bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystallization and Wear Behavior of SiO2-Al2O3-ZrO2-Ba(Sr, Ca)O Glass-Ceramics Added with Cr2O3 By Different Methods
Authors: Feng Min , Chen Minghui , Wang Fuhui
Published: December 2020

The merits of glass-ceramics are mainly derived from the refractory crystallites, but controlling crystallization of glass is a complicated process. Although substantial work was conducted on crystallization and its effect on mechanical and thermal properties of glass-ceramics, few were available on the effect of crystallization on friction. In the current work, Cr2O3 was incorporated into a, BaO-rich, SiO2-Al2O3-ZrO2-Ba(Sr, Ca)O based glass system through two methods: (1) melted into the glass; (2) added as foreign ceramic crystallites. After heat treated at high temperature, it transformed to glass-ceramics. Then crystallization and its influence on friction of the glass-ceramics were carefully studied.

The results showed that, on annealing at 1173 K, SiO2 and acicular BaSi2O5 crystallites were precipitated out from the silicate glass-ceramics which thereafter possessed high friction coefficient and wear rate. Adding Cr2O3 retarded the precipitation of BaSi2O5 and decreased wear resistance. But this retardation effect varied with the way that Cr2O3 was added. When Cr2O3 was added by ball milling, precipitation of BaSi2O5 was only partly retarded, and wear rate was decreased marginally. However, adding Cr2O3 during the smelting process, the precipitation of BaSi2O5 was almost fully prohibited, and BaCrO4 and/or BaCr2O4 substituting BaSi2O5 precipitated out. The nanoscale barium chromates promoted the formation at worn surfaces of a lubricating glaze layer that decreased largely the wear rate and friction coefficient.

Figure 1
Silicone Oil-Impregnated Nanoporous Oxide Layer of Metals for Anti-Corrosion
Authors: Lee Junghoon , Kim Donghyun , Joo Jaehoon , Kim Kwonhoo
Published: December 2020

Hydrophobizing coating and oil-impregnation have been considered as a promising surface treatment to realize multifunctionalities. Since such surfaces reduces a direct contract between corrosive media and metal surface, the corrosion resistance of metals can be significantly enhanced. The oil-impregnated surface shows better anti-corrosion property compared to the hydrophobic surface, but it needs a hydrophobizing coating on porous structure for a good affinity with immiscible oil. In this study, we fabricated the oil-impregnated surfaces on porous oxide structured Mg alloy, Al alloy, stainless steel and copper alloy using silicone oil, which make PDMS (Poly(dimethylsiloxane)) brush on oxide surface showing hydropbizing effect. Then, the enhancements of corrosion resistance of four metals were investigated with electrochemical method. The silicone oil enabled the simple fabrication of water-repellent oil-impregnated surface with a significant enhancement of corrosion resistance.
Membrane Scaffolds Silver Nanoparticles As a New Platform of Antiviral Personal Protective Equipment for COVID-19
Authors: Kalil Haitham , Maher Shaimaa , El-falouji Abdullah I. , Samir Omar , Gad Emad , Youssef Mohamed F.
Published: December 2020

The coronavirus disease 2019 (COVID-19) emerged as a worldwide challenge to researchers and scientists. All research communities are working relentlessly in their labs hoping to find cure for the current COVID-19 pandemic. Developing a new vaccine for COVID-19 is not down on the road, it is a long process that needs numerous clinical trials. Moving the battle out of the body requires personal protective equipment (PPE), particularly masks and gloves. Together, they will limit spread of the virus, whether by reinforcing the PPE and developing synergistic antiviral coatings or finding a cure and vaccine to COVID-19.

Virus infection is one of the major global health challenges. In the meantime, several antiviral agents have been under testing to assess their efficacy as potential therapies for COVID-19. The viral resistance and the side effects associated with antiviral agents are adding more challenges, which resulted in lagging of their effectiveness as antiviral treatment. This opens the door for the development of safe and potent alternative antiviral drugs. In the current study, silver nanoparticles loaded fiber mat have emerged as a new antiviral platform in terms of their capability to deactivate a wide array of viruses. Silver nanoparticles have been studied exhaustively for their antimicrobial activity against wide-ranging of bacteria. Besides they have also shown promising activity versus several types of viruses including hepatitis B, human immunodeficiency virus (HIV), herpes simplex, monkey pox, and respiratory syncytial virus. Silver nanoparticles provide an alternative route as a new antiviral therapy. Interestingly, silver metals have the power to attack multiple targets in the virus, which results in diminishing its possibility to develop resistance as compared to imitative antivirals.

Considering the ongoing challenge, our lab has been preparing silver nanoparticles loaded on filter papers, cellulose membrane, polymer dressings, and cotton fabrics. These new generation of fiber mats will be fully characterized and tested against several viruses. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS) will be used to determine the morphology of our fibers and measure the particle size of the embedded nanoparticles.
Secondary Effects in Electrical Behavior of Body-Diode Integrated AlGaN/GaN HEMTS
Authors: Mahaboob Isra , Yakimov Michael , Rocco Emma , Hogan Kasey , Meyers Vincent , Shahedipour-Sandvik F. Shadi
Published: December 2020

We have recently demonstrated dual-gate control in AlGaN/GaN high electron mobility transistors (HEMTs) with the integration of body-diode based back-gate [1]. To integrate body-diode, conventional AlGaN/GaN HEMT structure is grown on a p-GaN layer and a back-gate terminal is connected to the underlying p-GaN layer. This design allows the back-gate voltage to control the depletion width of the body-diode, which in turn modulates the two-dimensional electron gas (2DEG) density at the AlGaN/GaN interface. A positive/negative shift in the threshold voltage is obtained by increasing/decreasing the depletion width of the body-diode with the application of back-gate voltage. With dual gate control, we have successfully demonstrated shift in the threshold voltage of a normally-ON HEMT towards normally-OFF mode along with improved breakdown voltage. Here we present, observations of secondary effects in the integrated body-diode AlGaN/GaN HEMT device structure. Secondary effects are investigated under both biased and floating back-gate conditions [2]. Our results show that, at higher drain voltages, bias at the drain terminal plays a crucial role in biasing the body-diode under dynamic operation. Secondary effects such as kink-effect in the saturation channel current and light emission under the source terminal are observed under dynamic operation. We will further discuss the effect of parasitic bipolar junction transistor (BJT) formation on the device performance in this integrated device configuration.

References

[1] I. Mahaboob, M. Yakimov, K. Hogan, E. Rocco, S. Tozier, and F. Shahedipour-Sandvik, “Dynamic Control of AlGaN/GaN HEMT Characteristics by Implementation of a p-GaN Body-Diode-Based Back-Gate,” IEEE J. Electron Devices Soc., vol. 7, no. 1, pp. 581–588, 2019.

[2] I. Mahaboob, M. Yakimov, E. Rocco, K. Hogan, and F. Shahedipour-Sandvik, “Drain Voltage Induced Secondary Effects in AlGaN/GaN HEMTs with Integrated Body-Diode,” unpublished, submitted to IEEE-TEDS.
Understanding the Durability and Degradation of Gas Diffusion Electrodes for Carbon Dioxide Electrolysis in Alkaline Media
Authors: Cofell Emiliana R. , Nwabara Uzoma , Henckel Danielle A. , Kenis Paul
Published: December 2020

Anthropogenic CO2 emissions present an immediate and unprecedented threat to our planet. Electroreduction of CO2 (ECO2RR) offers the dual benefits of reducing CO2 emissions from point sources and producing valuable chemicals such as CO, formic acid, and ethanol in a carbon-neutral manner.1,2 Over the past decade, a significant body of research has focused on improving the product selectivity and activity of CO2RR catalysts, but studies regarding long-term stability and durability of these electrocatalytic systems have been rare.3 To date, only a few studies have reported performance durations exceeding 100 hours, and even fewer have reported on possible mechanisms underlying decrease in performance and system failure.4 Techno-economic analyses suggest a lifetime of 3000 hours or greater is needed for economically feasible ECO2RR systems5. Progress in this area will be crucial for further development of ECO2RR technology.

This poster will report key findings from our comprehensive review of durability testing in ECO2RR systems, specifically common degradation mechanisms. We will focus primarily on gas diffusion electrodes (GDEs), used in high-performance alkaline flow and membrane electrode assembly systems. In our alkaline flow system, we have observed a number of degradation mechanisms consistently impacting our GDEs including leaching and carbonate formation. Characterization of used GDEs, including SEM, EDX, XRD, and Micro-CT, was employed to understand how operating at high current densities (–100 to –200 mA cm-2) in alkaline electrolytes impacts structure and chemical composition.

Secondly, this poster will outline ways in which we have attempted to improve durability in our GDEs. By applying insights from the literature to studies carried out in our flow system, we have evaluated changes in the electrolyte, electrode substrate, catalyst deposition method, and catalyst ink binder to optimize GDE design and augment durability. Lastly, we will report on accelerated durability and stress testing (ADT/AST) methods that we have developed, and our findings from implementation of these methods in our system. These accelerated procedures can be broadly applied to highly active (≥200 mA cm–2), lab-scale ECO2RR systems to determine long-term stability and degradation modes in shorter timeframes.

Acknowledgement

We gratefully acknowledge financial support from Shell’s New Energies Research & Technology - Dense Energy Carriers Program and I2CNER.

References:

Oerlemans, J. Science
308, 675-677 (2005).

Jhong, H. R., Ma, S. C. & Kenis, P. J. A. Curr Opin Chem Eng
2, 191-199 (2013).

Hori, Y. Mod Asp Electrochem, 89-189 (2008).

Cofell, E., Nwabara, O., Negro, E., Verma, S., Kenis, P. J. A., Chemsuschem
13, 855-875 (2020).

Verma, S., Kim, B., Jhong, H., Ma, S. C. & Kenis, P. J. A. Chemsuschem
9, 1972-1979 (2016).
Tuning of D-Band Center of Platinum Nanoparticles By Changing Transition Metal Oxide Support Materials for Enhancement of Oxygen Reduction Reaction (2)
Authors: Ando Fuma , Gunji Takao , Ohsaka Takeo , Matsumoto Futoshi
Published: December 2020

The enhancement of oxygen reduction reaction (ORR) on platinum nanoparticles (Pt NPs) was examined by changing transition metal oxide as a support material for Pt NPs. In order to use transition metal oxide having low electron conductivity as electrocatalyst support materials, thin transition metal oxide supports were formed on cup-stacked carbon nanotubes (CSCNT). In addition, mixed transition metal oxides having various ratios of two transition metal ions were prepared to produce continuous changes in the electron state (d-band center) of Pt NPs that was interacted electrically with the mixed transition metal oxides. The ORR activity measured in an acidic aqueous solution depended on the kinds of the metal oxide supports. The plot of the d-band center of Pt NPs deposited on the metal oxides vs. their ORR activity showed a volcano shape. That is, the volcano plot could be drawn by changing the support materials for the first time and maximum ORR activity could be observed at an optimized level of the d-band center. The metal oxide of TiNbOx (Ti:Nb = 1:6.6) could produce the optimized d-band level and could reach the ORR activity to the maximum activity. It was made clear from X-ray photoelectron spectroscopy (XPS) measurements that the d-band center could be down-shifted moderately by donation of electron from the metal oxide supports to Pt NPs for enhancing the ORR.

Figure 1. Schematic illustrations of (A-E) preparation of Pt NPs/metal oxide/CSCNT samples and possible positions of Pt NPs deposited on metal oxides and contacted with metal oxides.

Figure 1
Development of Short Time Impedance Measurement Method for PEM Electrolysis Cell
Authors: Murooka Takuki , Watanabe Hikari , Hoshi Yoshinao , Shitanda Isao , Itagaki Masayuki , Katayama Noboru , Sato Koki , Haneda Takahide
Published: December 2020

Electrochemical impedance spectroscopy (EIS) is expected as a method to evaluate a polymer electrolyte membrane (PEM) water electrolysis cell. The internal state of electrolysis cell can be investigated by EIS without destruction. However, it may be difficult to measure stable impedance during electrolysis at high voltage since the large amount of oxygen is generated on the anode. Therefore, a short time impedance measurement is required. The purpose of this study is to develop short time impedance measurement method1,2) that can estimate the electrolyte membrane resistance R
M and the charge transfer resistance R
ct in a short time.

A Japan Automobile Research Institute (JARI) standard cell with an electrode area of 25 cm2 was used as the test cell. The impedance measurement was performed in a frequency range from 100 mHz to 1 kHz and started from high frequency toward low frequency in the logarithmic scan.

The Nyquist plot of impedance spectrum shows inductive behavior caused by wiring in the high frequency region and capacitive semicircle related to the anode in the middle frequency region. Under the condition of high current density, it was found that impedance spectrum was scattered in the low frequency range. The scattering originated from oxygen evolution at the anode when the measurement time is long. The measurement time was about 80 s to obtain an impedance spectrum, thus it is necessary to measure in a shorter time. Therefore, we obtained R
ct in a short time by the two-point frequency method proposed by Haruyama et al.1,2) The equation (1) is used to calculate R
ct.

R
ct = Re [Z] - R
M + Im [Z]2/( Re [Z] - R
M) (1)

In the equation (1), R
M is the electrolyte membrane resistance, which is the real component of the impedance at the high frequency. The real and imaginary parts of the impedance at the low frequency are represented by Re [Z] and Im [Z]. The measurement was performed by fixing the frequency at 1 kHz as a high frequency value and changing the low frequency value from 100 Hz to 10 mHz. R
ct obtained from the measurement results by the two-point frequency method was compared with R
ct obtained from the curve fitting of the impedance spectrum with the equivalent circuit. As a result, the relative error of the R
ct calculated from the measurements at two frequencies 1 kHz and 10 Hz was -2.15% from the fitted result, and the measurement time was 5.33 s. From these results, it was found that the two-point frequency method was able to reduce the measurement time significantly compared to the normal EIS and to estimate R
ct accurately.

References

1) S. Haruyama, T. Tsuru, ASTM STP 727, ASTM Philadelphia, p.167 (1981).

2) T. Tsuru, S. Haruyama, Boshoku Gijutsu, 33, p.579-582 (1984).
Electrocatalytic Oxygen Reduction Reaction Improved By Facilitated Proton Transfer
Authors: Shin Seokmin , Lee Dong-Gyu , Yoon Subhin , Lee Yeongdae , Song Hyun-Kon
Published: December 2020

Electrocatalytic oxygen reduction reaction (ORR) in aqueous media proceeds along a pathway having multiple steps in which multiple surface intermediates are involved (* -> *OO -> *OOH -> *O -> *OH where * = active site of catalyst). Proton supplied from media plays a crucial role on the ORR mechanism. Therefore, pH of media affects the kinetics of ORR significantly. In the same vein, it is expected that the ORR activity is improved in the presence of proton donor (HD) around active sites of catalysts. In this presentation, we demonstrate a possibility that a series of proton donors are involved in protonation of the surface intermediates. The ORR overpotential was improved by 100 mV at pH 13 on transition metal oxide catalysts. The overpotential improvement was intensified as the pH of media decreased. It is suspected that the pH affects deprotonation of the proton donors (HD -> H+ + D-). High pH deprotonate the proton donors so that the effects of proton donors decrease. However, the proton of HD survives in acidic media so that the proton transfer from HD to active site is facilitated. The ORR overpotential gain was as large as 400 mV at pH 4 even if the oxide catalyst was not stable at the acidic pH. At pH 7, the overpotential improvement was estimated at 200 mV.
The Behavior of Microdroplets By the Acoustic Wave Interference
Authors: Lee Hai-Joong , Park Tae-Hoon , Lee Hyo-Soo
Published: December 2020

The microdroplet in the air have been recently issued in the view of environmental pollution and infectious virus. The microdroplet with fine dust have been challenged to solve with conventional techniques such as filtering, electrostatic, etc. We investigated the novel technology for decreasing the fine particles in air induced by sound wave with the frequency ranging from 20Hz to 20kHz and the sound pressure level (SPL) from 0 to 100dB.

The test systems in our study were set up with constraint box, sound wave actuator, ultra-fine particle distributor, particle counter, decibel meter, etc. the variation of density of ultra-fine particles from distributor was characterized with operating time of sound wave, and compared with the density as no operating.

When the low frequency and the SPL under 50Hz and 100dB were applied in the constraint box containing ultra-fine particles, the rate of decrease of ultra-fine particles in density was nearly 5 times higher than that without operating. And it can be applied to increase the efficiency of the conventional particle collection technology such as the commercial filter.

It is concluded that the behavior of microdroplets was effectively analyzed by the acoustic wave interference, and also is expected to be applied to the various fields
Erroneous Evaluation on Intrinsic Activity of Electrocatalysts
Authors: Ji Sanggu , Choi Chang Hyuck
Published: December 2020

In general, the assessment of the electrocatalysts in (photo-)electrochemical system is conducted in conventional three-electrode system comprising of working, counter and reference electrodes in a batch cell configuration. Depending on the targeted electrode, the proper use of counter electrode, balancing the reaction of the working electrode, is recommended to elude possible contamination arising from the electrochemical system unexpectedly. Herein, electrochemical analyses are introduced with two different model systems, highly sensitive to the chemical changes on the surface of electrode. First, we have investigated a model reaction of hydrogen evolution reaction (HER) in a conventional three-electrode system, using p-Si as a photocathode with Pt counter electrode. Alternatively, polycrystalline platinum was used as a model cathode to investigate HER and oxygen reduction reaction (ORR) with the employment of graphite counter electrode. Substantial changes in the electrocatalytic activities were verified. Potential variations on the Pt and graphite counter electrodes were simultaneously monitored during the evaluations, of which results were coupled to the online inductively coupled plasma-mass spectrometry (ICP-MS) and in situ differential electrochemical mass spectrometry (DEMS), to monitor metal dissolution and carbon corrosion concurrently during the reactions. Significant dissolution of Pt and their subsequent redeposition on p-Si photocathode were confirmed in the former system, while strong poisoning of active Pt surface by evolved CO from graphite counter electrode was demonstrated in the latter one. Microscopic/spectroscopic analyses on the post-reaction electrodes further confirm the redeposition of dissolved species on the electrode surface. From these studies, we can suggest the most suitable form of electrochemical system based on the targeted electrode for precise evaluation.
Enhanced Photocatalytic Hydrogen Production with Treated Cus/Znos from S2-/so3
2- Solution
Authors: Hayashi Ryoya , Furukawa Mai , Tateishi Ikki , Katsumata Hideyuki , Kaneco Satoshi
Published: December 2020

Recently, with the problems of energy environment and global warming, the use of hydrogen as energy in the future has been attracting attention. Also, waste water containing dyes causes environmental pollution and gives a harm for the health of living organisms [1].

Previously, we reported ZnO/ZnS composites for the photocatalytic hydrogen production. The photocatalyst ZnS/ZnO with CuS as a cocatalyst can simultaneously treat H2 production and dye decolorization. The hydrogen production was 2,110 µmol/g･h with CuS/ZnO0.5S0.5 (molar ratio ZnO/ZnS = 5/5). Furthermore, methyl orange solution of up to 80 ppm could be decolorized with about 90% efficiency.

In the present study, ZnOS was prepared via a solvothermal method [2]. Firstly, ZnS was prepared by hydrothermal synthesis.Typically, Zn(Ac)2･2H2O of 10 mmol and thiourea of 30 mmol were dissolved in 15 mL of pure water for stirring for 30 min at room temperature. Fourty mL of ethylenediamine were then added into the above aqueous solution. After the stirring for 30 min, the solution was added into 15 mL pure water, and was stirred for more 30 min. Next, autoclave treatment was perfprmed at 160 ℃ under autogenous pressure for 4 h. After cooling to room temperature, the products were washed with pure water and ethanol, and were dried at 60 ℃ in vacuum overnight. The ZnS photocatalyst was sintering at 600 ℃ for 2 hours convert to obtain ZnO. ZnO was dissolved in 50 mL of pure water. Next, Na2S was added to the aqueous solution during magnetic stirring. A nanocomposite of ZnO core and ZnS shell could be prepared. Sintering was performed in an air atmosphere using an electric furnace to obtain ZnOS.

The amount of hydrogen production using ZnOS with CuS as a cocatalyst was 2230 µmol / g･h.

References

[1] K. Chu, L. Ye, W. Wang, D. Wu, D. Chan, C. Zeng, H. Yip, J. C. Yu, P. Wong, Chemosphere
2017, 183, 219.

[2]P. Li, T. He, Appl. Catal. B : Environ.
2018, 238, 518
Direct Measurement of Electron Transfer Rates between Iron(II) Phthalocyanine and Gold with Different Interface Structures
Authors: Kondo Taisei , Motobayashi Kenta , Ikeda Katsuyoshi
Published: December 2020

Electron transfer in a metal/molecule system has been extensively studied using various methods. In particular, the relation between the structure of metal/molecule junctions and the electron transfer property is of great interest in the research field of molecular devices. In this study, we measured electron transfer rates of iron(II) phthalocyanine/gold system with different junctions to study the contribution of the atomistic interfacial structures to the electron transfer characteristics.

An Au single-crystal disk with (111) or (100) orientation was modified with self-assembled monolayers of imidazole-terminated alkanethiols with the alkyl chain of ten carbon atoms (ImC10SH). Then, iron(II) phthalocyanine (FePc) complexes were attached on top of the monolayer through the axial ligation of the central Fe ions with the imidazole groups. The Au-S bonding structure was measured using Surface-enhanced Raman spectroscopy (SERS).1) The electron transfer rate between Au and FePc was measured by analyzing the cyclic voltammogram (CV) of redox behavior for FePc in 0.1 M perchloric acid aqueous solution.

SERS measurements showed that the Au-S bonding structures were different between Au(111) and Au(100). According to the peak position of nAu-S, the dominant Au-S structure was determined to be three-fold hollow geometry on Au(111) and two-fold bridge geometry on Au(100). Figure shows the scan rate dependence of CVs of FePc/ImC10SH/Au(100) and FePc/ImC10SH/Au(111). With increasing the scan rate, the peak separation between the oxidation and reduction peaks became larger in both cases. However, the magnitude of the separation was larger for Au(111) than for Au(100), suggesting that the electron transfer through the Au-S junction was slower at the hollow site on Au(111) than at the bridge site on Au(100). The electron transfer rate can be calculated from the relation between the peak separation and the scan rate. We will present detailed quantitative analysis of the electron transfer rate for different Au-S bond structures, alkyl chain lengths, etc.

1) M. Inagaki, K. Motobayashi, K, Ikeda, J. Phys. Chem. Lett., 8, 4236 (2017)

Figure. Scan rate dependence of CVs of FePc/ImC10SH/Au(100) and, FePc/ImC10SH/Au(111) in 0.1 M perchloric acid aqueous solution.

Figure 1
Electrochemical Sensor for Food Toxins with Molecularly Imprinted Polymer for Selective Determination of Heterocyclic Aromatic Amines
Authors: Ayerdurai Viknasvarri , Garcia-Cruz Alvaro , Cieplak Maciej , Sharma Piyush Sindhu , D'Souza Francis , Kutner Wlodzimierz
Published: December 2020

Quinoxaline heterocyclic aromatic amines (HAAs), are formed during meat and fish cooking, frying or grilling at high temperatures. HAAs are classified as potent hazardous carcinogens, even though the HAAs are usually generated at very low concentration (~ng per g of a food sample). This is because the HAA food contaminants effectively damage DNA by intercalation or strand break. Hence, chronic exposure to HAAs, even in low doses, can cause cancers of lung, stomach, breast, etc. Currently, HPLC is used for determination of these toxins in food matrices. However, this technique is expensive, tedious, and time-consuming. Therefore, fast, simple, inexpensive, and reliable HAAs determination procedures, without need of separation of these toxins, in the protein food matrices are in demand. Molecularly imprinted polymers (MIPs) are excellent examples of bio-mimicking recognition materials. Therefore, they have found numerous applications in selective chemosensing. Within the present project, we synthesized a nucleobase-functionalized molecularly imprinted polymer (MIP) as the recognition unit of a chemosensor for selective detection and determination of 2-amino-3,7,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (7,8-DiMeIQx) HAA. MIP-(7,8-DiMeIQx)-film coated electrodes were sensitive and selective with respect to 7,8-DiMeIQx. The linear dynamic concentration range of the devised chemosensor extended from 12 µM to 0.4 mM 7,8-DiMeIQx and the imprinting factor was high, IF = 14.

This work is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 711859. Scientific work was funded from the financial resources for science in the years 2017-2021 awarded by the Polish Ministry of Science and Higher Education for the implementation of an international co-financed project and National Science Centre Poland (grant No. NCN 2014/15/B/NZ7/01011 to W.K.)
(Invited) Domain Adaptation for the Semantic Segmentation of the Unmanned Surface Vehicle
Authors: Zhan Wenqiang , Xiao Changshi , Haiwen Yuan , Zou Xiong , Chen Qianqian , Yang Tiantian
Published: December 2020

Recently, deep learning has great development and is applied in various fields. But the performance of the network depends on a large amount of label data training. After training in a specific domain, a network model can have a good performance. But it may have a poor performance when transferred into a new domain. This paper addresses the visual semantic segmentation model transfer for the unmanned surface vehicle (USV) system. An adaptive cross-domain incremental learning method is proposed, which enables USV adaptive to navigate in unknown new environments. In our work, the knowledge of the trained segmentation network model and the feature information of the input image is used for the network incremental learning. First, the trained semantic segmentation network is used to classify each pixel of the input image. Then, pixels with high prediction probability are selected as seed points. At the same time, a convolution network for feature extraction is used to obtain the embedded feature space vector of each pixel. A mask centered on the seed point is generated based on the similarity between pixels in the feature space. The mask is labeled based on the segmentation network prediction. Multiple masks are fused to generate the label of the input image. Finally, the automatically generated labels are used to update the network to realize the adaptability of the network in the new environment
(Invited) Hybrid Nanomanufacturing of Heterostructured Wearable Devices for Self-powered Smart Wearables
Authors: Wu Wenzhuo
Published: December 2020

The seamless and adaptive interactions between functional devices and their environment (e.g., the human body) are critical for advancing emerging technologies, e.g., wearable devices, consumer electronics, and human-machine interface. The state-of-the-art technologies, however, require a complex integration of heterogeneous components to interface the environmental, mechanical stimulus, which is ubiquitous and abundant in the above applications. These limitations have severely hampered the advancement and broader utilization of related technologies. Moreover, all existing technologies require a power source, which complicates the system design and limits operation schemes.

In this talk, I will discuss our recent progress in developing self-powered human-integrated nanodevices through the hybrid nanomanufacturing of heterostructured nanodevices. This new class of wearable devices are conformable to human skins and can sustainably perform self-powered, non-invasive functions, e.g., physiological monitoring and gesture recognition, by harvesting the operation power from the human body. Such an operation scheme is fundamentally hinged on the polarization induced current term in Maxwell’s displacement current. This research is expected to have a positive impact and immediate relevance to many societally pervasive areas, e.g., biomedical monitoring, consumer electronics, and intelligent robotics.
Electrochemical Deposition and Characterization of Ni-Fe composite Nanowires As Supercapacitor Anode
Authors: Verma Sonali , Khosla Ajit , Arya Sandeep
Published: December 2020

With increasing energy demands in hybrid vehicles and portable electronics, the scientific community and society shows more interest towards the development of the technologies capable of storing large amount of energy [1,2]. Researchers, all around the world are working hard for the development of energy storage devices such as capacitors, batteries, supercapacitors etc [3-5]. Supercapacitor devices are safe and promising alternative energy storage devices as compared to batteries [6]. Among the supercapacitors, pseudocapacitors due to their high performance and low cost are favored choice with the possibility of commercialization. Also for high performance supercapacitor, the selectivity and morphology of the electrode material plays key role. As a result, various transition metals, their oxides as well as composites with different morphologies are explored as electrode materials. Among these, metal ferrites demonstrate high potential in energy storage applications as well as nickel, due to its high conductivity gains great interest in this field. In this work, the electrochemically deposited Ni-Fe composite nanowires were investigated as supercapacitor anode in 6M KOH solution. The electrodeposition is performed in a three electrode electrochemical cell using a flexible conductive copper tape as substrate into a polycarbonate membrane. The electrodeposition is achieved cathodically in an electrolyte consisting of 10mM Iron nitrate nonahydrate (Fe(NO3)3.9H2O) and 40mM Nickel nitrate hexahydrate (Ni(NO3)2.6H2O) in 50ml DI water, with 99.99% platinum (Pt) wire as counter, silver/ silver chloride (Ag/AgCl with saturated KCl) as the reference electrode and the electrolyte as working electrode at -1.4 V at room temperature for 20 minutes. Then the synthesized Ni-Fe composite nanowires were allowed to dry at room temperature and after that dichloromethane (CH2Cl2) is used for releasing nanowires from polycarbonate membrane as dichloromethane will dissolve the polycarbonate membrane leaving behind only the vertical nanowires. Further, SEM, EDX, CV, GCD etc characterizations were performed to investigate the structure, morphology and electrochemical properties of the synthesized nanowires for energy storage application.

References

[1] Yan, Q. Wang, T. Wei, Z. Fan, Adv. Energy Mater. 4, 1300816 (2014).

[2] Wang, Y. Chen, O. G. Schmidt, C. Yan, Chem. Soc. Rev. 45, 1308 (2016).

[3] Xu, F. Lin, M. M. Doeff, W. Tong, J. Mater. Chem. A 5, 874 (2017).

[4] R. Salunkhe, Y. V. Kaneti, J. Kim, J. H. Kim, Y. Yamauchi, Acc. Chem. Res. 49, 2796 (2016).

[5] Anasori, M. R. Lukatskaya, Y. Gogotsi, Nat. Rev. Mater. 2, 16098 (2017).

[6] M. Vadiyar, S. S. Kolekar, J. Y. Chang, A. A. Kashale, A. V. Ghule, Electrochim. Acta 222, 16041615 (2016).
Machine Learning the Metastable Phase Diagram of Carbon
Authors: Sankaranarayanan Subramanian K. R. S.
Published: December 2020

We integrate first-principles physics and atomistic simulations with machine learning (ML), and high-performance computing to allow rapid exploration of the metastable phases of a given elemental composition and construct "metastable" phase diagrams for materials far-from-equilibrium. Using carbon, a prototypical system with a vast number of metastable phases without parent in equilibrium, we demonstrate automatic metastable phase diagram construction to map hundreds of metastable states ranging from near equilibrium to those far-from-equilibrium (500 meV/atom). Moreover, we incorporate the free energy calculations into a neural-network-based learning of the equations of state that allows for efficient construction of metastable phase diagrams. We use the metastable phase diagram and identify domains of relative stability and synthesizability of metastable materials. High temperature high pressure experiments using a diamond anvil cell on graphite sample coupled with high-resolution transmission electron microscopy (HRTEM) confirm our metastable phase predictions. Our introduced approach is general and broadly applicable to single and multi-component systems.
Application of Nanocarbons Modified with Anthraquinone Polycondensation Polymer to Electrochemical Double Layer Capacitance
Authors: Nishiyama Katsuhiko , Yamaguchi Kaisei , Minamoto Hironori , Yoshimoto Soichiro , Takafuji Makoto
Published: December 2020

Carbon-based fine particles have been widely used as fillers for enhancing the reinforcement for bulk materials. In addition, the excellent physical stability and unique chemical properties of these fine particles expand their potential utility in electroconductive materials, carriers for catalysis, packing materials such as pigment and colorant for inks, paints, and resins. Recently, it was reported that one-pot polymerization of 1.5-dihydoroxynaphtalene (DHN) and 1,3,5-1,3,5-trimethyl-1,3,5-triazinane(TA) in ethanol or other related solvents without any additives, and subsequent calcination at relatively enables us to control the diameter of the resultant particle in the range of submicron to a couple of microns. In this study we report that the nano carbons modified with an anthraquinone polycondensation polymer prepared by this one-pot polymerization method using an aromatic hydrocarbon with OH groups and TA function as an electrochemical double layer capacitors (EDLC).

Anthraquinone derivatives having two OH groups and 1,3,5-trimethyl-1,3,5-triazinane (TA) were purchased from Tokyo Chemical Industry Co., Ltd. and used as received. Carbon black powders (DENKA Black) and mineral oil were purchased from DENKA Co. Ltd. and Sigma, respectively. Cyclic voltammetry (CV) and potential step chronocoulometry were performed with a ALS model 621 electrochemical analyzer. A platinum plate and Ag/AgCl (KCl sat.) were used as a counter and reference electrode, respectively.

CV in 0.1 M HClO4 at a bare carbon black (CB) electrode shows very small charging current without redox waves. In contrast, at the CB modified with anthraquinone condensation polymer (AQP), redox waves of anthraquinone moieties associated with a large charging current. The capacitance calculated from CV depended on the kind and concentration of the supporting electrolyte used, the kind of carbon black, and modification conditions of the AQP. The capacitance of 1.34 F cm-2 was obtained at the AQP modified CB (DENKA Black HS-100) in 0.1 M HClO4. This modification method is very simple, versatile, and effective for modifying nanocarbons.
Nano-Si/C Composite Via Carbothermal Shock for Lithium Ion Battery Anode
Authors: Cho Changhyun , Kim Soyeun , Kim Moosung , Joh Chung-Hyung , Lim Chang-ha , Woo Changse , Yang Kap seung , Park Min-Sik
Published: December 2020

Nowadays, Li-ion batteries are ubiquitous and dominate the portable storage market. However, their utilizations for high-energy applications are limited and they present huge social challenges for the future, especially for the applications to electric and hybrid electric vehicles (EVs and HEVs respectively). One strategy, praised by both academics and industry, the high capacity electrode materials, notably silicon, as it is considered an attractive graphite substitute in Li-ion battery anode. Silicon (Si) is recognized as a representative anode material for next-generation lithium-ion batteries due to properties, such as a high theoretical capacity, suitable working voltage, and high natural abundance. However, inherently, a large volume expansion (~ 400%) during lithiation/delithiation introduces poor electrical conductivity and unstable solid electrolyte interfaces (SEI) films, the Si-based anodes possess serious stability problems hindering practical applications. To overcome the issue, Si-nanoparticles(Si-NPs) has been proposed as a promising solution to overcome the volume expansion and the flowing fracturing problems of the micron-size particles. Thus, various nanoparticles and nano-objects (0D, 1D, 2D and 3D) have been tried for the Li battery anode in the last decade.1, 2 It has been demonstrated that Si-NPs smaller than 150 nm can be avoided the further fracturing upon the repeating lithiation.

We propose a technology for preparations of novel Si-NPs/carbon(Si/C) composites on the basis of thermal shock of the carbon materials such as natural and artificial graphites. We developed a facile, one-step carbothermal shock method for transformations from micro-Si to Si-NPs less than 150 nm size and well dispersed on carbon matrix (Figure 1.). The particle size distribution of the Si-NPs was narrow and the dispersion was uniform. The Si/C composite anode exhibited a high specific capacity (>1,000 mAh/g) and predominant fast charging behavior.

Reference

[1] R. Chen, T. Zhao, X. Zhang, L. Li and F. Wu, Advanced cathode materials for lithium-ion batteries using nanoarchitectonics, Nanoscale Horiz., 2016, 1, 423-444

[2] D. Ma, Z. Cao and A. Hu, Si-Based Anode Materials for Li-Ion Batteries: A Mini Review, Nanomicro Lett., 2014, 6(4), 347-358

Figure 1. SEM images of Si-NPs/carbon (Si/C) composites

Figure 1
Highly Stable Transition Metal Alloy Catalysts Wrapped with C-Dots for Hydrogen Evolution Reaction in Acidic Solution
Authors: Ali Yousuf , Nguyen Van-Toan , Nguyen Ngoc Anh , Larina Liudmila L. , Choi Ho Suk
Published: December 2020

This work reports a large-scale and low-cost synthesis of highly effective, durable, and cheap NiCoPt/C-dot catalysts for hydrogen evolution reaction (HER). Simultaneous co-reduction of the metal precursors and carbon dots (C-dots) was confirmed by TEM, XPS, and Raman techniques. The SEM result clearly indicates that C-dots act as a structure-directing agent assisting to generate 3D nanosponge complex structure, which has an abundance of the electrochemically active sites. Synthesis procedure yields NiCoPt/C-dot nanoporous alloy wrapped with graphene, where the synergetic effect of the metal alloy constituents with outer graphene dots stimulates the electrochemical catalytic activity. Graphene dots additionally act as a protective layer. The optimization of the alloy composition along with lowering Pt loading (down to 0.04mM) for the highest catalytic activity for HER yields Ni48Co48Pt4/C-dot nanohybrid. XPS analysis revealed the nanohybrid surface is enriched up to 86.7 at% of Pt, suggesting that the surface composition of an alloy is controlled by the tendency of Pt metal segregation towards the surface. Such surface electronic structure led to the superior catalytic activity of Ni48Co48Pt4/C-dot, which generates an overpotential of only 45.54 mV at a current density of 10 mAcm-2 in acidic solution. The highest catalytic activity correlates well with the lowest charge transfer resistance in conjunction with the highest ECSA value of 57.51 cm2 of the nanohybrid. The synthesized nanocomposite showed good stability retaining 94% of current density after 21 hours of operation. The catalytic activity and durability of developed nanocomposite catalyst are comparable to those of the commercial Pt/C. The aforementioned advantages allow stating that 3D Ni48Co48Pt4/C-dot nanosponge is a low-cost, durable, and efficient electrocatalyst for hydrogen evolution. The developed nanohybrid may be considered as an upcoming alternative catalyst for hydrogen gas production.

Figure 1
Hydrogen Storage on Nanoporous Carbon Foam for Electrochemical Applications
Authors: Kusdhany Muhammad Irfan Maulana , Li Hai-wen , Mufundirwa Albert , Sasaki Kazunari , Hayashi Akari , Lyth Stephen Matthew
Published: December 2020

To be able to mitigate the threat of climate change, we need an alternative to fossil fuels. The use of hydrogen in fuel cells is an ideal candidate because hydrogen can be produced in many different ways and has a high energy density. However, one challenge in using hydrogen as a fuel is its storage. Storing hydrogen as compressed gas typically requires large pressures to meet US Department of Energy (DOE) targets, which leads to large losses during compression. By using solid state storage, we can use lower pressures for storage. Of the different kinds of solid state storage, physisorption on carbon materials has great potential because of its fast kinetics, reversibility, and the cost effectiveness of carbon materials.

In this research, we investigate the storage of hydrogen gas through physical adsorption on a sodium ethoxide-derived carbon foam. This carbon foam has all the necessary requirements of a good hydrogen sorbent: very large surface area and a large micropore volume. This material is also easy to synthesize: sodium ethoxide is pyrolyzed in N2 to make carbon, which is then washed in DI water and vacuum filtered. Unlike many other high surface area carbon materials, this carbon foam does not require a two-step carbonization-activation process, nor does it require a sacrificial template. This means it is more scalable and energy efficient compared to other synthetic carbon materials. [1,2]

The hydrogen adsorption capability of this material is tested at both 77K and 298K at elevated pressures (up to 9.5 MPa). Both the excess hydrogen uptake and the total hydrogen uptake are discussed. The values obtained are comparable with benchmark materials such as MOF-5 and IRMOF-20, which have 8 wt% and 10 wt% total uptake at 10 MPa, respectively, [3] and could plausibly meet US DOE targets for light duty vehicle application (5.5 wt% total uptake) at a much lower pressure than conventional compressed gas storage (usually 70 MPa). This work shows the potential of nanoporous carbon materials such as ours to work as a new storage system or as a ‘range extender’ of sorts for existing fuel cell vehicles.

[1] Lyth, S. M., Shao, H., Liu, J., Sasaki, K., and Akiba, E., 2014, “Hydrogen Adsorption on Graphene Foam Synthesized by Combustion of Sodium Ethoxide,” Int. J. Hydrogen Energy, 39(1), pp. 376–380.

[2] Choucair, M., and Mauron, P., 2015, “Versatile Preparation of Graphene-Based Nanocomposites and Their Hydrogen Adsorption,” Int. J. Hydrogen Energy, 40(18), pp. 6158–6164.

[3] Ahmed, A., Seth, S., Purewal, J., Wong-Foy, A. G., Veenstra, M., Matzger, A. J., and Siegel, D. J., 2019, “Exceptional Hydrogen Storage Achieved by Screening Nearly Half a Million Metal-Organic Frameworks,” Nat. Commun., 10(1), pp. 1–9.
Cobalt Boride Graphene Composites As a Novel Catalyst for Hydrogen Evolution
Authors: Abdel-Fattah Tarek M , Biehler Erik , Phillips Erin , Quach Qui , Elzamzami Ahmed
Published: December 2020

Carbon allotropes like carbon nanotubes and graphene like materials are useful for improving the catalytic ability of transition metals.1 These materials are notable for structural stability and high surface area for the dispersion of catalyst.2 This study explored a novel cobalt catalyst supported on graphene like materials CoB@G for the hydrolysis of sodium borohydride (NaBH4). Sodium borohydride is a hydrogen feedstock material (HFM) that contains 10.8% hydrogen by weight and reacts in water.3 This makes it a choice material for the generation of hydrogen gas; however, this react occurs slowly. CoB@G was synthesized from the reduction of a cobalt metal organic framework (MOF) supported on graphene oxide (CoMOF-5@GO). Hydrolysis of NaBH4 was conducted at temperatures of 283K-303K. Compared to bulk metals: nickel, cobalt, and raney nickel, our catalyst had a great activation energy of 54 kJ mol-1.4 Our product was characterized with Powder X-Ray Diffraction (P-XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM, Figure 1), Energy Dispersive X-Ray Spectroscopy (EDS), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), and Transmission Electron Microscopy (TEM). This product also should good reusability, producing similar amounts of hydrogen after 5 consecutive trials. The hydrolysis of sodium borohydride using our novel catalyst will aid in the mass production of hydrogen for use as an alternative energy source.

Works Cited:

Huff, C., Dushatinski, T., & Abdel-Fattah, T. M.. Gold nanoparticle/multi-walled carbon nanotube composite as novel catalyst for hydrogen evolution reactions. International Journal of Hydrogen Energy (2017) 42(30), 18985 18990.doi:10.1016/j.ijhydene.2017.05.226

Machado, B. F.; Serp, P. Graphene-Based Materials for Catalysis. The Royal Society of Chemistry
2011, 43 (13), 54–75.

Schlesingehr H.I.; Brown, H.C.; Finholt A.E.; Gilbreath J.R.; Hoekstra H.R.; Hyde E.L.; Sodium Borohydride, Its Hydolysis and its Use as a Reducing Agent in the Generation of Hydrogen; Chem. Soc., (1953), 75 (1), pp 215–219

Kaufman, C. M., & Sen, B. (). Hydrogen generation by hydrolysis of sodium tetrahydroborate: effects of acids and transition metals and their salts. Journal of the Chemical Society, Dalton Transactions, 1985 (2), 307. doi:10.1039/dt9850000307

Figure 1: Graphene supported cobalt borides are shown with SEM imaging. The graphene sheets formed large structures, some of which were over 100 microns in length

Figure 1
Purification of Small-Cage Endohedral Metallofullerenes Using Wet Chemistry
Authors: Franklin Hannah M. , Stevenson Steven
Published: December 2020

With much attention focused on larger cage metallofullerenes (e.g., Mx@C80-Mx@C100), there is little information available pertaining to metal atoms entrapped within smaller carbon cages (i.e., C70-C78). This is primarily due to their small yield in soot extract and co-eluting HPLC species. In this presentation, our method for isolating these smaller metal-containing cages will be discussed. This approach calls for a two-step isolation protocol in which aminoalkanols react and remove the majority of fullerene contaminants. This sample contains an increased percentage of desired small-cage metallofullerenes. As such, this enriched sample is much more amenable to HPLC fraction collection.