bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Charging of CdSe Quantum Dots: Effects of Adsorption Versus Intercalation
Authors: Puntambekar Ajinkya , Wang Qi , Miller Lauren , Smieszek Nicholas , Chakrapani Vidhya
Published: February 2020

Effects of electrochemical charging of quantum dots (QDs) have been reported in the past, wherein optical and electrical properties could be modulated through cation adsorption and electron injection into the quantum-confined 1Se states. In this presentation, we report two different modes of electrochemical double-layer charging in CdSe QDs and their effects on the electronic and optical properties. We show that the charging mechanism at the interface involves cation intercalation for smaller ions, such as Li+, Na+, or K+, and cation adsorption for larger bulky ions, such as tetrabutylammonium ions, where steric hindrance precludes intercalation. As a result, it was observed that while cation adsorption leads to an increase in the absorbance in the mid-infrared spectral range, cation intercalation into the CdSe core results in an absorbance increase from the visible to infrared spectral range, an enhancement in radiative lifetime of e−, an increase of 158% in the intensity of band-edge photoluminescence, and strong emission in the near-infrared spectral range as a result of the formation of Se vacancies. In this talk, the nature of charging mechanisms will be discussed using the results from combined photoluminescence studies, radiative lifetime studies, and X-ray photoemission studies. The cation-coupled electronic and optical modulation reported here in CdSe QDs have important implications for electrochromic smart windows, photovoltaics and other devices.
(Invited) Corrosion of Semiconductors at the Solution Interface in Integrated Solar Fuel Devices: Challenges and Perspectives
Authors: Sun Ke , Xiang Chengxiang("CX") , Lewis Nathan S
Published: February 2020

Corrosion of technologically important small band-gap (
E

G<2 eV) semiconductors is a common behavioral response to the photoelectrochemical environment such as illumination condition, potential, pH, buffer ions, and etc. Importantly, this corrosion process of semiconductors is generally recognized as the leading failure mechanism in integrated solar fuel devices. Therefore, understanding the corrosion reaction is critical to the development of stabilization strategies toward the realization of efficient and stable solar fuel conversion devices. Depending on the materials behavior in response to the corrosive environment and electrochemical stress, the corrosion process can be categorized into dissolution and passivation corrosion depending on the dissolution rate of the thermodynamically decomposed products at the semiconductor solution interface. In this work, photo-passivation and -corrosion processes of two representative semiconductors under working conditions have been identified. Functions of the decomposed product that remains at the semiconductor interface have been investigated including effects to the interfacial energetics and co-stabilization. For the semiconductor that involves dissolution corrosion under operation, two effective new designs that are promising in maintaining the functionalities of the integrated photoelectrodes have been experimentally studied. Challenges and future research directions will be also discussed.
Investigation of Thermal Treatment Processes for Dissimilar Wafer Bonding
Authors: Wang Chenxi , Li Yue , Liu Yannan , Yuan Zhitian , Tian Yanhong , Wang Chunqing , Suga Tadatomo
Published: February 2020

Wafer bonding, also termed as “direct bonding” or “wafer direct bonding”, has one of the main advantages for its ability to integrate dissimilar materials in various areas of microelelctronics, optoelectronics, micro/nanoelectromechanical systems (M/NEMS). Silicon is the most extensively used material for semiconductor industry. To meet demands on superior electrical, optical and acoustic applications, it is important to combine silicon with appropriate materials, such as GaAs, quartz glass, and LiTaO3. In general, two wafers are brought into contact at room temperature (~25ºC) and followed by thermal treatment processes (>100ºC) enabling reliable bonding strength to withstand subsequent mechanical grinding or polishing processes. During thermal treatments, the major concern in dissimilar bonded wafer pairs is the thermal stress originating from a mismatch in thermal expansion coefficients. Higher thermal stresses above a critical temperature may cause sliding, debonding, cracking or misfit dislocation between two bonded wafers. It is therefore highly desirable to predict the critical temperatures and optimize the thermal steps for dissimilar bonded wafer pairs with various materials and thicknesses.

In this paper, a thermal stress model is developed based on analytical as well as finite element methods. To ensure a good bonding, the thermal stress should be smaller than the critical yield stress of the bonded materials. Meanwhile, the deformation energy should be lower than the bonding energy so that no sliding or debonding occurs during the thermal treatments. Under these two conditions, the critical temperatures for various dissimilar bonded wafer pairs (Si/GaAs, Si/Quartz and Si/LiTaO3) are calculated and predicted. The effects of wafer thickness are also demonstrated. To verify our calculation results, 100-mm silicon wafers are combined to LiTaO3 wafers by plasma activated bonding process. The bonded wafer pairs are heated at different temperatures to strengthen bonding. Experimental results show the critical temperature value is in agreement with our calculation. We believe our model provides a tool to optimize the thermal treatment processes during the dissimilar wafer bonding. It has great potentials to improve the bonding processes for wafer-level hybrid integration.
(Invited) Unified Band Diagram Framework for the Development of Cation Intercalation Materials for Next Generation Batteries
Authors: Young Matthias J , Holder Aaron M. , Musgrave Charles Bruce
Published: February 2020

Next generation batteries may shift from lithium ion chemistries to those based on more earth-abundant cations such as sodium, potassium, or magnesium ions and employ ionic liquid or solid electrolytes with stability windows of over 6 volts. We have developed a new theoretical approaches to analyze lithium ion battery cathode materials to gain insight into the requisite properties for electrode materials in next-generation batteries, which we demonstrate using spinel lithium manganese oxide (LiMn2O4). Nanoscale spinel LiMn2O4 is a potential high-rate cathode material for advanced battery technologies and other electrochemical applications. Using a coupled electrochemical and band structure analysis of LiMn2O4 informed by screened hybrid density functional theory calculations we identify new features of the charge storage properties and stability of LiMn2O4. The accuracy and predictive power of this theoretical framework to determine the equilibrium potential(s) for charge-transfer in intercalated compounds is validated by comparison with experimental results. We first demonstrate the synthesis of ultrathin films of spinel LiMn2O4 between 20 and 200 nm in thickness by room-temperature electrochemical conversion of MnO grown by atomic layer deposition (ALD). Next, we investigate the charge storage properties of LiMn2O4 thin films in electrolytes containing Li+ with Na+, K+, and Mg2+. Our CV experiments demonstrate that for sweep rates between 1 and 400 mV/s, up to 30% of the capacity of LiMn2O4 arises from bulk electronic charge-switching which does not require compensating cation mass transport. The hybrid ALD-electrochemical synthesis, coupled electrochemical and electronic structure analysis, and unique charge storage mechanism we describe provide a fundamental framework to guide the development of future nanoscale electrode materials for ion-incorporation charge storage.
Vacancy-Induced Semiconductor–Insulator–Metal Transitions in Nonstoichiometric Transition Metal Oxides
Authors: Wang Qi , Puntambekar Ajinkya , Chakrapani Vidhya
Published: February 2020

Metal–insulator transitions in strongly correlated transition metal oxides (TMOs) induced by electrochemical charging have been attributed to formation of vacancy defects. However, the role of native defects in affecting these transitions is not well understood. This presentation will discuss a new type of phase transition in p-type, nonstoichiometric nickel oxide involving a semiconductor-to-insulator-to-metal transition along with the complete reversal of conductivity from p- to n-type at room temperature induced by the interaction of native vacancy defects with redox species such as Li+ during electrochemical charging. Direct observation of vacancy-ion interactions using in-situ near-infrared photoluminescence spectroscopy show that this transition is a result of passivation of native nickel (cationic) vacancy defects and subsequent formation of oxygen (anionic) vacancy defects driven by Li+ insertion into the lattice. Changes in the oxidation states of nickel due to defect interactions probed by X-ray photoemission spectroscopy support the above conclusions. In contrast, n-type, nonstoichiometric tungsten oxide shows only insulator-to-metal transition, which is a result of oxygen vacancy formation. The defect-property correlations shown here in these model systems can be extended to other oxides to enable rational engineering of a new robust class of nanoscale, low temperature TMO catalysts and sensors having tailored functionality and selectivity.
(Invited) Real-Time, Selective Detection of Lead Ions in Water Using a Graphene-Based Field-Effect Transistor Sensing Platform
Authors: Chen Junhong
Published: February 2020

Water plays an important role in the economic world; only 3% of available water is potable, and with increasing demand, the need for safe drinking water is rising. The National Academy of Engineering identified “providing access to clean water” as one of the top 10 grand challenges for engineering in the 21st century. Heavy metal ions, e.g., lead, mercury, and arsenic, are widely present in water systems. These heavy metal ions are poisonous and may lead to serious damage to organs, tissues and bones, and nervous systems of humans. Existing water quality monitoring mostly occurs at the water supply intake or water treatment plant, instead of along water distribution lines and at the point of use, which is considered inadequate given potential changes in water quality and associated risks within water distribution systems. Current detection methods for aqueous heavy metal ions are often too expensive or unsuitable for in-situ and real-time detection (an unmet need). A field-effect transistor (FET) device-based sensor is developed to specifically detect Pb2+ ions in an aqueous environment. Reduced graphene oxide (rGO), as the semiconducting channel material, is utilized in the FET device through a self-assembly method. An L-glutathione reduced (GSH) is employed as the capture probe for the label-free detection. By monitoring the electrical characteristics of the FET device, the performance of the sensor is measured and investigated. Compared with conventional detection technologies, this sensor enables real-time detection with a response time of 1-2 seconds. A lower detection limit for Pb2+ ions as low as 10 nM is achieved, which is much lower than the maximum contaminant level (MCL) for Pb2+ ions in drinking water advised by the World Health Organization (WHO). Furthermore, the rGO FET sensor is able to distinguish Pb2+ from other metal ions. Without any sample pretreatment, the platform is user-friendly.
(Invited) Thin-Film Nanofluidic Devices for Single-Molecule Science: Electronic, Optical, and Force Sensor Platforms
Authors: Bandara Y. M. Nuwan D. Y. , Whelan Julie C. , Karawdeniya Buddini Iroshika , Nichols Jonathan W. , Dwyer Jason R.
Published: February 2020

Thin film nanofluidic devices, such as nanopores, offer a diverse range of platform architectures and capabilities for sample characterization and single-molecule sensing. Nanochannels formed between, or within, thin films offer two domains for device optimization and method development: the dimensions and properties of the films, themselves, and the scale and nature of the confined volumes. Transmission electron microscopy can be carried out on liquid samples, for example, through the use of properly constructed windowed sample chambers. Most nanopore devices offer electronic readout of the presence of an analyte in solution; the signal is an analyte-perturbed ionic current through the nanopore, and the signal thus allows significant insight into interfacial and sample physicochemical properties, beyond the usual considerations of analyte presence and concentration. (Nano)confinement also offers sample perturbation and manipulation capabilities where the structure and interfacial properties of the channel become key design considerations requiring, because of the small length scales, advances in fabrication. Nanopore force spectroscopy uses the nanopore as physical barrier, tuned to the dimensions of a complex, to explore intermolecular interaction energetics through the timescale for complex rupture under force. Fabrication efforts have led to additional analytical capabilities, such as surface-enhanced Raman spectroscopy being performed essentially on demand on a host of different support materials, including those with structures that offer additional analytical capabilities. Fabrication strategies, nanochannel characterization methods, and bioanalytical and biophysical measurements will be presented in concert to demonstrate the unique capabilities—for discovery and application—offered by thin-film nanofluidic devices.
(Invited) Flexible Polymer Nanogenerators for Biomechanical Energy Harvesting
Authors: Wang Xudong
Published: February 2020

Harvesting mechanical energy from biological systems possesses great potential for in-vivo powering implantable electronic devices. Nanogenerator (NG) is a promising technology for harvesting biomechanical energy either in vivo or ex vivo. In this talk, I present a development of flexible piezoelectric nanogenerator (NG) based on mesoporous poly(vinylidene fluoride) (PVDF) films. Monolithic mesoporous PVDF was fabricated by a template-free sol-gel-based approach at room temperature. By filling the pores of PVDF network with poly(dimethylsiloxane) (PDMS) elastomer, the composite’s modulus was effectively tuned over a wide range down to the same level of biological systems. A close match of the modulus between NG and the surrounding biological component is critical to achieve practical integration. Upon deformation, the composite NG exhibited appreciable piezoelectric output that was comparable to or higher than other PVDF-based NGs. An artificial artery system was fabricated using PDMS with the composite NG integrated inside. Effective energy harvesting from simulated blood pressure fluctuation was successfully demonstrated. The simple and effective approach for fabricating mesoporous PVDF with tunable mechanical properties provided a promising route toward the development of self-powered implantable devices. In vivo biomechanical energy harvesting was further demonstrated. The PVDF NG was encapsulated by polydimethylsiloxane (PDMS) and embedded into rodents. No toxicity or incompatibility sign was found in the host after carrying the packaged NG for 6 weeks. Moreover, the electric output of this NG was extremely stable and exhibited no deterioration after 5 days of in vivo operation or 1.512 x 108 times mechanical deformation. This NG device could practically output a constant voltage of 52 mV via a 1 mF capacitor under living circumstance. The outstanding efficiency, magnificent durability and exceptional biocompatibility promise this mesoporous PVDF-based NG in accomplishing self-powered bioelectronics with potentially lifespan operation period.
Solution-Processed Tellurium Nanowires for Stretchable and Wearable Piezoelectric Device
Authors: Wang Yixiu , Wu Wenzhuo
Published: February 2020

Nanowires made of materials with non-centrosymmetric crystal structure are under investigation for their piezoelectric properties and suitability for next-generation self-powered nanodevices. In this work, we report a systematic study on synthesis of trigonal tellurium nanowires with well-controlled dimensions. After assembling the tellurium nanowires on the stretchable substrates, a stretchable, soft piezoelectric nanogenerator has been developed with the capability to efficiently convert mechanical stimuli into electric power. We revealed the correlation between the piezoelectric outputs from the integrated devices and the diameters of as-produced tellurium nanowires. We further studied the feasibility of using the as-fabricated piezoelectric device for biomedical applications, such as gesture recognition. This work establishes the process-structure-property-performance relationship in the piezoelectric nanogenerator that may pave way for the nanomanufacturing and practical application of piezoelectric nanomaterials.
(Invited) Silicon-Based Hydrogel Nanocomposites for the Treatment and Diagnosis of Pulmonary Diseases
Authors: Andrew Jennifer
Published: February 2020

Lung cancer is the most frequent cause of cancer worldwide for men, and second only to breast cancer for women. Lung cancer is the leading cause of cancer death worldwide. Yet, if cancer is detected in the earliest stages it is a treatable, if not curable disease. However, we lack the tools to detect early stages of this disease in a non-invasive manner. To overcome this challenge we have developed a simple non-invasive urine-based test for the early detection of lung cancer using a silicon-hydrogel composite microparticles. Hydrogel-based microparticles are particularly attractive for pulmonary delivery. Their size can be engineered for efficient delivery into the bronchi, where they subsequently swell, avoiding macrophage uptake. Here, I will present our work in developing enzyme-responsive peptide functionalized hydrogel microparticles via emulsion synthesis. Additionally, these hydrogels will include silicon nanocrystals as a reporter particle. We will present a top-down approach to fabricate silicon nanocrystals with diameters smaller than 6 nm from a porous silicon template. The viability of these composite hydrogel microparticles to serve as drug delivery vectors and as diagnostic agents will be reported.
(Invited) Simultaneous Ionic Current and Potential Detection of Biomolecules and Nanoparticles By a Multifunctional Nanopipette
Authors: He Jin
Published: February 2020

Nanopore sensing based technologies have made significant progress for biomedical applications. In recent years, multimode sensing by multifunctional nanopores shows the potential to greatly improve the sensitivity and selectivity of traditional resistive-pulse sensing method. In this talk, we will show that two label-free electric sensing modes can work cooperatively to detect biological entities, such as biomolecules and biological nanoparticles, in ionic solution by a multifunctional nanopipette. The multifunctional nanopipettes containing both nanopore and nanoelectrode (NE) at the tip are fabricated quickly and cheaply. We will discuss the detection mechanism and demonstrate that the ionic current and local electrical potential changes can be detected simultaneously during the translocation of individual entities. With the combination of ionic current and potential measurements, we are able to detect not only the translocation of single entity but also the motions of entities outside the nanopore entrance, revealing rich information of biological entities.
Surface Enhanced Visible Light Photocurrent and Switching Behavior of Metal Oxide Semiconductor Electrodes Modified with Plasmonic Nanoparticles
Authors: Pan Shanlin
Published: February 2020

Hematite (α-Fe2O3) is a promising photocatalyst for solar water splitting because of its favorable band gap of 2.2 eV, low cost, and abundance in nature. Surface plasmon-enhanced light absorption for photoelectrochemical water splitting at α-Fe2O3thin film electrode modified with Au nanoparticles (NPs) or nanorods (NRs) is described. About 3 times higher light absorption and photocurrent enhancement are obtained from thin hematite films containing Au NPs than with pristine hematite films. The plasmonic enhancement increases with the amount of Au NPs for the same thickness of hematite. Thickness-dependent study of photoactivity indicates a higher enhancement in hematite thin films compared to thicker films due to reduced charge transport distance and optimal local field enhancement effect. Such enhancement can be obtained by self-assembling Au NRs onto a hematite thin film electrode using electrostatic force between their positively charged cetyltrimethylammonium bromide (CTAB) layer and negatively charged hematite surface functionalized with poly(4-styrenesulfonate). The photoelectrochemical reaction of the plasmon active substrate for water oxidation reaction is performed and compared at various hematite layer thicknesses. When the α-Fe2O3 electrode is biased at a small potential +0.2 V (vs Ag/AgCl), the photocurrent of water oxidation is reduced because of increased recombination of holes and electrons at the surface of the Au NRs. When the bias potential is increased to +0.5 V (vs Ag/AgCl), a plasmon enhancement of the photoelectrochemical reaction of water oxidation at wavelengths near the plasmon resonance condition is observed at the α-Fe2O3 thin film electrodes accompanying a dramatic increase in the background current. The significant increase in photocurrent in the region of surface plasmon absorption is attributed to the enhanced visible light absorption of α-Fe2O3 in the presence of the plasmon active Au NPs and NRs.
An ATR-Seiras Study on Cu-Based Catalysts for CO2 Electrochemical Reduction
Authors: Zhu Shangqian , Shao Minhua
Published: February 2020

The CO2 concentration in the atmosphere has increased significantly during the past decades.1 Electrochemical reduction of CO2 into various valuable chemical fuels provides a promising solution to extenuate this issue and leads to the renewable development of society.2-3 However, the unsatisfactory performance of electrocatalysts has prevented the widespread commercial use of this technique. The poor understandings on reaction mechanisms are one of the reasons that hinder the development of more advanced catalysts.

In this study, surface enhanced infrared absorption spectroscopy (SEIRAS) with the attenuated total reflection (ATR) technique was used to probe the reaction mechanisms of CO2 reduction on Cu thin films deposited on a hemispherical Si prism. Various reaction intermediates (e.g. CO, COH, OCH3) were detected on CO2 electrochemical reduction for the first time (Figure 1). The evolution of reaction intermediates during cathodic potential sweep were direct observed and possible reaction pathways on Cu surfaces were proposed.

This work added new insights into the reaction mechanisms of CO2 electrochemical reduction and would help the rational design of catalyst with a higher activity and selectivity.

References

1. World Meteorological Organization Greenhouse Gas Bulletin, 2014.

2. Hori, Y., in Modern Aspects of Electrochemistry, Springer, New York, 2008.

3. Qiao, J.; Liu, Y.; Hong, F.; Zhang, J. Chemical Society Reviews
2014, 43, 631-675.

Figure 1. Real-time SEIRA spectra recorded during CO2 electrochemical reduction on a Cu thin film in the cathodic potential sweep in a CO2-saturated 0.1 M KHCO3 solution.

Figure 1
Hybrid Catalytic Materials for Determination and Speciation of Electrochemically Inert Analytes: Arsenic(III) and Arsenic(V)
Authors: Kulesza Pawel J , Ozimek Weronika , Cox James A. , Rutkowska Iwona Agnieszka
Published: February 2020

There has been growing interest in development of new methods for the determination of arsenic due to its high toxity and increasing population in the environment. Electrochemical methods for the determination of arsenic can be considered as complimentary to spectroscopic and chromoatographic ones because they are fairly simple and they are subject to different selectivity criteria. In this respect, various stripping voltammetric procedures are becoming popular. The actual stripping voltammetric measurement consists of two steps in which preconcentration of an analyte at the electrode surface is followed by the so called „stripping” step involving electrode reaction recorded in a form of the voltammetric peak. A representative approach involves reduction of the analyte anions upon application of the sufficiently negative potential to form As(0) on the electrode (e.g. gold) surface; this step is followed by voltammetric oxidation (anodic stripping) of the deposit (to As(III)). In a case of so called cathodic stripping voltammetry, the stationary Hanging Mercury Drop Electrode (HMDE) is often used. During the preconcentration step, an insoluble salt (e.g. Cu3As2) is produced on the electrode surface.

Because sensitivity and detection limit in electroanalytical determinations strongly depend on the current densities measured, there is a need to search for specific catalytic materials that would induce otherwise highly slow and irreversible redox processes of As(III) (oxidation) and, in particular, As(V) (reduction). Our research interests concern development of highly specific catalytic systems leading to the enhancement of the electrooxidation of arsenic (III). We explore here the capability of various noble metals nanoparticles (Pt, Rh, Pd) of inducing the arsenic(III) oxidation in acidic medium. The recorded currents have been compared to those observed previously at the electrodes modified with oxocyanoruthenates, the most potent system for the electrocatalytic oxidation of AsIII(OH)3. Reduction of arsenic (V) is even the more inert reaction. Network films of bimetallic (PtRu) nanoparticles (bare and derivatized) permit preconcentration of arsenic(V) species on their surfaces. The stripping step would allow determination of low concentrations of arsenic (10-6 mol/dm-3 or lower).
Improved Stability and Photoelectrochemical Performance of Cds/1D Zr:Fe2O3 Nanorod Arrays with Al2O3 Passivation Layer for Hydrogen Generation
Authors: Mahadik Mahadeo A , Subramanian Arunprabaharan , Cho Min , Jang Jum Suk
Published: February 2020

CdS sensitized 1D Zr:Fe2O3 nanorod arrays have been synthesized on fluorine-doped tin oxide (FTO) by hydrothermal method. The photoelectrochemical measurement results of CdS/1D Zr:Fe2O3 photoelectrode shows the current density of 4.2 mA.cm-2 at 0 V (vs. Ag/AgCl) which is 2.8 time higher than the bare 1D Zr:Fe2O3. The reduced recombination, and the effective transport of photogenerated holes in CdS facilitates the enhancement in photoelectrochemical performance. Furthermore, the photocurrent and stability of the CdS/Zr:Fe2O3 nanorods was significantly enhanced by Al2O3 layer as compared to bare CdS/Zr:Fe2O3 heterojunction due to its ability to act as an effective hole transport as well as passivation layer. The chemical analyses and nanostructural study of the Al2O3 coated CdS/1D Zr:Fe2O3 photoelectrodes confirms the presence of Al2O3 on surface of CdS and 1D Zr:Fe2O3 nanorods embedded in the CdS flakes. These remarkable enhancements in light energy harvesting, improvement in charge transport and stability directly suggest the usefulness of photoelectrodes for solar hydrogen generation. KEYWORDS: Zr:Fe2O3 nanorod arrays, CdS Sensitizer, Al2O3 passivation layer, Hydrogen generation ACKNOWLEDGMENT: This research was supported by the BK21 plus program, the Korean National Research Foundation (Nano-Material Fundamental Technology Development, 2016M3A7B4909370).
Coral-like Oxide-Derived Cu Decorated Sn for Efficient CO2 Electrochemical Reduction
Authors: Cui Xiaodan , Fang Yuxin , Xu Wangwang , Flake John , Wang Ying
Published: February 2020

Currently, one of the main obstacle for CO2 electrocatalytic reduction is the development of economical and efficient electrocatalysts. Among various electrocatalysts, Sn-based materials are especially appealing due to their low toxic and low cost for large scale use. However, the practical electrolysis of Sn-based electrocatalyst is severely hindered by its low energy efficiency and electrochemical stability. In this work, a coral-like Cu decorated Sn electrocatalyst is prepared by electrochemical reduction of Cu doped SnO2 developed by a facile hydrothermal synthesis process. By introducing subsurface metastable oxide and incorporating Cu into Sn, the binding nature of electrocatalyst is effectively altered. Meanwhile, a well-designed coral-like matrix nanostructure contributes to an improved electrocatalytic activity and stability. With the protection of the matrix, the migration of atoms is constrained to a certain range, which resolves the sintering problem essentially. With ultra-small nanoparticles both spaced and connected by the matrix, facilitated electrolyte diffusion and unimpeded electron transfer are ensured at the same time. Therefore, the study of the coral-like Cu decorated Sn electrocatalyst may path a new way for the practical application in CO2 electrochemical reduction.
Ionic Liquid Based Sensors for Sensitive Detection
Authors: Jain Rajeev
Published: February 2020

Ionic liquids (ILs) may be conveniently described as compounds composed entirely of ions that are liquid at a temperature less than 100ºC. Recently the use of ionic liquids in electrochemical investigations have greatly increased due to their excellent properties such as high viscosity, high thermal stability, wide liquid range, tunable solvent properties, good ionic conductivity and wide electrochemical potential window. ILs are termed as ‘‘Green Solvents’’ as they possess negligible vapor pressure. ILs due to their interesting properties have widely been used for electrode modification purposes. ILs are being extensively employed to modify the surfaces of glassy carbon electrodes, screen printed electrodes, gold electrodes etc. better detaction limits have been obtained with the use of IL-based voltammetric sensors. The advancement in the field of ILs indicates a bright future for their use in research purposes and further development of them to serve the research community.

Keywords:
Ionic Liquid, Voltammetry, Electrochemical detection.
Uniformity and Safety Evaluation of 18650 Lithium Battery Pack By in-Situ Stress-Strain Measurement
Authors: Zhou Shuo
Published: February 2020

The primary challenge in designing a monitoring system for hybrid electric vehicles (HEV) and electric vehicle (EV) is to evaluate safety and uniformity of battery in operating conditions. In this research, strain gauges are adopted to real-time monitor the stress of every commercial Li(Ni1/3Co1/3Mn1/3)O2 lithium ion battery in the battery package under various conditions. This is an efficient experimental technique to determine the uniformity and safety of battery package.

Otherwise, the shell exhibits elastic deformation behaviour, and the strain-stress relationship is established. The reliability of the monitoring tests, along with the relationship among macroscopic mechanical stress, State-of-charge (SOC) and State-of-health (SOH) has been analyzed. The reasons for such stress changes have also been discussed. The uniform level of a commercial battery pack has been evaluated.
Thermal Runaway Analysis of a Lithium Ion Battery Under Two Different Heating Modes
Authors: Wu Tangqin , Wang Qingsong , Chen Haodong , Sun Jinhua
Published: February 2020

Lithium ion battery is widely used in electronic products with the advantages of its high specific energy, high theoretical capacity and long span life. The thermal runaway of lithium ion battery is rare in probability, but the thermal runaway caused fires and explosions always occur with the huge used numbers. It is necessary to find how the thermal runaway developing in a single battery. The thermal runaway processes under external heating mode and internal heating mode were investigated in an extended volume accelerating rate calorimeter (EV-ARC) in this work, respectively. The batteries were charged to 0, 25, 50, 75 and 100% SOC, and then they were put into a 150 °C cavity to simulate the external heat conditions, respectively. The results show that the time to thermal runaway decrease with the SOC increasing. The discharging was used to simulate the internal heat influence on the thermal runaway, and the discharging rates were set from 1 A to 5 A with 1 A interval. The results show that the normal cycle number decreases with the current increasing before the thermal runaway, and the time to thermal runaway is shortened. The thermal runaway always occurs at the end of constant voltage charge stage during internal heat experiments. The experimental results indicate that the SOC plays an important role in the process of thermal runaway. The internal exothermal reactions process of battery during thermal runaway could be summarized as the SEI decomposition, anode reaction consumption of Li, separator melting, reactions between internal materials, and then inner short circuit, followed by temperature rising rapidly.
Plastic Crystal Polymer Electrolytes: A New Material Solution for Safer/Flexible Batteries
Authors: Choi Keun-Ho , Lee Sang-Young
Published: February 2020

On-going surge in demand for high-energy density rechargeable lithium-ion batteries has simultaneously raised serious concerns on safety failures. Such safety issues become more significant for flexible/wearable power sources because mechanical deformation exerted to cells tends to trigger internal short-circuit failures between electrodes, resulting in cell fire or explosion. From the battery materials point of view, conventional carbonate-based liquid electrolytes are considered a major cause to provoke the cell safety problems. To address this issue, solid-state electrolytes have been extensively investigated as an alternative to liquid electrolytes. Here, we demonstrate a new class of nonflammable plastic crystal polymer electrolytes (PCPEs) with well-balanced electrochemical properties and mechanical deformability as a new material strategy. The plastic crystal electrolytes (PCEs), which are composed of lithium salts and plastic crystals bearing good solvation capability, are characterized with unusual thermal stability and ionic transport behaviors. Succinonitrile (SN, NC-CH2-CH2-CN) is a representative organic matrix showing plastic crystal behavior with a plastic crystalline phase in temperature range between around - 40 (a transition temperature from crystalline to plastic crystalline phase) to 60 oC (from plastic crystalline phase to melted state). A distinct feature of the PCEs is superior thermal stability (negligibly volatile up to 150 oC) and nonflammability. Intrigued by this exceptional thermal characteristic, we develop PCPEs comprising PCEs and polymer matrices. Depending on final applications, a variety of polymers are combined with PCEs, including ultraviolet (UV)-cured polyacrylates, semi-interpenetrating networks (IPNs), and porous nonwoven skeleton. In-depth structural/physicochemical characterization of the PCPEs is conducted and discussed in terms of molecular interaction (and phase separation) between PCEs and polymers. Based on this material understanding, potential application of the PCPEs as a new solid-state electrolyte for safer/flexible lithium-ion batteries is explored by investigating their cell performance, safety, and flexibility. Moreover, in order to ensure wider application versatility of the PCPEs, the electrochemical performance of the cells assembled with the PCPEs are quantitatively examined under harsh operating conditions such as physically deformed state (e.g., wrinkled form), high temperature, and high current densities. The PCPEs presented herein hold great promise as a promising solid-state electrolyte with outstanding thermal tolerance, mechanical deformability, and electrochemical performance which lie far beyond those accessible with conventional liquid electrolytes. (Insert Figure 1.png)

Figure 1. A schematic illustration of UV curing-assisted fabrication process and chemical structure of the PCPE, along with a photograph showing mechanical flexibility of a lithium-ion cell containing the PCPE.

Figure 1
(Invited) Ultrasonic Spray Coating of Electrochromic Nanomaterials
Authors: Maho Anthony , Manceriu Laura , Colson Pierre , Henrist Catherine , Vertruyen Bénédicte , Cloots Rudi
Published: February 2020

Ultrasonic spray deposition is a promising and versatile method for both fundamental and industrial researches and applications. It leads to the formation of uniform thin films on large area substrates at atmospheric pressure, with a fine control of the resulting morphology and thickness by adjustment of the practical spray conditions (substrate temperature, nozzle-to-substrate distance, deposition pattern, solution flow rate, carrier gas nature and pressure…). The ultrasonic atomization of the injected precursor solution/suspension is also particularly advantageous as it reduces overspray and energy consumption [1-2].

In our recent works [3-7], we are considering the spray deposition of thin films of electrochromic oxides such as WO3and NiO, which are exploited as nanomaterials for various optical-related devices, notably “smart windows” for energy-efficient fenestration in glass buildings [8-9]. A specific attention is thus paid to the composition of the sprayed solution/suspension (precursor type and concentration, solvent…) as it has a significant influence on film deposition mechanisms and properties. Substrate nature (morphology, crystallinity, conductivity…) is of particular importance too, and different types of transparent conductive oxide (TCO) coated glass are therefore investigated. Incorporation of selected surfactants is also acknowledged for influencing wettability, nucleation and growth processes, and resulting functionality. Consequent characterizations analyze crystallinity, microstructure and porosity, ionic reversibility and diffusion, cycling response, optical modulation, coloration/bleaching kinetics, tint and haze.

References

[1] P.S. Patil, Materials Chemistry and Physics 59 (1999) 185-198.

[2] J.H. Bang, K.S. Suslick, Advanced Materials 22 (2010) 1039-1059.

[3] J. Denayer, P. Aubry, G. Bister, G. Spronck, P. Colson, B. Vertruyen, V. Lardot, F. Cambier, C. Henrist, R. Cloots, Solar Energy Materials and Solar Cells 130 (2014) 623-628.

[4] J. Denayer, G. Bister, P. Simonis, P. Colson, A. Maho, P. Aubry, B. Vertruyen, C. Henrist, V. Lardot, F. Cambier, R. Cloots, Applied Surface Science 321 (2014) 61-69.

[5] D. Chatzikyriakou, A. Maho, C. Henrist, R. Cloots, Microporous and Mesoporous Materials 240 (2017) 31-38.

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From Capacitance-Controlled to Diffusion-Controlled Electrochromism in Nb-Doped TiO2 Nanocrystalline Electrodes
Authors: Barawi Mariam , Da Silva Rafael , Giannuzzi Roberto , De Trizio Luca , Manna Liberato , Manca Michele
Published: February 2020

A reliable exploitation of localized surface plasmon resonance in transparent conductive oxides is being prospected to push the blooming of a new class of advanced dynamic windows, which offer the unique opportunity to selectively, and dynamically, control the intensity of the incoming thermal radiation without affecting the transparency in the visible range. In this view, Nb-doped TiO2 colloidal nanocrystals are particularly promising as they have a wide bandgap and their plasmonic features can be largely modulated across the near infrared region, by varying the concentration of dopants. Four batches of Nb-doped TiO2 nanocrystals with different doping levels (from 0% to 15% of niobium content) have been used here to produce highly transparent mesoporous electrodes for near-infrared selective electrochromic devices, capable of dynamically modulating the intensity of the transmitted radiation upon the application of a relatively small bias voltage. An engineered dual-band electrochromic device (made of 10%_Nb-doped TiO2 nanocrystals) has been eventually fabricated. Such device was shown to provide two complementary spectroelectrochemical responses, which can be independently controlled through the intensity of the applied potential: a large modulation of the optical transmittance in the near infrared region -via the intensification of the LSPR scattering- is achievable in the 0-3V voltage window, reaching values greater than 64% in the spectral range from 800 to 2000 nm, whereas the visible absorption can be also intensively varied at higher potentials (from 3V to 4V), driven by the consistent Li intercalation into TiO2 anatase lattice
Active Layer Thickness Dependent Electro-Optical and -Chemical Propertiesof Inorganic All-Solid-State Electrochromicdevices:WO3/Ta2O5H+/NiO
Authors: Guo JunJi , Diao Xungang
Published: February 2020

Effects of active layer thickness on the performances of inorganic all-solid-state electrochromic(EC) devices WO3/Ta2O5(H+)/NiO prepared by DC magnetron sputtering are investigated. Beer-Lambert law is used to predict the maximum optical contrast (~76%, significantly higher than previously reported) and the corresponding thickness(~260 nm) of the cathodic(WO3) EC layer. Studies by cyclic voltammetry suggest that the optimum thickness of the anodic(NiO) EC layer should be confined close to 140 nm, in order to maintain charge balance within the devices. Furthermore, the optical switching behaviors for the devices with 100-nm-thick electrolyte[Ta2O5(H+)] layer are demonstrated to be qualitatively and quantitatively different from those with 700-nm-thick electrolyte layer, though all of them are sensitively dependent on the number of protons in the devices. Besides, the work principle scheme of the proton−based solid−state EC device was illustrated for the

first time. The obtained results could enlighten mechanistic understanding, and enable rational design for EC device with outstanding EC performances.
Hydrothermal Growth of Hierarchical NiO Nanostructures and Their Application in a Complemetary Electrochromic Device
Authors: Ma Dongyun , Wang Hongzhi , Wang Jinmin
Published: February 2020

NiO is one of the most popular electrochromic (EC) materials due to its high EC efficiency, good cyclic reversibility and low material cost. As an anodic EC material, NiO can be used as a complementary electrode with WO3, where the optical modulation increases due to the simultaneous modulation of both electrodes. We have demonstrated that porous NiO nanostructures film can be grown directly on FTO-coated glass substrates using a template-free hydrothermal technique. A variety of NiO nanostructures, including nanoflake array, nanorod-based networks, hexagonal nanoplates and hierarchical microflakes, could be obtained by tuning the composition of the precursor solution.

Among the obtained NiO nanostructures, hierarchical structure holds the advantages of both nanometre-sized building blocks and microsized assemblies. Thus, the complementary EC device based hierarchical NiO microflake and self-weaving WO3 nanoflake film shows a high optical modulation (73.2% at 550 nm), large coloration efficiency (146.9 cm2 C-1 at 550 nm) and fast switching responses with a coloring time of 1.8 s and a bleaching time of 3.2 s, making it attractive for practical applications.
Electrical Studies on the ZnO/SiNWs P-N Junction Prepared from Si Nanowires Grown By Electroless Etching
Authors: Velez Victor H. , Sundaram Kalpathy B
Published: February 2020

Zinc Oxide (ZnO) is a well-known prospective candidate for impurity doping specially when doped with group III elements due to improvements in properties of the films. The promising properties of zinc oxide such as good thermal stability, lower resistivity, nontoxicity, wide band gap (about 3.3 eV), and high conductivity make it an attractive candidate for many applications [1]. In particular, thin films of silicon doped ZnO have shown great interest in researchers to develop applications including transparent conductive oxide (TCO) properties with significant drop in resistivity values [2]. Furthermore, the low processing cost, natural abundance and the larger exciton binding energy of ZnO (60 meV) enable this material for luminescent and photovoltaic applications [3, 4].

In this study, we propose a new model of cost effective and high efficiency p-n junction based on Si nanowires (SiNWs) and ZnO with potential applications in solar energy. The ZnO grown on SiNWs may work as an active n-layer as well as antireflection coating improving reflectance obtained before, as shown in [5].
The Improved Photocatalytic Ability for Ag3PO4 through the Use of a PEDOT:PSS Layer
Authors: Syue Ming-Tong , Ting Jyh-Ming
Published: February 2020

We report in this study the improved photocatalytic ability and the photo-corrsion resistance of Ag3PO4. We have used PEDOT:PSS as an protective layer to create Ag3PO4/PEDOT:PSS nanocomposite photocatalyst. Ag(NH3)2
+ and Na2HPO4 were used as the precursor to synthesize Ag3PO4. Precursor concentration and ratio were varied. A chemisorption method was then used to make Ag3PO4/PEDOT:PSS nanocomposites. Nanocomposites having different ratios Ag3PO4/PEDOT:PSS were prepared and investigated. Moreover, Triton-X was used as an additive for further enhancing the conductivity and catalytic power of the Ag3PO4/PEDOT:PSS nanocomposite. Methylene blue was used to study the photodegradation performance of the obtained photocatalyst. The photodegradation performance of such a novel nanocomposite is demonstrated.
Carbon Nitride/TiO2 Nanocomposite in Treatment of Water Contaminated with Phenol
Authors: Al-Kandari Halema Ali , Abdullah Aboubakr Moustafa , Al-Kandari Shekhah Ali , Mohamed Ahmed meslam
Published: February 2020

A nanocomposites (CNTi) of carbon nitride (CN) and TiO2 nanoparticles (Ti) of different mass ratios were prepared by a hydrothermal treatment method and characterized using X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), UV-Vis diffuse reflectance spectroscopy (DRS) and Transmission Electron Spectroscopy (TEM). UV-Vis diffuse spectrum showed that the CNTi composites exhibited absorption in the visible light range. The kinetics of the phenol degradation using the as-prepared nanocomposite photocatalyst compared to the bare TiO2 nanoparticles was tested using Xenon lamps (mainly a visible light source) as a photoexcitation source in presence and absence of H2O2 and/or O3. The photodegradation of phenol was evaluated using UV spectrophotometer and total organic carbon (TOC). It was revealed that the photocatalytic activity of the CNTi composites significantly higher than TiO2 nanoparticles. Furthermore, 0.1CNTi composite showed the best phenol degradation when H2O2 and O3 were simultaneously used in which the degradation percentage of phenol was more than 90% within 30 min. Table 1 shows Rate constant, rate coefficient, degradation % (%D) and degradation % from TOC of TiO2, 0.1CNTi, 0.5CNTi, I CNTi in presence and absence of H2O2, 0.1CNTi with O3 and 0.1CNTi with both H2O2 and O3

parameter

Catalyst

TiO2

0.1% CNTi

0.5CNTi

1CNTi

0.1CNTi

+ O3

0.1CNTi

+ H2O2 + O3

-
+
H2O2

-
+ H2O2

-
+ H2O2

-
+
H2O2

r

0.021
0.030
0.032
0.056
0.030
0.051
0.023
0.043
0.038
0.080

R2

0.99
0.99
1.00
1.00
0.99
1.00
1.00
1.00
0.99
0.99

% D

49.1
61.3
62.6
81.2
60.7
77.8
49.7
72.9
69.1
91.4

TOC

54.4
72.8
63.1
81.3
59.9
78.0
49.9
73.0
71.08
92.1

Table 1: Rate constant, rate coefficient, degradation % (%D) and degradation % from TOC of TiO2, 0.1CNTi, 0.5CNTi, I CNTi in presence and absence of H2O2, 0.1CNTi with O3 and 0.1CNTi with both H2O2 and O3