bluuebunny/crossref_metadata_2025 huggingface dataset:
(Digital Presentation) Electrochemical Behavior of Ionic Liquid Modified of Lithium Bis(fluorosulfonyl)Imide Based Electrolyte for Lithium-Ion Batteries
Authors: Thien Phung Thien , Akhtar M. Shaheer , Yang O-Bong
Published: November 2022

The high efficient energy storage, lithium-ion batteries (LIBs) is accounted as one of the most important storage devices to facilitate the transition of renewable energy conversion. The electrolyte component is the most important in deciding the capacity of LIBs. Lithium bis(fluorosulfonyl)imide (LiFSI) is recently considered as promising conducting electrolyte salt for LIBs because it shows enabling high voltage, high energy density, long cycle life, and accelerates the fast-charging Li-ion batteries. Generally, Additionally, LiFSI and LiPF6 based electrolyte are used in the most of commercial LIBs. Last few years, LiFSI is regarded as an alternative electrolyte to the classical LiFP6 due to its high ionic conductivity, good thermal stability, and HF free nature. In this work, the controlled mixing of ionic liquids (ILs) (imidazolium salts and pyridinium salts) in LiFSI electrolyte was carried out to enhance the ionic conductivity, thermal stability, viscosity, and solubility in organic solvents. The ILs modified LiFSI electrolyte was prepared by adding a constant 1.0 M LiFSI and varying the concentration of ILs from 5 to 20% volume in trimethyl phosphate (TMP). After the modification by ILs, the ionic conductivity of LiFSI electrolyte (10.623 mS/cm) was considerably increased as compared to LiFSI only. The flammability test of electrolyte revealed that ILs modified LiFSI electrolyte was non-flammable, indicating excellent stability in any circumstances. The prepared ILs modified LiFSI electrolyte was used to fabricate coin cell LIBs using double-coated side electrodes (both CMS graphite/Li-NCM (5:2:3) and CMS graphite/LiFePO4). From GCD analysis, the fabricated LIBs with ILs modified LiFSI electrolyte showed a significant improvement in the charging/discharging ability as compared to commercial LIBs with LiPF6 electrolyte. This study manifests that the modification of LiFSI by novel ILs would be promising to achieve highly efficient liquid electrolytes for high performance LIBs.
K-Edge and L-Edge Spectroscopy of Ni0.8Mn0.1Co0.1O2 Cathodes Under Expanded Voltage Conditions Via Soft X-Ray Absorption Spectroscopy
Authors: West Patrick J , Quilty Cavlin , Li Wenzao , Dunkin Mikaela R. , Wheeler Garrett , Kern Christopher , Tallman Killian , Housel Lisa M. , Takeuchi Esther S. , Takeuchi Kenneth J. , Bock David C , Marschilok Amy C.
Published: November 2022

Mixed transition metal oxides, such as Ni0.8Mn0.1Co0.1O2 (NMC811), are intended to combine the high capacity of nickel oxides, the rate capability of cobalt oxides, and the structural stability of manganese oxides to meet the capacity and power demands of electric vehicles and commercial portable electronics. However, the capacity fade mechanisms in Ni-rich chemistries (x >y+z in NixMnyCozO2) can be elusive due to factors at the crystallographic, particle, or electrode level. In this study, bulk and surface x-ray spectroscopy characterization of NMC cathodes was used to explore cathode degradation mechanisms as influenced by cycling protocol, namely current rate and upper voltage limits. Soft x-ray absorption spectroscopy (sXAS) was used to probe the surface of recovered NMC electrodes via transition metal L-edge and O K-edge spectroscopy. The effect of rate and upper voltage potential under charge will be discussed to illustrate the versatility of sXAS for NMC cathode electrode characterization.
Novel Rechargeable Lithium-Ion Battery Based on a Cathode of Potassium-Cobalt(II) Octacyanomolybdate
Authors: Muñoz Eduardo , Rojas Victor , Cáceres Gustavo , López Silvana , Navarrete Emilio , Herrera Francisco , Caballero Álvaro , Gomez-Camer Juan Luis
Published: November 2022

In this work, the influence of the synthesis parameters (concentration, temperature, and reaction time) on the electrochemical performance of potassium-cobalt(II) octacyanomolybdate (KCoOCM) as a cathode material for its application in lithium-ion batteries was studied. The compound was synthesized hydrothermally using a chemometric approach and characterized by different techniques (FESEM, XRD, TGA). The KCoOCM showed a change in its morphology from prismatic structures to nanorods according to the synthesis conditions. Additionally, there was an influence on the specific capacity as a function of the synthesis parameters, i.e., precursor’s concentrations, temperature, and reaction time. The capacity values reached by the material was 50 mAh g−1, which is close to the theoretical value of the KCoOCM (60 mAh g−1). The statistical method employed would allow finding a condition where it is possible to maximize the capacity value of the material, which has been scarcely studied in this area. Finally, the performance of a lithium-ion battery based on a cathode of KCoOCM is reported for the first time in literature.

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Malonic-Acid-Functionalized Fullerene Enables the Interfacial Stabilization of Ni-Rich Cathode in Lithium-Ion Batteries
Authors: Lee Eunryeol , Park Chanhyun , Kim Su Hwan , Kwak Sang Kyu , Choi Nam-Soon , Song Hyun-Kon
Published: November 2022

The continued demand for long-lasting batteries essentially drives us to contribute to a development of high-performance cathode materials, because a cathode material which is one of essential components in Li-ion batteries (LIBs) critically determines an overall energy density of a battery. High-capacity Ni-rich NCM (x > 80%, LiNixCoyMnzO2, x+y+z=1) cathode materials have been regarded as one of the most promising candidates to realize high-energy density Li-ion batteries. However, the complete application has been limited due to some critical problems, especially the unstable interfacial stability resulting from the massive formation of residual lithium compounds and the severe electrolyte decomposition. In this study, we investigate the roles of fullerene-based electrolyte additive in Ni-rich NCM-based LIB system and reveal that the fullerene-based additives functionalized with malonic acid moieties, MA-C60, effectively stabilize the unstable interface of Ni-rich cathodes, which are demonstrated by combined experimental and computational studies. According to differential electrochemical mass spectroscopy (DEMS), nuclear magnetic resonance (NMR) analysis and the first principles calculation, the MA-C60 additives deactivate reactive radical species (O2
•-, LiOCO3
•, and Li(CO3)2
•) induced by electrochemical oxidation of residual lithium compound, Li2CO3 on the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode surface thanks to a highly favorable affinity of the malonic acid moieties with the reactive radical species. Furthermore, the additive mitigates the parasitic reaction of residual lithium compounds with LiPF6 through the formation of a stable cathode-electrolyte interphase. These roles of the new additive effectively prevent an aging in the cell system by suppressing attacking the interface of Ni-rich cathodes against the harmful reactive oxygen species and drastically enhance the cyclic performance over 400 cycles (nearly ~50 % improvement of capacity retention). Our work offers the potential of new-type of fullerene-based additive for the stable cathode-electrolyte interphase and would help to realize a commercialization of high-energy density LIB cathodes.

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Chemically and Microstructurally Tailored Concentration Gradient Layered Cathode for Advanced Li-Ion Batteries
Authors: Park Geon-Tae , Kim Myoung-Chan , Sun Yang-Kook
Published: November 2022

The recharging capability of Ni-rich layered cathodes deteriorates rapidly upon cycling, mainly from mechanical instability caused by removing a large amount of Li ions from the host structure.1,2 The resulting microcracks expose the cathode particle interior to electrolyte attack in addition to undermining the mechanical integrity of the cathode particle. In this study, we develop a Ni-rich layered cathode by combining precursor engineering and a new doping strategy during lithiation that generates minimal microcracking and exhibits substantially improved cycling stability. Excess Al is deliberately introduced into a concentration-gradient (CG) hydroxide precursor, which exhibits a highly oriented geometry in which elongated primary particles are aligned in the radial direction of a spherical secondary particles. The excess Al ions enable the refinement of the primary particles in a controlled manner and the precise tailoring of their morphology and orientation. It is demonstrated that the chemical and microstructural engineering of a Li[NixCoyAl1–x–y]O2 (NCA) cathode starting from its precursor stage produces a unique structure that relieves the detrimental mechanical strain and significantly extends the battery life. Thus, the designed CG Li[Ni0.86Co0.1Al0.04]O2 retains 86.5% of the initial capacity after 2000 cycles and an unprecedented 78.0% even at a severe operation condition of 45 oC. The proposed CG Li[Ni0.86Co0.1Al0.04]O2 represents a new class of Ni-rich NCA cathodes that can meet the energy density required for next-generation electric vehicles, without compromising the battery life and safety.

Reference
s
:

[1] S. Watanabe, M. Kinoshita, T. Hosokawa, K. Morigaki, K. Nakura, J. Power Sources 258 (2014) 210–217.

[2] H.-H. Ryu, K.-J. Park, C. S. Yoon, Y.-K. Sun, Chem. Mater. 30 (2018) 1155–1163.
Influence of Polymeric Binders on Robust Performance of Lithium-Ion Electrodes
Authors: Gonzalez Miguel , Gueon Donghee , Renderos Genesis , Marschilok Amy C. , Takeuchi Kenneth J. , Takeuchi Esther S. , Reichmanis Elsa
Published: November 2022

Lithium-ion batteries have become ubiquitous in a variety of energy storage applications ranging from grid storage to consumer electronics to electric vehicles. However, their continued usage in a vastly dynamic world predicates on their ability to be not only safe, sustainable, and reliable, but also contain high capacity under a variety of fast charge/discharge conditions. Multiple studies have shown that increased performance at fast charge/discharge rates can be achieved through systematic manipulation of key interfaces at various nano-, micro- and mesoscales of the electrode. Through careful tuning of the processing and chemical modification of polymeric binders, capping agents, and conductive additives, rational design of battery electrodes with specific performance characteristics can be achieved. Careful manipulation of interfacial chemistries can help push the boundaries of electrochemical performance in a wide variety of cell components. This presentation will focus on the chemical manipulation of polymers within a composite electrode to gain fundamental insights needed for the realization of next-generation battery systems.
Solvent-Based Electrode Recovery Toward Sustainable Direct Recycling of Lithium-Ion Batteries
Authors: Bai Yaocai , Belharouak Ilias
Published: November 2022

Lithium-ion batteries (LIBs) are dominating in the fields of consumer electronics and electric vehicles. Given the high demand and fast-growing market of LIBs, manufacturing of LIBs is ramping up dramatically, so are the electrode scraps and end-of-life batteries. One promising recycling approach is to directly recover electrode materials like NMC and graphite with useful morphology and comparable electrochemical performance, which will substantially reduce the battery costs, mitigate both energy and environmental impacts, as well as secure the battery supply chain. However, electrode materials are tightly adhered to metal current collectors, making it challenging for separation and recovery. To this end, a green solvent-based recovery process, which enables low-temperature and highly efficient separation of electrode materials from their current collectors without damaging active electrode materials nor corroding metal foils, will be presented. In addition, we will demonstrate the direct recycling and reprocessing of electrode scraps for new battery manufacturing. It is believed that the solvent-based electrode recovery process developed here paves the way for the direct recycling of LIBs.
Optimized Purification Methods for Metallic Contaminant Removal from Directly Recycled Li-Ion Battery Cathodes
Authors: Fink Kae , Colclasure Andrew M. , Schulze Maxwell
Published: November 2022

The viability of emerging direct recycling techniques for lithium-ion battery materials relies on achieving a high-purity material output. Residual metallic contaminants in recycled cathodes are of particular concern, as they introduce significant variability in cell performance and may cause catastrophic cell failure. Thus, shredded battery materials (i.e., black mass; BM) must undergo a purification process to remove metallic contaminants. In the present work, we demonstrate optimized process conditions for the corrosion of solid impurities to ionic form using tailored alkaline chemistry, without incurring damage to the target cathode material (Li(NixMnyCo1-x-y)O2; NMC). Complete ionization of industrially relevant levels of Al and Cu impurities is achieved under conditions of mildly elevated temperature, ultrasonication, and the use of a chelating agent. Structural (XRD, SEM) and electrochemical (impedance, cycling, dQ/dV) analysis of NMC subject to treatment conditions suggests that purification method does not disrupt the cathode’s bulk physico-electrochemical properties. We have applied this purification technique to a laboratory-simulated BM and demonstrated a restoration of pristine performance. Finally, we report on our efforts to tune post-treatment conditions to ensure optimal surface structure and chemistry for subsequent direct recycling processes.

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Interplay of Lithium Plating Quantification on Thermal Safety Characteristics of Lithium-Ion Batteries
Authors: Zhou Hanwei , Fear Conner , Joshi Tapesh , Jeevarajan Judith , Mukherjee Partha P.
Published: November 2022

Adverse lithium plating is a significant side reaction during the fast charging of lithium-ion (Li-ion) batteries when the Li-ion flux exceeds the intercalation or diffusion limits of graphite electrodes. Accurate quantification of lithium plating has always been a tough challenge given the severe defects of online detection methods such as coulombic efficiency and voltage relaxation plateau, making the mathematical correlation between cell-level thermal safety hazards and quantitative lithium plating events still a bottleneck problem. In this study, we apply a three-electrode (3E) Li-ion cell configuration and the accelerating rate calorimeter (ARC) to comprehensively investigate the interplay of unfavorable lithium plating on thermal runaway characteristics of Li-ion batteries. Lithium plating is introduced by cycling 3E Li-ion cells at low temperatures and quantified by analyzing potential-based plating energy, coulombic inefficiency, internal resistance, and voltage relaxation plateau. Surface microscopic characterization is carried out on graphite electrodes to reveal the morphologies and chemical states of lithium deposition. ARC experiments are implemented at full-cell and partial-cell scales to fundamentally understand the effects and contributions of thermally unstable lithium plating to the overall safety performance of Li-ion cell chemistries.
(Invited) III-Oxide/III-Nitride Heterostructures for Power Electronics and Optoelectronics Applications
Authors: Fu Houqiang
Published: November 2022

Due to their large bandgap, high critical electric field, and availability of high-quality large-size melt-grown bulk substrates, III-oxides including Ga2O3, Al2O3, In2O3, and their alloys have been extensively investigated for a myriad of electronic and optoelectronic applications. Recently, β-Ga2O3 based power electronics, RF transistors, and ultraviolet (UV) photodetectors have been demonstrated with promising performance. However, p-type β-Ga2O3 is still elusive due to high dopant activation energy (>1 eV), large hole effective mass, and hole trapping. This significantly limits the design freedom for β-Ga2O3 devices. Other p-type semiconductors have been proposed to form heterostructures with β-Ga2O3 such as p-NiO, p-Cu2O, and p-type III-nitrides. As popular wide bandgap semiconductors, III-nitrides are promising candidates to form III-oxide/III-nitride heterostructures to enable advanced device structures and new functionalities. Furthermore, III-oxides and III-nitrides can be epitaxially grown on each other with small lattice mismatch (< 5% for GaN and β-Ga2O3) by the industrial standard epitaxial method MOCVD. For example, vertical GaN violet LEDs grown on n-type β-Ga2O3 substrates have been reported. This talk will present our recent work on III-oxide/III-nitride heterostructures in power electronics and optoelectronics.

For power electronics, β-Ga2O3/GaN p-n heterojunctions will first be discussed. The heterojunction via mechanical exfoliation shows decent forward rectifying behaviors and thermal stability up to 200 °C but relatively low breakdown voltages (BV). To improve the breakdown capability, we carried out a comprehensive TCAD simulation study to design mesa edge termination for kV-class β-Ga2O3/GaN p-n heterojunctions. It was found that the electric field crowding effect is the main reason for the low BV. Several mesa edge termination structures were investigated such as deeply-etched mesa, step mesa, and p-GaN guard ring. Second, normally-off AlN/β-Ga2O3 field-effect transistors using polarization-induced doping will be discussed. A large two-dimensional electron gas is formed at the AlN/β-Ga2O3 interface due to polarization effects, and p-GaN gate is used to realize tunable positive threshold voltage. The device transfer and output characteristics with different device structures are also studied. For optoelectronics applications, self-powered spectrally distinctive Ga2O3/GaN heterojunction UV photodetectors grown by MOCVD will be discussed. Opposite current polarities are observed under different illumination wavelengths due to different carrier transports, which can be utilized to distinguish different spectra. These results indicate that (ultra)wide bandgap III-oxide/III-nitride heterostructures are a promising platform to enable new device structures and functionalities.
Intrinsic Channel Mobility Associated with Extended State Transport in IGZO TFTs
Authors: Kabir Muhammad Salahuddin , Powell Eli , Manley Robert G. , Hirschman Karl D.
Published: November 2022

There is wide variation in the understanding of the interaction and/or independence of channel mobility and charge trapping in IGZO TFTs. A new interpretation of transport behavior proposes an intrinsic channel mobility with distinctive temperature dependence. Bottom-gate TFTs were fabricated with a 50 nm IGZO film sandwiched between a 50 nm gate oxide and a 50 nm passivation oxide layer. The working metal was molybdenum for the gate electrode and source/drain contacts. A passivation anneal was done and a capping layer was added to promote electrical stability; full process details are provided in a previous report. Devices were tested using a Lakeshore cryogenic probe station, with transfer characteristic measurements taken from room temperature to below 100 K.

Electrical measurements made on long-channel devices (L = 12 µm) has revealed temperature-dependent behavior that is not explained by existing TCAD models employed for defect states and carrier mobility. An IGZO TFT device model has been recently developed using Silvaco Atlas, which accounts for the role of donor-like oxygen vacancy defects, acceptor-like BTS, acceptor-like interface traps, and a temperature-dependent intrinsic channel mobility. The model demonstrates a remarkable match to transfer characteristics measured at T = 150 K to room temperature. The temperature-dependent mobility follows a power-law relationship resembling behavior consistent with ionized defect scattering; the source of which is proposed. Details of the material and device model, and associated defect distribution parameters will be presented.

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(Invited) Hydrogenated Polycrystalline In2O3 (In2O3:H) Thin-Film Transistor with High Mobility Exceeding 100 cm2V−1s−1 Via Solid-Phase Crystallization
Authors: Magari Yusaku , Kataoka Taiki , Yeh Wenchang , Furuta Mamoru
Published: November 2022

Oxide semiconductors have been extensively studied as active channel layers of thin-film transistors (TFTs) for electronic applications. However, the field-effect mobility (μ
FE) of oxide TFTs is not sufficiently high to compete with that of low-temperature-processed polycrystalline-Si TFTs (50–100 cm2V−1s−1). Here, we propose a simple process to obtain high-performance TFTs, namely hydrogenated polycrystalline In2O3 (In2O3:H) TFTs grown via the low-temperature solid-phase crystallization (SPC) process. In2O3:H TFTs fabricated at 300 °C exhibit superior switching properties with µ
FE = 139.2 cm2V−1s−1. The hydrogen introduced during sputter deposition plays an important role in enlarging the grain size and decreasing the subgap defects in SPC-prepared In2O3:H. The proposed method does not require any additional expensive equipment and/or change in the conventional oxide TFT fabrication process. We believe these SPC-grown In2O3:H TFTs have a great potential for use in future electronic applications.
(Invited) Oxide TFT Applications: Principles and Challenges
Authors: Kuo Yue
Published: November 2022

The main advantage of the thin film transistor (TFT) is that it can be fabricated on non-wafer substrate independent of the size, flexibility, and morphology. All composing films of the TFT are deposited at the low temperature. Therefore, TFTs can be applied to a broad range of consumer, biological, chemical, and optical products that are difficult to fabricate with the wafer based MOSFETs.

There are many reports on a-Si:H and poly-Si TFT applications in displays, imagers, sensors, drivers, flexible electronics, and circuits (1,2). In principle, oxide TFTs can be applied to similar products. However, since the device characteristics and compositing materials of the oxide TFT are different from those of the a-Si:H and poly- Si TFTs, as shown in Figure 1 and Table 1, there are advantages and disadvantages in former’s applications. In this presentation, oxide TFT applications in the following three areas will be discussed.

Control of the attached device, such as pixel-driving in displays,

Integrated circuits, such as drivers or inverters, and

Changing of characteristics with environment, such as pH, optical, and temperature sensors.

L. Antonuk, Chapt. 10, and Y. Kuo, Chapt. 11, Amorphous Silicon Thin Film Transistors, pp. 395-505, Kluwer Academic Publishers, 2004.

B.-D. Choi, et al., Chapt. 11-13, Polycrystalline Silicon Thin Film Transistors, Y. Kuo Editor, pp. 360-495, Kluwer Academic Publishers, 2004.

Kuo and G. W. Chang, ECS Trans, 64(10), 145-153 (2014).

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(Invited) Carbon Dots – Unlocking Optical Properties for Applications in Imaging, Sensing and Energy
Authors: Naccache Rafik
Published: November 2022

In recent years, nanomaterials (defined as materials < 100 nm in a single dimension) have garnered a significant interest for the development of novel applications in the physical and life sciences. One such class of nanomaterials are carbon dots, a relatively new member in the carbon allotrope family, which possesses versatile optical properties rendering it attractive for sensing, catalysis, bioimaging and drug delivery applications, to name a few. Their ultra-compact size, low cytotoxicity, resistance to photo-bleaching/blinking and tunable photoluminescence, combined with simple, environmentally-friendly and low-cost synthesis, makes them ideal candidates for study. We synthesize carbon dots via bottom-up synthesis methods, with simple organic precursors (e.g. citric acid) as the carbon source. We passivate the surface of our carbon dots to achieve high fluorescence quantum yields. Moreover, our work focuses on trying to elucidate the fluorescence mechanisms in carbon dots, which remain a subject of debate. Finally, we exploit their optical properties in order to design multifunctional materials as chiral, pH or temperature sensors, as well as heterogeneous catalysts for green energy applications.
(Invited) Carbon Materials for Sustainability
Authors: Dong Pei
Published: November 2022

To pursue a sustainable society, there is an urgent need of having energy-efficient devices with green processes. To effect this change, materials design plays a key role in supporting new emerging technologies. For example, hybrid & hierarchical structures could give scientists the ability to create specifically tailored nanocomposites that combine the advantages of each material constituent to enhance functionality. This talk summarizes current efforts on the design, synthesis, and characterization of carbon materials and their applications in water treatment, public health, and energy areas.
(Invited) Nanostructured Electrochemical Devices and Self-Powered Systems for Biosensing
Authors: Lin Yuanjing
Published: November 2022

Self-powered systems for biosensing have attracted tremendous research interest in recent years, mainly due to the rapidly expanding market of wearable and portable devices for applications in clinical diagnosis and physiological monitoring. In our work, novel and unique hierarchical nanostructures were designed and synthesized to realize electrochemical devices with high performance, especially the sensor stability and energy storage capability. Meanwhile, scalable and printable approach was developed to integrate these electrochemical devices into monolithically integrated self-powered systems. The as-developed nanostructured electrochemical devices in conjunction with printable approach show great potency in fabrication of various wearable integrated self-powered devices for personalized healthcare monitoring applications. Our research highlights are as follow:

Development of nanoporous membranes for electrochemical sensor applications. It eliminates enzymes escaping and provides sufficient surface area for molecular/ion diffusion and interactions, so as to ensure the sustainable catalytic activities of the sensors and generate reliable measurable signals during noninvasive monitoring. The highly improved stability of sensors is extremely desirable for investigation of metabolic activities in physiological systems.

A fully integrated and self-powered system in a smartwatch fashion for continuous monitoring of sweat glucose levels during both equilibrium status and dynamic activities. The smartwatch can be self-powered by flexible photovoltaic cells, without external charging, the harvested energy can also be stored in the flexible Zn-MnO2 batteries as backup power source. It is also capable for real-time and in situ data analysis/display with integrated circuit board and E-ink screen.

A monolithically integrated self-powered smart sensor system with energy supplied by fully printable planar supercapacitors and embedded solar cells, was fabricated on plastic substrate with inkjet printing technique as a proof-of-concept. The as-developed printable nanostructured electrochemical devices in conjunction with printable approach for system integration show great potency in fabrication of various wearable integrated self-powered devices for personalized healthcare monitoring applications.
(Invited) Flexocatalysis of Single Pt Atoms Loaded Graphitic Carbon Nitride (g-C3N4)
Authors: Wang Yu Teng , Wu Jyh-Ming
Published: November 2022

Single-atom catalyst as an advanced co-catalyst shows promising potential in energy fields such as water splitting, degradation of pollutants, chemical conversion field, etc. It takes advantage of increased active sites and sub-nanometer size effects with electron confinement by reducing the size of supported noble metals; furthermore, a single-atom catalyst maximizes the atomic efficiency of metals and provides a low atomic coordination number for the active center. In this work, we discovered that the isolated single atoms (SAs) stabilized by the support of g-C3N4 as named by SA-Pt/g-C3N4. Single-atom catalyst is synthesized by anchoring Pt atoms in graphitic carbon nitride (g-C3N4) with different Pt-loading [0.01wt% to 1wt% H₂PtCl₆·(H₂O)₆]. Under flexocatalytic process, the k rate constant of the SA-Pt/g-C3N4 with 0.01wt% of Pt is 3×10-3 s-1 for decomposition of dye molecules, which is 2 times the pristine g-C3N4. In addition, the flexocatalytic hydrogen evolution of SA-Pt/g-C3N4 provides H2 production, reaching nearly 125 μmolgh-1, which is 312% of the pristine g-C3N4 (~40 μmolgh-1). The working mechanism of flexocatalytic activity suggests the mechanical strain-induced flexoelectric potential (flexopotential) and proceeding with redox's electrochemical reaction. In addition, the single-atom act as a critical role in attracting electrons to accelerate the reaction process. The single-atom catalyst of 2D materials is highly potential for applying in water splitting and degradation of pollutants through the flexocatalytic process.
(Best Student Presentation Award) Ppb-Level Detection on Formaldehyde By Phase-Engineered 2D-WSe2 Layers Grown By Plasma-Assisted Chemical Vapor Reaction
Authors: Kuo Tzu-Wen , Kuangye Wang , Lee Pin-Hsien , Wu Pei-Hua , Lee Ling , Chueh Yu-Lun
Published: November 2022

Layered transition metal dichalcogenides (TMDs) have attracted increasing attention for semiconducting applications owing to their distinctive properties, such as high surface-to-volume ratio, good electronic transport and phase-engineered. However, most of the methods for fabricating thermodynamic metastable phase have so far been induced by conventional CVD process. The high synthesis temperature may cause damages to the substrate and also the processing time is extended. In this concept, here, we incorporated a plasma function into a typical selenization process, which is then applied to metal oxides, namely, a plasma-assisted chemical vapor reduction (PACVR) process, to overcome the disadvantage of CVD process since the presence of high-energy Se ions under plasma treatment lower the energy barrier for a reaction and facilitate the formation of TMDCs at lower temperature. In this work, we developed a facile method to achieve phase control and report a ppb-level detection gas sensor on formaldehyde. Tunable phase synthesis of WSe2 can be achieved by varying conditions such as temperature, carrier gas flow rate and plasma power in a low-temperature PACVR system. Through the detailed investigation of chemical bonding in WSe2 by Raman and XPS, it was found that 100% 2H phase and hybrids of 1T’ and 2H phases can be achieved, and the ratio of 1T’/2H is tunable, relying on substrate temperatures under plasma treatment. By investigating the sensing behavior towards HCHO gas, the performance is highly associated to the ratio of 1T’/2H. The responsivity of 33 % can be achieved with the ratio of the hybrids around 0.46 in WSe2. The phase-engineered 2D-WSe2 layers grown by plasma-assisted chemical vapor reaction with tunable performance can be applied to detect other VOCs efficiently.

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Ultrasound-Mediated Triboelectric Nanogenerator as an Innovative Energy Solution for on-Demand Transient Electronics
Authors: Lee Dong-Min , Kim Sang-Woo
Published: November 2022

On-demand transient electronics, technologies referring subsequent material disintegration under well-defined triggering events and programmed timelines, offer exceptional clinical experiences in diagnosis, treatment, and rehabilitation. Despite potential benefits, such as the elimination of surgical device removal and reduction of long-term inimical effects, their use is limited by the non-transient conventional power supplies. Here, we report an ultrasound-mediated transient triboelectric nanogenerator where ultrasound determines the energy generation and degradation period. Our findings on finite element method simulation show that the porous structures of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) enables opposing transient behaviors under different ultrasound intensity, 0.5 W/cm2 and 3.0 W/cm2. Besides, the addition of polyethylene glycol improves triboelectric output performance; the voltage output increased by 58.5 %, from 2.625 V to 4.160 V. We successfully demonstrate the tunable transient performances by ex-vivo experiment using a porcine tissue. This study provides insight into practical use of implantable triboelectric nanogenerators based on ultrasound-triggered transient material design.
(Digital Presentation) Resistive Switching and Brain-Inspired Computing in Perovskite Nanowires and Quantum Wires
Authors: Poddar Swapnadeep , Zhang Yuting , Chen Zhesi , Ma Zichao , Fan Zhiyong
Published: November 2022

In the past decade, halide perovskites (HPs) have shot to fame in the genre of optoelectronics and photovoltaics owing to their large absorption co-effcient, high color purity, tunable bandgap and long charge diffusion lengths. Besides these traits, HPs also possess innumerable charge transport pathways, inherent hysteresis, high charge-carrier and ionic mobilities which render them as ideal candidates for resistive random access switching memories (RRAMs). However owing to material and electrical instability associated with HP thin-film devices, the figures-of-merits (FOMs) namely retention, endurance and switching speed were not up to the state of-the-art standard until recently. In order to revolutionize HP Re-RAMs we devised a unique device structure where we replaced the thin-film architecture with vertically aligned high density HP nanowires and quantum wires embedded in a porous alumina membrane (PAM) sandwiched between metallic silver and aluminum contacts. The excellent passivation provided by the PAM imparted the requisite electrical and material stability to the environmentally delicate HPs by drastically reducing the surface diffusion pathways and thereby thwarting the moisture induced attacks. Extrapolated retention time as high as 28.3 years and measured device endurance of a million cycles were obtained. Utilizing the single crystalline HP nanowires and quantum wires and their associated high ionic and electronic mobilities, switching speed as fast as 100 ps was also obtained. These FOMs represent record values for HP RRAMs ever reported. Furthermore a 14 nm lateral size HP quantum wire RRAM cell was fabricated and a cross-bar device architecture with a unique sneaky path mitigation scheme were developed, which successfully exhibited the scalability potential of our devices. We further coupled the optoelectronic and switching behaviors and were able to obtain optical programmability among the low resistance states. Besides data storage, the HP nanowires and quantum wires were employed in developing neuromorphic devices enabled with low power and high precision computing capabilities. Specifically, we obtained robust multi-level states in two types of brain-inspired devices capable of performing analog processing tasks by using silver as the top electrode and precisely controlling the current injection in the monocrytalline switching medium and by using indium doped tin oxide as the top electrode and inducing a novel valence change mechanism in the HP nanowires triggering the gradual conductance change. All in all, our nanowire and quantum wire devices propel HP RRAMs to the state-of-the-art standard in multifarious applications concerning future data storage and neuromorphic computing.
(Invited, Digital Presentation) Vertical Heterogeneous Integration of Metal Halide Perovskite Quantum-Wires/Nanowires for Flexible Narrowband Photodetectors
Authors: Zhang Daquan , Fan Zhiyong
Published: November 2022

Charge collection narrowing (CCN) has been reported to be an efficient strategy to achieve optical filter-free narrowband photodetection (NPD) with metal halide perovskite (MHP) single crystals. However, the necessity of utilizing thick crystals in CCN limits their applications in large scale, flexible, self-driven, and high-performance optoelectronics. Here, for the first time, we fabricate vertically integrated MHP quantum wire/nanowire (QW/NW) array-based photodetectors in nanoengineered porous alumina membranes (PAMs) showing self-driven broadband photodetection (BPD) and NPD capability simultaneously. Two cutoff detection edges of the NPDs are located at around 770 and 730 nm, with a full-width at half-maxima (fwhm) of around 40 nm. The optical bandgap difference between the NWs and the QWs, in conjunction with the high carrier recombination rate in QWs, contributes to the intriguing NPD performance. Thanks to the excellent mechanical flexibility of the PAMs, a flexible NPD is demonstrated with respectable performance. Our work here opens a new pathway to design and engineer a nanostructured MHP for novel color selective and full color sensing devices.

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(Invited) Progress in Elucidating the Growth Process for Basic Ammonothermal GaN
Authors: Pimputkar Siddha
Published: November 2022

Gallium nitride (GaN) is an attractive materials platform for the pursuit of high-power, high-efficiency (opto-)electronic devices. Key to allowing this wide band gap material system to achieve its full potential is the availability of low-cost, large-area, high-crystal-quality native substrates. While important advances have been made to this effect, continued progress and breakthroughs are required to truly meet this objective.

The ammonothermal method, which utilizes supercritical ammonia to preferentially dissolve and crystalize GaN on a native seed, offers a true bulk crystal growth process to yield large, inexpensive GaN substrates. To further enhance the growth rate and quality of GaN, much still needs to be learned and gained from an improved understanding of the chemical processes and growth mechanisms occurring in the ammonothermal environment. A key challenge to achieving this, is the difficulty in obtaining in-situ information during growth of GaN due to the use of thick-walled autoclaves containing the corrosive environment at temperatures up to ~ 650 °C and pressures up to ~ 2500 atm.

This talk will present the progress made in our understanding of the underpinnings of the basic ammonothermal growth of GaN. Specifically, it will discuss advances made to allow us to understand the thermodynamic foundation of the solvent, for the first time. This is achieved by the creation and application of a new, simple equation of state for supercritical ammonia under ammonothermal conditions. Additionally, by combining this solvent knowledge with in-situ temperature, total system measurements, and GaN single crystal growth, various aspects of the crystal growth process and solute behaviors are elucidated and will be presented. Consequences towards our ability to enhance the growth rate of basic ammonothermal GaN will then be discussed.
Investigation of the Area Defects in Ammonothermal Grown Gallium Nitride Substrate Wafers
Authors: Liu Yafei , Peng Hongyu , Chen Zeyu , Cheng Qianyu , Hu Shanshan , Raghothamachar Balaji , Dudley Michael
Published: November 2022

Gallium Nitride (GaN) is one of the most promising wide band gap semiconductor materials that are replacing silicon (Si) in power electronic applications. However, the quality of the material is limiting its application in high performance power electronic materials. Apart from the threading dislocations reported in our previous studies [1, 2], some area defects are observed in both ammonothermal GaN substrates by synchrotron X-ray topography (XRT) (Figure 1). Information on the nature of these defects is important to prevent the formation of such defects and improve the crystal quality.

In this study, synchrotron X-ray rocking curve topography (SXRCT), Nomarski optical microscopy (NOM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) are adopted to investigate the nature of the area defects. Apart from XRT images, these domain features are visible in the NOM images (Figure 2). SXRCT results show that these areas have a different strain level from the rest of the wafer area. SEM images in RBSD mode show that the area defects are observed as a diffraction contrast. To investigate the atomic configuration of these domains, HRTEM of specimens sliced from the domains are being compared with those from outside the domains. The characterization results from SXRCT, SEM and TEM analysis in conjunction with observations from other techniques like XRT and NOM will be discussed to determine the nature of the area defects and their formation mechanisms will be deduced.

[1] Y. Liu, B. Raghothamachar, H. Peng, T. Ailihumaer, M. Dudley, R. Collazo, J. Tweedie, Z. Sitar, F.S. Shahedipour-Sandvik, K.A. Jones, Journal of Crystal Growth 551 (2020) 125903.

[2] Y. Liu, H. Peng, T. Ailihumaer, B. Raghothamachar, M. Dudley, Journal of Electronic Materials 50 (2021) 2981-2989.

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Effect of Transition Metal (Fe, Co) Ion Doping on TiO2 Nano Particles.
Authors: Siddhapara kirit Kumar
Published: November 2022

Keywords: Growth from solution, Nanomaterials, Oxides, Photocatalytic, Sol-Gel method, DMS.

Abstract.
we report the growth of [Fe, Co]xTiO2 (x=0.01, 0.02 & 0.04) Nano quantum dots prepared by Sol-Gel technique, followed by freeze-drying treatment at -30°C temperature for 12hrs. The obtained Gel was thermally treated at different temperature like 200,400,600, 800°C. The crystalline size of 4 to 40 nm is achieved. X-ray diffraction pattern of samples show anatase phases of TiO2, up to 600°C. At 800°C, the phase is Rutile. Figure 1 shows the XRD patterns acquired from different samples heated at different temperatures. The diffraction peak at 25.22°, 25.49°and 25.6° observed from the XRD pattern of the Fe, Co doped TiO2 shows that the main crystal phase is anatase, and the peak at 27.47° indicates the presence of the rutile phase. All the peaks in the XRD patterns of the sample calcined at 200°C, 400°C and 600°C of TM doped TiO2 can be designated to the anatase phase (most active phase) without any indication of other crystalline phases such as rutile or brookite . As a variant valence metal cation, Fe, Co ions can react with Ti4+ on the surface of TiO2, and Ti4+ is reduced to Ti3+ which inhibits the transformation of anatase to rutile [1]. It leads to the reduction in the oxygen vacancies on the TiO2 surface and suppresses the crystallization of other phases by adsorbing onto the surface of the TiO2 particles [2]. The photocatalytic degradation of formaldehyde has been successfully demonstrated using a 250 V UV lamp with TM doped TiO2 nano powder in a specific experimental setup. The degradation rate increases linearly with dopant content increases. This indicates that the photocatalytic reaction in this experiment was effected by dopant concentration. The results obtained in this research contribute to the understanding of binary doped transition metal ions in TiO2 nanoparticles can lead the efforts of enhancing their environmental application. Study of Magnatic proprty has been carried out by using VSM. The magnetic susceptibility of the Fe, Co doped TiO2 nanopowder increases with increase in doping concentration. Fe, Co doped TiO2 exhibits ferromagnetism at room temperature.

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(Digital Presentation) Liquid-Metal-Printed Ultra-Thin ITO-Thin-Film Transistor
Authors: Tang Yalun , Nomura Kenji
Published: November 2022

Indium oxide is one of the promising materials for the n-channel layer for high-mobility oxide-TFT because of its high electron mobility characteristics due to the nature of spatially spread-In 5s orbital. However, excess carrier electrons in In-based channels cancel field-effect gate modulation and causes the formation of a short depletion layer. Moreover, it is challenging to reduce the electron density without the degradation of electron transport. Therefore, developing fully-depletion operated TFT using an ultra-thin channel is a straightforward strategy to demonstrate the high potential of In-based materials for TFT applications.

In this work, we developed an ultra-thin tin-doped Indium oxide (ITO) channel (~ 1.9 nm-thick.) and demonstrated a fully-depleted ITO-TFT exhibiting high mobility of 27 cm2/Vs. The ITO channel was grown by a cost-effective vacuum-free liquid-metal-printing route at the maximum process temperature of ~ 200 oC in an ambient atmosphere. Post-thermal annealing in air made significant improvement of device characteristics originating from the reduction of shallow acceptor-like in-gap defects in the ITO channels, and high-performance n-channel ITO-TFT with a large on/off-current ratio of 109 and a sharp threshold slope was achieved. By controlling air-annealing temperature, we also successfully fabricated both enhancement and depletion-mode devices and developed a full signal swinged-oxide-NMOS inverter composed of a depletion-load structure.
Platinum Dissolution Induced Catalyst Layer Degradation in Polymer-Electrolyte Fuel Cells for Heavy-Duty-Vehicle Applications
Authors: Boyer Hailey , Radke Clayton J. , Weber Adam Z.
Published: November 2022

Interest in electrifying the transportation sector has intensified as the value in reducing carbon emissions is recognized globally. Polymer-electrolyte fuel cells (PEFCs) provide an option for electrifying transportation if hydrogen is produced electrolytically from water and without carbon emissions if the electricity is provided by renewable energy resources. Though research in fuel cell powered vehicles has been ongoing, hydrogen infrastructure and concerns about hydrogen storage safety limit the technology’s uptake in the passenger vehicle market. However, fuel cells applied to heavy-duty-vehicle (HDV) transportation may address these shortcomings. HDV provide predictable routes allowing for more simple hydrogen infrastructure and larger cargo allowance in HDV allows for more secure hydrogen storage and safety. Fuel-cell-powered-HDV require higher operating temperature, pressure, and potential to realize the power-demands of the vehicle, therefore, durability requirements increase, and a better understanding of degradation is a priority. A major cause of performance degradation is due to catalyst dissolution, migration, and reprecipitation. This causes a loss of electrochemically active surface area (ECSA) which reduces the activity of the catalyst and is particularly detrimental in the cathode where the limiting factor for performance is often sluggish oxygen reduction kinetics. This loss in ECSA is due to an overall broadening of the particle size distribution (PSD) within the catalyst layer and a net loss of catalyst to the formation of a Pt band in the membrane. In this work, a Pt catalyst degradation model is developed which considers particle size dependent Pt oxidation and dissolution kinetics, Pt migration, and reprecipitation of Pt within the cell. This work interrogates the particle size dependence of these processes to explain experimentally observed loss in ECSA and changes in PSD. The degradation model is coupled with a PEFC performance model through the ECSA loss to study how the HDV-relevant operating conditions impact the cathode catalyst degradation behavior observed in PEFCs.