bluuebunny/crossref_metadata_2025 huggingface dataset:
Hard Carbon with Intensified Graphitization Induced By Graphene Oxide for High Initial Coulombic Efficiency Anode in Sodium Storage
Authors: Zhang Wenfeng , Zhang Huimin , Xiang Yu , Zhang Hao , Cao Gaoping
Published: May 2020

Hard carbons hold the most promising practical application among all anode materials for sodium-ion batteries. However, the low initial Coulombic efficiency (ICE) limits their further commercialization. Herein, one kind of hard carbon with Intensified graphitization induced by graphene oxide was prepared by a new coupled carbonization strategy, in which the mixture of phenolic resin (PF) and grapheme oxide (GO) was heat-treated at high temperature directly. The as-prepared hard carbon exhibited outstanding electrochemical behaviors such as superior ICE. We also believe that the strategy may provide a constructive instruction for high performance hard carbon material designing.

For synthesis of hard carbon (GHCs), GO aqueous suspension was first prepared via a modified Hummer’s method. Then PF was dissolved in the GO aqueous suspension (mass ratio of PF:GO was 50:1 to 200:1). The slurry was cured and dried at 120 °C, and further carbonized above 1000 °C.

With increasing mass ratios of GO to PF, the interlayer distance of carbon decreased from 3.88 Å to 3.70 Å, less than 3.93 Å of pure PF, suggesting that the addition of graphene oxide may enhance the graphitization of PF derived carbon. La and Lc of GHCs also increased accordingly with the increasing of GO proportion, indicating the development of graphitic microcrystallite. C1s X-ray photoelectron spectra showed that, the sp2 C content of GHCs increased from 48.4% to 54.5%, which was several time larger than the pure contribution from physical addition of graphene theoretically (from 0.5% to 2%, corresponding to the mass ratio of PF:GO from 200:1 to 50:1 ). From HRTEM and SAED images, a signiﬁcant improvement of short-range ordering degree can be clearly detected with the increasing of GO content. Those results were so consistent, indicating that GO gives an effcient induced local graphitization in hard carbon.

The sodium storage performances of GHCs were characterized in a half cells with metal Na as the counter electrode, using 1.0 M NaPF6 in ethylene carbonate /dimethyl carbonate (1/1 in volume) as the electrolyte. As-prepared hard carbon delivered a superior ICE over 90%, high reversible capacity of 343 mAh/g and excellent cycling performance beyond 150 cycles with a capacity retention over 90%. This may be due to the characteristics of GHCs with less defective and lower surface area , especially with the Intensified local graphitization induced by graphene oxide.

Figure 1
High Capacity Retention of Batteries Using Scalable Micro-Structured Silicon-Polymer Composite As Anode
Authors: Niu Junjie
Published: May 2020

The emerging demands in large energy storage for portable electronic devices and transportations are attracting more interest in developing next-generation lithium-ion batteries (LIBs) with a series of new electrode materials, thus achieving a 3-5 times higher capacity to meet a strategic perspective energy-density of 500 Wh/kg or higher. Silicon, with a theoretical capacity up to 4000 mAh/g, is considered as one of the promising anodes to achieve this goal. The industry R&D in Si-leaded anodes is widespread, and the release of commercial products for portable electronics seems imminent, although simultaneous achievement of high capacity and sufficient calendar life for automotive applications remains to be demonstrated due to a 360% volume expansion of silicon. The current ratio of silicon in graphite anode is less than 10%, which largely limits the overall energy density. The degraded battery performance and complex synthesis process of various nano-structured configurations pose challenges on mass production industry.

Here we present the improved battery performance using micro-sized silicon skeleton caged by polymer as anode, which was synthesized via a facile wet-chemical strategy (
ACS Nano
, 13 (2019), 12032-12041). The industry available, micro-sized AlSi alloy was used as precursor, which ensures a scalable production with low cost. The hollow skeleton configuration provides sufficient spaces to accommodate the drastic volume expansion/shrinkage upon charging/discharging while the minimum amount of conductive polymer serves as a protective layer and fast channel for Li+/e- transport. The battery with the micro-silicon cage as anode displays an excellent capacity retention upon long cycling at high charge/discharge rates and high material loadings. The areal capacity of as high as >6.0 mAh/cm2 was obtained, which suffices a high battery energy density in powering large devices such as electric vehicles (EVs).
Graphite Edge Effects and Doping Implications on Lithium Intercalation for Graphite Anodes
Authors: Peng Chao , Kramer Denis
Published: May 2020

The interface between graphite material and electrolyte plays a crucial role for lithium (Li) intercalation and has significant impact on the charging/discharging performance of Lithium-Ion Batteries (LIBs). However, atomistic understanding of interface effects that would allow the interface to be rationally tuned is largely missed. Therefore, in this work, we comprehensively study the thermodynamics and kinetics of Li intercalation near the main non-basal surfaces of graphite, namely the armchair and zigzag edges. Both types of edge sites show a stronger adsorption for Li than in the bulk of graphite. Therefore, lithiation of these sites would proceed at higher voltage than in the bulk. Furthermore, this effect is significantly more pronounced at the zigzag edge compared to the armchair edge due to its unique electronic structure. The “peculiar” topologically stabilized electronic surface state found at zigzag edges strongly interacts with Li; thereby changing Li diffusion behavior at the surface as well. Finally, boron (B)/nitrogen (N) doping was identified as a promising strategy to tune the Li intercalation behaviors at both edge systems, which might give some guidance for the modification of graphite anodes with a view enhance intercalation kinetics.
Alloying with Ge and Hollowing Reduces Lithiation-Induced Stresses in Si Nanopillar Anodes
Authors: Pala Raj Ganesh , Bansal Abhishek , Bhandari Arihant , Chakraborty Pirtam , Bhattacharya Jishnu
Published: May 2020

High energy-density batteries are crucial to energy storage solutions. In Lithium Ion Batteries (LIB), Si nanopillars are promising anodes due to their highest theoretical specific capacity. However, volume expansion and fracture during cycling inhibit its widespread adaptation. Ge, which is isomorphic with Si, shows better fracture resistance and higher cycle life but has higher molecular weight and cost. Alloying Si with Ge offers a trade-off in optimizing stresses, weight and cost. Here, we computationally evaluate the effect of alloying Si with Ge in reducing stresses generated during lithiation. Hollowing, which creates additional free surface for expansion is also considered. First, we model the stress evolution in nanopillars of Si, Ge, Si-Ge core-shell and Si0.5Ge0.5 alloy. Alloying Si with Ge uniformly, reduces the maximum circumferential stress by around 17%, however, the Si core-Ge shell structure shows stress reduction only when Lithiation is confined only to the Ge. Stresses in Si/Ge alloyed nanotubes considering lithiation from the outer boundary as well as from both boundaries are considered. We find a non-monotonous change in Lithiation stress with varying radius ratio (Rin/Rout) and Rin/Rout=0.4 leads to the least maximum Hoop stress. The stress reduction in Si-nanotubes in such configuration is found to be 16%.
(Invited) Understanding the Graphite Anode Electrode Failure Mode in Cycled Commercial Lithium-Ion Batteries
Authors: Liu Gao
Published: May 2020

The structure degradation of commercial Lithium-ion battery (LIB) graphite anodes was investigated and reported here. The first was to investigate the electrode degradation by examining the PVDF binder degradation after extended cycling. We concluded that the PVDF binder is extremely stable and has no structure degradation after 800 cycles. The graphite materials with different cycling numbers and charge rates was investigated by focused ion beam (FIB) and scanning electron microscopy (SEM). The cross-section image of graphite anode by FIB milling shows that cracks, resulted in the volume expansion of graphite electrode during long-term cycling, were formed in parallel with the current collector. The crack occurs in the bulk of graphite particles near the lithium insertion surface, which might derive from the stress induced during lithiation and de-lithiation cycles. Subsequently, crack takes place along grain boundaries of the polycrystalline graphite, but only in the direction parallel with the current collector. Furthermore, fast charge graphite electrodes are more prone to form cracks since the tensile strength of graphite is more likely to be surpassed at higher charge rates. Therefore, for LIBs long-term or high charge rate applications, the tensile strength of graphite anode should be taken into account.
(Invited) 2D NC-FET, FE-FET and FeS-FET
Authors: Ye Peide D
Published: May 2020

The so-called Boltzmann Tyranny defines the fundamental thermionic limit of the subthreshold slope (SS) of a metal-oxide-semiconductor field-effect transistor (MOSFET) at 60 mV/dec at room temperature and, therefore, precludes the lowering of the supply voltage and the overall power consumption. Adding a ferroelectric dielectric as a negative capacitor to the gate stack of a MOSFET may offer a promising solution to bypassing this fundamental barrier. Meanwhile, two-dimensional (2D) semiconductors, such as atomically thin transition metal dichalcogenides (TMDs) due to their low dielectric constant, and ease of integration in a junctionless transistor topology, offer enhanced electrostatic control of the channel. In this talk, we will review the recent progress on negative capacitance field-effect transistors (NC-FET) and ferroelectric field-effect transistors (Fe-FET) using TMDs as the transistor channels. [1,2] More importantly, a new device concept, which we call as ferroelectric semiconductor field-effect transistor (FeS-FET), was proposed and experimentally demonstrated. [3] In this novel FeS-FET, a 2D ferroelectric semiconductor α-In2Se3 is used to replace conventional semiconductor as channel. α-In2Se3 is identified due to its proper bandgap, room temperature ferroelectricity, the ability to maintain ferroelectricity down to a few atomic layers and the feasibility for large-area growth.

[1] M. Si et al. Nature Nanotechnology 13, 24-28 (2018).

[2] M. Si et al. 2017 IEDM, pp. 573-576 (2017).

[3] M. Si et al. Nature Electronics 2, in press (2019).
Graphitic Nanoporous Carbon Thin Films: Fabrication Method, Structural, Electrical and Gas Sensor Properties
Authors: Slobodian O. M. , Gomeniuk Y. V. , Vasin A. V. , Rusavsky A. V. , Okholin P N , Gudymenko O. Yo. , Khyzhun Oleg Yu , Nikolenko A. , Lytvyn P. , Korchovyy A. , Yatskiv R. , Nazarova Tamara M. , Stepanov V. , Kisyl D. , Nazarov A. N.
Published: May 2020

Carbon nanoporous thin films are very attractive for application in fields of supercapacitors, fuel cells, gas sensors and others. However due to it very high resistance an employment of this material for resistance gas sensor is problematic. At the same time graphene based materials are very sensitive to different gas ambient and have a resistivity suitable for testing. In this work the new method of formation of high porous graphite-like thin films by RF magnetron plasma enhanced chemical vapor deposition (MPECVD) from argon-methane/argon-acetylene gas mixture followed by annealing at 650ºC, is suggested. A comparative study of transformation of nanoporous carbon film produced in different carbon-hydrogen atmosphere into graphitic one, their structural and electrical properties are presented. The films of nanoporous carbon were fabricated on silicon or SiO2/Si wafers. To clarify chemical structure of the film FTIR spectroscopy and XPS were used. Micro-Raman spectroscopy and AFM were applied to determine of structure and surface morphology correspondingly. X-ray refraction (XRR) method allows us to determine a density and a thickness of the films. Four point probe method and transmittance line (TSL) technique were used for the analysis of electrical properties. Additionally, electrical conductivity at different temperature and frequency was examined by measurement of resistance between two nearest Ni contacts. The same contacts were used to estimate of the gas sensitivity.

It was shown that initial deposited films have mainly sp3 C-H bonds without appearance of silicon bonds. AFM demonstrates nanostructured surface morphology with size of the surface fluctuation about 3 nm; a density of the films is about 1.3 g/cm3 for both carbon films, that corresponds to nanoporous carbon; resistivity is about 108 Ohm×cm. After thermal annealing at 650°C for 30 min in N2 atmosphere the sp3 C-H bonds are disappeared, and C=C sp2 bonds are formed. Besides the resistivity the films synthesized in argon-methane gas mixture decreases to 104 Ohm×cm whereas the films synthesized in argon-acetylene gas mixture decreases their resistivity up to 102 Ohm×cm. The density of the C films synthesized in in argon-methane gas mixture reaches about 1.5 g/cm3 that corresponds to 34% of porosity, and material shows layered structure. The density of the C films synthesized in in argon-acetylene gas mixture falls to 1.01 g/cm3 that corresponds to 55% of porosity. Graphitized films synthesized in argon-methane gas mixture appears sensory sensitivity to moisture and ammonia whereas the films synthesized in argon-acetylene gas mixture show low sensitivity to these gases. The nature of the gas sensor resistor sensitivity is discussed.
Interface Chemistry and Charge Transfer Resistances at the Interface of the Nasicon Solid Electrolyte and Oxide Cathode System
Authors: Rahman Anisur , Yildiz Bilge
Published: May 2020

The solid-state lithium-ion battery promises high energy density, safety, and stability over liquid electrolyte-based batteries. Their development and practical implications are mainly hindered due to high resistance at the interface between the ceramic cathode and solid-state electrolyte and lack of understanding of the interfacial chemistry at high temperature, which is required to improve the contact between them. The interface characterization and engineering the interface at the operando conditions is therefore extremely important for the realization of the practical solid-state battery. Despite the recent developments, identification of interfacial compounds at the operando conditions, at different sintering temperature and during charging and discharging, remains elusive due to challenges associated with the investigation of buried interfaces with nondestructive methods.

To address this challenge, we utilized thin film approach, deposited a thin layer of cathode material (LiCoO2 and LiNi0.6Mn0.2Co0.2O2) on top of the solid electrolyte Li1.4Al0.4Ti1.6(PO4)3, and the non-destructive X-ray scattering techniques including XANES, EXAFS, APXPS, and XRD to characterize the interface at the different sintering environment ( Air, O2, CO2, N2, and H2O vapor) and under applied bias. The crystal phase and crystallinity of the cathode material is found to be sensitive to the sintering environment and inter-diffusion of elements at the interface leads to secondary phase formations at the interface. The evolved secondary phases has been characterized by non-destructive X-ray scattering technique and the variation of the charge transfer resistances on the resulting cell could be attributed to the secondary phases of the interface.

We strongly believe the identification of the secondary phases and understand the degradation process at the operando conditions could guide the field to identify suitable process parameters to develop stable and efficient solid-state batteries with good electrochemical properties.
Si and Si@C Nanoparticles for Lithium-Ion Batteries Anodes: Electrode/Electrolyte Interface Evolution
Authors: Desues Antoine , Alper John P , Boismain Florent , Demers Hendrix , Veillette René , Clément Daniel , Zaghib Karim , De Vito Eric , Franger Sylvain , Trudeau Michel , Haon Cédric , Herlin Nathalie
Published: May 2020

Due to increasing demand in energy storage, much attention has been paid to Si as an anode material in Li-Ion batteries because of its theoretical capacity (3579 mAh/g in the Li15Si4 alloy vs 372 mAh/g for graphitic carbon). However, silicon suffers from several drawbacks, including rapid pulverization and SEI ripening, limiting its use. Nanostructuration and protection of silicon with a carbon coating are proven methods to improve the behavior of silicon-based anodes [1]. Using the laser pyrolysis method, the synthesis of silicon-carbon core-shell nanoparticles was achieved in a continuous way, without intermediate manipulations between the synthesis of the core from silane precursor and the shell from ethylene [2].

The influence of the carbon coating on electrochemical performances was studied in coin cells in operando conditions by using electrochemical impedance spectroscopy (EIS) as well as post mortem analysis of the anode by using (X-Ray Photon electron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM)). Special attention was paid to the first cycle because of its major importance in the formation and growth of the SEI and the long term behavior of the battery. By comparing measurements on Si and Si@C materials, EIS clearly demonstrates the beneficial effect of the carbon shell in the SEI stabilization. The stability of the the SEI resistance shows the protective effect of the the carbon shell while the SEI resistance is strongly modified and increases during lithiation. Such behavior can be related to the evolution of the chemical composition determined by XPS at different potentials during lithiation and delithiation.

Figure 1
A Comprehensive Comparison of the Phase Change Material-Based Internal and External Cooling Systems
Authors: Zhao Rui , Liu Jie , Ma Fai
Published: May 2020

Being employed in a wide range of energy storage applications, such as solar energy storage systems and electric vehicles (EVs), lithium-ion batteries (LIBs) have become an important link in the chain of clean energy harvest and delivery and have played a crucial role in low-carbon energy transitions. Thermal management is critical for maintaining the efficiency, safety, and longevity of LIBs due to the exothermic behavior and high temperature sensitivity of LIBs. A desirable thermal management system should be able to help sustain a desired operating temperature range and a small temperature gradient within batteries.

The heat accumulation effect in the center of cylindrical LIBs has been observed and experimentally studied by Shah et al. [1] and Zhang et al. [2]. The insufficient cooling at the battery center can cause temperature nonuniformity and lead to performance degradation of batteries in long-term operation. We have previously reported a phase change material (PCM)-based internal cooling system for alleviating the heat accumulation in 18650-type LIBs [3, 4]. In this presentation, the internal cooling system will be thoroughly compared with an external PCM-based cooling system in terms of their weight and volume added to the entire battery systems, their cooling effectiveness for single batteries of different sizes and radial thermal conductivities, and the necessity of increasing the thermal conductivity of PCM through adding additives.

References:

[1] K. Shah, C. Mckee, D. Chalise, and A. Jain, Energy, 113, 852-860 (2016).

[2] G. Zhang, L. Cao, S. Ge, C. Y. Wang, C. E., Shaffer, and C. D. Rahn, J. Electrochem. Soc., 161, 1499-1507 (2014).

[3] R. Zhao, J. Gu, and J. Liu, Int. J. Energy. Res., 42, 2728-2740 (2018).

[4] R. Zhao, J. Gu, and J. Liu, Energy, 135, 811-822 (2017).

Figure Caption:

Figure 1. Comparison of the measured and simulated temperature profiles of the a) internally and b) externally cooled single cell, where T1, T2, and T3 are the temperatures measured at the battery center, battery surface, and plastic case surface, respectively. The tests were performed in a wind tunnel under natural convection with a convective heat transfer coefficient of 20 W m-2 K-1.

Figure 1
High-Performance 18650 Lithium-Ion Batteries Using Ni-Rich Cathode and Silicon Nanoparticles/MCMB Composites
Authors: Amnuaymucha Nontawan , Duriyasart Farkfun , Sawangphruk Montree
Published: May 2020

Silicon nanoparticles and MCMB (MesoCarbon MicroBeads) materials as well as their composites are used as anode materials of lithium-ion batteries with Ni-rich cathode materials. The particle size and loading content of silicon nanoparticles in the composite are investigated. The cylindrical lithium-ion batteries (18650) were fabricated in the dry room condition with a dew point of -40 °C. The stable structure of carbonaceous materials can alleviate the expansion problem of silicon by supporting silicon nanoparticles on its excellent conductive surface and structure. Therefore, the silicon-MCMB composite is a promising material for use as anode in Li-ion batteries. In this work, the silicon nanoparticles with < 10 nm in diameter exhibit high charge-storage performance. The NCA//Silicon-MCMB shows the first cycle capacity of 2.65 Ah per cell with an energy density of > 250 Wh/kg, an initial columbic efficiency of > 90%.
Evaluation of Skin Cell Damage Under UV Exposure with FET Sensors
Authors: Wu Sung-Yu , Su Chao-Ming , Dong Guo-Chong , Chen Jung-Chih , Chen Po-Hsuan , Wang Shin-Li , Wu Chang-Run , Chiang Chen-Wei , Wang Yu-Lin
Published: May 2020

The cell membrane potential can be reflected by the ionic gradient exchange. It has been shown in many cell detection systems to be involved in exploring cell functions. In this research, we have developed a rapid and highly selective array using Field-Effect-Transistor-based sensor to monitor the real time electrical signal change of cell membranes. High sensitivity, low cost, convenient to use and portability are the advantages of our sensor. There is a layer of gelatin immobilized on the sensing site, afterwards utilizing gelatin to capture cells.

Around the cell membranes surface is covered with many negative charges, and then the negative ones will attract the positive charges to form electrical-double layer (EDL). According to the charge enhancement, the capacitance generated by the cells will be changed as well as. The change of EDL will also induce a change in the overall capacitance of solution which implies that the gate voltage and drain current gain will also be changed.The current gain has been defined as the difference in absolute drain current before and after the applying the gate voltage.

One of the most incredible application of using this novel technology is to detect the cellular conditions. Of note, when the conditions of cells are not good, then the binding of cells and gelatin will be different from the normal ones. From the previous study, binding of cells will cause upward-trend electrical signal. On the other hand, we reasonably speculate there will be a downward-trend occurring during cells suffer from the damage. Many evidences suggest that UV light will directly change or destroy the cytoplasmically located factors, that’s why the biologically fatal dose of Ultraviolet radiation will be used in this experiment because we want to impose the serious damage on the cell membranes and alter the membrane potential of human keratinocyte cells in vitro.

Figure 1
Photonically Encoded Silicone Lenses For Smartphone-Based Microscopy And Imaging In Biology And Nanomedicine
Authors: Mariani Stefano , Robbiano Valentina , Iglio Rossella , La Mattina Antonino A. , Nadimi Pantea , Wang Joanna , Kim Byungji , Kumeria Tushar , Sailor M. J. , Barillaro Giuseppe
Published: May 2020

In this work [1], we describe the moldless preparation of a poly(dimethylsiloxane) (PDMS) lens embedding nanostructured porous silicon (PSi) optical components. Casting of uncured PDMS onto a PSi surface shapes a droplet

with contact angle easily controllable by tuning of the nanostructure features (i.e., thickness and porosity of PSi). Design of the PSi layer as an optical component (e.g., distributed Bragg reflector, rugate filter, resonant cavity) allows the preparation of lightweight, freestanding PDMS lenses (10 mg mass and 4.7 mm focal length) with embedded optical elements. The fabrication process of the PDMS lens shows high reliability (yield >95%), low-cost (0.01 $), and good flexibility for a wide range of applications. For instance, using a single monolithic lens/filter element self-adhered to a commercial smartphone camera, we demonstrate: the fluorescence imaging and counting of live/dead isolated human cancer cells with high magnification and rejection of the excitation light; the selection of a narrow wavelength band from a fluorescent emission; and the tuning of the color of a white light emitting diode (from red to blue) through shaping of the emission spectrum.

[1] S. Mariani et al., Adv. Funct. Mater.2019, 1906836
(Invited) Piezoelectric Biomaterials: From Controlled Growth to New Applications
Authors: Yang Rusen
Published: May 2020

Piezoelectric materials are important for many physical and electronic devices. Although many piezoelectric ceramics exhibit good piezoelectricity, they often show poor compatibility with biological systems that limits their biomedical applications. Piezoelectric peptide and metabolite materials benefit from their intrinsic biocompatibility, degradability and convenient biofunctionalization and are promising candidates for biological and medical applications. Herein, recent advancements to piezoelectric biomaterials like peptide-based micro/nanostructures are provided. Synthetic methods, morphological features, and piezoelectric performance of piezoelectric biomaterials are presented. The effect of growth direction, phase and structure of piezoelectric biomaterials on their piezoelectric activity are discussed. The applications of piezoelectric biomaterials in the field of nanogenerators are provided at the end.
(Invited) Biomimetic Engineering of Polymer Semiconductors and Devices for Interfacing with Biological Systems
Authors: Wang Sihong
Published: May 2020

The vast amount of biological mysteries and biomedical challenges faced by human provide a prominent drive for seamlessly merging electronics with biological living systems (e.g. human bodies) to achieve long-term stable functions. Towards this trend, one of the key requirements for electronics is to possess biomimetic form-factors in various aspects for achieving the long-term biocompatibility. To enable such paradigm-shifting requirements on materials for electronics, polymer semiconductors are the uniquely promising for combining advanced electronic functionalities with biomimetic properties. In this talk, I will introduce our new molecular design and physical processing concepts for polymer semiconductors, which enabled the incorporation of multiple biomimetic properties with advanced electronic functionalities. Fundamental understandings that have been obtained about the structure property relationship on these unprecedented material designs are serving as the foundation for opening up this new research direction for polymer semiconductors. Towards benefiting the targeted application areas of biological studies and biomedical engineering, the incorporated biomimetic properties have also been transformed onto electronic devices that are designed to interface with biological systems.
(Invited) Rational Design of Efficient Bifunctional Electrocatalysts for Rechargeable Zn-Air Batteries
Authors: Sun Shuhui
Published: May 2020

Rechargeable zinc-air batteries (ZABs) have been considered as highly promising alternatives for the next-generation energy storage technologies due to their advantages of high energy density, low cost, high safety, and environmental friendliness. Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the cornerstones of rechargeable ZABs. The exploration and of high-performance, durable and non-precious metal bifunctional oxygen electrocatalysts is highly desired for the large-scale application of rechargeable ZABs.

In this talk, I will introduce our recent progresses on the rational design of a series of high performance bifunctional oxygen electrocatalysts for ZABs. First, we developed various bimetallic and trimetallic nitrides-based nanostructures for high performance bifunctional ORR/OER catalyst in realistic rechargeable ZABs systems. The novel nanostructures exhibit excellent energy density and ultra-long cycling lifetime over 850 cycles (850 h) which are among the best ORR/OER catalysts reported so far. These novel catalysts demonstrate outstanding power density (326 mW cm-2) and excellent charging/discharging performance, far better than those of commercial Pt/C and Ru/Ir-based catalysts. We also employed the in situ XAFS to investigate the origins of the excellent structural stabilities of the bifunctional catalysts.

The utilization of bio-mass waste as valuable materials is of strategic importance to our future. We developed a simple and inexpensive metal-free catalyst by employing the bio-waste reed as the single precursor for both carbon and silicon. This reed waste derived Si-N-C metal-free catalyst exhibits better ORR activity and stability than the Pt/C in alkaline media. Moreover, this Si-N-C catalyst exhibits excellent performance as an air cathode for a Zn-air battery device. DFT calculation indicate that the coexistence of Si and N is essential for the high ORR activity. These new findings will not only open an avenue for the rational design of highly active ORR electrocatalysts, but also symbolize an exciting area for sustainable and low-cost materials for advanced clean energy.

References

1. Wu, G. Zhang, S. Sun, et al. Nano Energy 2019, 61, 86.

2. Wu, G. Zhang, S. Sun, et al. Energy Storage Materials, 2019, j.ensm.2019.08.009.

3. Wu, G. Zhang, S. Sun, et al. Energy Storage Materials, 2019, 21, 253.

4. Yu, Q. Wei, S. Sun, et al. Journal of Power Sources, 2018, 396, 754.

5. Wu, Q. Wei, S. Sun, et al. Advanced Energy Materials, 2018, 1801836.

6. Wei, Y. Fu, G. Zhang, S. Sun. Current Opinion in Electrochemistry, 2017, 4, 45.

7. Qiu, J. Gao, S. Sun, et al. Applied Catalysis B: Environmental, 2019, 118431.

8. Wei, M. Cherif, S. Sun, et al. Nano Energy, 2019, 62, 700.

9. Wei, G. Zhang, S. Sun, et al. J. Mater. Chem. A
, 2018, 6, 4605.[Cover Page]

Figure 1
Nano Energy Generated By Microfluidic Flow
Authors: Hsu Wen-Po , Huang Yi-Chen , Lin Chih-Ting
Published: May 2020

Energy harvesting is one of the most popular and important global issues for years. Through capturing or storing renewable energy, different energy-harvesting methods developed to provide additional power sources. In this work, a method to collect nano-scale energy by microfluidic flow was presented. Transferring microfluidic dynamic energy into electrical energy, we investigated the relationship between the extracted electrical current versus different electrode distances and the pH of an aqueous solution. The device was designed and implemented in a microfluidic channel with a gold-electrode grating. In the experimental testing, the flow rate was 300 μL/min. Based on the experimental results, the extracted output current was proportional to the electrode distance. The longer the distance (from 0.5 to 3 cm) was, the higher the output current (from 0.3 to 0.7 nA) obtained. In addition to the electrode-distance examinations, different aqueous solution with different pH value (from 5 to 10) were also investigated. To adjust the pH value of the solutions, hydrochloric acid (HCl) and sodium hydroxide (NaOH) were employed. In the pH-related experiments, the electrode distance was 3 cm and the flow rate was 300 μL/min. According to the experimental results, we can extract more electrical current (about 0.5 ~ 1.0 nA) with higher pH solution. In summary, this work demonstrated a potential method for energy harvesting. It could be used in different aqueous environment (ex. rain, river, marine etc.) or running water to generate current autonomously. This could be further integrated with applications of environmental monitoring.
(Invited) Phonon Engineering in Thermoelectric Materials and Flexible Thermoelectric Devices for Body Heat Harvesting and Personal Thermoregulation
Authors: Kim Woochul
Published: May 2020

In the first part of the talk, our efforts on phonon engineering for thermoelectric application will be delivered. We are going to present our recent work on SnTe exhibiting zT ~ 1.9 at 929 K. The main reason for such reduction was also for the thermal conductivity reduction. The SnTe grains were coated with nanosized CdTe which is very efficient to coherently scatter phonons. In the second part, we demonstrate that conventional inorganic materials can be used in wearable systems despite their bulky and rigid nature. Here, we present two different device architecture for wearable application, i.e., body heat harvesting and personal thermoregulation. In particular, we proposed a bracelet-like modular design of a thermoelectric (TE) module with a heat sink made of rigid inorganic bulk materials for body heat harvesting. When the device is worn on the wrist, it generates an output power of 6.97 μW/cm2 while the subject is walking. To operate wearable sensors, the flexible thermoelectric device is integrated with batteries for stable power generation and energy storage. Near field communication (NFC) was used to communicate or translate data from the sensor operated by the flexible thermoelectric device based on the body heat harvesting. For personal thermoregulation, we propose a mat-like flexible thermoelectric system (FTES) based on rigid inorganic bulk materials. For thermoregulation, using portable batteries as power sources, the refrigerated skin temperature was lowered by several degrees which is adequate for humans to perceive coldness, according to theoretical analysis. These show potential for wearable refrigeration and body heat harvesting.
Novel Data Science Driven Chemical and Biological Agent Sensors: Towards Better Discrimination in Complex Environments
Authors: Uzarski Joshua R , Wiederoder Michael S , Luckhardt Clark , Weiss Matthew L. , Paffenroth Randy , Su Ruitao , McAlpine Michael C.
Published: May 2020

Chemical and biological agents remain a persistent threat to both Warfighters and civilian personnel in both combat and non-combat environments. While many useful detection technologies exist to provide early warning, many of them suffer from similar drawbacks. Most common are unacceptable false positive response rates and inability to discriminate target analytes in complex or obscurant-laden environments. A typical approach to this problem is to develop material solutions for more specific and sensitive sensors. While useful, these solutions are often too expensive, not practical, or non-deployable. Our approach fuses both material and data science to extend the power of multiplexed sensor arrays towards more accurate and faster detection and discrimination.

This presentation will discuss our approach towards both vapor and liquid analytes using two different multiplex array systems. For vapor phase detection, sorptive and conductive graphene-based nanocomposite films are used for semi-selective affinity towards chemical agent simulants in binary mixtures with common obscurants. For the liquid phase, graphene arrays functionalized with antimicrobial peptides are encapsulated with a 3D printed self-supporting microfluidic cell, creating a multiplexed sensing platform for electrochemical detection towards the discrimination of bacterial species and strains. For both systems, response data are pre-processed using a novel algorithm called the Autoencoder Kalman Filter and the entire response dataset is used to train neural networks for analyte discrimination. Robust machine learning is enabled via response curve simulations, providing more accurate response training. Ultimately, both more accurate and faster responses are provided, leading to much lower false positive rates and quicker decision times. Using our approach, we first show that the chemical agent vapor simulant, dimethyl methylphosphonate (DMMP) can be identified from a mixture with JP8/kerosene, a common battle field contaminant. Next, we show that bacteria samples of the same species but different strains can be identified in complex media.
(Invited) Chimeric and Single-Site Mutant Enzymes for the Design of Nanostructured Bioelectrodes in Enzymatic Fuel Cells and Sensors
Authors: Le Goff Alan
Published: May 2020

Control over redox enzyme immobilization and electrical interfacing at electrode is a major challenge when building an electrode for enzymatic sensor or fuel cell. An adequate environment has to be created in order to maximize the number of active enzymes and minimize electron transfer distances between enzyme active sites and conductive surfaces or redox partners. In this respect, the production of specific mutants is a powerful way to introduce a level of control over orientation and organization of redox enzymes at the electrode. In addition, the combination of these enzymes with nanomaterials is aimed at maximizing the number of wired enzymes per surface unit while also providing rapid electron transfer pathways and enhancing electrocatalytic current densities.1 A chimeric protein can be designed by combining a prion domain and a small iron-sulfur redox protein such as rubredoxin.2 Thanks to the ability of the prion domain to self-assemble in amyloid fibers, protein-only redox nanowires can be produced. These protein nanowires are able to entrap redox enzymes such as multicopper enzymes or [NiFe] hydrogenases, while ensuring interprotein electron transport between enzyme active sites and electrode surface.2,3 Chimeric laccases was also designed by combining this multicopper enzyme with a hydrophobin domain. In this case, hydrophobin strongly interacts with the pi-extended network of chemically-exfoliated graphene or carbon nanotubes. These biofunctionalized nanomaterials were used in electrochemical sensors for polyaromatic and phenolic compounds.4 Single-site mutation at the surface of enzymes is also a powerful means to control the immobilization and orientation of enzymes at the surface of nanostructured electrodes. We have especially investigated the covalent and non-covalent functionalization of single-site mutant laccases for the rational immobilization and direct wiring of the enzymes at the surface of carbon nanotubes and gold nanoparticles. 5 These nanomaterials are able to provide novel self-assembled nanostructured redox bioassembly or favor heterogeneous electron transfer to the enzyme by promoting specific orientations.

1 A. Le Goff and M. Holzinger, Sustainable Energy Fuels, 2018, 2, 2555–2566.

2 L. Altamura, C. Horvath, S. Rengaraj, A. Rongier, K. Elouarzaki, C. Gondran, A. L. B. Maçon, C. Vendrely, V. Bouchiat, M. Fontecave, D. Mariolle, P. Rannou, A. Le Goff, N. Duraffourg, M. Holzinger and V. Forge, Nat Chem, 2017, 9, 157–163.

3 S. Rengaraj, R. Haddad, E. Lojou, N. Duraffourg, M. Holzinger, A. Le Goff and V. Forge, Angew. Chem. Int. Ed., 2017, 56, 7774–7778.

4 I. Sorrentino, I. Stanzione, Y. Nedellec, A. Piscitelli, P. Giardina and A. Le Goff, submitted.

5 N. Lalaoui, P. Rousselot-Pailley, V. Robert, Y. Mekmouche, R. Villalonga, M. Holzinger, S. Cosnier, T. Tron and A. Le Goff, ACS Catal., 2016, 6, 1894–1900.
Arraying of Two Modified Sensors By Controlled Growth of Co-Cu and Functionalized Carbon Nanotube for Highly Sensitive and Selective Non-Enzymatic Sensing of Glucose in Sweat
Authors: Eslami Reza , Azizi Nahid , Ghaffarian Reza , Zarrin Hadis
Published: May 2020

Due to a relation between glucose in sweat and blood, there is an opportunity to monitor the glucose level of patients non-invasively through sweat. There is a high demand for developing highly selective and sensitive biosensors in order to sense biomarkers like glucose and therefore the diseases based on those biomarkers. However enzymatic sensors are selective to specific biomarkers, they are suffering from high sensitivity to the fluctuation of temperature, oxygen, pH, humidity, detergents, organic reagents and toxic chemicals which subsequently affect their stability, sensitivity, and reproducibility. Therefore, developing non-enzymatic sensors have gotten more attention recently due to their stability against those parameters. But these non-enzymatic sensors are almost non-selective toward just one contaminant. Here we proposed a combination of two sensors that can help us to improve the selectivity of these non-enzymatic sensors. Two electrochemical arrayed sensor has been developed. The first electrochemical sensor has been achieved by controlled growth of cobalt nanowire and copper nanoparticles on carbon substrate in order to measure the glucose level at low concentrations and the second electrochemical sensor has been modified by MWCNT- CO-NH-cyanuric-NH2 in order to measure the uric acid and eliminate the interference of it in glucose measurement results. In order to show the morphology of the glucose sensor, the SEM and EDX have been conducted. Also, the FT-IR test has been shown to confirm the functionalization of MWCNT. The electrocatalytic and electrochemical performance of each sensor has been evaluated in the presence of the various contaminants of sweat. The glucose sensor showed the limit of detection (LOD) of 25 μM of glucose and less than 15% interference by ascorbic acid, sodium bicarbonate, lactic acid at the max range of contaminants in the sweat. For eliminating the interference of uric acid, the second sensor has developed which has no response to the glucose and high sensitivity to the uric acid. The calibration curve of each sensor has been provided and a simple method of arraying has been applied to improve the selectivity of the sensors. At the end, the sweat of a male and a female have been collected continuously over 8hours to compare the glucose level of sweat monitored by the sensors and the blood monitored with the commercial glucometer in the same period of time.
DNA-Based Electrochemical Biosensor for Microrna-155 Detection By Exonuclease III -Aided Cascade Target Recycling
Authors: Yang Xiao , Feng Ming hui , Zhang Fei fei , Wang Zong hua
Published: May 2020

MicroRNAs (miRNAs) are important biomarkers for early diagnosis and prognosis of genetic diseases including human cancers and neurological diseases, etc. They are a class of small (about 22 nucleotides) single-stranded non-protein-encoding RNAs, whose abnormal expressions are closely related to the pathogenesis of many malignant tumors. However, they have intrinsic characteristics such as low abundance, short length and sequence homology, so accurate and rapid analysis of miRNAs is of great significance for biological research, diagnosis and treatment of diseases. In this study, based on exonuclease III (Exo III) -aided cascade target recycling, a simple and sensitive electrochemical biosensor is developed for miRNA-155 detection, which is of an important biomarker for the diagnosis of breast cancer. At the same time, Ti3C2 MXene was synthesized and used as a support due to its special layered structure and metallic property. Noble metal nanoparticles were used to enlarge the electro-active surface area and facilitate the electron mobility of electrochemical biosensors. Moreover, MXene nanosheets embedded with noble metal nanoparticles (such as Au NPs, Ag NPs, Pt NPs) could totally ensure MXene nanosheets with improved conductivity and enhanced electrochemical properties. Therefor AuNPs/Ti3C2 MXene three-dimensional composite was selected as substrate for immobilizing capture DNA (cDNA) by Au-S chemical bonds. The whole sensing system is named as cDNA/AuNPs/ Ti3C2 Mxene /Au E. The cDNA was modified with methylene blue (MB) at the end of 3', resulting in a large initial electrochemical signal. In the presence of miRNA-155, Exo III cleaved the 3' end of the cDNA in the double strands, caused the electrochemical signal molecule MB to be released from the electrode surface, thereby reduced the electrochemical signal. The concentrations of miRNA-155 could be monitored simply and effectively by measuring the peak current difference of MB redox (ΔI=Ic﹣Ih, Ic represents the DPV peak current value obtained in the absence of miRNA-155, Ih represents the peak current value recorded in the presence of miRNA-155, and ΔI represents the change in peak current value). Under the optimal experimental conditions, the electrochemical sensor achieved a detection limit of 0.35 fM (S/N =3) with a linear range from 1.00 fM to 100 pM. This method also shows desirable stability, reproducibility and specificity. In conclusion, with its excellent analytical performance, the biosensor may have the potential to be used in the clinical diagnosis of breast cancer.

Keywords: Exonuclease III; miRNA-155; Au NPs; Ti3C2 Mxene; Electrochemical biosensor;

Figure 1
Oxide Coated Nano-Porous Ag Thin Film for Chemical Sensing By Gas Flow Sputtering
Authors: Hwang Sehoon , Park Young Min , Kim Hyun-Jong , Son Seong Ho , Yun Sungho , Lee Ho-Nyun
Published: May 2020

A completely non-destructive analytical method is one of the great advantages of Raman spectroscopy. However, low efficiency of Raman signals should be improved to be widely used for detecting less than ppm of chemicals. Surface enhanced Raman scattering (SERS), which is a valuable technique for detecting the target substance very sensitively, is a method of amplifying Raman signals by the plasmon coupling effect at the gap between the nanoparticles. For this reason, materials and the nano-structure such as particle size, shape, gap and density were major factors for determining the performance of the SERS substrate.

In this study, gas flow sputtering (GFS) was used for fabricating SERS substrates. The nano-porous structure was observed using scanning electron microscope (SEM) and crystal structures were also analyzed by X-ray diffraction (XRD). The density of the nano-porous structure was calculated using the thickness of the film and the mass difference before and after deposition.

Silver (Ag) was widely studied as SERS substrate, due to excellent SERS effect and lower price than that of other noble metals. However, Ag has a significant degradation in SERS effect with time which appears to be a problem caused by oxidation of the Ag surface. Owing to this problem, fabricating a highly reproducible SERS substrate is a challenging issue and many researchers are conducting study.

To solve this problem, Ag dense film and oxide film were sequentially deposited. Then, Ag nano-porous thin film was deposited on the oxide film to form a dielectric nano-gap between Ag dense film and Ag nano-porous thin film. Also, to protect from oxidation, Ag nano-porous thin film was coated with a thin oxide film using in-situ co-sputtering. The structure of nano-porous thin film was controlled by varying the sputtering power, time, process pressure.

As a result, rhodamine 6G of less than 0.5 uM was successfully detected and it showed much improved Raman signal compared with single Ag nano-porous thin film. In addition, the aging problem, which was the most important issue, also reduced noticeably.