bluuebunny/crossref_metadata_2025 huggingface dataset:
Nmr's Perspective of Speciation Process in Lithium Sulfur Batteries
Authors: Wang Hao , Key Baris , Sa Niya , He Meinan , Vaughey John T. , Nazar Linda F , Balasubramanian Mahalingam , Gallagher Kevin G.
Published: February 2020

Lithium sulfur (Li-S) battery is a promising alternative technology of lithium ion batteries. However, due to the complicity of the chemistry in Li-S batteries, the mechanism is not well understood. In addition, the co-existence of soluble species and insoluble species limits the application of other characterization techniques. The sensitivity and element selectivity make NMR spectroscopy a powerful tool to study the changes in local chemical environment and speciation process in Li-S batteries. In this study, in situ
7Li NMR spectroscopy was employed where plastic pouch cells were assembled and cycled in the magnet while NMR spectra were acquired simultaneously. Method to quantitatively study entire lithium inventory in a Li-S battery is developed and implemented, and the cell design is optimized for electrochemical performance and spectroscopic resolution. This methodology can be readily extended to Li-S batteries with other electrolytes where the speciation process can be tracked and analyzed. The development of electrolyte will also benefit greatly from the detailed understanding of the Li-S battery speciation process as well as the additive development.

[1] See, et. al., J. Am. Chem. Soc., 2014, 136 (46), pp 16368–16377

[2] Xiao, et. al., Nano Lett., 2015, 15, 3309-3316
The Lithium and Oxygen Concentration Dependence in Li-O2 Batteries Studied with Electrochemical Quartz Crystal Microbalance and Cylindrical Microelectrodes
Authors: Lindberg Jonas , Wickman Björn , Behm Mårten , Lindbergh Göran
Published: February 2020

The Li-O2 battery is a promising chemistry suggesting very high energy densities. In the literature it is agreed upon that during the discharge process Li2O2 is the final product formed via the intermediate LiO2. However, the nature of the intermediate is not fully understood, e.g. how long is the lifetime and how does it proceed to form the final product (chemical or electrochemical reaction). This study sets out to shed light on the reaction mechanism of the Li-O2 battery by studying the effects of different concentrations of lithium and oxygen. Experimentally this is done using an electrochemical quartz crystal microbalance (EQCM) and a cylindrical microelectrode. The EQCM results show that the system is unable to return to its initial mass, i.e. there is a buildup of reaction product during cycling. Further, it is not possible to recover all the discharge electrons during recharge. The intermediate is believed to diffuse away from the electrode rendering it unavailable for recharge. This result is further strengthened by the measurements on microelectrodes where intermediate is believed to diffuse away from the electrode more easily. There is also a discrepancy when looking at the change in mass and the expected mass change from the corresponding current suggesting that both electrochemical and chemical processes occurs. In conclusion it can be said that this study provides additional knowledge to the surface confined processes in the Li-O2 battery. The EQCM provides information that otherwise would go unnoticed, i.e. solely measuring the current response will not provide detailed quantitative information of the mass response.
Tin Oxide Anchored on Reduced Graphene Oxide Sheet to Provide Improved Electrochemical and Structural Properties for Alkali Ion (Li, Na) As an Anode Material for Rechargeable Battery
Authors: Jo Chang Heum , Jo Jae Hyeon , Myung Seung-Taek
Published: February 2020

Lithium secondary batteries have played important roles as energy storage and conversion devices EV(electric vehicle) and ESS(energy storage system). In this respect, improvement of electrodes is being progressed towards ensure long cycling performances, stability, safety, and so on. For anode materials, in particular, conversion reaction materials need to be further developed because alloy and conversion reaction enabled high capacity delivery though the cyclability should be improved. However, severe volume expansion impedes the utilization of those electrode materials in commercial batteries. Tin oxide is composited with rGO to ensure structural and cycle stability in both lithium and sodium systems.

In this study, we synthesized SnO2 nanoparticle was anchored on rGO sheet by layer by layer self-assembly method. For synthesize SnO2 nanoparticle, we used hydrothermal method. To confirm the physical and electrochemical properties, XRD, SEM, TEM, RAMAN, galvanostatic test. The synthesized SnO2 and rGO/SnO2 had same crystal structure and particle size was about 10-20nm. Both materials exhibited high charge capacity of about 1000mAh/g and much improved rate capability was achieved by rGO sheets in Li cell. Similarly, much improved electrochemical properties were found for SnO2/rGO composite in Na cells as well.

It is thought that rGO sheet assisted electro chemical stability by their 2D network during repetitive volume expansion.
Hierarchically Porous and Heteroatom Doped Carbon Host Matrix for Long Life Li/S Battery: A Mechanistic Investigation By in-Situ Raman Spectroscopy and Ex-Situ XPS
Authors: Vinayan Bhaghavathi Parambath , Fichtner Maximilian
Published: February 2020

Lithium-sulfur (Li/S) batteries are considered as one of the promising rechargeable battery technology due to their low cost, ecofriendly and high theoretical energy density (~2500 Whkg-1).1, 2 The high theoretical specific capacity (~1672 mAh g-1) of Li/S battery is the result of reversible two electron conversion reactions between sulfur and lithium (S8 + 16Li+ + 16e− ↔ 8Li2S) at an average voltage of 2.1 V with respect to Li/Li+ and finally form solid lithium sulfide (Li2S) through a series of intermediate liquid polysulfides.2, 3 The physiochemical properties of the carbon host matrix and their sulfur loadings at the cathode side play a major role in the electrochemical performance of lithium-sulfur (Li/S) batteries. We have designed a highly sulfur loaded (~ 75 wt. %) carbon matrix (S/NGC), with hierarchically organized micro/meso pore structures and containing nitrogen and oxygen functional groups, using metal oxide nano templates. The S/NGC electrodes give the reversible capacities of 868 and 666 mAh g-1 at C/5 current rates, with the sulfur loadings of 2.2 and 3.4 mgSulfur cm-2, respectively. Based on the advantages of the hierarchical porous structure and nitrogen doping, S/NGC electrode gives a long cycling stability (0.03% capacity decay per cycle up to 1000 cycles) and very good coulombic efficiency (Fig. 1a). Further, the charge/discharge mechanism of the cell is investigated in detail by insitu Raman spectroscopy (Fig. 1b) and ex-situ X-ray photoelectron spectroscopy (XPS). In-situ Raman spectroscopy analysis of the Li/S cell shows the formation of short chain polysulfides (S3
.-, Li2Sx, x = 4-1) already at higher discharge potentials (> 2 V).The presence of nitrogen on carbon support is found to enhance the bonding between sulfur and oxygen functional groups present in the carbon support, which is supposed to take a major role in the prevention of sulfur/polysulfides species dissolution to anode side.

References

 1. Y. V. Mikhaylik, I. Kovalev, R. Schock, K. Kumaresan, J. Xu and J. Affinito, ECS Transactions, 2010, 25, 23-34.

 2. L. F. Nazar, M. Cuisinier and Q. Pang, MRS Bulletin, 2014, 39, 436-442.

 3. P. G. Bruce, S. A. Freunberger, L. J. Hardwick and J.-M. Tarascon, Nat Mater, 2012, 11, 19-29.

Figure 1
Electrochemical Properties of Birnessite As a Positive Material for Aqueous Calcium-Ion Batteries
Authors: Hyoung June E , Hong Seung-Tae
Published: February 2020

Recently, calcium-ion batteries (CIBs) have received attention as a candidate for next generation batteries due to slight difference of standard reduction potential about 0.17 V above that of lithium and relative abundance of calcium compared to lithium.1 It is known that the birnessite-type manganese oxide, characterized by a layered structure consisting of edge-shared MnO6 octahedral with interlayer distances of ~7 Å as shown in Fig. 1a, allows high mobility of the interlayer cations of lithium or sodium with fast kinetics and little structural rearrangement.2 In this study, the electrochemical properties of the birnessite have been investigated as a cathode candidate material for rechargeable aqueous CIBs.

The birnessite was synthesized by thermal decomposition of KMnO4 according to the previous report.3 The working electrodes consisted of the active material (birnesstie), conducting carbon (super P), and binder (polyacrylonitrile) with the weight ratio of 80:10:10. Activated carbon and Ag/AgCl were served as the counter and the reference electrode, respectively. The galvanostatic discharge/charge experiments were carried out at C/10 in the voltage range of -0.4­ – 0.8 V vs. Ag/AgCl in 1.0 M Ca(NO3)2 aqueous electrolyte. Reversible calcium-ion intercalation was observed in the electrolyte system as shown in Fig. 1b, c. The initial discharge/charge capacities were 182 mAh g-1 and 151 mAh g-1, respectively. The average discharge voltage was estimated to be around 2.8 V vs. Ca2+/Ca. The capacities were faded rapidly from the following cycles, probably due to the instability of the host material accompanying manganese dissolution. Detailed analyses with ICP-OES, EDX, XRD, and cyclic voltammetry (CV) with different scan rates indicated that both the intercalation and pseudo-capacitance are responsible for the reactions. As the research on calcium-ion batteries at an initial stage, this work demonstrates an example suggesting a possibility of discovering other new electrode materials for the calcium-ion batteries.

References

[1] A. Ponrouch, C. Frontera, F. Bardé, M. R. Palacin, Nature Materials
15, 169 (2016)

[2] R. Ma, Y. Bando, L. Zhang, T. Sasaki, Adv. Mater.
16, 918 (2004)

[3] S. Komaba, N. Kumagai, S. Chiba, Electrochimica Acta
46, 31 (2000)

Figure 1
The Development of Ester-Based Electrolyte Solutions for Magnesium Rechargeable Batteries
Authors: Sugita Miki , Doi Takayuki , Inaba Minoru
Published: February 2020

Introduction

 Magnesium (Mg) metal has attracted attention as an active material of a negative electrode for next-generation innovative rechargeable batteries because of its high volumetric capacity (3800 mAh cm-3) and low standard electrode potential (-2.73 V vs. NHE). High safety during charge/discharge cycles is also expected because Mg should be deposited uniformly without dendritic growth. Electrochemical deposition/dissolution reactions of Mg have been already reported using ether- and sulfolane-based electrolyte solutions such as Grignard reagents. However, the polarization of the Mg deposition/dissolution reactions was very high1). In addition, these electrolyte solutions are easily oxidized, and corrode aluminum current correctors. Therefore, the development of electrolyte solutions is necessary to realize magnesium rechargeable batteries with high working voltages above 3 V. In this study, we focused on ester-based electrolyte solution which is relatively stable against oxidation. We prepared electrolytes consisting of gamma-butyl lactone as a solvent and Mg(BF4)2 as a salt for magnesium rechargeable batteries. The electrochemical deposition/dissolution reactions of magnesium on Cu electrodes were investigated.

Experimental

 The electrolyte solution used in this study was 0.1 mol dm-3 Mg(BF4)2 dissolved in gamma-butyl lactone, which was prepared in a glove box filled with Ar gas with a dew point below -80 oC. The water content was determined by Karl Fischer titration. The working, counter, and reference electrodes were Cu foil, Mg wire, and Ag/Ag+ electrode, respectively. Cyclic voltammetry was carried out between -1.00 and -4.00 V vs. Ag/Ag+ at a scan rate of 1 mVs-1 using three-electrode cells.

Results and discussion

 0.1 mol dm-3 Mg(BF4)2/GBL used in this study contained 680 ppm water. Figure 1 shows cycle voltammograms of Cu in 0.1 mol dm-3 Mg(BF4)2/GBL at the first and fifth cycles. The cathodic current was observed at potentials below -3.3 V during the initial scan and a corresponding anodic current was seen at around -2.8 V. The reaction potentials were close to the standard potential of Mg (ca. -3.2 V vs. Ag/Ag+), and therefore the couple of redox currents should be assigned to deposition and dissolution reactions of magnesium on Cu. These results show that reversible deposition/dissolution reactions of magnesium can proceed in ester-based electrolyte solution. Mg(BF4)2 is considered as a promising salt for electrolyte solutions for magnesium rechargeable batteries. However, cycle performance needs to be improved; both the cathodic and anodic current densities decreased with cycle number, as shown in Fig.1. Charge/discharge characteristics and surface morphology of the electrode will be shown in our poster presentation.

Reference

 1) D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, R. Turgeman, Y. Cohen, M. Moshkovich, and E. Levi, Nature, 407, 724 (2000).

Figure 1
Sulfur-Infiltrated Hierarchical Porous Carbon (HPC) Cathodes for Lithium-Sulfur Batteries
Authors: Jung Dae Soo , Roh Kwang Chul , Choi Jang Wook
Published: February 2020

Lithium sulfur (Li-S) batteries have been considered as promising candidates for next-generation battery applications because of its high theoretical capacity (1675 mAh/g is 5 times higher than those of traditional cathode materials based on transition metal oxides or phosphates), abundance, safety, low cost, and eco-friendliness. However, the practical implementation of Li-S batteries is greatly hindered by the high resistance of sulfur (5 x 10-30 S cm-1 at 25 oC) and dissolution of soluble long-chain lithium polysulfides (Li2Sn, 4≤n≤8) in the polar organic electrolytes, and volume expansion of sulfur during discharge process, resulting in an insufficient cycle life.

To this end, a number of studies have focused mainly on the development of carbon-sulfur composite with the intention to improve the cycle stability. Many types of mesoporous carbon materials have been studied as the electrically conducting host materials for improving the electrical conductivity of sulfur and preventing dissolution of soluble long-chain lithium polysulfides, which are intermediates formed as reaction in both discharge and charge processes in the electrolytes.

Those approaches improve the electrical conductivity of sulfur, but are associated with inherent limitation of the dissolution of polysulfides due to the limitation of physical adsorption of the polysulfides by mesopores, which tends to limit the electrochemical performance of carbon-sulfur composite cathode materials.

Recently, to overcome these problems, microporous carbon materials have been designed. Although the characterization of sulfur confined in micropores is not completely determined, the micropores have indeed turned out to be efficacious in mitigation of the soluble lithium polysulfides via various mechanisms: (1) strong adsorption of soluble polysulfides, (2) construction of solvent-free environment, and (3) formation of insoluble small S2-4 molecules. Because of these attributes, the microporous carbon-sulfur composites show outstanding cycling performance and rate capability. Additionally, Manthiram et al. reported a novel Li-S cell configuration having carbon interlayers with micropores between the separator and the regular sulfur electrodes. This interlayer works as polysulfide stockroom to maintain the cycle stability.

Based on these micropore approaches, we combined sulfur encapsulation and micropores into a single electrode component by developing a hierarchical porous carbon (HPC) structure. In the HPC structure prepared by spray pyrolysis process, the inner meso- and macro- pores are surrounded by outer carbon shell with micropores. Hence, stable cycling was achieved by the outer micropores that shut dissolution of lithium polysulfides down, while most of active sulfur was loaded in the larger inner pores.
Vanadium Dioxide Reduced Graphene Oxide Composite As Cathode Materials for Rechargeable Li and Na Batteries
Authors: Myung Seung-Taek , Mahadi Nurul Huda , Park Jae sang , Sun Yang-Kook
Published: February 2020

In recent years, new cathode materials have been intensively investigated, as the demand for rechargeable batteries are increasing with the rapid growth of technology for electronic devices and electric vehicles. Among them, metastable form of vanadium dioxide, denoted as VO2(B), has gained great interest owing to its electrode potential and its tunnel structure which is ideal for ions intercalation/deintercalation. In this study, VO2(B)]modified with and without reduced graphene oxide (rGO) were synthesized via solvothermal method. The obtained products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). X-ray diffraction study reveals that the electrochemical reaction of VO2(B)/rGO is progressed based on deintercalation and intercalation of alkali ions (Li+ and Na+) into and out of the crystal structure; this is caused by the presence of open channels in the crystal structure of VO2(B). As a result, the resulting electric conductivity of the VO2(B)/rGO composite is improved to ~10-4 cm S-1 (from ~10-7 S cm-1 for the as-received VO2(B)). Electrochemical data of the VO2(B)/rGO composite, tested in both Li and Na cells, shows markedly enhanced electrochemical performance compared to bare VO2(B). The effect of electro-conducting rGO is more evident at high rates. The results show that solvothermally synthesized VO2(B)/rGO composite can be a potential cathode material for rechargeable batteries.
Electrochemical Performance of NaNiCoMnO2 for Cathode Material in Sodium Ion Batteries
Authors: Shin Gyuho , Kim Sung-soo
Published: February 2020

Lithium ion batteries have emerged as the best suited power source for portable electronics. They are also being considered as strong contenders to meet the energy demands of the transport sector. However lithium cannot be considered as an abundant element and its natural resources are unevenly distributed.

Sodium-ion batteries (NIB) appear as a promising alternative to the well-established lithium batteries technology. Sodium natural resources are unlimited everywhere as sodium is the fourth most abundant element on earth. Layered sodium transition metal oxides, NaxMO2 (M = transition metals), appear as very interesting cathode materials. The interest in these layered oxides probably arose from their high capacities and ease of synthesis

In this study, we synthesized NaNiCoMnO2 as the cathode material and its electrochemical performance was measured. Also the Na ion intercalation and deintercalation behavior was studied using Galvanostatic Intermittent Titration Technique(GITT) and Cyclic voltammetry (CV)
Insight into the Na-Storage Mechanism of Bismuth Oxyiodide Anode Materials
Authors: Liu Xiaoxiao , Huang Yunhui , Hu Xianluo
Published: February 2020

Sodium ion batteries, as an important alternative to lithium ion batteries, and a new kind of energy powering device, have attracted intensive attention because of the high natural occurrences of sodium on the earth and also its similar chemical nature to lithium.[1] Sodium ion has larger radius than lithium ion, nevertheless, which would immediately affect Na+ ion insertion into active materials, resulting in a poor battery performance.[2] Therefore, it has become an urgent task to find novel materials with outstanding sodium storage properties.

The novel application of BiOI, as a new anode material for sodium ion batteries, is reported here for the first time. BiOI microspheres were directly synthesized by a simple solution method, which is promising for large-scale industrial production. The Na-storage mechanism was explored in details by ex-situ X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), which are powerful tools for investigating electrochemical reaction mechanisms. Our results showed that the layered BiOI underwent irreversible structure changes in charge-discharge processes. The final discharged product was detected to be a sodium bismuth alloy compound, while the charged product was not BiOI instead of the Bi metal. It acts as the active material taking part in the following electrochemical reactions, especifically the alloying-dealloying reactions. Furthermore, we also found a facile way through coating BiOI with rGO to improve the cycling performance of this novel anode material. The detailed understanding and the modifying methods might shed lights on investigating and applying other kinds of materials toward a broader range of both energy and other areas.

[1] C. Chen, Y. Wen, X. Hu, X. Ji, M. Yan, L. Mai, P. Hu, B. Shan, Y. Huang, Na(+) intercalation pseudocapacitance in graphene-coupled titanium oxide enabling ultra-fast sodium storage and long-term cycling, Nature Communications, 6 (2015) 6929.

[2] M.D. Slater, D. Kim, E. Lee, C.S. Johnson, Sodium-Ion Batteries, Advanced Functional Materials, 23 (2013) 947-958.

Figure 1
Degradation Mechanisms of NaTi2(PO4)3 Aqueous Anodes and Mitigation Techniques
Authors: Mohamed Alexander I , Whitacre Jay
Published: February 2020

Aqueous rechargeable alkali-ion batteries offer an attractive alternative to Li-ion batteries for large scale installations because of their lower cost and higher degree of safety. However, with the exception of activated carbon anodes, demonstrated chemistries have generally showed poor cycle stability. Understanding the failure mechanisms of aqueous anode materials is of vital importance for commercialization of these batteries. In this study we have investigated three primary mechanism for capacity loss in NaTi2(PO4)3 (NTP) based anodes (1) dissolution of active material at high pH, (2) loss of active surface area due to gas entrapment from hydrogen evolution, and (3) alkaline oxidation of the carbon conductive additive. Inductively coupled mass spectrometry (ICP-MS) was used to quantify the solubility of NTP as a function of pH and helps explain the formation of a secondary reduction peak during extended low C-rate cycling. This degradation mechanism has been mitigated using a conformal polydopamine based carbon coating. Gas chromatography was used to quantify the production of H2, CO, and CO2 due to hydrogen evolution and alkaline oxidation of carbon. Electrochemical cycling followed by gas removal and re-infiltration of the porous electrodes was used to quantify the loss of electrochemical surface area due to gas entrapment and is found to be the primary cause of apparent capacity loss. A composite of the NTP electrode with a PTFE bound activated carbon was found to be effective in preventing gas entrapment with in the porous electrode.
(Invited) Development of the Battery-Driven SnO2 Thin Film Gas Sensor
Authors: Ohnishi Hisao , Nonaka Atsushi , Suzuki Takuya
Published: February 2020

We have developed a micro methane sensor obtained by laminating “nano-columnar structure SnO2 thin film" and catalyst layer on the circular diaphragm support layer with a built-in thin film heater. Ultra-low power consumption (0.06mW) required for 5 year battery operation was achieved by separating the functional elements of gas sensors, optimizing the materials and structures in charge of each function, microminiaturizing, and driving with low power ultra-short pulse. Furthermore, this sensor has realized higher sensitivity and higher selectivity than conventional methane sensors. In May 2015, Osaka Gas released the world's first battery-driven city gas alarm equipped with this sensor.
Biochemical Gas Sensors Using Self-Assembled Nanostructures
Authors: Lee Do Hoon , Kim Taewan , Song Wonbin , Lee Byung Yang
Published: February 2020

Nano-scale materials such as metal and metal-oxide based nanowires and nanoparticles (NWs, and NPs) have attracted wide attention due to their remarkable electrical, optical and mechanical properties. In some applications, they exhibit capabilities superior to conventional silicon-based electronic devices. However, the building of hierarchical structures using these nanomaterials require the development of non-conventional assembly methods. Here, we will present versatile assembly strategies for nanoscale material-based structures and integrated devices, where surface molecular patterns guide the assembly of NW/NPs on molecularly patterned solid substrates. The metal and metal-oxide based nanoscale materials assemble and align on molecularly patterned surfaces by minimizing the interface energy between NW/NPs and solid surface. The aligned NPs and NWs can be further processed to fabricate integrated circuitry based on NPs and NWs. Gas sensors and biochemical sensors for the detection of VOCs and environmental hormones can be easily implemented with the development of appropriate binding receptors. Combining this assembly method with capillary force-based assembly method, we can further generate large-area patterned substrates of biological materials and NPs of controllable thickness and optical properties. We will show also the assembly of cellulose and bacteriophages (biological NWs) into films with structural colors for optical applications.
Continuous Interstitial Glucose Monitoring Sensors Modified with Biocompatible Nitric Oxide-Releasing Nanofiber Coatings: Wireless In Vivo Evaluation in a Rat
Authors: Shin Jae Ho , Heo Min , Park Minji , Yang Hyunhee , Son Soo Ji , Lee Do Yeon , Lee Gi Ja
Published: February 2020

Reliable, user-friendly in vivo glucose sensors should have a significant impact on health care in the near future. Indeed, a continuous interstitial glucose monitoring sensor provides maximal information about varying blood glucose levels throughout the day, and is able to facilitate the making of optimal treatment decisions for diabetic patients. However, upon implantation of a sensor into a body, a cascade of inflammatory response (known as the foreign body response, FBR) is initiated, ultimately making in vivo glucose measurement erratic. Therefore, the appropriate fusion of biocompatible coating materials and glucose sensing devices has been one of the most critical issues. With discovery of nitric oxide (NO) as a potent anti-thrombotic and anti-inflammatory agent, a variety of NO storage/release nanomaterials have been reported to improve the biocompatibility of indwelled medical devices, including metal/metal oxide clusters, silica nanoparticles, dendrimers, and polymeric nanofibers. Herein an implantable glucose microsensor modified with NO-releasing silica/polymer hybrid nanofibers is demonstrated. By controlling NO release properties (e.g., total NO storage amount, half-life time of NO release, and maximum flux), the sensor performance in vivo (using a rat model equipped with a wireless signal transmitter/receiver device) will is evaluated, in terms of sensor lifetime, accuracy, and stability.
(Invited) Electrochemical Sensing Using Molecule-like Gold Nanoclusters
Authors: Kumar S. Senthil , Kwak Kyuju , Lee Dongil
Published: February 2020

Gold nanoclusters with atomic precision, for example, Au25(SR)18, Au38(SR)24, Au67(SR)35 and Au144(SR)60, where SR is organothiol, have attracted much attention in recent years because of their importance in both fundamental science and technological applications. These molecule-like nanoclusters display unique properties, such as quantized single-electron charging and molecule-like redox activities, that differ substantially from those of the corresponding atoms and bulk materials. This presentation reports electrochemical and optical properties of these nanoclusters and their use in electrochemical sensing. Voltammetry of these nanoclusters exhibited well-resolved, reversible redox peaks and size-dependent electrochemical HOMO-LUMO gaps that could be correlated to optical and calculated energy gaps. These nanoclusters also showed excellent electrocatalytic activity toward oxidation of biologically relevant analytes. The modified electrode film prepared with Au25 nanoclusters exhibited excellent mediated electrocatalytic activity that was utilized for amperometric sensing of dopamine and glucose. The electron transfer dynamics in the Au25 film was examined as a function of Au25 concentration, which manifested the dual role of Au25 as an electronic conductor as well as a redox mediator. The electron transfer study has further revealed the correlation between the electronic conductivity of the Au25 film and the sensing sensitivity.
Label-Free, Fragmented Antibody (Fab')-Immobilized Immunosensors Via Use of Ferrocene-Modified Silica Nanoparticles
Authors: Hyun Hae Ry , Kwon Jiyoon , Shin Jae Ho
Published: February 2020

Antibody-based immunosensors as a promising approach for selective and sensitive analysis provide a rapid and convenient alternative approach to traditional analytical methods. Despite many advantages, it is still a challenge to find new approaches that could improve the simplicity, specificity, and sensitivity for clinical uses. To enhance performance of antibody-based immunosensors, it is particularly important to develop label-free detection methods. Several strategies to achieve label-free immunoassays have been demonstrated by using fluorescence, electrochemistry, quartz crystal microbalance (QCM), and surface plasmon resonance (SPR) spectroscopy. Herein we reported on a new approach to design a label-free immunosensor via use of electrochemically active nanoprobes such as ferrocene (Fc)-modified silica nanoparticles. The Fab’ (i.e., fragmented antibody) immobilized on a gold electrode leads to changes in the interfacial electron transfer properties. Indeed, the surface coverage with target proteins specifically bound to Fab’ prohibits the access of electroactive probes to the electrode surface. To amplify such blocking effects associated with target protein-Fab’ complex formation, Fc-modified silica nanoparticles are utilized as a scaffold to design macromolecular electroactive probes. Various conjugation techniques and addressed fabrication methods for Fab’ oriented immobilization on a gold surface will be evaluated. In addition, the effects of particle size (15 to 500 nm) and surface net charge of Fc-modified silica nanoparticles on sensor performance (e.g., sensitivity and detection limit) will be discussed. Furthermore, we investigate the feasibility of applying the concept to develop the label-free, Fab’-based immunosensor to detect the biomarkers of allergic rhinitis, i.e., Clara cell protein 16, tryptase, and eosinophil cationic protein.
Electrochemical Study of Conducting Poly(thionine) Electropolymerization in Two Methods and Its Significance for the Detection of Dopamine
Authors: Rahman Mohammad Mahbubur , Ge Chuang-ye , Lee Jae Joon
Published: February 2020

In this research, we investigated the electrochemical behaviors of conducting poly(thionine) (PTH) on glassy carbon electrode (GCE) for the interference-free detection of dopamine (DA). The PTH films on GCE were prepared in two methods: direct potential sweeping (single step, PTH-S), or a constant potential oxidation of GCE followed by potential sweeping (double step, PTH-D). Our electrochemical investigation revealed that the simple variation of the electropolymerization conditions dramatically changed the PTH formation mechanism without altering the chemical structure of the polymers as well as the catalytic activity for the oxidation of DA in the presence of ascorbic acid (AA) and uric acid (UA). The PTH-D exhibited higher sensitivity for the detection of DA compared to the PTH-S, which can be attributed to the higher accumulated surface charge/polymer amount on the PTH-D films compared to the PTH-S. The PTH-S could easily suppress the signals of AA and UA in the presence of DA, while, the PTH-D could easily separate the oxidation signals of AA, DA, and UA with higher sensitivity. These interesting features will help the researchers to control the sensitivity for DA oxidation and other analytes by using PTH and other conducting polymers.
Applications of Electrochemical Impedance Spectroscopy in pH Sensor Characterization and Failure Analysis
Authors: Huo Jinshan
Published: February 2020

pH sensors have been widely used in wet labs in research & development and production lines in various industries. Measuring the potential differences between pH and reference electrodes in pH buffers is usually used for calibration and performance test of a pH sensor. Electrochemical Impedance Spectroscopy (EIS), as a powerful analytical technique, has been used for the study of various electrochemical systems and processes. Nevertheless, the information about EIS study of pH sensors is rarely available from published resources.

This work presents: electrochemical impedance spectra of normal pH sensors and sensors with different defects, which result in different failure modes; how EIS can be used to facilitate the failure analysis of pH sensors; how EIS is used to study the aging mechanism of glass electrodes of steam-sterilizable pH sensors.

The work has shown that EIS can be used to facilitate the failure analysis of pH sensors by largely reducing destructive dissection work; hence save a lot of time for the process. EIS has also successfully been used to study the mechanism of glass electrode failure and the possibility to resume its performance after exposed to high temperature (Refer to Fig.1).

Figure 1
Step Response Analysis of MEMS Electro-Thermal Gas Sensors of Differing Geometry
Authors: Hesketh Peter , Mahdavifar Alireza , Shirke Amol , Stetter Joseph R , Struk Daniel
Published: February 2020

MEMS gas sensors have the advantage of low power operation, fast response time, and have attracted a lot of interest because of their potential low cost. There is a need for monitoring of changes in the environment, in particular for carbon dioxide and methane. These gases can be detected using electro-thermal method based upon thermal conductivity changes. MEMS based micro-TCD which are ultra-low power, requiring less than 6 uJ per measurement and have a response time 100uS or less [1]. Because of their rapid response time they are also very suitable for MEMS-GC systems [2]. We have investigated different modes of pulsed operation for these sensors using constant current, constant resistance, constant power and constant energy. The detection of helium and hydrogen in nitrogen indicated a low level of detection less than 500ppm or better. A comparison of thermal time constants and resistance response for micro-thermal conductivity sensors with different aspect ratio, surface area to volume, operated at constant power density or at similar average temperatures will be discussed. Fitting a model based upon kinetic theory of gases to temperature dependent sensor response of gas mixtures has potential for evaluation of multi component mixtures.

References

[1]A. Mahdavifar, M. Findlay, J. R. Stetter, P. J. Hesketh, “Transient thermal response of micro-thermal conductivity detector for the identification of gas mixtures: An ultra-fast and low power method,” Nature Microsystems and Nanooengineering Vol. 1, pg. 15025 (2015).

[2] A. Mahdavifar , M. Navaei , P. J. Hesketh , J. D. Dimandja , J. R. Stetter , G. McMurray, “Implementation of a polysilicon micro electro-thermal detector in gas chromatography system with applications in portable environmental monitoring,” Journal of Solid State Science and Technology, Vol. 4, No. 10, pp. S1-S5 (2015).
3-D Printed Polymer MEMS
Authors: Takamatsu Kyuichiro , Yamada Naoya , Wada Masato , Ahmed Kumkum , Kawakami Masaru , Kassegne Sam , Furukawa Hidemitsu , Khosla Ajit
Published: February 2020

This paper describes fabrication of complex 3-D printed Polymer MEMS Devices. Since geometric complexity is not a concern for 3-D printing, complex 3D microfluidics, MEMS and lab-on-a-chip devices can be easily fabricated that are otherwise time consuming and difficult to manufacture with state of the art 2-D MEMS fabrication technology. Furthermore, 3-D printed MEMS technology elimates the need for expenisve infrastruce required to manufacture MEMS devices such as clean room, photolithography equipment, masks etc.
Detection of Telomerase Activity Based on the Steric Hindrance Change in the Pore of Anodic Alumina Nanochannels
Authors: Liu Xu , Liu Yuan Jian , Wei Wei
Published: February 2020

It has been confirmed that telomerase are closely related to cancers. [1] Urine telomerase measurement is nondestructive compared to blood analysis and pathology tests, which is significant for cancer discovery, development and prognosis. [2]

In this paper, a new method for detection of urine telomerase activity based on increment of steric hindrance in the porous anodic alumina (PAA) nanochannels was proposed. Telomerase primer (TS primer) was assembled firstly on the inner wall of PAA nanochannels. Then, under the action of active telomerase, TS primer was extend with repeat G-rich sequences (TTAGGG)n, which experienced configurational change to G-quadruplex in the presence of K+. As a result, the steric hindrance in the nanochannels changed accordingly. Telomerase activity measurement were proposed based on these steric hindrance changes. The increased anodic current, produced by ferricyanide, has a linear correlation with the HeLa cell number in the range of 10 - 5000 cells, with the detection limit of 7 cells. Compared with previously reported detection method based on the steric hindrance change in the PAA pore, the anodic change in this method is bigger because multiplex G-quadruplex formed with the action of telomerase, which was advantage to improve the detection sensitivity.[3] The method was simple and reliable, which was significant to the clinical cancer diagnosis.

References
：

[1] Moyzis, R. K.; Buckingham, J. M.; Cram, L. S.; Dani, M.; Deaven, L. L.; Jones, M. D.; Meyne, J.; Ratliff, R. L.; Wu, J. R. P. Natl. Acad. Sci. USA.,
1988, 85, 6622-6626.

[2] Wu, L.; Qu, X. G. Chem. Soc. Rev.,
2015, 44, 2963-2997.

[3] Yu, J. C.; Zhang, L. Q.; Xu, X.; Liu, S. Q. Anal. Chem., 2014, 86, 10741-10748.
Invsetigation on High Charge Density of States in Electrocheimcal Polymer Transistor
Authors: Lee Jiyoul
Published: February 2020

Using temperature-dependent charge transport measurements, we investigated spectral density of states (DOS) in the bandgap of polythiophene thin-films under high carrier densities (< 3.5 x 10^20 cm-3) induced by electrochemical doping. The thermally activated charge transport indicates that the electrical currents in the polymer thin-film under high charge density state follows the Meyer-Neldel rule. The spectral DOS extracted from the electrolyte-gated polymer film lie in the range of 8.0 x 10^19 cm-3eV-1 ~ 8.0 x 10^21 cm-3eV-1, which are at least two orders of magnitude larger than the DOS extracted from the same polymer film at relatively low induced carrier densities by general oxide dielectrics. This is believed to result from the complete passivation of trap sites distributed in the polymer thin-film bulks by the high carrier density induced in the device. By using such a method, DOS distributions close to the intrinsic energy distribution of the polythiophenethin-film could be estimated.
Graphene Polyaniline/Polyoxometalate Hybrid As Cathode for Lithium Ion Batteries with Improved Lithium Storage Capacity
Authors: Diao Guowang
Published: February 2020

Abstract: polyaniline/polyoxometalate nanospheres hybrid were synthesized via a facile interfacial polymerization method, and evaluated as a cathode material for lithium ion batteries. However, both polyoxometalate and polyaniline/polyoxometalate can be easily dissolved in LiPF6 eletroyte. In order to solve this problem，polyaniline/polyoxometalate nanospheres were first embedded into the interspaces of grapheme, leading to the formation 3D free-standing rGO@PANI/POM hybrid. The molecular cluster battery in which the RGO@PANI/PW12O34 hybrid was adopted as a cathode active material exhibited a higher battery capacity and stability than the PANI/ PW12O34 and the microcrystal polyoxometalate. The phosphotungstic acid polyanions not only exhibit a large theoretical capacity of about 260 mAh g−1, but also reduce the charge transfer resistance of electrode leading to the enhanced reversible capacity and rate capability.

Reference

[1] Liu, K.; Zheng, J. M.; Zhong, G. M.; Yang, Y. Poly(2,5-dihydroxy1,4-benzoquinonyl sulfide) (PDBS) as a Cathode Material for Lithium Ion Batteries. J. Mater. Chem. 2011, 5, 4125.

[2] Shao, L.; Jeon, J. W.; Lutkenhaus, J. L. Polyaniline/Vanadium Pentoxide Layer-by-Layer Electrodes for Energy Storage. Chem. Mater. 2012,24, 181.

[3] Zhang, L., Wu, H. B., & Lou, X. W. D. Iron-oxide-based advanced anode materials for lithium-ion Batteries . Advanced Energy Materials, 2014, 4, 1032.

ACKNOWLEDGEMENTS

This work was financially supported by the National Natural Science Foundation of China (Grant No. 21273195), a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the Natural Science Foundation of Education Committee of Jiangsu Province (12KJB150023).
A Sensitive Electrochemical Glucose Biosensor Based on Flower-Shaped Zinc Oxide Nanostructures
Authors: Li Juan , Tong Jingjing
Published: February 2020

In this work, flower-shaped zinc oxide nanostructures were used to develop sensitive electrochemical glucose biosensor. The flower-shaped zinc oxide nanostructures were prepared by solvothermal method, which was different from the previous method [1], and characterized by scanning electron microscope and X-ray diffraction spectroscopy. A novel glucose biosensor was fabricated based on the immobilization of glucose oxidase (GOx) on the flower-shaped zinc oxide nanostructure. Flower-shaped zinc oxide with large specific surface area can load large amounts of glucose GOx, and provide excellent microenvironment for the immobilized enzyme[2,3,4,5]. Fig. 1 shows the amperometric response of the GOx/Nafion/GCE and GOx/ZnO/Nafion/GCE in pH 7.0 air-saturated PBS containing different concentrations of glucose at –0.37 V applied potential. The proposed biosensor shows a wide linear range from 0.005–1.6 mM, high sensitivity of 15.6 mA M−1 cm−2, and low detection limit of 0.004 mM. The performance of the GOx/ZnO/Nafion/GCE is much better than that of GOx/Nafion/GCE. The resulting biosensor with excellent selectivity, stability and reproducibility can be successfully applied in the detection of glucose at –0.37 V in human serum samples.

References:

[1] H. Zhang, D. Yang, Y.J. Ji, X.Y. Ma, J. Xu, D.L. Que, J. Phys. Chem. B 2004, 108, 13

[2] M. K. Ram, M. Adami, S. Paddeu and C. Nicolini, Nanotechnology, 2000, 11, 112.

[3] F. F. Zhang, X. L. Wang, S.Y. Ai, Z. D. Sun, Q. Wan, Z. Q. Zhu, Y. Z. Xian, L. T. Jin and K. Yamamoto, Anal. Chim. Acta, 2004, 519, 155.

[4] S. P. Singh, S. K. Arya, P. Pandey, B. D. Malhotra, S. K. Sreenivas and V. Gupta, Appl. Phys. Lett., 2007, 91, 63901.

[5] X. L. Zhu, I. Yuri, X. Gan, I. Suzuki and G. Li, Biosens. Bioelectron., 2007, 22, 1600.

Figure 1
Capacity Enhancement of Electrochemical Flow Capacitor Using Quinonic Compounds Couple
Authors: Saito Hayate , Tomai Takaaki , Honma Itaru
Published: February 2020

The semi-solid flow cell system, consisting of an electrochemical charge-discharge cell connected to an external circulatory system of pumps and reservoirs, has been proposed as the grid-scale energy storage. Among the flow cells, electrochemical flow capacitor (EFC) stores electrical charge in an electrical double layer at the carbon-electrolyte interface in a flowable carbon-electrolyte suspension (slurry), so the EFC exhibits higher power density than that of semi-solid flow battery [V. Presser, et al., Adv. Energy Mater, 2, 895 (2012).]. However, compared to the battery system, EFC has the limited energy density only derived from electrical double layer capacitance.

 Our previous study revealed that the impregnation of redox-active organic compounds into the nanoporous carbon enable to enhance the high energy density (＞20 Wh kg-1) of aqueous electrochemical capacitor with maintaining the high power density (＞5 A g-1) and long cycle lifetime (more than 10000 cycles) [T. Tomai, S. Mitani, D. Komatsu, Y. Kawaguchi, I. Honma., Sci. Rep.,
4, 3591, (2014).]. In this study, to address the limitation of the energy density of EFC, we employed the nanoporous carbon beads holding quinonic/hydroquinonic compounds to carbon-electrolyte suspension (quinone/carbon complex slurry) for both flowable electrodes of the EFC.

The flowable quinonic/hydroquinonic slurry electrode was prepared by dispersing the organic compound-carbon composite in 0.5 M H2SO4 and 0.05 M HCl aqueous solution. We employed tetrachlorohydroquinone (TCHQ) as cathode active material and dichloroanthraquinone (DCAQ) as anode active material in positive and negative slurry electrodes, respectively. The weight ratio of the quinonic/hydroquinonic compound to the nanoporous carbon bead was fixed to be 3:7. The weight ratio of the organic compound-carbon composite to 0.5 M H2SO4 and 0.05 M HCl aqueous solution was fixed to be 13:87. Charge-discharge measurement at static operation, the EFC using the quinone/carbon complex slurry shows the high energy density (19.4 Wh/kg) in the applied potential range between 0-1 V. This value is about two times larger than that of the EFC using the unmodified carbon slurry. Thus, by using the redox reactions of quinonic/hydroquinonic compounds in positive and negative slurry electrodes, we achieved the enhancement of the energy density of EFC. Notably, the EFC using TCHQ/carbon complex slurry and DCHQ/carbon complex slurry for both electrodes investigated in this study exhibits 1.6 times higher energy density than the EFC using only hydroquinone/carbon complex slurry [M. Boota, K. B. Hatzel, E. C. Kumbur, Y. Gogotsi., ChemSusChem 2015, 8, 835.]. Moreover, charge-discharge measurement at intermittent flow operation, we demonstrated the prepared slurry electrodes were applicable to semi-solid flow system.