bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemically Mediated Amine Regeneration for Efficient CO2 Separation: Development and Characterization of Blend Electrolytes
Authors: Hassan Ahmad , Rahimi Mim
Published: February 2024

Climate change mitigation necessitates the development of effective carbon dioxide (CO2) separation technologies. A wide range of electrochemical processes were recently developed for CO2 separation from various sources, including high concentration streams such as power plant flue gas and dilute streams like air [1]. Our focus is on the electrochemically mediated amine regeneration process, which is inspired by the conventional amine scrubbing process. This novel electrochemical approach offers a sustainable and potentially lower energy alternative for CO2 separation, with reduced absorbent degradation rates [2-4]. In this presentation, we discuss our latest findings on absorbent development, with a primary focus on the electrochemical aspects. We have tested several blended amine electrolytes and investigated their impact on the electrochemical performance of the system. Key parameters, such as resistance components and heterogeneous kinetic rate transfer, were examined using electrochemical impedance spectroscopy (EIS) and rotating disk electrode (RDE) techniques, respectively. Our results demonstrate significantly improved electrochemical performance for the newly developed blend electrolyte compared to benchmark single amine systems. Furthermore, we have successfully designed and implemented a large-scale continuous electrochemical cell using the novel electrolyte formulation. This system has demonstrated efficient and continuous CO2 separation from simulated industrial power plant flue gas, paving the way for sustainable CO2 separation technologies.

References:

[1] Rahimi M, Khurram A, Hatton TA, Gallant B. Electrochemical carbon capture processes for mitigation of CO2 emissions. Chemical Society Reviews. 2022;51:8676-95.

[2] Rahimi M, Diederichsen KM, Ozbek N, Wang M, Choi W, Hatton TA. An electrochemically mediated amine regeneration process with a mixed absorbent for postcombustion CO2 capture. Environmental Science & Technology. 2020;54:8999-9007.

[3] Wang M, Rahimi M, Kumar A, Hariharan S, Choi W, Hatton TA. Flue gas CO2 capture via electrochemically mediated amine regeneration: System design and performance. Applied Energy. 2019;255:113879.

[4] Rahimi M, Zucchelli F, Puccini M, Alan Hatton T. Improved COA capture performance of electrochemically mediated amine regeneration processes with ionic surfactant additives. ACS Applied Energy Materials. 2020;3:10823-30.
Towards Electrobiofuels: Economics and Environmental Impacts
Authors: Saffron Christopher M.
Published: February 2024

Our changing climate necessitates a transition to biomass-based hydrocarbon fuels to power aviation, shipping, and long-haul trucks that service essential supply chains to deliver food, textiles, and other consumer goods including electronic devices. To accomplish this transition, renewable energy systems are needed that efficiently deconstruct biomass and superimpose non-carbon emitting electrical energy with bioenergy to increase output energy in liquid fuels. Fast pyrolysis and electrocatalytic hydrogenation (py-ECH) is a technology sequence that first converts biomass into a liquid, known as bio-oil, which is then electrocatalytically hydrogenated to stabilize its properties. Products formed after py-ECH include linear and branched polyols, tetrahydrofurans, and alkyl cyclohexanols. Evidence of lignin oligomer cleavage has also been observed, as has the subsequent appearance of monomeric cyclohexanols. Building on these encouraging results, the commercialization potential of py-ECH was determined by economic analysis and life cycle assessment. These analyses co-locate ECH after pyrolysis at decentralized biomass upgrading depots, with the aim of stabilizing pyrolysis bio-oil for subsequent transport to centralized hydroprocessing refineries. The results of these analyses suggest that electrocatalytic hydrogenation is the keystone technology for coupling non-carbon emitting electrical energy with biomass carbon to generate a greater amount of liquid fuel than otherwise possible. A pathway to liquid fuel less than $3 per gallon of hydrocarbon equivalent fuel can be established, especially if renewable electricity is provided at low cost. Finally, “electrobiofuels” can be made with negative net carbon emissions with well-managed agriculture, biochar soil amendment, and when renewable electricity powers ECH.
Investigating the Effect of Alkali Metal Cations on Kolbe Electrolysis
Authors: Ashraf Talal , Mul Guido , Mei Bastian
Published: February 2024

Carboxylic acids, a major fraction of pyrolysis oil can be transformed electrochemically in alkanes and alcohols by Kolbe and Hofer Moest reaction. The selectivity of electrochemical decarboxylation depends on various factors, i.e. electrode material and reaction conditions (supporting electrolyte, pH and current densities) which are well explained in the literature1–3. Alkali metal cations (Li+, Na+, K+, Cs+) are widely considered inert,4 nevertheless in recent studies, a significant influence on different electrochemical reactions such as methanol5,6, ethanol7, and formic acid8 oxidation is reported. It is assumed that oxygenated species present on the electrode surface form (strong/weak) non-covalent interaction with the alkali metal cations.

In this work, we studied the electrochemical oxidation of acetic acid (Kolbe electrolysis) and explored the influence of monovalent alkali metal cations (Li+, Na+, K+ and Cs+). It is observed that the product distribution and overall electrochemical activity are influenced by the presence of cations with K+ being most suitable for Kolbe electrolysis (order of activity Li+<Na+<K+~Cs+). The trend was observed irrespectively of the electrolyte conditions throughout the entire pH range at low current densities (25 mA/cm2), i.e. at pH 3 where OER is dominating, pH 5 where OER transitioned to Kolbe electrolysis and pH 9 where Hofer Moest reaction occurs. With increasing current densities (>50 mA/cm2), the influence of cations on electrooxidation diminishes showing the limitations of the effect of non-covalent interactions.

To confirm the surface coverage and transition of OER to Kolbe reaction with increasing potential, we probed reaction selectivity in the inflection zone potential regime by means of RRDE. The analysis confirmed that the OER is suppressed completely in the presence of K+ cations after reaching potentials of ~2.5VRHE (inflection zone), while for Li+, OER still proceeds as confirmed by the ORR reaction at the ring electrode. Because surface coverage reflects the high activity of Kolbe electrolysis, we confirmed that the smaller cations interfere more strongly with the electrode surface adsorbed oxygenates due to strong non-covalent interaction and thus affecting the reaction.

References

F. J. Holzhäuser, J. B. Mensah, and R. Palkovits, Green Chem., 22, 286–301 (2020).

C. Stang and F. Harnisch, ChemSusChem, 9, 50–60 (2016).

T. Ashraf, A. P. Rodriguez, B. Mei, and G. Mul, Faraday Discuss. (2023)

H. J. Schäfer, in Comprehensive Organic Synthesis, B. M. Trost and I. Fleming, Editors, p. 633–658, Pergamon, Oxford (1991)

K. Silambarasan, J. Joseph, and S. Mayavan, Applied Surface Science, 489, 149–153 (2019).

D. Strmcnik et al., Nature Chem, 1, 466–472 (2009).

C. Han et al., ACS Appl. Mater. Interfaces, 14, 5318–5327 (2022).

B. A. F. Previdello, E. G. Machado, and H. Varela, RSC Advances, 4, 15271–15275 (2014).

Figure 1
Towards Zero Waste Recovery of Li-Ion Battery
Authors: He Ze
Published: February 2024

The proliferation of lithium-ion batteries (LIBs) has prompted a critical exploration of sustainable waste management strategies within the battery life cycle. This abstract focuses on waste materials generated during LIB recycling, specifically emphasizing waste water, including the presence of lithium ions, which is most generated at delamination and leaching process, and waste graphite.

Waste water, a significant outcome of LIB recycling, often contains valuable lithium ions. Efficient extraction and purification of lithium ions from waste water not only recovers a precious resource but also mitigates the ecological consequences of improper disposal. Advanced methodologies such as solvent extraction, hydrometallurgy and membrane filtration demonstrate promising avenues for selectively recovering lithium ions from waste water streams.

Furthermore, addressing the disposal of waste graphite electrodes presents an imperative challenge. Graphite, a cornerstone of LIBs, holds substantial potential for reclamation. Innovations encompassing thermal and chemical processes have been explored for graphite extraction from discarded electrodes. In this study, the recycled graphite after heat treatment direct reuse in batteries is performed. This approach aligns with the principles of a circular economy, promoting resource efficiency and reducing the dependence on primary graphite sources.

In conclusion, the recycling of lithium-ion batteries generates waste materials, with a particular focus on waste water enriched with lithium ions and waste graphite electrodes. Confronting these challenges mandates the implementation of advanced recycling techniques. By harnessing valuable materials and alleviating environmental pressures, the LIB recycling sector can lead the transition toward sustainable practices, significantly contributing to a greener and more resource-conscious energy landscape.
(Invited) Novel Surface Reactions in Low-Temperature Regime for High-Aspect-Ratio Dielectric Etching
Authors: Honda Masanobu , Suda Ryutaro , Tanaka Koki , Yokoi Masahiko , Tomura Maju , Kihara Yoshihide
Published: February 2024

The most critical issue to achieve High-Aspect-Ratio (HAR) dielectric etching is the transport of both radicals and ions to the bottom of a feature [1]. Current HAR dielectric etching uses fluorocarbon and hydrofluorocarbon gases combined with high applied bias power. However, the etch rate drastically decreases at high depth due to the decline of radicals being supplied to the etch front. Alternative methods have long been required to solve this problem. To address the radical transport issue, we propose adopting a novel precursor with low molecular weight to enhance Knudsen transport. In addition, cryogenic temperature regimes are also known to enhance etch rates [2][3] but have not yet been implemented for HAR dielectric etching.

In this work we evaluated a novel precursor in cryogenic temperature regime for HAR dielectric etching. For the first time, we demonstrate a synergy effect between cryogenic temperature and this novel precursor by successfully developing an innovative HAR dielectric etch process. We confirmed that this process is capable of etching beyond a ten-micron depth for a 3D-NAND channel hole with a hundred nanometer critical dimension in diameter, thus an aspect ratio of over one hundred to one. The key to enabling high etch rate is strongly correlated with the adsorption of the precursor on the surface, which is enhanced at cryogenic temperature. Detailed surface adsorption reaction mechanisms will be described in the conference.

This new process not only enables higher etch rate, higher selectivity and higher aspect ratio etching capability, but also significantly shortens the process time with 84% carbon footprint reduction of greenhouse gas emissions.

[1] K. Ishikawa, et al., Jpn. J. Appl. Phys. Vol. 57, No. 6S2, 06JA01, (2018).

[2] T. Ohiwa, et al., Jpn. J. Appl. Phys. Vol.31, p.405, (1992).

[3] R Dussart, et al., J. Phys. D: 47, 123001, (2014).
Chemical Vapor Treatment to Develop Solid-Electrolyte-Interphase and Remove Residual Lithium Compounds
Authors: Pathak Rajesh , Shevate Rahul , Rozyyev Vepa , Elam Jeffrey W.
Published: February 2024

Lithium metal anode (LMA) is considered a promising material for next-generation lithium metal batteries (LMBs). The poor cycling performance of LMBs is due to the presence of residual lithium compounds (RLCs) on the LMA surface, unstable solid-electrolyte interphase (SEI), and lithium dendrite growth. In this study, an atomic layer deposition(ALD)-like process, chemical vapor treatment (CVT) has been utilized to remove RLCs such as LiOH and Li2CO3 from the surface of LMA and develop stable & robust SEI. The XPS investigation shows the conversion of LiOH and Li2CO3 surface contaminants into Li3PO4 via self-limiting surface chemical reactions. Chemical vapor-treated lithium (CVTL) symmetrical cells, and CVTL paired with high capacity/voltage cathodes demonstrated stable cycling, lower voltage hysteresis, and higher-rate capability compared to the bare LMA during electrochemical cycling. The removal of RLCs improves the Li-ion transport and the formation of robust SEI inhibits the continuous side reaction and suppresses the Li dendrite growth.

Keywords: chemical vapor treatment, lithium metal anode, solid-electrolyte-interphase, residual lithium compounds, fast charging.
(Invited) Nanostructured Solid State Battery Architectures Enabled by Atomic Layer Deposition
Authors: Kozen Alexander C
Published: February 2024

Solid state batteries (SSBs) are considered the most promising next-generation energy storage technology both due to their increased safety over conventional wet Li-ion cells and their ability to fabricate novel architectures with simultaneous high energy and power density. However, the ionic conductivities of many solid electrolyte materials are orders of magnitude lower than liquid carbonate-based electrolytes. In order to offer SSBs with competitive charge/discharge rates, SSB active layers need to be thin (for fast ion diffusion) but have a large surface area (to enable large ion flux from anode to cathode). These geometric constraints establish the need for 3D electrode (and solid electrolyte) structures for a high performance battery architecture. Atomic layer deposition (ALD) is ideally suited to fabricate such devices due to its highly conformal nature and Angstrom-scale thickness control, however many challenges remain with materials fabrication and process integration.

I will discuss development of both plasma-enhanced ALD (PEALD) and thermal ALD processes for the Li, Na, and K alkali polyphosphazene (A*PON) electrolytes1,2,3,4. The PEALD A*PON processes, by virtue of their 4-precursor synthesis route, allow some degree of chemical composition tuning. The thermal A*PON processes, unlike their PEALD counterparts, have a predetermined P-N ratio fixed by use of the precursors, however there is a tradeoff between the low temperature deposition enabled using plasma-based A*PON processes, and the conformality offered using the thermal A*PON processes. I will discuss and compare the reaction mechanisms and growth behavior among the entire family of A*PON solid electrolyte thin films, as well as discuss the integration challenges on the path to developing all-ALD planar and 3D SSBs.

Pearse, A.; Schmitt, T.; Sahadeo, E.; Stewart, D. M.; Kozen, A.; Gerasopoulos, K.; Talin, A. A.; Lee, S. B.; Rubloff, G. W.; Gregorczyk, K. E., Three-Dimensional Solid-State Lithium-Ion Batteries Fabricated by Conformal Vapor-Phase Chemistry. ACS Nano
2018,
12 (5), 4286-4294.

Pearse, A. J.; Schmitt, T. E.; Fuller, E. J.; El-Gabaly, F.; Lin, C.-F.; Gerasopoulos, K.; Kozen, A. C.; Talin, A. A.; Rubloff, G.; Gregorczyk, K. E., Nanoscale Solid State Batteries Enabled by Thermal Atomic Layer Deposition of a Lithium Polyphosphazene Solid State Electrolyte. Chemistry of Materials
2017,
29 (8), 3740-3753.

Nuwayhid, R. B.; Jarry, A.; Rubloff, G. W.; Gregorczyk, K. E., Atomic Layer Deposition of Sodium Phosphorus Oxynitride: A Conformal Solid-State Sodium-Ion Conductor. ACS Applied Materials & Interfaces
2020,
12 (19), 21641-21650.

Kozen, A. C.; Pearse, A. J.; Lin, C-F.; Noked, M.; Rubloff, G. W.; Atomic Layer Deposition of the Solid Electrolyte LiPON. Chemistry of Materials
2015,
27 (15), 5324-5331.
(Invited) Thermal Atomic Layer Deposition of Elemental Antimony and Bismuth Films
Authors: Winter Charles H. , Beh Daniel , Devereaux Zachary J. , Knisley Thomas
Published: February 2024

The elements antimony (Sb) and bismuth (Bi) are important components of many thin film materials. In many applications, films need to be grown in high aspect ratio features with perfect conformality and Angstrom-level control of film thicknesses. Atomic layer deposition (ALD) is a method that can afford uniform thickness and conformal films, even in narrow and deep nanoscale features. To date, there have been several ALD processes reported for elemental Sb films using SbCl3 and Sb(SiR3)3 (R = Me, Et), but no reports of Bi films grown by ALD have been published.1,2 Herein, several families of thermal ALD processes will be described for the growth of elemental Sb and Bi films. Precursors that were explored for Sb and Bi include SbCl3, BiCl3, BiPh3, and Bi(NMe2)3. Reducing precursors encompassed 2-methyl-1,4-bis(trimethylsilyl)-2,5-cyclohexadiene,3 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine,3 and nitrogen sources such as ammonia, hydrazine, alkyl hydrazines, and alkyl amines. The processes employing the nitrogen co-reactants are proposed to occur through unstable SbN and BiN, which then decompose with loss of N2 to afford elemental Sb and Bi films. Self-limited Sb and Bi film growth was established between 25 and 175 °C. High purity Sb (>98%) and Bi (>94%) films were demonstrated by X-ray photoelectron spectroscopy analysis. X-ray diffraction analyses revealed the growth of crystalline Sb and Bi films. The results of additional film characterization will be presented.

Al Hareri, M.; Emslie, D. J. H. Chem. Mater. 2022, 34, 2400-2409.

Pore, V.; Knapas, K.; Hatanpää, T.; Sarnet, T.; Kemell, M.; Ritala, M.; Leskelä, M.; Mizohata, K. Chem. Mater. 2011, 23, 247– 254.

Klesko, J. P.; Thrush, C. M.; Winter, C. H. Chem. Mater. 2015, 27, 4918-4921.
Effect of Surface Pretreatment to Reduce the Incubation Period of Iridium Thin Films Grown by ALD on the Oxide Surface
Authors: Jung Myung Jin , Kwon Se-Hun
Published: February 2024

Iridium (Ir) has low figure of merit(×λ) and high melting temperature properties, so it has been recently spotlighted as a very important copper (Cu) alternative interconnect material in next-generation semiconductor devices. In particular, in the case of depositing a thin film using atomic layer deposition (ALD) technology, it can be expected to deposit extremely thin film with conformal, uniform and excellent step coverage characteristics even in a very complex structure or a trench structure of several nm dimension due to the inherent self-limiting characteristic of ALD. In this regard, ALD-Ir is considered as one of the most suitable metallization process for the application of advanced semiconductor interconnects. Therefore, considerable efforts have been conducted to develop a reliable ALD-Ir process having improved film qualities. And, ALD-Ir process with excellent thin film properties such as low electrical resistivity and negligible oxygen impurities was recently reported using Tricarbonyl (1,2,3-η)-1,2,3-tri(tert-butyl)-cyclopropenyl iridium (C18H27IrO3 or TICP) precursor and oxygen [1]. However, in the case of this TICP precursor, it was difficult to deposit extremely thin and continuous Ir films on the hydroxyl-terminated oxide layer due to its long incubation delay.

Therefore, in this study, a method for depositing a very thin, uniform and continuous ALD-Ir thin film with low resistivity even on oxide materials was explored by reducing the incubation period and promoting nucleation using various surface pretreatment conditions. In addition, the nucleation behavior as well as film properties of ALD-Ir on the oxide material were systemically compared and analyzed according to the surface pretreatment conditions, and finally, ALD-Ir thin film with excellent properties on the oxide surface was obtained.
Plasma Anneal As a Stress Control Method in Low Temperature Al2O3 ALD Coatings
Authors: Kools Jacques , Zakhster Alter , Caries Pierre , Hill John
Published: February 2024

The control of mechanical physical stress is an important requirement in a variety of applications, such as flexible electronics or thick optical coatings where film stress can cause delamination. Traditionally, in thermal ALD it has been difficult to control the stress. Al2O3 deposited at low temperature is consistently found to have a tensile stress level in the range of a 300 to 450 MPa ( refs 1-3). It is well established that In magnetron sputtering , film stress can be controlled straightforwardly using the Argon pressure during deposition, as this affects the level of bombardment of the growing film with energetic particles.

Paranjpe et al ( ref 1) have demonstrated that the use of a plasma anneal leads to densification and transition of the stress from tensile to compressive. The process consists of a sequence of deposition of a thin layer ( e.g. 5 nm) by thermal ALD, followed by exposure to a low energy plasma. The atomic displacements caused by low energy ions from the plasma tend to lead to filling of nanoscopic voids and point defects, thus releasing tensile stress.

In this presentation, we will review an in depth study of the effect of various process parameters on the ability of a capacitively coupled in-situ plasma anneal to control stress. The following parameters will be reviewed:

Gas composition: Argon plasmas, Oxygen plasmas and Argon oxygen mixtures are compared.

Gas Pressure: The effect of gas pressure on plasma characteristics and the resulting modification of the coating is studied

RF Power: RF Power was varied between 0 and 300 W ( 1.32 W/cm2)

Plasma duration
: The duration of the plasma treatment was varied from 0 to 60 seconds.

A process window was identified where the plasma anneal can be used as an effective, controllable tool to reduce stress in the coatings. This is illustrated in fig. 1, which shows the substrate warpage (“bow”) observed in 75 mm thick PET foils with a 50 nm Al2O3 coating deposited at 90 °C. It can be seen that the untreated coating (0 sec plasma) has a bow corresponding to a tensile stress of 370 MPa, in accordance with literature values. As the plasma anneal time increases, the stress value decreases. Applying a 60 sec plasma every 5 nm allows to deposit a virtually stress free coating. Simultaneously with the stress reduction, an increase of the optical index and a slight reduction of the thickness are observed, consistent with a densification of the coating.

References:

Ajit Paranjpe et al, “ Atomic Layer Deposition of AlOx for Thin Film Head Gap Applications” Journal of The Electrochemical Society, 148 (9) G465-G471 (2001)

David C. Miller et al “Thermo-mechanical properties of alumina films created using the atomic layer deposition technique” Sensors and Actuators A 164 58–67 (2010)

L. Puurunen et al “Implementing ALD Layers in MEMS processing” ECS Transactions, 11 (7) 3-14 (2007)

Figure 1
Amorphous Carbon Monolayer: A Novel and Effective Interlayer for Metal/Oxide Interface
Authors: Lee Viswanath G. , Lee Sangyeob
Published: February 2024

We investigate the effect of one-atom thick Amorphous Carbon Monolayer (ACM) as an interfacial layer (IL) for high-k/Ge MOS structure, with the aim of suppressing the dangling bonds on the Ge surface and reducing the interfacial defects between high-k oxide and Ge layers. The frequency-dependent C-V characteristics indicated that the ACM layer eliminates the weak inversion response resulting in a steeper C-V slope and an increase in accumulation capacitance. The G-V analysis further confirmed the lower density of interface traps in the ACM layered device. The Dit values were extracted as 1.2×10¹¹ cm⁻²eV⁻¹ for Al2O3/ACM/Ge structure, which is almost two orders of magnitude lower than that of the Al2O3/Ge structure without the ACM layer. The observed improvements are attributed to the effective blocking role of the ACM interlayer against the in-diffusion of oxygen and out-diffusion of Ge and the suppression of dangling bonds at the Ge surface. Our findings suggest that the Al2O3/ACM/Ge structure exhibits superior electrical quality with lower hysteresis and interface charge trapped density, which has important implications for the development of high-performance ultra-small-scale devices based on Ge substrates.
Modified Carbonyl Iron Powders to Have Partial Interface Bonding for Stretchable Polymer Matrix Composites
Authors: Hwang Byungil , Yoon Hyungsub , Ha Heebo
Published: February 2024

With the technological progress of wearable electronics operated in 5G network communication system, a stretchable noise suppressor at GHz bandwidth that is reliable under severe deformation coming from the user’s motion should be developed. However, current material systems for the noise suppressor showed a limited stretchability. In this study, the CIP/PDMS composite with partial interface bonding between particle and polymer matrix was introduced as a solution to enhance the stretchability dramatically. Modulation of surface condition of CIPs to have the partial interface bonding (CIP-PID) provided the large freedom for PDMS matrix in a composite to elongate similarly to the pure PDMS. The CIP-PID based composites showed an ultra large strain of ~165% even at the 40 vol% of CIP-PIDs, while only ~75% of strain was observed for CIPs with the full interface bonding (CIP-FID) at the same particle contents. Microstructural analysis of the strained composites and FEM simulation revealed that PDMS matrix partially bonded to CIPs formed the free surface that can be deformed as pure PDMS, thereby resulting in the similar stretchability to those of pure PDMS even in the form of composites. Moreover, CIP-PID based composites showed a proper disperionability and high noise suppressing efficiencty, which are comparable to those of CIP-FIDs. Our work provides ways to the increase in stretchability of polymer-based composite films with a proper noise suppressing efficiency at GHz bandwidth in application to the next generation wearable devices requiring massive data communication.
Efficient Xe Filling of MEMS Vapor Cells Empowered by Customized Triple Stack Wafer Bond Processing
Authors: Roshanghias Ali , Kaczynski Jaroslaw , Rodrigues Augusto , Hübner Martina , Zauner Markus , Grosso Giovanna , Andrianov Nikolai , Khan Muhammad , Grömer Thomas , Fuchs Tino , Binder Alfred
Published: February 2024

Nuclear-magnetic-resonance (NMR) gyroscopes based on MEMS vapor cell technology are currently being investigated worldwide and show superior advantages over current MEMS gyroscopes. However, there are still challenges in the upscaling and further deployment of NMR gyroscopes, due to the extremely high cost of the required gases (i.e. 129Xe, 131Xe), size, and high power consumption. To tackle these bottlenecks, in this study, a miniaturized, chip-scale, and low-cost NMR gyroscope has been conceptualized and fabricated. Here, a cost-effective and scalable filling of MEMS vapor cells with isotropic Xe filling was developed via an innovative microfabrication and wafer stacking process flow. By utilizing ultra-thin glass wafers, Taiko-processed silicon wafers, and an external gas flow system integrated into the wafer bonders, a sequential anodic bonding technique was executed to create a hermetically sealed chamber through which Xe gas can flow in a minimal volume. Fig. 1 shows the configuration of the triple-stack bonded wafer featuring the sealed chamber, the gas inlet, and the outlet. The Xe mass flow rate during the efficient filling process was 3.2528 *10-7 kg/s with a total filling time of <100 sec, as verified by the two-way Fluid-Structure Interactions (FSI) simulation data. As a result, it was demonstrated that the consumption of Xe gas during device filling can be dramatically reduced, which has a substantial impact on the total cost of the MEMS vapor cell.

Figure 1. A demonstration of the triple-stack bonded wafer (glass-Silicon-glass) with an efficient Xe gas-filling process

Figure 1
Phase Transition Engineering of Vanadium Dioxide Induced by Oxygen Vacancies
Authors: Bajaj Samiksha , Wu Jyh Ming
Published: February 2024

A reconfigurable optical functional system is a pioneering and comprehensive approach for portable future flexible electronics, irrespective of traditional silicon-based technology. VO2 shows tremendous temperature-dependent structural and electrical phase transitions as a complex correlated metal oxide, presenting it as a potential candidate for bolometers, thermal camouflage, and optoelectronics applications. However, the structural stability and high transition temperature restrict room-temperature applications. The present study reports the oxygen vacancies-assisted phase transition engineering in the VO2/muscovite heterostructure. The ion bombardment alters the oxygen stoichiometry of VO2/muscovite thin film at room temperature. A significant decrease in lattice constant has been observed during the transition of the insulating M1 (monoclinic) phase into the metallic R (tetragonal) phase, which was confirmed through high-resolution XRD. The change in oxygen vacancy concentration determined using X-ray photoelectron spectroscopy (XPS) actively suppressed and stabilized the epitaxial thin film of VO2 near room temperature. We investigated whether applying increasing power-mediated ion bombardment for a few minutes affects the oxygen vacancy formation on the VO2/muscovite film’s surface. Consequently, a change in KPFM and 4 orders of magnitude change in resistance of VO2 thin film have been observed. This report reveals the fundamental understanding of controlling the MIT in epitaxial VO2 thin film via facile and clean phase transition engineering techniques for advanced flexible electronic devices.
Single-Atom Pt Decorated ZnO Nanoflowers
Authors: Chen Po-Han , Wu Jyh Ming
Published: February 2024

Single-atom catalyst has drawn significant attention in the field of environmental engineering nowadays. In this research, single atoms Pt have highly dispersed on the wurtzite ZnO nanoflowers, evidenced by the high-angle annular dark field (HAADF-STEM) image. The single atom Pt/ZnO catalyst (SAPt/ZnO) was used to degrade organic dye through the piezo-photocatalytic process. The results showed that the SAPt/ZnO catalyst could fully decolorize 10 ppm RhB dye in 60 minutes under synergetic ultrasonication and light irradiation with Kobs of 0.089 min-1, while pristine ZnO nanoflowers have a Kobs of 0.050 min-1, proves the fact that the decoration of single atom Pt increases catalytic activity. In comparison, Kobs of SAPt/ZnO were found to be 0.021 min-1 for ultrasonicate only and 0.014 min-1 for light irradiation only, which indicates the strong enhancement of the piezo-photocatalytic effect. The theoretical study was then conducted with the density functional theory (DFT) approach to investigate the detailed mechanism. The Pt single atom was found to adsorb on the ZnO (101) surface with an adsorption energy of -1.28 eV, and the charge was localized on the top of the Pt atom after the chemisorption of SAPt on ZnO surface, providing abundantly active sites on the surface of the ZnO nanoflower.
(Invited) Role of Heterojunctions in Metal Oxide Heterostructures for Energy and Environmental Applications
Authors: Pinna Nicola , Raza Muhammad Hamid
Published: February 2024

Heterostructures made from metal oxide semiconductors are fundamental for the development of high-performance gas sensors and electrocatalysts, for examples. Here, I will introduce hierarchical heterostructures composed of p-, n-type and insulating metal oxide shells.

Precisely controlled films of alternating metal oxides can be uniformly deposited onto the inner and outer walls of the CNTs and onto mesoporous substrates by atomic layer deposition. The morphological, microstructural and electrical characteristics of the heterostructures were thoroughly investigated. Electrical resistance measurements highlighted the large influence of the metal oxides thickness and charge carriers types, suggesting that the conductivity of the electrodes are dominated by Schottky barrier junctions across the heterojunctions.

The behavior of the heterostructured electrodes in sensors and in electrocatalysis applications was investigated for low concentrations of volatile organic compounds and pollutants, and the oxygen evolution reaction in acidic media, respectively. For examples, the gas sensing response of the heterostructures showed a strong dependence on the thickness of the metal oxide shell layers and the type of heterostructures formed. On the other hand, the electrocatalytic performances are strongly related to the surface catalyst/stabilization layer and the electrical conductivity of the heterostructured electrode.

On the basis of the morphological, microstructural and electrical characterization, and electrode performances, the mechanisms which account for the performances of our heterostructured electrodes will be correlated and discussed.
Active Diatomic Pairs Induced Interlayer Spacing Engineering in 2D Materials for Highly Efficient Energy Conversion Device
Authors: Chen DONG , Zhang Shaoce , Hou Yue , Zhang Rong , CUI Huilin
Published: February 2024

Ammonia, the second largest commercialized synthetic chemical in the world, is widely used for fertilizer and all nitrogen-atom-containing chemicals production. Energy conversion devices by electrochemical nitrate reduction reaction (eNO3RR) offer a green and appealing approach for sustainable ammonia synthesis but hindering by the multi-step chemical reaction and competitive hydrogen generation. To this end, exploring efficient nitrate-to-ammonia conversion devices play a critical role in developing ammonia electrosynthesis. Two-dimensional (2D) materials, like MoS2 and SnS2, have been considered promising energy electrocatalytic materials owing to the advantages of large specific areas that not only provide much more active sites but act as appropriate support to combine other materials. Recently, interlayer engineering on 2D materials has attracted intense interest from scientists because it could tune the chemical affinity of absorbates, which determines the energy barriers during multi-step electrocatalysis device. Therefore, it is valuable to investigate the effect of interlayer spacing in 2D materials on eNO3RR. Active diatomic A-B pairs, such as diatomic Pt-Ce and Pd-Ce pairs, have strong interactions that can be introduced into 2D materials to trigger the interlayer spacing change. For example, the lanthanide series rare earth element (Ce) can be a potential candidate to achieve interlayer expansion since it has a relatively higher atomic radius than most of the atoms, while intercalating Pt or Pd can close the interlayer spacing through solid interaction. In this work, by introducing active diatomic Pt-Ce and Pd-Ce pairs into SnS nanosheets through doping and intercalating, the interlayer spacing of 2D SnS nanosheets achieves both expansion (~6.5 %) and compression (~8.0%). More importantly, the samples with various interlayer spacing show distinguishing nitrate reduction efficiency. The SnS nanosheet with compressed interlayer spacing can reach high ammonia Faradaic efficiencies (surpassing 90%) and yield rate (~0.31 mmol cm−
2 h−
1). Different characterize tools are applied to investigate the mechanism, including in-situ Raman spectra and DFT calculations. The results attribute to the variational delocalized electron density of localized p-orbital in Sn, which contribute to the faster conversion of the rate-determining step (*NO3→*NO2) and the higher chemical affinity of NO3
- and NO2
- in eNO3RR, and the suppressed hydrogen evolution reaction in the meantime. Taken together, our work verifies the feasibility of tailoring the interlayer spacing of 2D materials by active diatomic pairs and further implicates interlayer engineering in promoting efficient electrochemical nitrate conversion devices.
(Invited) Recent Advancements in the Development of Semiconductor Quantum Dots for Solid-State Light Emitting Diodes and Photovoltaic Devices
Authors: Chen Hsueh-Shih
Published: February 2024

Semiconductor quantum dots (QDs) have emerged as a promising class of nanomaterials with diverse applications in areas such as lighting, displays, photo-detectors, and image sensing. The successful commercialization of QD-based displays, exemplified by QLED TVs, demonstrates the technology's market viability. Ongoing research on QD color down-converters for mini-LED and micro-LED technologies, as well as electroluminescent QD devices, holds considerable promise for advancing future lighting and display technologies. Additionally, QDs have exhibited potential in photovoltaic applications, including photo-detectors and image sensors. This presentation will report our recent progress and developments in QD technology, with a particular emphasis on mini/micro-LED, electroluminescent devices, and photovoltaic applications. We will discuss advancements in QD synthesis and device fabrication, while addressing current challenges and exploring potential future research directions. The report shall provide a comprehensive overview of the current state of QD technology in practical applications and its potential to revolutionize the field of solid-state emission and photovoltaic including up-conversion devices.
Heat Generation Mechanisms of 18650 Lithium-Ion Battery Cells: An in-Depth Analysis
Authors: Maher Kenza , Zakaria Yahya
Published: February 2024

Lithium-ion batteries are known for their exceptional properties such as high energy density and long-life cycle, making them popular in various applications, including electric vehicles and energy storage systems. However, the growing concern over the safety of lithium-ion batteries in hot environments with limited cooling has prompted an in-depth analysis of their heat generation mechanisms.

To address this concern, it is important to understand the heat generation mechanisms of lithium-ion batteries. In this study, we conducted an in-depth analysis of the heat generation mechanisms of 18650 lithium-ion battery cells. We investigated the impact of temperature on the primary aging mechanisms of the batteries, such as capacity fade and impedance growth. We also studied the thermal behavior of the batteries, including the heat generation and thermal stability.

Our analysis involved the disassembly of both fresh and aged 18650 lithium-ion battery cells, followed by a physico-chemical analysis on the electrodes at the microscale level to investigate the chemical and physical changes in the electrodes. We used advanced techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to analyze the cells.

Our results showed that high temperatures can accelerate the chemical reactions within the battery, leading to an increase in heat generation. We also found that the aged battery cells had a higher degree of degradation in the electrodes compared to the fresh cells, which affected the battery's overall performance. Our analysis revealed changes in the surface morphology of the electrodes, which could impact the thermal behavior of the battery.

During the presentation, I will delve into the specific findings of our analysis of the 18650 lithium-ion battery cells. I will provide a more detailed explanation of the state of health, capacity fade, and impedance growth of the batteries, including how these aging mechanisms were affected by the high temperatures. Additionally, I will discuss the specific changes observed in the electrodes, such as the changes in the surface morphology, and how they impacted the battery's overall performance.

Overall, the presentation will provide a comprehensive overview of our study's findings and their significance for the future of lithium-ion batteries in high-temperature environments.
Rapid Electrochemical Diagnosis of Battery Health and Safety from Cells to Modules
Authors: Gasper Paul , Knutson Bryce , Sunderlin Nathaniel
Published: February 2024

Rapid electrochemical diagnosis of battery health and failure is critical for ensuring reliable battery performance and battery safety. Traditional battery health diagnostics such as capacity measurements and DC pulse tests are reliable and well-understood, however, these measurements of battery capacity and resistance do not capture all aspects of battery degradation. Other aspects of degradation, such as electrolyte decomposition, lithium-plating, and particle cracking are difficult to detect electrochemically but are crucial to measure to get a full picture of battery safety and flag out potential failures. In this work, lab- and field-aged commercial lithium-ion batteries and modules of various chemistries and formats are tested using a variety of traditional electrochemical characterization methods as well as using 2-minute pseudo-random DC pulse sequences at rest and during charge/discharge. The electrochemical measurements are compared to physical cell measurements, cell efficiency, drive cycle performance, physical and thermal heterogeneity, and qualitative safety metrics using statistical and machine-learning methods to discover if a comprehensive ‘battery health map’ can be accurately identified using only rapid DC measurements.
(Invited) Switching Characteristics of GaN Power Transistors
Authors: Shur Michael , Liu Xueqing , Ytterdal Trond
Published: February 2024

A shorter switching time is one of the key advantages of GaN power devices over Si IGBTs. [1] In this paper, we report on the simulation of GaN power transistor switching and investigate the effect on the switching time novel design approaches ranging from the gate edge engineering (beyond just using field plates [2] for optimizing the voltage distribution in the drain-to-gate spacing to using the quantum well channel designs [3] that lead to the electron wave function penetration into wide band gap cladding layers with the commensurate increase in the breakdown voltage while keeping the advantage of high mobility in the device channel. We also report on the effect of a low conducting passivation for smoothing or even eliminating the sharp maximum of the electric field in the vicinity of the gate and field plate edges on switching time.[4] Additional contacts in the drain-to-gate spacing for the field control and variable doping implants could also decrease the switching time. Further optimization could be achieved with the perforated channel designs [5] decreasing the parasitic series resistance and improving the heat dissipation.

[1] A. Tüysüz, R. Bosshard, and J. W. Kolar, erformance Comparison of a GaN GIT and a Si IGBT for High-Speed Drive Applications, Proceedings of the International Power Electronics Conference - ECCE Asia (IPEC 2014), Hiroshima, Japan, May 18-21, 2014

[2] S. Karmalkar, M. S. Shur, G. Simin and M. A. Khan, Field-Plate Engineering for Heterostructure Field Effect Transistors, IEEE Trans. ED, 52, 12, pp. 2516- 2532, December (2005)

[3] M. Dyakonov and M. S. Shur, Consequences of Space Dependence of Effective Mass in Heterostructures, J. Appl. Phys. Vol. 84, No. 7, pp. 3726-3730, October 1 (1998)

[4] G. Simin, M. Shur and R. Gaska, SETI-0070: Semiconductor device with low-conducting field-controlling element App. No 13/396,059, November 19, 2013 as US Patent No. 8,586,997

[5] G. Simin, M. Gaevski, M. Shur, R. Gaska, Perforated Channel Field Effect Transistor, US patent 9,467,105, October 11, 2016
(Invited) Understanding Mg-Related Defects for Vertical GaN p-n Junction Structures Via p-Type Ion Implantation
Authors: Goorsky Mark S. , Liao Michael Evan , Huynh Kenny , Wang Yekan , Tweedie James , Sitar Zlatko , Collazo Ramon , Sierakowski Kacper , Bockowski Michal , Huang Xianrong
Published: February 2024

Vertical GaN power devices have emerged to become promising candidates for next-generation high power applications due to superior material properties such as high breakdown voltage, low on-resistance, and high mobility compared to devices based on Si and SiC. GaN-based p-n junction switching devices enable higher voltage power with significantly higher efficiencies with added advantages of systems with reduced size and weight. A technological limitation of GaN, however, has been the inability to achieve high p-type doping in a planar, vertical device. Here, we will focus on recent developments to achieve high p-type efficiency though ion implantation, novel high temperature annealing schemes, and the importance of defects and morphology in native substrates and epitaxial layers.

Mg-implanted homoepitaxial GaN annealed at temperatures at or above 1400 °C eliminates the formation of inversion domains and leads to improved dopant activation efficiency. Extended defects in the form of inversion domains contain electrically inactive Mg after post-implantation annealing at temperatures as high as 1300 °C (one GPa N2 overpressure), which results in a low dopant activation efficiency. While residual defects, such as dislocation loops, still exist after annealing at and above 1400 °C, chemical analysis at multiple dislocation loops shows no sign of Mg segregation. Meanwhile, an overall decreasing trend in the dislocation loop size and density is observed after annealing at the higher temperatures and longer times. Earlier work addressing electrical measurements of these types of samples showed that annealing at ~1400 °C leads to a dopant activation efficiency that is an order of magnitude higher than that observed at 1300 °C. This work complements the earlier work by identifying the microscopic defects (inversion domains) which incorporate Mg, and points to the benefits, in terms of defect density and p-type dopant activation, of using higher temperature (1400 °C) annealing cycles to activate Mg in GaN.
Taking Advantage of the Operating Heterogeneities in PEMFC: Numerical Study with a Pseudo-3D Model
Authors: Cornet Marine , Morin Arnaud , Poirot-Crouvezier Jean-Philippe , Schott Pascal , Bultel Yann
Published: February 2024

A Proton Exchange Membrane Fuel Cell (PEMFC) is an open system. Its operation is therefore inherently heterogeneous. Indeed, in a cell, electrochemical reactions do not take place homogeneously on the active surface area. It has already been pointed out that operating heterogeneities over a large cell active area can cause a decrease of performance and durability. In fact, studies to date have focused on the relation between operating heterogeneities and local degradation on the active surface area for a small selection of operating conditions.

The objective of our study is to find a way to control the current, temperature and water distributions by adjusting the operating conditions to, hopefully, optimize performance and improve durability. In order to define those control strategies, a better understanding of the heterogeneities for a wide range of operating conditions is necessary. To that end, a first numerical approach seems to be the most appropriate.

This numerical study is based on a pseudo-3D multi-physics and single-phase model of a large cell, developed on COMSOL Multiphysics®. One novelty of our study, from a methodological point of view, is the calibration of the model. Instead of calibrating the model with the electrochemical response of a large cell for some chosen operating conditions as per usual, it has been calibrated with the electrochemical response of a small cell (1.8 cm²), called differential cell, emulating local operating conditions on a larger cell. Three areas of the large cell were emulated for different operating conditions: inlet, middle and outlet. Once calibrated, the pseudo-3D model was used to calculate the distributions for 108 operating conditions, which were chosen from a full factorial design of experiment defined according to the automobile application of PEMFC. The statistical analysis of these simulation results will give the influence of operating conditions (gases pressure, the magnitude and orientation of the thermal gradient of the cooling fluid, gases temperature and relative humidity) on the current density, temperature and water distributions on the active surface area. These results will later be useful for the design of strategies for controlling heterogeneities, which will be finally tested on PEM stack.

Figure 1