bluuebunny/crossref_metadata_2025_split huggingface dataset:
Researches and Applications of Nanostructured 2D Materials growth By Continuous Wavelength Laser Process
Authors: Yang Tzu Yi , Chueh Yu-Lun 
Published: November 2022

Two-dimensional (2D) nanomaterials, such as graphene and hexagonal boron nitride (hBN), have recently attracted increasing attention of researchers due to their unique phonon and electronic structures. These nanomaterials have been widely used in applications, such as sensors, catalysts, and optoelectronic devices, due to the lack of interlayer bonds and the quantum confinement of electrons. There have been several well studied methods to synthesis 2D materials including chemical vapor deposition(CVD), physical vapor deposition(PVD), liquid exfoliation, Li-intercalation exfoliation,wet chemistry,ultrasonic-ball milling, Among them, CVD is the most famous method to fabricate electronic device with high quality materials characteristic. However, CVD processes will cause extremely harsh heat budget to substrate during high temperature process. Recently, researchers have established transfer method fabricating device on other undamaged substrate. It is the trickiest problem make it cannot apply to industry.
In this research, we built an indirect laser projection transfer method. First, we sputter requiring material on Si wafer as donor chip. Followed, placed the donor chip upside down on acceptor substrate, and radiated by laser on the donor chip backside. The deposited component on donor substrate would evaporate, and the vapor would fill between two substrates interspacing. Then, the vapor will recrystallize on the cooler acceptor surface. We have successfully transferred low melting temperature 2D materials such as SnSex, NiSex, SbSex on different acceptor substrate, even on flexible and flammable paper. By controlling laser intensity and irradiation time, we can control the amount of Se scattering, finally manipulate SnSe/SnSe2 phase ratio successfully. The mechanism has been demonstrated by SEM, RAMAN, TEM, XPS, XRD. Owing to indirection irradation, it can transfer materials on several fragile substrates without any heat budget, which reveals the great potential of this method for electronics applications. In this report we successfully demonstrate transferred SnSe/SnSe2 have good feasibility in energy storage system and sensor device.
Dual Threshold and Memory Switching Induced By Conducting Filament Morphology in Ag/WSe2 Based ECM Cell
Authors: Chaudhary Mayur , Chueh Yu-Lun 
Published: November 2022

In recent years, two-dimensional (2D) materials-based RRAMs have gained high importance because of their thermal and mechanical stability, and better potentiation-depression controllability. 2D materials based conductive bridge random access memory (CBRAM) has been considered as promising approach for neuromorphic and image processing technology [1]. Despite much progress in CMOS technology, the growth and deposition technology of 2D materials for semiconductor integrated circuit are much complex and is generally available at wafer scale [2]. In addition, high growth temperature for high quality of 2D materials complicates direct wafer growth and makes transfer process desirable. At the device level, challenges are linked to controlled and uniform growth of 2D material for high density electronic structure.
Recently, discreet 2D based memristor have been used in crossbar structure as synapse for neuromorphic computing. However, the plasma-assisted chemical vapor reaction (PACVR) based memristor for neuromorphic application are rarely demonstrated. Here, we report the co-integration of plasma-assisted chemical vapor reaction (PACVR) with silicon CMOS technology to provide brain-inspired computing device. PACVR offers compatibility with temperature limited 3D integration process and also provides much better thickness control over a large area. Furthermore, it an easy platform for direct and controlled synthesis of TMDs compared to conventional CVD approach. The PACVR grown WSe2 layer (~2 nm) on silicon substrate is realized, which exhibits both threshold and bipolar switching. The threshold and bipolar switching emulate integrate-fire neuron function and is obtained by modulating the compliance current in the device. The dynamics of the switching is closely related to the diffusive dynamics of the active metal (Ag or Cu) which can be controlled by device current. As a result, the WSe2/Si memristor shows synaptic behavior for neuromorphic system with learning accuracy of 96%.

References:

Wang, C.-Y. et al. 2D layered materials for memristive and neuromorphic applications. Electron. Mater. 6, 1901107 (2020)

Zhang, X. et al. Two-dimensional MoS2-enabled flexible rectenna for Wi-Fi-band wireless energy harvesting. Nature
566, 368–372 (2019).

Figure 1
Electrocatalytic Reduction of Nitrogen to Ammonia By Janus Wsse Nanowalls
Authors: Peng Yu-Ren , Tang Shin-Yi , Yang Tzu-Yi , Wu Shu-Chi , Chueh Yu-Lun 
Published: November 2022

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have been made in improving the NRR for the significant effort in catalytic activity due to its unique crystal structures, electronic properties, and promising nonprecious catalysts. However, many studies have provided solutions to activate the inert basal plane with low improvement. With highly asymmetric configuration, Janus monolayer with intrinsic strain and electric field can enable a way to tune the activity in TMDs-based catalysts. Although the first successful experimental synthesis of Janus structure (MoSSe) has gained significant interest and become a fast-growing TMDs-based material, the structure remains limited in the low dimensional and hard to expose the edges site to enhance the catalytic activity. Besides the common benefits of 2D TMDs, such as high surface area, short carrier migration distance, and tunable electronic structure. In this regard, the inherent structural asymmetry of Janus WSSe nanowalls as a new means to enhance the NRR activity was investigated. Janus TMDs nanowalls as the catalyst by taking advantage of its introduction of in-gap states with a shift in the Fermi level in nitrogen adsorbed system because of Janus asymmetry from the origin of stimulating NRR activity. Raman spectra showthe related main modes for WSSe Janus structure as shown in Fig. 1a, for which peaks at 271 and 333 nm can be found, respectively. The linear sweep voltammetric (LSV) curves of the catalysts as shown in Fig. 1b confirm the onset potential of the NRR, which increases with the different materials. Janus WSSe Janus nanowalls exhibit outstanding NRR performance over its parent materials (WS2 and WSe2). The results should propose a new path to design high performance and a novel structure for Janus TMD-based catalysts.
Fig1. (a) Evolution of Raman spectra in the WSSe nanowalls as a function of chemical composition (b) LSV curves for WS2, WSe2, WS2-XSe2-2X alloy, and WSSe Janus nanowalls

Figure 1
(Digital Presentation) Scalable Growth of Transition Metal Dichalcogenides for Next-Generation Nanoelectronics
Authors: Tong Shi Wun , Ng Man-Fai 
Published: November 2022

Alternative channel materials for future ultra-scaled electronic devices have been intensively pursued nowadays since the feature size of silicon-based transistors has been scaled down to their physical limit. Atomically-thin semiconducting transitional metal dichalcogenides (TMDCs) including WS2, MoS2, WSe2, MoSe2, e. have shown a lot of unique properties compared to their bulk crystals, such as indirect-to-direct bandgap transitions, strong spin-orbit coupling and valley polarization. In particular, monolayer WS2 has shown the highest theoretical room temperature electron mobility among other semiconducting TMDCs as a result of its low effective mass. Combined with the large exciton/trion binding energy with high photoluminescence quantum yield, monolayer WS2 is a strong candidate as a potential channel material for high-efficiency optoelectronic applications.
However, it is still challenging to grow wafer-sized, highly uniform and strictly monolayer TMDCs continuous film through the conventional chemical vapor deposition (CVD) due to the uncontrollable growth kinetics. The evaporation rates and amounts of the heated precursors are uncontrollable because the saturation vapor pressure of the precursor is exponentially dependent on the temperature inside the furnace. The sulfurized film is thus consisted of a mixture of monolayer, bilayer and multiple layers of TMDCs. The film with such unreproducible quality is not applicable for real industrial applications.
In this work, we provide a self-limiting growth strategy based on modified CVD process to prepare the wafer-sized monolayer TMDCs. Theoretical simulations were performed to understand the fundamental thermodynamically mechanism of the strictly monolayer growth. The property-variation in TMDCs due to difference in electronic structure between different layers of TMDCs can be significantly reduced based on this new approach. The following figure indicates that the PL spectra detected from different spots (spot 1 to 5) of the WS2 film. All spectra measured from the 4'' wafer-sized sample show characteristics unique to monolayer WS2. This poses a reliable route for the growth of large-area monolayer TMDCs, which is essential for their reliable and robust applications in nanoelectronic devices.

Figure 1
Insights into PEMFC Water Management with Different Layer Properties
Authors: Sabharwal Mayank , Wang Shiyi , Arman Tanvir Alam , Komini Babu Siddharth , Pasaogullari Ugur , Spendelow Jacob S. , Kusoglu Ahmet , Weber Adam Z. 
Published: November 2022

Hydrogen based proton-exchange-membrane fuel cells (PEMFCs) provide a sustainable, potentially decarbonized solution to meet the future energy needs for mobility applications especially heavy-duty vehicles. Water management plays a critical role in determining the performance and efficiency of PEMFCs.1 Low water content in the membrane-electrode assembly (MEA) can lead to membrane dehydration and subsequently increased ohmic overpotentials, while high water content can result in local flooding of the porous media, thereby leading to mass-transport limitations. The structure and properties of the porous media and membrane govern the water transport in the MEA and thus, parameterizing the effect of these properties on the water balance in the MEA is important for the design of next generation materials, a task that mathematical modeling is ideally suited to tackle.
In this work, a 2D half-land half-channel MEA model,2 modified to explicitly include gas crossover, is used to study the effect of different layer properties on PEMFC performance. The model is used to examine both impact of membrane thickness in traditional PEMFCs, as well as water management with thicker electrodes and asymmetric diffusion media with non-platinum-group-metal PEMFCs. For the former, the tradeoffs between crossover and water gradients versus ohmic losses is quantified including explicit membrane-thickness-dependent properties.3 For the latter, specific cases of diffusion media with different pore size distributions and permeabilities is explored. Water-balance and voltage-breakdown analysis elucidate the design parameters limiting the PEMFC performance.

References

A. Z. Weber et al., Journal of The Electrochemical Society, 161, F1254–F1299 (2014).

L. M. Pant, S. Stewart, N. Craig, and A. Z. Weber, Journal of The Electrochemical Society, 168, 074501 (2021).

X. Luo et al., Journal of The Electrochemical Society, 168, 104517 (2021).
Imaging Liquid Water in a PEFC with High-Energy X-Ray Compton Scattering
Authors: Tsuji Naruki , Miyazawa Tetsuya , Kaneko Takuma , Orikasa Yuki , Tsuji Yoichiro , Uchimoto Yoshiharu , Imai Hideto , Sakurai Yoshiharu 
Published: November 2022

Water management is important for stable operation of PEFCs (Polymer Electrolyte Fuel Cells), since the proton conductivity depends on water content and excessive water hinders electrochemical reactions. As the durability of PEFC has become a major issue, the correlative behavior between liquid water and cerium oxides (radical scavengers) is drawing much attention. Till now, the water content and its inhomogeneous distributions have been reported by neutron radiography and X-ray computed tomography (CT). In this paper, we present a high-energy Compton scattering imaging (CSI) technique for non-destructive observation of liquid water in PEFC.
The advantage of high-energy CSI over X-ray CT is that the CSI technique has direct access to a two-dimensional cross section inside a PEFC without its rotation. The radiation damage on polymer electrolyte membranes is negligibly small since the photoelectric absorption is substantially reduced at such high-energy X-rays. Although high-energy X-ray CT is not sensitive to light-element materials, X-ray Compton scattering has its sensitivity to light elements.
Figure 1 shows the cross-sectional images of GDL (Gas Diffusion Layer) materials and liquid water [1]. The GDL materials are made of porous carbon fibers and carbon composites with Teflon treatment, TGP-H-300 (TORAY Industries, Inc., Tokyo, Japan). The area of the cross sections is 2mm x 2mm, and its thickness is 10μm. The spatial resolution is 75 μm. Figure 1(a) shows the image of dry GDL materials, displaying the distribution of carbon fibers and carbon composite, and Figure 1(b) does the difference image between dry and wet, representing the liquid water distribution. Negative contributions are observed in the carbon fiber and carbon composite region, which indicates possible interactions between the GDL materials and liquid water.
In this presentation, applications to a model cell under operation are also presented, together with correlation mappings of liquid water and cerium. The capability of CSI for vehicles’ PEFCs (TOYOTA MIRAI) is also discussed.
This work was performed under the NEDO FC-Platform project.
[1] N. Tsuji et al., Appl. Sci.
11, 3851 (2021)
Figure Caption:
Fig.1: Cross-sectional images of GDL materials and liquid water.

Figure 1
(Digital Presentation) Small-Angle Neutron Scattering Analysis of Fuel Cell Materials
Authors: Suzuki Jun-ichi , Kawamura Yukihiko , Ohishi Kazuki , Shibayama Mitsuhiro , Hiroi Kosuke , Takata Shin-ichi , Kawakita Yukinobu , Otomo Toshiya , Imai Hideto , Ohki Maria , Asaoka Takahiko , Tsuji Yoichiro , Amemiya Kazuki 
Published: November 2022

In order to improve the reaction efficiency of fuel cells, the structure of carbon and ionomer affecting electronic and proton conduction and the distribution of voids affecting oxygen diffusion and drainage have been studied to find the guideline for the optimum structure of the catalyst layer. In this study we are developing a method to evaluate the dispersed structure of carbon and ionomer and the thickness of the ionomer layer by using the small and wide angle neutron scattering instrument, TAIKAN at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The dependence of ionomer-to-carbon weight ratio of small-angle neutron scattering (SANS) cross section of the solid carbon catalyst layer and the hollow carbon catalyst layer was evaluated comparatively. Furthermore, the relative humidity dependence of SANS cross section of the solid carbon catalyst layer and the hollow carbon catalyst layer was also evaluated by using the contrast variation method.
This presentation is based on results obtained from a project, JPNP20003, subsidized by a New Energy and Industrial Technology Development Organization (NEDO).
Comparing and Contrasting Fuel Cell and Electrolyzer Characterization Techniques
Authors: Mukundan Rangachary , Komini Babu Siddharth , Myers Deborah J. , Cullen David A. , Alia Shaun M , Borup Rod L. 
Published: November 2022

This talk will discuss several characterization techniques that have traditionally been used to characterize the performance and durability of fuel cells and discuss their implications to electrolysis systems. With the announcement of the DOE’s hydrogen shot to get the price of clean hydrogen to $1/kg in a decade, there has been an increased emphasis on improving the durability of Polymer electrolyte membrane electrolysis systems. This talk will discuss various in-operando, in-situ and ex-situ characterization techniques used to study and track the durability of both electrolysis and fuel cell systems. The presentation will include work from the DOE’s Million Mile Fuel Cell Truck (M2FCT) and Hydrogen from Next generation of Electrolyzers of Water (H2NEW) consortiums.
In specific, the talk will discuss various electrochemical characterization techniques including cyclic voltammograms, Impedance Spectroscopy and limiting current measurements that can be used to highlight changes in the polarization behavior of fuels cells and electrolyzers. We will also discuss the usefulness of Fluoride emission rate of the effluent water and CO2 concentration in the exhaust in tracking membrane and carbon degradation respectively. Finally, we will present results from various in-situ/ex-situ techniques including Xray analysis and microscopy to track changes in catalyst composition and morphology over time and correlate those changes to device performance.
Comparison of Serpentine and Interdigitated Monopolar Plates on the Performance of an Anion Exchange Membrane Fuel Cell By CFD
Authors: Valentín Reyes Jonathan , Leon Sotelo Maria Isabel Isabel , Nava José L. , Perez Tzayam , Romero Tatiana 
Published: November 2022

The continuous energy demand and the growing population have focussed the scientific research on developing alternative energy sources or green fuels.
The anion exchange membrane fuel cell (AEMFC) arises as an excellent alternative because of its low-cost electrocatalyst used at the cathode, energy production, and no pollutants emissions to the environment. Nowadays, several studies have been conducted to improve the performance of the AEMFC modifying membrane materials, types of gas diffusion layers (GDL), and catalysts, among other cell components.
However, the design of the flow channels by changing plate topologies and materials is still under development. About flow channels topologies, conventional geometries array (pin, straight, parallel, and serpentine) flow fields lead the flow in the direction parallel to the electrode surface, and the reactive gas flow towards the catalyst layer (CL) mainly by molecular diffusion. On the other hand, interdigitated flow fields provide convection velocity normal to the CL and forced convection flow in GDL for better mass transfer. The interdigitated flow fields could prevent water flooding and improve high current density operations performance.
These flow fields have been tested in proton exchange membrane fuel cells (PEMFC) with excellent results at low current densities. Nonetheless, there is an essential balance and management of water in an AEMFC. It presents simultaneous production and consumption of water in anode and cathode, respectively, where the production is twice the consumption.
Poor water management could provoke anode flooding or membrane drying. These scenarios are undesirable due to mass transport limitations, membrane polymer degradation, and cathodic channels flow can be flooded. Therefore, an appropriate design of flow field that allows the correct water balance on AEMFC is needed for optimal performance.
This research deals with the computational fluid dynamic (CFD) comparison of serpentine and interdigitated flow fields on the performance of an AEMFC. For the development of this model, the Navier-Stokes and Brinkmann equations were implemented for momentum transfer. In addition, the average mixture model represents the transport of chemical species, and the Butler-Volmer equation denotes the electrochemical reaction at the CL; water balance is analyzed at low and high current densities to evaluate the scenarios above mention.
Preliminary results indicate that a serpentine design is functional at the anode due to the water management is favored. An interdigitated flow field is implemented at the cathode to improve the distribution of the reactants from channels until the CL.
(2021-2022 ECS Toyota Young Investigator Fellowship) Understanding and Suppression of Cation Transport into Polymer Electrolyte Membrane Fuel Cell
Authors: Arman Tanvir Alam , Sabharwal Mayank , Neyerlin Kenneth C. , Spendelow Jacob S. , Weber Adam Z. , Pasaogullari Ugur , Mukundan Rangachary , Borup Rod L. , Komini Babu Siddharth 
Published: November 2022

Polymer electrolyte membrane fuel cells (PEMFCs) are a viable zero-emissions option for the electrification of the heavy duty transportation sector. However, PEMFCs still suffer from degradation of materials over the fuel cell lifetime. Cation contaminants can be generated from corrosion of bipolar plates and balance of plant components, water contaminants, and environmental sources (e.g., Fe3+, Ca2+, Na+), making them present in the fuel or oxidant stream during operation(1). Cations have been shown to be detrimental to the performance of the PEMFC by reducing water uptake, ionic conductivity, and O2 transport, resulting in performance loss and degradation. Metal cations such as Fe3+ can also lead to chemical degradation of the membrane ionomer (2-4). It is critical to understand the mechanism and rate of cation transport from the bipolar plate channel to the membrane to develop mitigation strategy to suppress the cation transport.
In this work, we present the study of the cation (Fe3+) transport mechanism through the gas diffusion layer (GDL) by introducing a cation solution in the cathode channel. Transport rates across the GDL are studied using an ex-situ GDL holder where Fe solution is introduced in the GDL substrate side with water transported through to the microporous layer side (MPL) and is collected and analyzed for Fe concentration, as shown in Figure 1a. Effect of the Fe concentration on transport rates is also studied using computational modeling. Understanding of the transport mechanism is then leveraged to identify mitigation solutions and suppress cation transport from the flow field to the electrode using a GDL with dual MPL architecture as shown in Figure 1b. Optimization of the dual MPL architecture for both durability and performance is also presented.

Acknowledgements

This research is supported by the 2021-2022 ECS Toyota Young Investigator fellowship and U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office, through the Million Mile Fuel Cell Truck Consortium (M2FCT). Authors acknowledge the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL).

References

D. D. Papadias, R. K. Ahluwalia, J. K. Thomson, H. M. Meyer, M. P. Brady, H. L. Wang, J. A. Turner, R. Mukundan and R. Borup, Journal of Power Sources, 273, 1237 (2015).

R. K. Ahluwalia, D. D. Papadias, N. N. Kariuki, J. K. Peng, X. P. Wang, Y. F. Tsai, D. G. Graczyk and D. J. Myers, Journal of the Electrochemical Society, 165, F3024 (2018).

J. P. Braaten, X. M. Xu, Y. Cai, A. Kongkanand and S. Litster, Journal of the Electrochemical Society, 166, F1337 (2019).

A. Kneer, J. Jankovic, D. Susac, A. Putz, N. Wagner, M. Sabharwal and M. Secanell, Journal of The Electrochemical Society, 165, F3241 (2018).

Figure 1