bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topological Insulator Bismuth-Antimony Alloy Contact for Two-Dimensional Semiconductor Based Electronics
Authors: Park Hyunjun , Kwon Gihyeon , Chu Jaeyoon , Cho Mann-Ho 
Published: December 2024

Two-dimensional (2D) semiconductors are considered as the most promising candidate for channel materials in next-generation electronic devices owing to their atomically thin nature [1]. In order to minimize the overall chip size, it is imperative to reduce both the channel length and the contact area of the devices. However, the reduction in contact area inevitably leads to an increase in the contact resistance (RC), and recent studies have been devoted to solving this problem. In particular, the significant achievements in reducing the RC to near quantum limits in 2D semiconductor based field-effect transistors (FET) were reported using semi-metal as bismuth (Bi) and antimony (Sb) as contact metals [2,3]. In spite of these advancements, research on the scaling-down of the metal contact with the exploration of alternative contact materials to shrink overall chip footprint remains limited.
To overcome these limitations, we propose the topological insulator (TI) as a contact metal for 2D-based electronics. TI is known to enable electron transport without backscattering at the surfaces owing to its unique surface band structures [4]. Result from these properties, the RC increase with a contact area reduction is lower compared to conventional metals, indicating high potential for TIs as an interconnector in extreme scaling regimes [5]. Additionally, the Dirac cone band structure on TIs surface [6] is expected to suppress metal-induced gap states (MIGS) similar to semi-metal contacts [2-3].
In this study, a 2D semiconductor FETs was fabricated with Bi-Sb alloy as the electrode material. Bi-Sb alloys are known to exhibit the TI phase with Sb composition ranging from 7% to 22% [7]. A 20 nm thick Ti-phase Bi-Sb alloy was synthesized using molecular beam epitaxy (MBE) on exfoliated MoS2 flakes with pre-patterned contact areas using a standard e-beam lithography process. The device was then completed by capping the TI contacts with gold. A systematic investigation of the electrical properties of the device showed that the on-current with the contact of the Ti-phase Bi-Sb alloy is enhanced compared to the bismuth-only configuration. Through this research, we aim to improve the contact characteristic of 2D based electronics in nano-scale regimes, and provide insights that can contribute to the development and commercialization of next-generation electronic devices.
References
[1] M. Chhowalla, et al., Nat. Rev. Mat, 1, 1-15 (2016).
[2] P. C. Shen, et al., Nat. 593, 211-217 (2021).
[3] W. Li, et al., Nat 613, 274-279 (2023)
[4] Y. Xia, et al., Nat. Phys, 5, 398-402 (2009).
[5] T. M. Philip, et al., IEEE Electron Device Letters, 38, 138-141 (2016).
[6] S. Tang and M. S. Dresselhaus, J. Mater. Chem. C, 2, 4710-4726 (2014)
[7] L. Fu, et al., Phys. Rev. B, 76, 045302 (2007).
(Invited) Progress in Fast 4H-SiC Crystal Growth and Defect Reduction By High-Temperature Gas-Source Method
Authors: Tsuchida Hidekazu , Kanda Takahiro 
Published: December 2024

Practical applications of 4H-SiC Schottky barrier diodes (SBDs) and metal-oxide-semiconductor field-effect transistors (MOSFETs) have started in various fields. Ongoing efforts to improve the productivity and quality of 4H-SiC wafers are crucial to further expand the production volume of the SiC power devices. The sublimation method is a standard growth process to produce SiC bulk crystals. In the method, powder source is sublimated at a temperature of ~2200ºC and recrystallized on a seed crystal. Although the growth techniques to obtain large diameter (150-200 mm) SiC substrates have developed using the sublimation method, the growth rates remain in about 0.3-0.5 mm/h. We have attempted to realize much higher growth rates in SiC crystal growth by the high-temperature gas-source method (high-temperature chemical vapor deposition) using SiH4 and C3H8 as the source gases and obtained ~3 mm/h or more at a high growth temperature at 2500-2550ºC and high input partial pressure of the source gases (>10 kPa for SiH4) [1]. Another topic in the high-temperature gas-source method can be realizing dislocation densities lower than those of the seed crystals. In the proper conditions, we observe no significant increase in the dislocation densities in the early stage of the growth and gradual reduction of the dislocation densities along the growth direction. In this paper, we introduce the key techniques in obtaining a high growth rate and high material quality in SiC bulk crystal growth by the high-temperature gas-source method.
[1] H. Tsuchida and T. Kanda, Materials Science in Semiconductor Processing 176 (2024) 108315.
(Invited) metal Organic Framework Templates for the Fabrication of High Performance Photoanodes
Authors: Rosei Federico 
Published: December 2024

The study of structure property/relationships in advanced materials is promising towards obtaining systems with desired functionalities. Such systems can then be used as building blocks for the fabrication of various emerging technologies. In particular, nanostructured materials synthesized via the bottom–up approach present an opportunity for future generation low cost manufacturing of devices. We focus in particular on recent developments in solar technologies that aim to address the energy challenge [1-5].
Here we present the use of Metal Organic Frameworks (MOFs) as templates for the fabrication of high performance photoanodes in next generation solar technologies. In particular, we describe the realization of NiO, mixed phase TiO2 and In2O3/CuO p-n heterojunction composite photoelectrodes, obtained using MOFs [6-8], for photoelectrochemical hydrogen generation from water.
[1] Nano Energy
79, 105416 (2021); [2] Chem. Eng. J.
446, 137312 (2022); [3] ACS Appl. Mater. Int.
15, 56413 (2023); [4] Small Meth.
8, 2300133 (2024); [5] J. Mater. Chem. A
11, 23821 (2023); [6] Appl. Cat. B
263, 118317 (2020); [7] Small
18, 2201815 (2022); [8] Small
19, 2300606 (2023).
(Invited) bridging MOFs to Applications Via Machine Learning
Authors: Moosavi Mohamad 
Published: December 2024

MOFs (metal-organic frameworks) are materials with the potential to significantly improve several energy-related applications by allowing customization of their properties. However, traditional scientific methods make the process of discovery of scalable materials that perform well in industrial processes slow and complicated. This is due to the need for a holistic approach that considers the entire design process, including exploring vast materials spaces, linking them to their properties, synthesis, and process design and engineering. To tackle this challenge, we are developing tools using machine learning and artificial intelligence to help navigate the vast design space, uncover hidden relationships between material properties and performance, and accelerate MOF design.
In this discussion, I'll elaborate on how these novel tools are being used to quantify the structural diversity of large MOF material databases, develop physics-constrained machine learning methods for low-data design tasks, learn from failures to design better experiments and perform the inverse design of MOFs.
Leveraging Functional High-Entropy Oxide Perovskites for Enhanced Piezocatalytic Degradation
Authors: Liu Heng-Jui , Ye Yi-Chen , Tsai Yun-Wei 
Published: December 2024

The escalating prevalence of water scarcity resulting from extreme climate events highlights a critical global challenge. This scarcity emphasizes the need for wastewater recycling, emphasizing the pivotal role of the water cycle in sustaining life and ecosystems. Among various wastewater treatment processes, chemical methods stand out for their high pollutant removal efficiency, scalability, and versatility in addressing diverse wastewater types. Advanced Oxidation Processes (AOPs) are particularly favored due to their low energy consumption, minimal equipment requirements, and superior remediation efficiency. Catalyst-triggered AOPs, particularly piezocatalytic processes, have recently emerged as highly promising systems, utilizing functional materials like ferroelectrics or piezoelectrics to degrade toxic organic pollutants with the assistance of sonication.
This presentation unveils a potential piezocatalyst system based on the concept of high entropy materials, demonstrating a rapid dye removal strategy. Specifically, we explore a lead-based high entropy perovskite, Pb(Mg,Nb,Zr,Ti,Hf)O3 (PMNZTH), through two synthesis methods to study its dye removal efficiency and corresponding mechanism. Hydrothermal-synthesized PMNZTH exhibits significant dark adsorption and piezocatalytic dye degradation effects simultaneously, achieving approximately 90% dye removal efficiency within 60 minutes. Results suggest that K2O compounds from the synthesis environment enhance PMNZTH's dark adsorption capability by increasing specific surface area and surface potential. This research underscores the potential of high entropy perovskites as efficient adsorbents and catalysts for wastewater treatment.
In the second part, focusing solely on the piezocatalysis effect on dye degradation, we adopt PMNZTH synthesized through the solid-state method. This approach offers a straightforward method to elucidate the proper mechanism behind two controversial models for piezocatalysis — the screening charge effects and energy band theory — by investigating key parameters such as piezoelectric coefficient and band gap. Results indicate a positive correlation between dye removal efficiency and the piezoelectric coefficient, but an inverse relationship with the band gap as the Ti/Hf element ratio varies, suggesting the dominance of screening charge effects in piezocatalysis. Our work provides insights into piezocatalysis mechanisms and proposes a rational design concept using high entropy materials as potential piezocatalysts for water purification.
Synthesis of Co@N-C Porous Electrocatalysts in Alkaline Electrolytes and Their ORR Applications
Authors: Kim Hee Soo , Lee Hae In , Lim Dong-Ha , Cho Jaehoon 
Published: December 2024

In recent years, petrochemical-based energy sources have been used for decades, and many researchers have been trying to switch from petrochemical energy sources to clean energy sources to solve the problem of global warming. Among the various green energy sources, fuel cells that use hydrogen and oxygen as raw materials to generate energy from water and electricity have recently gained attention. However, problems such as platinum's small reserves and poor durability have been a major obstacle to the widespread use of fuel cells. In order to solve these problems, we synthesized catalysts in the form of carbon composites doped with inexpensive transition metals and nitrogen with excellent electrical conductivity and evaluated their performance as ORR catalysts in alkaline electrolytes. Depending on the optimal heat treatment synthesis conditions and the ratio of Co and dopamine precursor, we found the best synthesis method in alkaline conditions of 0.1 M KOH, which shows excellent ORR performance due to the synergistic effect of nitrogen-doped carbon and Co. Although the performance is still inferior to that of commercial platinum catalysts, further improvements are expected to improve the performance to that of platinum catalysts.
<This research was supported by PEO24016 (KITECH)>

Figure 1
Catalytic Activities of Pt-Y-Ni/C Synthesized Using Microwave-Polyol Process for Oxygen Reduction Reaction in PEMFC
Authors: Kim Tae-Won , Jeong Seo-Jin , Lee Hyeon Bin 
Published: December 2024

Developing highly active and durable catalysts for sluggish cathodic oxygen reduction reaction (ORR) has been a core issue for the broad commercialization of proton exchange membrane fuel cells (PEMFCs) Despite Pt/C being used as a typical ORR catalyst in commercial PEMFC stacks, lots of efforts are being made to overcome the high loading and poor durability of Pt/C [1]. Recently, the notable results of Pt-based binary alloys with rare-earth metals or transition metals have been reported to demonstrate promising catalytic performance as an ORR catalyst [3, 4]. Nevertheless, further optimization for higher activity and durability of ORR catalysts under harsh operating conditions is strongly required from the viewpoint of the industrialization of PEMFCs.
In this study, we report highly active and durable Pt-based ternary electrocatalysts, PtYNi/C, synthesized using a simple microwave-polyol process. The Pt-based ternary electrocatalysts were uniformly dispersed on the surface of the V-72R carbon support, with mean particle sizes ranging from 3.4 to 4.2 nm, depending on the composition ratio of Pt, Y, and Ni. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) measurements using a rotating disk electrode (RDE) revealed that the specific activity of the PtYNi/C catalysts decreased from 602 mA/cm² to 332 mA/cm², and the mass activity decreased from 390 mA/mgPt to 264 mA/mgPt at 0.9ViR-free, as the Pt content decreased from 90 at% to 65 at% in the PtYNi/C catalysts. Nevertheless, these values are superior to those of the TKK Pt/C catalysts used as a reference. We have demonstrated that the reduction of Pt loading by alloying with abundant elements can be achieved using microwave-polyol synthesis, thereby enhancing the activity of the catalyst. In the presentation, we will discuss the detailed structural, compositional, and chemical characterization results for PtYNi/C synthesized using microwave-polyol synthesis, including their catalytic activity loss after 30k ADT cycles.
References

K. Debe, Nature, 2012, 486,43–51.

Cui, R., Mei, L., Han, G. et al. Scientific Reports., 2017, volume 7, 41826

Shaik Gouse Peera, et al. Sustainable Energy Fuels, 2019,3, 1866-1891
Carbon-Embedded Pt Alloy Cluster Catalyst: Properties and Oxygen Reduction Activity
Authors: Shin Sang yong , Lee Hyunjoo 
Published: December 2024

Carbon-embedded PtFe alloy cluster catalysts have emerged as promising candidates for enhancing the performance and durability of oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). These catalysts, synthesized through a multi-step process involving carbonization of hyper-crosslinked polystyrene particles with Fe precursors, doping of nitrogen species, deposition of Pt precursors, and subsequent reduction, exhibit remarkable properties and catalytic activity.
Advanced imaging techniques, including aberration-corrected scanning transmission electron microscopy (ADF-STEM) and scanning electron microscopy (SEM), have revealed that the metal clusters are embedded beneath the carbon support surface. X-ray absorption fine structure (XAFS) analysis further confirmed the Pt-Fe alloy structure of the metal clusters, which are approximately 1.5 nm in size. The carbon-embedded PtFe alloy cluster catalysts demonstrate high mass activity and exceptional durability for the ORR. Despite being embedded within the carbon matrix, the Pt sites within the clusters serve as active sites for electrochemical reactions. Co-adsorption of Br- ions with protons alters cyclic voltammetry (CV) curves similarly to typical Pt/C catalysts, indicating the accessibility of Pt sites. Moreover, small molecules such as protons formic acid, and methanol can effectively diffuse through the carbon layer to reach the Pt surface.
When applied in the cathode of PEMFCs with a low Pt loading of 0.05 mg Pt cm-2, the PtFe cluster catalysts exhibit high current density at 0.65 V and excellent durability. After 30,000 cycles, the current density remains nearly unchanged, highlighting the superior performance of these catalysts compared to conventional Pt/C or PtFe/C catalysts. Density functional theory (DFT) calculations further elucidate the catalytic mechanism of the carbon-embedded PtFe alloy clusters. Carbon atoms stably adsorb on Fe sites of PtFe clusters, making nearby Pt sites active for ORR with optimal adsorption strength of oxygen intermediates. This comprehensive understanding of the catalytic behavior and properties of carbon-embedded PtFe alloy cluster catalysts opens up new avenues for the development of highly active and durable ORR catalysts in PEMFCs, with minimized Pt usage.

Figure 1
Enhancement of Alkaline OER Performance of the Electroplated Ni-P Catalysts Using Electrochemical Dealloying Technique
Authors: Oh Hyunjun , Eom Kwang Sup 
Published: December 2024

With the growing attention on renewable energy, hydrogen is receiving attention as an energy carrier to resolve the temporal and spatial constraints of renewable energy. Electrical energy generated from renewable energy can be efficiently stored and transported in the form of hydrogen. Here, water electrolysis consists of two reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and the high activation energy of OER is the main bottleneck of water electrolysis. Consequently, highly active catalysts are indispensable. Currently, the Pt- and Ir-based noble metal catalysts boast the highest performance for OER, but face significant commercialization hurdles due to their high cost.
Transition metal-based compounds are promising as substitutes of Platinum group materials for OER catalysts due to their high catalytic activity and earth-abundant properties. In particular, transition metal phosphides (TMPs) such as Ni-P are receiving much attention due to its remarkable catalytic performance approaching that of Pt-based one. In Ni-P, electrons are transferred from Ni to P due to the difference in electronegativity, allowing the energy of the HER and OER intermediate to be controlled for optimal activity. Furthermore, the Ni-P synthesized through electrodeposition has high potential as a promising substitute because they can have a variety of P ratios on the N-P surface, that can significantly affect catalytic activity and improve it more. Unfortunately, however, the electrodeposited Ni-P mostly has a flat and aggregated morphology, resulting in a low surface area and hence low catalytic performance. Therefore, to maximize the catalytic performance of the electroplated Ni-P. it is necessary to increase in surface area and number of active sites as well as the optimization of surficial P ratio.
In this context, we propose a morphology control method using electrochemical dealloying, which can greatly increase the surface area of the electroplated Ni-P. Specifically, under acidic conditions, a potential higher than the reduction potential of Ni causes partial dealloying of Ni on the Ni-P catalyst. Then, the partial dealloyed Ni creates defects between grains and forms a porous structure. As a result, the surface of the dealloyed Ni-P catalyst was exposed along the grain boundaries through SEM, and a quantitative increase in surface area was confirmed through cyclic voltammetry (CV). In addition, it was confirmed through XPS analysis that the bond between Ni and P became stronger, and based on this, it was confirmed that the tafel slope and TOF of the catalyst increased. The increase in overall performance of the catalyst was confirmed through the polarization curve as surface area and intrinsic activity increased.

Figure 1
Highly Active Raney-Nickel Electrodes Based on 3D Pin Structures for Use in High Temperature Alkaline Electrolysis
Authors: Albers Justin , Lau Marius , Bernaecker Christian Immanuel , Ashaju Abimbola , Harbiye Ahmad , Weissgaerber Thomas , Key Adam 
Published: December 2024

The efficiency of alkaline electrolysers can be improved in a multitude of ways from overall system design to optimal operation conditions. One possibility is to increase the operating temperature which usually is 80 °C for industrial electrolysers. Increasing the temperature is a straightforward way to increase system efficiency significantly but leads to escalating corrosion problems due to the high concentration of KOH and the presence of oxygen (dissolved and gas phase) in the anolyte.
In this work we have developed highly active electrodes for the use at 120 °C. The electrodes are based on engineered 3D pin structures that were coated with Raney-Nickel. Since the interplay between electrode structure and catalyst layer are crucial for electrode performance in alkaline electrolysis a selection of nickel pin structures based on nickel mesh with differences in pillar as well as hole shape and size were investigated to find a optimal configuration. The aluminum for the formation of leachable NiAl-phases was applied by rolling Aluminum foil of varying thickness onto the pin structures. A following heat treatment and leaching resulted in a layer of Raney-Nickel on the substrates. The general performance at standard operating conditions was investigated as well as the behavior at 120 °C in 40 wt% KOH. The obtained electrodes showed excellent performance at a current density of 500 mA/cm² with overvoltages below 110 mV as cathodes and below 300 mV as anodes. During these tests and an additional testing campaign, the corrosion resistance of the Ni substrate and specially developed alloys under anodic conditions were evaluated.

Figure 1
The Potential of Ruthenate Pyrochlores As Anodic Electroctalysts for PEM Water Electrolysisoral Presentation
Authors: Heath Megan Muriel , Fosdal Closs Elise , Sunde Svein , Reksten Anita Hamar , Sunde Tor Olav , Müller Magdalena , Røe Hågen , Rajbhandari Abhishek , Seland Frode 
Published: December 2024

Green hydrogen is becoming a hot commodity in the light of escalating oil and gas prices and their uncertain future availability. Among various electrolysis technologies, PEM water electrolysis (WE) is favorable for its portability, modularity, and the ability to integrate with intermittent, renewable energy sources. However, the upscaling of PEMWE is not feasible yet due to the need for rare and expensive metals as electrocatalysts. Specifically, iridium oxide is used as state-of-the art anodic electrocatalyst. Ruthenium oxide also has an excellent activity towards the anodic oxygen evolution reaction (OER), but is highly unstable. To address this limitation, this study investigates ruthenate pyrochlores as alternative anodic electrocatalysts. The pyrochlore structure may stabilize ruthenium. The pyrochlores in this study have been synthesized using a traditional citrate sol-gel method,1 as well as a novel combustion synthesis route. Physical characterization of the electrocatalysts has been conducted using x-ray diffraction (XRD), scanning (transmission) electron spectroscopy (S(T)EM) and Raman spectroscopy. Additionally, ex-situ electrochemical characterization has been performed in a three-electrode setup. Linear-sweep voltammetry results of Y2Ru2O7 synthesised via the citrate sol-gel route indicate an overpotential of 300 mV at a current density of 10 mA cm-2. This result agrees well with what has previously been reported for this electrocatalyst.2 Y2Ru2O7 synthesised via the novel combustion route performs better than the aforementioned due to increased surface area. Various A-site dopants have also been introduced into the pyrochlore structure to generate oxygen vacancies, modify the electronic structure and increase the stability. These materials have also been tested in a full-cell setup to gauge their performance for practical applications compared to state-of-the-art IrO2 and RuO2.

References

(1) Kim, J.; Shih, P.-C.; Tsao, K.-C.; Pan, Y.-T.; Yin, X.; Sun, C.-J.; Yang, H. High-Performance Pyrochlore-Type Yttrium Ruthenate Electrocatalyst for Oxygen Evolution Reaction in Acidic Media. J. Am. Chem. Soc.
2017, 139 (34), 12076–12083.
(2) Feng, Q.; Zou, J.; Wang, Y.; Zhao, Z.; Williams, M. C.; Li, H.; Wang, H. Influence of Surface Oxygen Vacancies and Ruthenium Valence State on the Catalysis of Pyrochlore Oxides. ACS Appl. Mater. Interfaces
2020, 12 (4), 4520–4530.