bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth of High-Quality Non-Polar Materials through Graphene via Anchor Point Nucleation
Authors: Hanus Tadeas , Diallo Thierno Mamoudou , Ruediger Andreas , Harmand Jean-Christophe , Patriarche Gilles , Boucherif Abderraouf 
Published: December 2024

The application of 2D-assisted epitaxy in the growth of freestanding membranes, hybrid 2D/3D heterostructures, and direct integration of highly mismatched materials has sparked significant interest in fields such as electronics, optoelectronics, and quantum devices. This method has been utilized for the growth of variety of materials, including III-N and III-V semiconductor compounds, various oxide compounds, perovskites, metals, and 2D materials, demonstrating its tremendous potential. However, one of its major challenges remains the growth of non-polar materials like Ge. This is mainly due to the minimal interaction between non-polar materials and 2D interface or underlying bulk substrate. This makes the nucleation and crystal orientation of epilayers very difficult, resulting in polycrystalline structures.
In this study, we unravel the key mechanisms governing the nucleation and growth of 3D non-polar materials on suspended single-layer graphene (SLG) from real-time observations of the growth by using in-situ Transmission electron microscopy (TEM)[1]. This powerful technique provides a unique opportunity to observe new and yet unexplored phenomena, which are not accessible to the standard ex-situ characterizations. Through direct observations, remote interactions are elucidated between Ge crystals through the graphene layer in double heterostructures of Ge/graphene/Ge. Based on these findings, we implemented a novel approach for growth of non-polar materials by 2D-assisted epitaxy, called “anchor point nucleation”[2]. This method involves the engineering of the SLG substrate, by introducing defects that act as preferential nucleation sited for the epitaxial growth and aid orienting the epilayer by the underlying substrate. Figure 1 illustrates this approach.
The engineering of the SLG was achieved through plasma treatment, and the effects of the treatment duration were analyzed by using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Experimental data confirmed the introduction of defects after the treatment, leading to an increase in nucleation sites shown by the increasing number of Ge nuclei on the treated SLG. These observations corroborate the pivotal role of induced defects in the nucleation process, enhancing surface energy and the reactivity of graphene. The high quality of the resulting epitaxial layers is demonstrated through TEM and electron backscatter diffraction (EBSD) characterizations. These findings mark the first demonstration of anchor point nucleation enabling high-quality growth of non-polar semiconductors through 2D-assisted epitaxy.
[1] T.M. Diallo et al., Small (2022), 18, 2101890. (https://doi.org/10.1002/smll.202101890)
[2] T.M. Diallo, T. Hanuš et al., Small (2023), 20, 2306038 (https://doi.org/10.1002/smll.202306038)

Figure 1
(Invited) Why Poly-OS IGO TFT Exhibits Mobilities >50 cm2/Vs
Authors: Tsuruma Yuki , Yamaguchi Koji , Sasaki Daichi , Kawashima Emi , Kadono Tasuke , Ide Keisuke , Katase Takayoshi , Kimura Mutsumi , Kamiya Toshio 
Published: December 2024

Poly-OS, a poly-crystalline oxide semiconductor, is one candidate for providing high-mobility backplane thin-film transistors (TFTs) for flat panel displays. Existing amorphous oxide semiconductor (Oxide) TFTs, like amorphous silicon (a-Si) are easy to fabricate in large areas. In addition, Oxide offers low power consumption due to their low off-leakage current. On the other hand, they have lower mobility than low temperature poly-crystalline silicon (LTPS), which is mainly used in today's small- and medium-sized displays. Poly-OS technology significantly improves mobility and enables high performance comparable to LTPS. This makes it possible to create products that combine the performance of existing backplane technologies (a-Si, Oxide, and LTPS) In fact, TFT mobility of 55.7 cm2/Vs has been achieved on a large-area substrate of the G6(1500×1800 mm) line by its sophisticated technology1 and IGO2 including indium, gallium and oxygen which one of Poly-OS material developed by us.
IGO is characterized by its ability to generate a poly-crystalline state using the conventional process (450 ℃ or lower) like existing oxide semiconductors. By using this poly-crystalline structure in the active layer, it is possible to maximize the inherent electron mobility of oxides. X-ray diffraction peaks observed in IGO film are in good agreement with the In2O3 crystalline bixbyite structure (space group Ia-3), and cross-sectional TEM and the fast Fourier transform (FFT) pattern indicate that the film has single crystal structure in a grain. Hall mobility(μ
H) of IGO films is remarkably higher than that of amorphous Oxide in high carrier concentration: nH
region (> 1 × 1019 cm-3). The μ
H - nH
trend is important in considering the field-effect mobility for carriers accumulated by the gate electric field. As a result, it is expected that IGO TFT which has carrier concentration more than 1 × 1019 cm-3 by the gate field exceed the mobility of 50 cm2/Vs.
We will explain why poly-OS exhibits high TFT mobilities over 50 cm2/Vs despite it exhibits μH
as low as 20 cm2/Vs when nH
corresponds to those used in TFT channels.

References:
1) M. Tsubuku, et. al. SID 2023 DIGEST 8-1, 78-81 (2023).
2) https://www.idemitsu.com/jp/news/2022/220621.html

Figure 1
(Invited) A Polaron Paradigm for Perovskite Nanocrystal Emitting States
Authors: Kuno Ken 
Published: December 2024

Perovskite nanocrystals (NCs) such as those made from CsPbBr3 have numerous uses. Most involve exploiting their light emission and are motivated by their defect tolerance and large, as-made emission quantum yields (QYs). For the latter, near unity QYs are possible. This leads to ready applications as light emitters but also intriguingly to possible material platforms for demonstrating semiconductor-based optical refrigeration.
Absent, though, is a fundamental understanding of perovskite NC emitting states, central to these applications. Of particular note are observations of near-universal, size-, temperature-, and composition-dependent absorption/emission Stokes shifts where observed energy differences are those that separate absorbing and emitting states. Moreover, efficient (near-unity efficiency), photoluminescence up-conversion, induced by exciting NCs below gap, motivates better understanding the microscopic nature of perovskite band edge states.
I will explain work we have done recently within the context of attempts to optically refrigerate a semiconductor. These studies now provide new insight into the band edge states of CsPbBr3 (and possibly CsPbX3) NCs. Starting with a microscopic mechanism for explaining how it is possible to obtain efficient, near-unity efficiency photoluminescence up-conversion to we extend the conclusions of these measurements to explain the origin of observed, size-dependent absorption/emission Stokes shifts. Here, despite some initial studies we and others have conducted, very little is known about their true origin. This is to be contrasted to more conventional NCs such as CdSe where band edge exciton fine structure quantitatively accounts for both global and resonant Stokes shifts, with emission emerging from a dark exciton. Although similar perovskite NC fine structure might account for their shifts, both theory and experiment predict bright/dark fine structure splittings easily an order of magnitude too small to account for experiment.
We now propose that perovskite NC emitting states are polarons, which result from the lattice accommodation of photogenerated charges. Polaron binding energies and lifetimes are, in turn, suggested to be the origin of observed l-, T-, and composition-dependent absorption/emission Stokes shifts and excited state lifetimes. This represents a significant departure from more conventional descriptions of NC band edge states, which exclusively involve exciton fine structure and dark exciton emitting states.
Polymer Electrolyte Fuel Cells Using Powerpaste
Authors: Bencomo Natalia , Lambourne Devon , Lynn Zachary , Matter Paul , Ocampo Minette 
Published: December 2024

Heavy duty vehicles are responsible for 30% of all transportation emissions (1.8 GtCO2-eq).1Therefore, electrification of heavy-duty transportation is urgently needed. However, heavy-duty PEM fuel cells operate under much harsher conditions than light duty fuel cells and are expected to last much longer in the field. These systems must operate successfully in the presence of impurities, starting and stopping, freezing and thawing, humidity and load cycling. Therefore, materials, components, and interfaces used in such systems must be highly resistant to severe mechanical and chemical stress. Furthermore, large systems such as planes, ships and trains need large amounts of fuel, i.e., a high-energy density fuel packaging for hydrogen is required. Fraunhofer’s magnesium hydride (MgH2) paste, POWERPASTE, is 90% H2, does not require a high-pressure tank and is safe to store in cartridges. The paste releases hydrogen when mixed with water and can be recycled back to MgH2. However, integration of POWERPASTE with fuel cell vehicles has not yet been established.
Giner will therefore develop US made propulsion systems using this high-power density fuel to electrify planes, ships and trains. To achieve energy density targets that equal or exceed 1,000 watt-hours per kilogram and 1,000 watt-hours per liter at the end of life, Giner will evaluate a suite of best-in-class catalyst, ionomer, and membrane materials to find the best performing fuel cell configuration. This includes novel, highly active stable PtCo catalysts with well-controlled particle size and composition, such as pH Matter’s PtCo/MFCS-C catalyst, which have been synthesized for enhanced fuel cell performance and durability at dry conditions, eliminating the need for a humidifier. Initial performance testing will be followed by long term accelerated stress tests on small scale membrane electrode assemblies (MEAs).
Acknowledgement: The project is financially supported by the Department of Energy’s ARPA-E Office (Phase I Grant).
1. “Electric Vehicle Outlook 2022” BNEF https://bnef.turtl.co/story/evo-2022.

Figure 1
Synthesis of Transition Metal Carbide Catalysts for Hydrogen Evolution Reaction
Authors: Qi Jing , Zhai Yunfeng , Bethune Keith 
Published: December 2024

Water electrolysis is one of the most promising ways for hydrogen production. Transition metal carbides are regarded as potential candidates to replace state-of-art but expensive platinum-group catalysts for hydrogen evolution reaction (HER). Considering the excellent electrochemical stability of TiC, a bimetallic VTiC with minor percentage of Ti would increase stability. Vanadium carbides were prepared from commercially available TiC as carbon sources and supports at 1000°C (denoted as VxTiC-1000°C) and 1100°C (denoted as VxTiC-1100°C). As shown in Figure 1a, VxTiC-1000°C and VxTiC-1100°C are a mixture of V8C7 and (Ti0.3V1-0.3)2O3 phases. While VxTiC-1000°C contains some unreacted TiC. Figure 1b shows numerous flakes grown on the particle surface of VxTiC that are expected to possess extremely large surface area. There is no phase change for VxTiC before and after treated in 3 M H2SO4 at 80 °C which means that VxTiC is acid resistant. Stability tests for VxTiC performed in 0.5 M H2SO4 up to 1.4 V exhibit excellent electrochemical stability and catalytic activity of VxTiC toward HER.
Figure 1. (a) X-ray diffraction patterns and (b) scanning electron microscopy image of VxTiC.

Acknowledgments

Authors are grateful to the Office of Naval Research (award N00014-19-1-2159, N00014-120-1-2270).

Figure 1
A Multiscale Modeling Approach to Investigate the Influence of Catalyst Layer Materials in Proton Exchange Membrane Fuel Cells
Authors: Jahnke Thomas , Gülicher Konrad , Mitzel Jens , Morin Arnaud 
Published: December 2024

In order to enable a simulation-based improvement of the MEA design, detailed physical models are required which accurately describe all relevant processes. This poses a major challenge as these processes span over about 10 orders of magnitude from the atomistic scale up to the cell and stack scale. In order to simulate the cell performance, volume averaged models are needed which describe the mass-, charge- and energy transport as well as the electrochemical reactions. The required transport and kinetic parameters are often unknown and material dependent. Therefore, lower scale models and dedicated experiments are required to determine these material dependent properties.
In this work we present a multiscale model developed within the project FURTHER-FC [1] which takes into account the microstructural properties of the cathode catalyst layer and GDL/MPL. Lattice Boltzmann modeling is used to derive the local oxygen transport resistance in the CCL on the sub-µm scale, while the effective transport properties through the thickness of the CCL and the GDL/MPL are obtained from DNS [2]. On the cell scale a 2D along-the-channel volume averaged model is developed which, in addition to the relevant transport processes, includes the contributions of inner and outer platinum particles to the ORR as well as the effect of ionomer poisoning. A thorough model validation is conducted where a particular focus is put on the hysteresis observed in polarization curve measurements as well as on the impedance spectra. The model is applied to MEAs with different catalyst layer materials and the effect of high surface area carbon (HSAC) vs. graphitized carbon as well as HOPI vs. D2020 as ionomer is investigated.
Figure: left: comparison of MEAs with HSAC and graphitized carbon at 80°C, 80%RH, 2 bar and 0.2 bar O2 ; right: model validation with impedance simulations for graph. carbon MEA

The project FURTHER-FC has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under Grant Agreement No 875025. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research.

[1] https://further-fc.eu/
[2] M. Ahmed-Maloum et al., Journal of Power Sources 561 (2023) 232735

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The Effect of Crystal Structure of Si Anode on Electrochemical Properties for Lithium-Ion Batteries
Authors: Yang Minji , Shim Jae-Hyun 
Published: December 2024

Silicon anode attention as a promising next-generation anode material capable of achieving high capacity/high density lithium-ion batteries, possesses the advantage of an extremely high theoretical capacity of 3,800 mAh/g. Si anode materials are known to experience volume expansion of about 400% during charging and discharging, leading to material cracking as a consequence. Therefore, in order to effectively utilize Si anode materials, it is necessary to mitigate the volume expansion issue by designing materials with lower expansion. For this, understanding the electrochemical mechanism differences of Si anode materials according to their crystal structure is crucial.
In this study, Si is synthesized using the RF thermal plasma synthesis technique. Using the synthesized Si anode material, fabricate SLP(single layer pouch type) cells and evaluate their electrochemical characteristics such as cyclability at room temperature and high temperature, C-rate, impedance and swelling. The results of the electrochemical characterization will be compared and analyzed, and compare materials with maximum and minimal expansion rates based on differences in crystal structure.
To analyze the irreversible phases related to the crystal structural differences during initial charging and discharging processes, Si 100% coin half cells be fabricated for ex-situ XRD analysis. Additionally, for more precise analysis, TEM analysis technique employed for comparative analysis.
In Situ Multi-Site Plasma Focused-Ion-Beam Tomography on Li-Electrolyte Interface in All-Solid-State Batteries
Authors: Risal Samprash , Milapati Sanam , Fan Zheng 
Published: December 2024

All-solid-state lithium metal batteries, poised to deliver one of the highest specific energy among rechargeable batteries, establish themselves as a front-runner for next-generation electric vehicle batteries; nevertheless, realizing high-performance solid-state Li batteries remains challenging due to the high impedance and (for the anode side) uncontrolled Li deposition at the interfaces between active electrode materials and solid electrolytes. The lack of direct and quantitative characterization tools for the active material−electrolyte interfaces has been a major hurdle towards high-performance solid-state batteries. Most studies had to rely on indirect characterization methods to approximate the identity, distribution, and evolution of species and structures at the interfaces. This work demonstrates a combined diagnostics of the interfaces and their evolutions during cell operation using in situ multi-site plasma focused-ion-beam (pFIB) tomography.
Utilizing the advanced capabilities of pFIB technology, which offers significantly higher material removal rates compared to gallium-based systems, we significantly reduce the duration of tomography sessions. This efficiency enhancement not only accelerates the morphological data acquisition but also supports the continuous and multi-site application of pFIB tomography on a single specimen through its electrochemical reaction cycle. In this experiment, the Li-electrolyte interface within a trilayer battery structure (Li/electrolyte/NMC-electrolyte composite) was characterized in situ at multiple sites using FIB. The tests were performed in a custom-built transfer vessel equipped with an in situ testing platform, enabling air-free specimen transfer from an argon-filled glovebox to the pFIB-SEM setup. This system also facilitates in situ charge/discharge cycling under simulated real-world conditions, including environmental stimuli like heating and pressing. The open-cell design of the battery specimen on this platform, with exposed and polished interfaces, provides direct visibility into the interface dynamics that is comparable to traditional Swagelok-cell setups but with enhanced observational capabilities.
The resultant tomography models from the Li-electrolyte interface during charging and discharging cycles elucidate the structural evolution of the components under different operational statuses. Key observations include the initiation, growth, and interaction of Li dendrites within the electrolyte layer, and the development of voids at the Li-electrolyte interface, particularly their dynamics during battery operation. While these phenomena have been extensively studied using other diagnostic techniques, the application of in situ multi-site pFIB offers unprecedented insights into the morphological changes induced by battery cycling, thereby contributing to a comprehensive understanding of the failure mechanisms in solid-state batteries.
(Invited) Let’s Roll – the Roll-to-Roll Consortium for Fuel Cell and Electrolyzer Manufacturing
Authors: Mauger Scott A , Serov Alexey , Zhang Yuepeng 
Published: December 2024

Proton exchange membrane fuel cell and electrolyzer manufacturing are in the early stages of rapid expansion. Many companies have announced plans for significantly increase their manufacturing capacity through new facilities or expansion of existing facilities. This increase in scale is necessary to achieve system-cost and emission-reduction targets. However, manufacturing speed is not a knob that can simply be turned up to produce high performance, durable systems. Manufacturing processes must be understood and developed to produce fuel cells and electrolyzers that meet the requirements for both throughput and performance.
The U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office (HFTO) has launched a new consortium, the Roll-to-Roll (R2R) Consortium, to conduct process science and engineering research for fuel cell and electrolyzer manufacturing. R2R’s mission is to advance efficient, high-throughput, and high-quality manufacturing methods and processes to accelerate domestic manufacturing and reduce the capital cost of durable and high-performing systems. Three major research thrusts in catalyst synthesis process science, MEA fabrication process science, and quality control are set to address challenges associated with high-volume manufacturing, which is supported by additional activities including the development of characterization tools suited for the needs of the manufacturing environment, process modeling, artificial intelligence and machine learning, and technoeconomic analysis (TEA). The objective of these activities is to enable increased production speed, yield, and efficiency to achieve fuel cell and electrolyzer manufacturing rate and cost targets. This talk will provide an overview of the R2R Consortium’s research activities.
Improvement of CO2 Conversion By Infiltration of Metal Additives (Ag, Cu, Ni, Co, and Ce) to Decorate Sr2Fe1.5Mo0.5O6-
δ Cathodes for Solid Oxide Electrolysis Cells
Authors: Lee Yi-Hsuan , Wei Tengruei 
Published: December 2024

The transformation of CO2 into CO and its conversion into biofuels has become a topic of interest due to the increasing severity of global warming. Solid oxide electrolysis cells are considered as one type of device to address this challenge. In this study, the cathode used for the electrolysis cell was Sr2Fe1.5Mo0.5O6-
δ (SFM). Surface modification was performed by infiltrating Ag, Cu, Ni, Co, and Ce at an operating temperature of 800 °C. The SFM sample before H2 reduction treatment show a performance of 100 mA/cm2 at 1.6 V, which is significantly lower than the 196 mA/cm2 achieved after reduction treatment. According to the XRD results, the formation of SrMoO4 before reduction could be a factor affecting its performance.
Furthermore, I-V curves were observed for SFM samples that were infiltrated with Ag, Cu, Ni, Co, and Ce before the reduction treatment. The performance of the infiltrated samples was better than that of the untreated SFM sample. Samples infiltrated with Ag and Cu exhibited a turning point at approximately 1.4 V, where the current density decreased significantly with increasing voltage. The Faradaic efficiency results for CO production indicate that the efficiency of Ag and Cu samples without reduction treatment significantly decreased at voltages above 1.4 V. This phenomenon was not observed in pure SFM samples. It is suggested to be due to the partial supply of current after 1.4 V was not utilized for CO2 reduction but rather for the reduction of Ag and Cu oxides.
Samples treated with H2 exhibited a significant increase in current density. Additionally, the turning point phenomenon observed in Ag and Cu samples was eliminated. SrMoO4 in SFM disappears after reduction treatment. Additionally, the Ag and Cu oxide particles involved in the reaction transform into nano-metal particles that no longer consume supplied electrons. Thus, the Faradaic efficiency results after reduction treatment were higher than that of the pure SFM sample. The Ag sample achieved conversion efficiencies of up to 90%.