G occurs at a value of φ
m at T
c
N and/or T
c
NM, and that (2) the values of Φ
m
a at T
B are about 0.3 independently of X
N.

We also demonstrate the significant impacts of electrostatic repulsive interaction on the colloidal gelation using the NIPAm-co-fumaric acid microgels. At pH 11, the attractive interparticle force through hydrophobic interactions is fully suppressed due to the highly charges surface of the microgels, with the result that neither colloidal gelation nor the crossover of the φ
m-dependence of G at T
c
NF occur. This result indicates that the repulsive electrostatic force with an appropriate strength requires for the stability of the network-like flocculation.

[1] S. Minami, T. Watanabe, D. Suzuki, K. Urayama, Polymer Journal, 48, 1079-1086, 2016

[2] S. Minami, T. Watanabe, D. Suzuki, K. Urayama, Soft Matter, 14, 1596-1607, 2018

Figure 1
Separation of Motile Euglena Using Microchannel
Authors: Nezu Kyosuke , Makino Masato , Takamatsu Kyuichiro , Khosla Ajit , Kawakami Masaru , Furukawa Hidemitsu
Published: February 2020

Euglena is a unique microorganism that combines characteristics of animals and plants and expected as new biofuel and microbial actuator. When the euglena is used for these purposes, high motility cells must be important. Conventionally, when taking out target microorganism , micropipette was used but it was time-consuming and there was a risk of damaging microorganism. In this study, we propose using microchannel to separate motile euglena efficiently and to avoid damaging. In order to achieve this purpose, first, we investigated the behavior of Euglena in flow. We quantitatively evaluated Euglena’s swimming mode and diffusion coefficient in a straight microchannel（width1000µm，hight100µm） using image analysis. We found that as the flow velocity rises，fraction of Euglena which swims parallel in flow increases. In addition, we found that Euglena has rheotaxis. Rheotaxis fraction increases rapidly around flow rate of 80µm/s and decreases over flow rate of 120µm/s. We analyzed Euglena’s diffusion coefficient with Particle Tracking Velocimetry (PTV) using ImageJ. Euglena’s diffusion coefficient rises as the flow velocity increases, but it decreases at flow rate of 60µm/s. This phenomenon seems to be due to Euglena’s rheotaxis. As a summary so far, we found that Euglena was strongly influenced by flow velocity, and the motion depends on the flow rate. Based on these experimental results, we made separating microchannel by soft lithography that using 3D printed mold. As a result, we succeeded in separating motile Euglena which is 12% higher on average swimming speed.
(Invited) Formation Process and Structure of Poly (acrylonitrile) Gels
Authors: Matsuba Go
Published: February 2020

We carried out small angle neutron scattering measurements to clarify the gelation processes of 10 wt% polyacrylonitrile solutions in various water contents. The water in the mixed solvent was accelerated with the phase separation and gelation because of poor solubility of poly(acrylo-nitrile) (PAN) in water.

The solute is amorphous PAN with weight-average molecular weight of Mw = 250,000 and a molecular weight distribution Mw / Mn = 1.8. Mixed solvent is DMF / H2O (0 ~ 9 wt%). amorphous PAN was dissolved in mixed solvent at 90 ºC (PAN : mixed solvent = 10 : 90) after quenching at room temperature. In order to observe the structure and formation process of PAN gels, we used various kinds of scattering methods, e.g. light scattering, small angle X-ray scattering (SAXS). These measurements conducted at room temperature. Time-resolved SAXS was performed using an apparatus installed at beamline BL10C, Photon Factory, KEK (Tsukuba, Japan). The wavelength of X-ray beam was 1.488 Å. The camera length was 2.0 m for SAXS measurements.

The inhomogeneities of polymer chains grow just after quenching then the correlation length increases with time at first. In the opaque gel case, we found the growth of crosslinking points with smooth surfaces. Around the gel point, the crosslinking points emerge and then, the correlation length decreases with time since increasing the crosslinking points. On the other hand, in the transparent gel, we did not observe scattering from surface of crosslinking points but only the correlation length. The correlation length increases during gelation process, then the entanglements of polymer chains play a role of crosslinking points.
(Invited) Rheology of the Low Fat Mayonnaise Containing Agar Micro-Gels
Authors: Kaneda Isamu
Published: February 2020

We developed agar micro-gel oil suspensions using a W/O emulsion system. A new type of low fat food can be made by substituting oil phase for the agar micro-gel oil suspension. We attempted to prepare a series of low-fat mayonnaise using the agar micro-gel oil suspensions. A model mayonnaise which contains 60% oil was prepared as a control (M60). A low-fat mayonnaise which was made by using the agar micro-gel oil suspension as its oil phase. Since the agar micro-gel oil suspension contained 40 wt % agar micro-gels, the oil contents of this sample reduced 60% in comparison with M60 (M36+agar). We also prepared another model mayonnaise which was just reduced oil content in 60% as negative control (M36). We measured rheological properties of these samples. The apparent viscosity of M36 decreased in comparison with M60 dramatically, however, consistency drop of M36+agar was minimal. We also analyzed the frequency dependence of the complex modulus using a weal-gel model. This analysis revealed that agar micro-gels worked as viscosity thickener in the aqueous phase. It can be expected that the texture of the low fat mayonnaise made by this new method is similar to a full fat mayonnaise.
Photolithographic Fabrication of Pocket-like Hydrogel Microstructures for Novel Cell Culture System
Authors: Tsukyukubo Atsushi , Sumaru Kimio , Kanamori Toshiyuki
Published: February 2020

Various functional hydrogels have been developed, and can be applied to the fields of bioengineering, such as cell culture substrates and microfluidic systems. It is very important to provide these materials with some functional shapes in a scale of micrometers when these applications are examined. In this study, we proposed the fabrication of unique hydrogel microstructures through photolithography, and examined its application to novel cell culture system. They are expected to be applied to compose novel cell culture system which can maintain physiological activity of living cells, and to contribute to increasing precision of drug screening through providing totally different culture environment from conventional systems composed of rigid materials.

First, we coated a solution containing a UV responsive photo acid generator (PAG) on polystylene (PS) surface, and then coated a methanol solution containing poly (acrylic acid) (PAAc). The micro-patterned light irradiation (wavelength: 365nm) was carried out to induce area-selective cross-linking. After flushing with water, ethanol and 1M NaOH aqueous solution, a micro-patterned cross-linked PAAc layer was obtained.

Next, we prepared a pre-gel layer by coating a solution containing hydroxypropyl cellulose (HPC) 1,3,4,6-tetrakis (methoxymethyl) glycoluril, an acid catalyzed cross-linker, and PAG, on the cross-linked PAAc layer. The pre-gel layer was irradiated with the light in a different micro-pattern, and was baked at 85 ˚C to promote acid-catalyzed cross-linking of HPC.

After flushing with water, a micro-patterned cross-linked HPC layer was obtained on the cross-linked PAAc layer. By soaking the patterned bilayer in 1M NaOH aqueous solution, HPC gel sheet lifted off of the substrate and swelled in the areas where the cross-linked PAAc had remained while the sheet was immobilized on the PS surface in the other areas. As a result, pocket-like semi-3D microstructures were obtained. To provided the hydrogel with the property of cell adhesion, we examined the coating of several polymer materials on HPC.
Preparation of DNA Quadruplex Nanogels and Their Application to DDS Carriers
Authors: Tatsumi Kohei , Sakamoto Kota , Tanaka Shizuma , Ohya Yuichi , Kuzuya Akinori
Published: February 2020

We have recently and successfully developed DNA quadruplex hydrogel, which instantly turn into gel in response to K
+

or Na
+
addition, by directly coupling several deoxyguanosine residues to the both ends of polyethylene glycols utilizing High-Efficiency Liquid-Phase (HELP) large-scale DNA synthesis technique. In this study, we examined a utility of this hydrogel as a Drug Delivery System (DDS) carrier. We found that nanoparticles of 100–200 nm diameter can be efficiently prepared by forming gels in sufficiently diluted solution of the macromonomers. The nanogels were fully characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM). High-speed video-rate AFM measurements enabled direct and real-time observation of selective dissolution of DNA Quadruplex nanogels triggered by the addition of a crown ether into the system. Drug loading of G-quaduplex-binding anticancer drug and its delivery into cells were also accomplished.
Friction Properties of Gel Rings and Plates
Authors: Yahagi Hikaru , Yoshida Kazunari , Wada Masato , Khosla Ajit , Kawakami Masaru , Furukawa Hidemitsu
Published: February 2020

Recently, the development of high strength gel has advanced, and it is at the stage of application to mechanical parts utilizing the low friction properties of gel. It is expected that the low friction gel has an ability to increase the energy efficiency in various fields.

In this study, we evaluated the friction properties of DN gel ring-shaped sealant by using unique friction measurement apparatus and investigated the effect of cross-linker ratio on friction properties of gel plates to apply the gel materials to mechanical parts. In the case of ring gel, we measured the frictions of rotational direction and vertical direction (see figure). We revealed that friction force along vertical direction was decreased with increase in rotational speed, and the friction force along rotational direction was increased with rotational speed. In addition, we measured the friction force of gel plates with various concentration of cross-linker. The hardness of gel is strongly influenced by the concentration of cross-linker. The results indicate that the friction forced of the soft gel is larger than that of hard gel. The cause of this behavior is difference of contact situations such as contact area.

Figure 1
Proton-Conducting Ceramics for Metal-Supported Solid Oxide Fuel Cells and Electrolysis Cells
Authors: Wang Ruofan , Byrne Conor , Lau Grace , Tucker Michael C
Published: February 2020

Proton conducting oxide electrolyte materials could potentially lower the operating temperature of metal-supported solid oxide cells (MS-SOCs) to the intermediate range 400 to 600 °C. The porous metal substrate provides the advantages of MS-SOCs such as high thermal and redox cycling tolerance, low-cost of structural materials, and mechanical ruggedness. The cell structure for fuel cell and electrolysis operation is shown in Figure 1. To incorporate proton-conductors into metal-supported cell configuration through co-sintering fabrication, a key factor is that the proton conductors must be compatible with reducing atmosphere sintering, as the porous metal substrate can not be fired in oxidizing atmosphere.

In this work, viability of co-sintering fabrication of metal-supported proton conducting solid oxide cells is investigated. Candidate proton-conducting ceramics including perovskite-type oxides BaZr0.7Ce0.2Y0.1O3-δ (BZCY), SrZr0.5Ce0.4Y0.1O3-δ (SZCY), and Ba3Ca1.18Nb1.82O9-δ (BCN), pyrochlore-type oxides La1.95Ca0.05Zr2O7-δ (LCZ) and La2Ce2O7 (LCO), and acceptor doped rare-earth ortho-niobates La0.99Ca0.01NbO4 (LCN) were synthesized via solid state reactive synthesis or sol-gel synthesis. These ceramics are sintered at 1450°C in reducing environment alone and supported on Fe-Cr alloy metal support, and their key characteristics such as phase formation, sintering property, and chemical compatibility with metal support are determined. Most electrolyte candidates suffer from one or more challenges identified for this fabrication approach, including: phase decomposition in reducing atmosphere, evaporation of electrolyte constituents, contamination of the electrolyte with Si and Cr from the metal support, and incomplete electrolyte sintering. BZCY is particularly interesting because of its high proton conductivity, but it is found to suffer from reaction with Si and Cr present in the metal support, and loss of Ba via evaporation during sintering. Various approaches to overcome these limitations are proposed, and preliminary assessment indicates that the use of barrier layers, low-Si-content stainless steel, and sintering aids warrant further development.

In contrast, La0.99Ca0.01NbO4 is found to be highly compatible with the metal support and co-sintering processing in reducing atmosphere, allowing dense electrolyte and porous electrode made of LCN to be co-sintered on porous stainless steel, Figure 2. A metal-supported cell is fabricated with La0.99Ca0.01NbO4 electrolyte, ferritic stainless steel support, Pt air electrode and nanoparticulate ceria-Ni hydrogen electrocatalyst. The total resistance is 50 Ω∙cm2 at 600 °C.

This work clearly demonstrates the challenges, opportunities, and breakthrough of metal-supported proton-conducting solid oxide cells by co-sintering fabrication.

Figure 1
(Invited) Surface Modified Polypropylene Membrane for High Performance Lithium Metal Coin and Pouch Cell Batteries
Authors: Pol Vilas G. , Kim Patrick , Manikandan P.
Published: February 2020

For the advanced Li metal batteries, lithium (Li) metal is considered as anode electrode because of its lowest redox potential (–3.04 V vs. standard hydrogen electrode), highest theoretical specific capacity (3,860 mAh g-1), and the low density (0.59 g cm-3). Nevertheless, Li metal anode seriously impede its practical use for viable market because of short-circuit based safety risk associated to dendrite growth and low Coulombic efficiency. Understanding those fundamental challenges, we designed a multifunctional tri-layer membrane by percolating a layer of a polydopamine (PDA) followed by depositing graphene-carboxymethyl cellulose (Gr-CMC) on the top of polypropylene (PP) separator, hypothesizing to improve the cycle stability and performance of Li metal electrodes. The novel, new trilayer comprising Gr-CMC layer of the designed separator depicted an excellent electrolyte wettability, an additional capacity of Li storage and an enhanced electrical conductivity.

In Li/Cu half-cell the Coulombic efficiency was significantly enhanced over 200 cycles after implementing PDA/Gr-CMC separator. LiFePO4 cathode vs Li full cell with trilayer separator directed to long term cycle retention (1000 cycles) with enhanced rate capability. Apart from room temperature, electrochemical stability at 0 oC demonstrated the sanguine potential of PDA/Gr-CMC separator for practical Li-metal batteries. Beyond coin cells, pouch cell studies and cycling abilities will be demonstrated.
High Precision Characterization of Li-Ion Batteries during Extreme Fast Charging
Authors: Karulkar Mohan , Torres-Castro Loraine , Lamb Joshua
Published: February 2020

With current lithium ion batteries optimized for performance under relatively low charge rate conditions, implementation of Extreme Fast Charging (XFC, 6C charging and above) has been hindered by drawbacks including Li plating, kinetic polarization, and heat dissipation. Novel electrode designs, including anodes optimized for rapid lithium diffusion, show promise in alleviating these drawbacks.[1] However, in order to assess potential anode improvements, materials must be characterized in relevant settings, with tools that can discern critical metrics. This submission will detail efforts at Sandia National Lab to assess battery performance under XFC conditions using ultra high precision coulometry to track cycle-to-cycle efficiency and in-cycle dQdV. Efficiency deviations can reveal lithium plating or cathode breakdown, while dQdV measurements can reveal unintended side processes like lithium stripping during discharge. This submission will also describe the need for quick-response temperature control during XFC testing to minimize the effect of cell heating on characterization.

Figure 1 shows dQdV vs V on a 5Ah NMC/graphite COTS pouch cell, for charge rates of 0.5C (cycle 3), 1C (cycle 6), and 6C (cycle 24) during a rate capability test. It also shows subsequent 1C discharge cycles, and a 1C/1C cycle after the rate capability (cycle 25). Of note is the particular clarity of the dQdV curves, enabled by high precision coulometry performed on a high precision Arbin battery cycler. Charge curves shift right and peaks become more spread out, which is a consequence of cell polarization at higher charge rates. Discharge curves, however, remain nearly identical throughout cycling, indicating that no lithium stripping processes are seen after increasing charge rates.

Figure 2 shows cycling and temperature data for 6C charging / 2C discharge, on the same 5Ah pouch cell type. In this case, rapid response cooling plates are fitted around the cell to reduce cell heating during the high charge rate. The temperature data shows a worst-case temperature rise of only 3oC at the peak of charging along the cell’s edge, which minimizes heating artifacts during cell characterization.

[1] S. Ahmed et al, J. Power Sources, 367, 250-262 (2017).

Figure 1
Aging and Electrode Inhomogeneity in Commercial 18650 Lithium-Ion Cells during Long-Term Cycling
Authors: Wang Han , Whitacre Jay
Published: February 2020

Li-ion battery production has increased dramatically in the past decade. The concerns over the limited source and environmental impact suggest the recycling of Li-ion battery after usage, especially the functional ceramic oxide cathode materials. Recently, a new approach to recycling cathode materials has been investigated: direct recycling method. The key concept of this method is that the aged cathode materials are chemically and/or thermally re functionalized, and we have previously reported that the properties of the aged cathode materials, including level of lithiation,1 SEI layer,2 and surface reconstruction layer,3 can have an effect on the direct-recycled cathode materials.

As such, in this work, we characterized the aging level, in terms of chemical, physical and electrochemical properties, of cathode materials (NCA) harvested from 18650 cells after long-term cycling under different conditions. Specifically, different charge protocols and testing temperatures were used. Different failure mechanisms and rates capacity loss were observed, which we document and explain using a phenomenological model

Additionally, we observed significant area-specific inhomogeneities in the cycled electrodes; certain patterned regions of were found to have different degrees of SEI formation as well as different degrees of lithiation. The potential mechanism behind this phenomenon will be discussed.

Reference:

Wang, Han, and Jay F. Whitacre. "Direct Recycling of Aged LiMn2O4 Cathode Materials used in Aqueous Lithium‐ion Batteries: Processes and Sensitivities." Energy Technology.

Xiong, Xunhui, et al. "Washing effects on electrochemical performance and storage characteristics of LiNi8Co0.1Mn0.1O2 as cathode material for lithium-ion batteries." Journal of Power Sources 222 (2013): 318-325.

Jung, Sung‐Kyun, et al. "Understanding the degradation mechanisms of LiNi5Co0.2Mn0.3O2 cathode material in lithium ion batteries." Advanced Energy Materials4.1 (2014): 1300787.

Figure 1
A Solvent-Free Approach to Lithium-Ion Battery Electrodes Using Melt-Processable Elastomeric Binders
Authors: El Khakani Soumia , Verdier Nina , Rynne Olivier , Ciszewski Dorian , Lepage David , Prébé Arnaud , Ayme-Perrot David , Badia Antonella , Dollé Mickael , Rochefort Dominic
Published: February 2020

Lithium-ion is currently the leading technology for electrochemical energy storage, especially in the transportation sector. The electrification of vehicles through the use of lithium-ion batteries (LiBs) is at the center of the world efforts to decrease atmospheric pollution by reducing CO2 emission. Due to the high efficiency of electrical motors, a net reduction in greenhouse gases is achieved upon electrification of vehicles even in areas where electricity is generated from fossil fuels. Yet, the rapidly growing production of LiB brings new concerns on the environmental cost of the technology. The analysis of a complete their life cycle, from mining precursors to recycling batteries at the end of their life, reveals that several steps of the cycle can be improved to further reduce the environmental footprint of lithium-ion batteries. It is in this context that our group got interested in developing alternative approached to electrode fabrication, a key aspect of LiB manufacturing. Currently, most of the electrode fabrication processes involves the use of organic solvents, typically N-methyl-2-pyrrolidone (or NMP), which is toxic and costly. As such, a considerable effort is spent during electrode fabrication to recuperate NMP vapors and prevent exposure to the workers and environment. Avoiding the use of any solvents during electrode fabrication would not only minimize the environmental impact but would also result into lower energy consumption.

This contribution presents a study of a new solvent-free melt process technique to LiB electrode fabrication through the use of elastomeric binders. The impact of formulation on active material dispersion, microscopic morphology, electronic percolation and porosity will be discussed. With such parameters optimized, the electrochemical response of composite electrodes based on LiFePO4 and Li4Ti5O12 active materials were characterized both individually and as full cells. The battery performance will be compared with PVDF-based electrodes made with a conventional approach.
Graphitic Carbon Nitride (g-C3N4) Modified N-Doped LaTiO3 As an Organic–Inorganic Hybrid for Higher Visible Light Photocatalytic and Photo-Electrochemical Performance
Authors: Rakibuddin MD , Shinde Mahesh Ashok , Kim Haekyoung
Published: February 2020

Photocatalysis mimics natural photosynthesis by converting solar energy into chemical energy, and hence, it has tremendous potential to be an alternative sustainable means for dealing with global energy crisis and environmental remediation. LaTiO3 is an important rare-earth-metal-based perovskite semiconductor, but unfortunately, the visible light photocatalytic and photocurrent activity of LaTiO3 has been rarely studied. In the present work, we report interesting results on enhancing visible light photocatalytic and photocurrent activity of LaTiO3
via N-doping and making heterojunction with metal free g-C3N4. We synthesized the g-C3N4 modified N-doped LaTiO3 (CLT) organic-inorganic hybrid via a sol-gel polymerized complex method followed by facile solid state transformation route. The synthesized hybrids are thoroughly characterized. The CLT hybrid exhibits not only longer wavelength absorption in the visible region but also an enhancement in the catalytic activity under visible light compared to pure N-doped LaTiO3 and g-C3N4. The improved visible light activity of the CLT hybrid is ascribed by its suitable band edge potential and better separation of photoinduced charge carriers through the heterojunction of g-C3N4 and N-LaTiO3. Based on the results of photoluminescence, electrochemical impedance, and radical scavenger studies, a possible photocatalytic mechanism for the hybrid is also proposed. The photostable and reusable CLT hetero-structure is expected to provide new insight for the application of organic-inorganic hybrid and perovskite in light energy conversion and could be suitable for water splitting under sun light as well.

Reference: 1. Appl. Surf. Sci. 2018, 452, 400-412

2. Angew. Chem. Int. Ed.
2017, 56, 2064–2068.
Chiral Discrimination By Porphyrin Supramolecular Aggregates Based Chemical Sensors
Authors: Paolesse Roberto , Stefanelli Manuela , Monti Donato , Magna Gabriele , Di Natale Corrado
Published: February 2020

The study of the formation of porphyrin aggregates characterized by supramolecular chirality is an important issue amenable to wide applications. One approach to prepare these architectures takes advantage by the presence of chiral substituents on the periphery of the macrocycles acting as specific chiral effectors during the molecular recognition event. We have exploited a tetraphenylporphyrin bearing a peripheral proline group in ethanol–water solvent mixtures (Figure 1 a); the aggregation led to the formation of extended J-type aggregates, featuring supramolecular chirality. The aggregates have been grafted onto ZnO nanoparticles and then QMB sensor surfaces have been coated with a thick film of such hybrid materials. Sensing properties of such hybrid materials have been extensively studied and results show that they have promising features for the development of reliable and efficient sensors based on the implementation of large chiral surfaces.

Figure 1
Superior Micro-Supercapacitors Based on Graphenequantum Dots
Authors: Zhang Maiwen , Liu Wenwen , Yu Aiping
Published: February 2020

Graphene quantum dots (GQDs) have attracted tremendous research interest due to the unique properties associated with both graphene and quantum dots. Here, a new application of GQDs as ideal electrode materials for supercapacitors is reported. To this end, a GQDs//GQDs symmetric microsupercapacitor is prepared using a simple electro-deposition approach, and its electrochemical properties in aqueous electrolyte and ionic liquid electrolyte are systematically investigated. The results show that the as-made GQDs micro-supercapacitor has superior rate capability up to 1000 V s −1 , excellent power response with very short relaxation time constant ( τ0 = 103.6 μs in aqueous electrolyte and τ0 = 53.8 μs in ionic liquid electrolyte), and excellent cycle stability. Additionally, another GQDs//MnO2 asymmetric supercapacitor is also built using MnO2 nanoneedles as the positive electrode and GQDs as the negative electrode in aqueous electrolyte. Its specific capacitance and energy density are both two times higher than those of GQDs//GQDs symmetric micro-supercapacitor in the same electrolyte. The results presented here may pave the way for a new promising application of GQDs in micropower suppliers and microenergy storage devices.
(Keynote) Electrochemical Artificial Muscle Yarns and Textiles That Harvest and Store Environmentally Available Energies
Authors: Baughman Ray H.
Published: February 2020

Mechanical energy harvesters are needed for such diverse applications as self-powered wireless sensors, structural and human health monitoring systems, and cheaply harvesting energy from ocean waves. The here reported nanofiber yarn harvesters can electrochemically convert tensile or torsional mechanical energy into electrical energy. Stretching coiled yarns generated 250 W/kg of peak electrical power when cycled up to 30 Hz, and up to 41.2 J/kg of electrical energy per mechanical cycle, when normalized to the weight of the harvester yarn. Unlike for other harvesters, torsional rotation produces both tensile and torsional energy harvesting and no bias voltage is required, even when electrochemically operating in salt water. Since homochiral and heterochiral coiled harvester yarns provide oppositely directed potential changes when stretched, both contribute to output power in a dual-electrode yarn. These energy harvesters were used in the ocean to harvest wave energy, combined with thermally-driven artificial muscles to convert temperature fluctuations to electrical energy, sewn into textiles for use as self-powered respiration sensors, and used to power a LED and to charge a storage capacitor. The development of “piezoelectrochemical spectroscopy” and insights into the hierarchical origins of capacitance increased fundamental understanding. When run in the reverse direction, these muscle types can provide powerful artificial muscles, and the same fibers used as harvesters and muscles can be used to store electrical energy. This work is collaborative with researchers at Hanyang University, University of Texas at Dallas, Lintec of America; Jiangnan Graphene Research Institute, Virginia Tech, and the Wright-Patterson Air Force Research Laboratory.
(Keynote) Some Commercialization Successes in Unconventional Micro/Nanotechnologies
Authors: Rogers John A
Published: February 2020

This discussion will touch on some personal experiences in commercialization of micro/nanotechnologies with origins in academic labs. Historical examples in semiconductor metrology, photovoltaics, information display and skin-interfaced wearables will be followed with detailed descriptions of recent activities in devices for capture, storage and chemical analysis of sweat for sports performance and in battery-free accumulation mode UV sensors for cosmetics and beauty, each of which now represents a category of products launched at scale with global brands.
Design and Construction of Novel High-Performance Paper-Based Flexible Micro-Supercapacitors
Authors: Liu Wenwen , Zhang Maiwen , Yu Aiping
Published: February 2020

With the rapid development of flexible portable/wearable devices, it is highly desirable to develop the flexible energy storage and conversion devices to meet these demands. Among these devices, flexible supercapacitors have caused great attention due to its excellent electrochemical performance, flexibility and compatibility. However, it is still a huge challenge to design and construct the flexible supercapacitors with outstanding performances. In this case, we design and prepare the paper-based flexible micro-supercapacitors with PEDOT-CNTs/Ag film as electrode material by ink-jet printing technology. Encouragingly, the resulting paper-based micro-supercapacitors show outstanding electrochemical performances including the ultra-high scan rates (up to 10000 mV/s), excellent rate capability, fast frequency responsibility (With short relaxation time constant of 8.5 ms), high specific capacitance, and long-term cycling stability (92% retention after 10000 cycles). These encouraging results presented here make the paper-based micro-supercapacitors promising application as power source for flexible portable/wearable devices, and also provide a reference for the construction of flexible micro-supercapacitors and other energy devices.
The Effects of Citric Acid on the Mechanical and Corrosion Resistant Properties of Ni-Y2O3 Coatings for Enhanced Corrosion Protection
Authors: Ngo Ngan , Argade Gaurav , Golden Teresa
Published: February 2020

The need to reduce the corrosion rate of metal structures in the oil and gas industry leads to increasing cost. Among different methods of protecting metals in corrosive environments; addition of coatings as a protective layer on the surface of metal components has been a useful technique in minimizing the impact of corrosion. Nanocomposite materials are composite materials that are made of two or more materials in which at least one dimension is in the nanometer scale. By decreasing the size of a particle embedded in a matrix, it helps to enhance the interactions between the metal matrix and reinforcements at phase interfaces. Therefore, incorporating nanoparticles into a metal or alloy matrix has shown an improvement to the mechanical and physical properties of the resulting coating. Yttrium oxide (Y2O3) is included in the rare earth (RE) sesquioxides group, it has a number of interesting properties such as high mechanical strength, high thermal conductivity, high melting point (2410 oC), wide bandgap (Eg is approximately 5.5 eV), and photoluminescence. It is also known to improve corrosion protection in corrosive environments when incorporate into metal and alloy coatings such as nickel, titanium, zinc, and Fe-Cr alloys. However, yttrium oxide was found to have high potential of absorbing hydrogen ions in aqueous solution to become a hydroxide, which leads to agglomeration of the nanoparticles in the electrolyte solution, making it difficult to form the coating when increasing the concentration of added Y2O3 nanoparticles. This agglomeration makes it difficult to insert high enough concentrations of nanoparticles to affect the corrosion resistance properties. A nickel-yttrium(III) oxide nanocomposite has been electrodeposited onto metal substrates using varying concentrations of yttrium(III) oxide nanoparticles in the nickel plating bath. In this environment, nickel and hydrogen ions tends to naturally absorb onto the surface of the yttrium(III) oxide nanoparticles during the electrodeposition process of Ni-Y2O3 coatings, thus, making the formation of Ni-Y2O3 coatings more challenging . Therefore, citric acid has been added to the electrolytic bath, not only as a buffer to aid in controlling the pH of the system, but also as a stabilizing agent for the nanoparticles prior to deposition. The effect of citric acid on the formation, morphology, and composition of the nickel-yttrium(III) oxide coatings was investigated by solution studies, powder x-ray diffraction, scanning electron microscopy, and microhardness measurement. The corrosion resistant properties of the coatings were investigated by exposure to chloride solutions, potentiodynamic polarization, and electrochemical impedance spectroscopy. The addition of Y2O3 nanoparticles was found to enhance the mechanical properties of the coatings which leads to an inherent improvement in their corrosion resistance.

Figure 1
Newly-Developed Molybdate-Based Protective Coatings for AZ31D Magnesium Alloys
Authors: Farhat Mahmoud
Published: February 2020

Molybdate-based eco-friendly protective coatings were developed for AZ31D magnesium alloy. Mg AZ31D substrates treated first in boiling molybdate for oxide thickening pretreatment followed by molybdate chemical conversion coating. Highly protective and uniformly distributed molybdate coatings were deposited over Mg AZ31D substrates. The corrosion resistance enhanced from ~ 2 KΩ.cm2 for the as-polished samples to ~ 8 KΩ.cm2 for the samples treated under the boiling molybdate conditions. The high performance of molybdate-based coatings can be attributed to molybdenum oxide role in rejecting chloride ions. It also stimulates blocking the pits and cracks initiated at the surface under the effect of corrosive medium attack. The designed coating treatment is characterized by its simplicity in which it can be deposited over the Mg AZ31D surface at room temperature via a free immersion technique. The eco-friendly coatings seems very promising and effective for improving the corrosion resistance of magnesium alloys in chloride containing solutions. Subsequent organic top coats are needed for adequate corrosion protection performance. The newly-developed approach can be extended to include other boiling solutions for oxide thickening as well as other metal substrates to explore its universal application.
Fatigue and Static Crack Growth Rate Study of Carbon Steel for Corrosion Prevention of Natural Gas Transmission Pipelines
Authors: Tylczak Joseph H. , Chandra Ashwini , Thodla Ramgopal , Ziomek-Moroz Margaret
Published: February 2020

Internal metallic and non-metallic coatings are being considered as parts of answers to allow current natural gas transmission pipelines to safely batch transport a variety of products, including natural gas, carbon dioxide and hydrogen. Sacrificial anode coatings, that contain Zn, are being considered for internal corrosion protection of standard carbon steel pipeline as they are known to galvanically protect steel. However, this can lead to the creation and ingress of hydrogen into the line pipe material, resulting in increased susceptibility to cracking under high static and cyclic loads associated with both steady state as well as startup and shut down conditions. The current study simulates the conditions expected to be encountered in field by performing crack growth rate measurements under static and fatigue loading conditions on fracture mechanics-based specimen extracted from API 5L X-65 steel. The effect of cyclic loading frequency on fatigue crack growth rate (FCGR) and the effect of applied cathodic polarization on static crack growth rates (SCGR) was investigated in a 3.5% NaCl solution in contact with CO2 at 25°C. The partial pressure of CO2 (pCO2) was 101.325 kPa. The applied cathodic potentials were those associated with mixed potential of the Zn- based coatings.
Electrochemistry Behavior and Surface Film Characterization of Fe50Mn30Co10Cr10 medium Entropy Alloy in Sulfuric Acid Solution
Authors: Lu Yi-Sheng , Huang Cheng-Yao , Yen Hung-Wei , Lee Yueh-Lien
Published: February 2020

The Fe50Mn30Co10Cr10 medium entropy alloy (MEA) has been found to yield superior mechanical properties to CoCrFeMnNi Cantor high entropy alloys (HEA) due to transformation induced plasticity (TRIP) effect. However, the corrosion resistance between these two alloys has not been compared. In this study, the corrosion behavior of MEA and HEA was investigated in 0.1M H2SO4 solution at ambient condition. The preliminary results showed that both alloys exhibited the passive behavior with similar passive current density in 0.1M H2SO4 solution; nevertheless, some differences in anodic features and critical anodic current densities were found by comparing their anodic branch of the polarization curve. The SEM surface observation revealed both alloys tended to suffer uniform corrosion and intergranular corrosion in 0.1M H2SO4 solution. The microstructure and composition of passive films formed in 2 h on MEA and HEA at 440 mVSCE in 0.1M H2SO4 solution were also investigated in this study. The high resolution transmission electron microscope (HRTEM) pictures showed that the passive film formed on the MEA was approximately 2-5nm thick with amorphous structure.
Multi-Phase Field Model of Localized Corrosion Kinetics with Corrosion Products Formation
Authors: Ansari Talha Qasim , Shi San-Qiang
Published: February 2020

Localized corrosion is one of the complex forms of corrosion which makes it difficult to detect and design-against. During metal corrosion in the corrosive environment, corrosion products are also formed as a result of electrochemical reactions inside the electrolyte. These products can precipitate on the corroding surface and stop/ slowdown the overall corrosion process. In order to understand this complex phenomenon, a multi-phase field model is proposed to simulate metal corrosion with corrosion products formation. Both anodic (metal oxidation) and cathodic (oxygen reduction) reactions along with other electrochemical reactions in the electrolyte are considered. The free energy of the system is described in terms of its metal ion concentration and the order parameters. Rather than considering linear kinetics (Allen-Cahn equation), inspired from classical rate theory, non-linear (Butler-Volmer) kinetics is considered to describe the temporal evolution of order parameters. The time dependent evolution of ionic species is governed by Nernst-Plank equations while electrostatic potential is governed by Poisson equation. The model results are compared with experimental findings and several examples are presented to show the practical applications of this model. One interesting example, which can be studied in detail with this methodology, is the formation of metal oxide nanowires (zinc/ aluminum oxide).
(Invited) Unraveling Synergistic Interactions driving the Chemical Mechanical Planarization Process
Authors: Keleher Jason J.
Published: February 2020

Due to the emergence of sub-10 nm technologies, next generation CMP slurry formulations have continued to increase in additive (nanoparticle and chemistry) complexity to meet stringent device specifications. Therefore, it is essential to probe the molecular level interactions at the nanoparticle/slurry chemistry/substrate interface and in turn correlate them to key performance metrics such as removal rate, post CMP defects, planarization efficiency. More specifically, this work has developed a suite of techniques that explore the adsorption/complexation dynamics that evolve during the CMP process. Employing a suite of techniques such as modified atomic force microscopy (AFM), electrochemical quartz crystal nanobalance (EQCN), dynamic contact angle measurements, fluorescence microscopy, pre/post polish characterization of particle properties (size and zeta potential), and in-situ rotating disk electrode open circuit potential measurement the critical static and dynamic mechanisms can be exposed. Correlation of this information gives way to modulation (desired or undesired) of the CMP performance potentially providing tunabilty (process and formulation) at advanced technology nodes to meet stringent electrical, topography, and defect requirements. Furthermore, these methods have shown great promise as a vehicle to probe the molecular level interactions at the nanoparticle/chemistry/ substrate interface. Results have shown excellent correlation to key process performance metrics and have provided insight into relevant surface chemistry changes that impact critical interactions during the CMP process. This presentation will address key interactions through a series of case studies focusing on probing the impact of inhibitor structure on the substrate surface energy relevant to Cu CMP, the role of slurry chemistry on controlling defectivity during STI post-CMP cleaning, and effect of organic additives on the modulation of nanoparticle surface properties to enhance STI CMP performance.