bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Desalination Performance of Flow- and Fixed-Capacitive Deionization Using Redox-Active Quinone
Authors: Cho Younghyun , Kang Hong Suk , Yoo Chung-Yul
Published: November 2022

Capacitive deionization (CDI) has newly emerged as a desalination technology because of its energy and cost effectiveness. In particular, CDI using a flow electrode (FCDI) significantly increased salt removal by continuous desalination even at salt concentrations of both brackish and seawater. Since CDI mainly uses the electrosorption of salt ions onto an electric double layer on electrodes, carbon materials and their derivatives have been widely used. Even with various approaches, including modification and synthesis of new carbon-based electrode materials, the salt-removal capacity of CDI and FCDI is still limited by the accessible surface area and charge-transfer properties of carbon electrodes. Hydroquinone (HQ) is a redox-active organic molecule with highly reversible properties in electrochemical reactions and is a low-cost and non-toxic material. In this study, we introduced quinone in the activated carbon (AC) electrodes for CDI and FCDI desalination systems. It exhibited a significant increase in salt-removal performance (for CDI, more than a 65% increase for 300 mM HQ, and for FCDI, more than a 19% increase for 500 mM HQ). Even though the specific surface area of an HQ-added AC electrode is reduced because of the penetration of small HQ molecules into pores in the AC surface, the pseudocapacitive contribution from HQ and benzoquinone (BQ) increased the salt removal performance. We analyzed such electrochemical properties by using cyclic voltammetry and electrochemical impedance spectroscopy. We expect that such an approach will open a new door for realizing excellent deionization of saline water, even of seawater, and will have a strong potential for large-scale desalination and energy-storage systems.

Figure 1
Design Rules for Porous Flow-through Electrodes Used in Membrane-Free Electrolyzers for Treatment of Desalination Reject Brine
Authors: Esposito Daniel V. , Fraga Alvarez Daniela V. , Mahmud Nafis , El-Naas Muftah
Published: November 2022

The world’s growing demand for fresh water is creating increasing stress on existing fresh water sources and environmental hazards related to the generation of high salinity reject brine streams that are produced during seawater desalination. Electrochemical separations technologies offer attractive sources to treat brines to reduce brine salinity and/or harvest valuable chemicals or materials from dissolved species present in the brine. In this work, our team has explored the use of membrane-free electrochemical electrolyzers for treatment and separation processes through their ability to create large pH differentials between anode and cathode effluent streams. Because these devices do not contain membranes, they are attractive for operating in the harsh brine environment, which contains many impurities that can result in membrane scaling or fouling. In the first part of this talk, I will describe the basic operating principles of these electrolyzers, which rely on the use of flow-induced separation of anode and cathode effluent streams to create large pH gradients. During operation, it is generally desirable to maximize pH differentials by choosing flow conditions that limit cross-over of product species, thus ensuring high current utilization, while avoiding unnecessary dilution of H+ and OH- within the product streams. This trade-off between cross-over and dilution was studied for porous flow-through electrodes, where we systematically explore the combined influences of volumetric flow rates, catalyst placement, and operating current densities on the pH differential generated by electrolyzers fed with pH neutral brine solutions. Aided by the use of in situ high speed videography and colorimetric imaging of pH differentials, these experiments show that the Damköhler number is an excellent descriptor that can be used to identify the optimal operating conditions that maximize pH differential. Further, we show that the in-plane distribution of active catalyst loading on the porous electrode support has a large impact on the maximum pH differential that can be achieved. Finally, this presentation will also describe the tolerance of electrode durability to the presence of dissolved alkaline earth metal ions such as Mg2+, which can deposit on cathodes and result in scaling if not properly managed.
(Invited) Unravelling Water-Ion Dynamics in Reverse Osmosis Membranes with Nuclear Magnetic Resonance Spectroscopy
Authors: Abbaszadeh Mahsa , Hatzell Marta , Hu Yan-Yan , Chen Yudan , Johannes Leisen
Published: November 2022

Fundamental understanding of the charge (ions and water) transport in polymeric membranes used at the forefront of the water-energy nexus challenge is yet uncertain and depends on the complex interplay between polymer structure and dynamics that facilitate transport. Herein, we investigated the dynamics-transport of proton and ion transport in a rather neutrally charged organic membrane (i.e., polyamide) using solid-state NMR spectroscopy. Specifically, the role of competing ions' effect in complex ionic mixtures at the membrane interface has been explored on a molecular level. Proton and sodium ion diffusion measurements are made using pulsed-field gradient NMR diffusometry. The energy barriers for proton and ion transport within the active layer of the reverse osmosis (RO) membrane are assessed using magic angle spinning (MAS) and static NMR spectral line shape analysis. We have investigated the dynamics-transport of water and sodium ions in complex ionic mixtures of polyamide polymeric media using solid-state NMR spectroscopy. Through monitoring 13C, 23Na, and 1H NMR nuclei, quantitative insights into the diffusion of water (1H), sodium mobile ion (Na+), and polymer membrane dynamics (13C) are extrapolated. Furthermore, the spin-lattice (T1) relaxation time of sodium and water ions is investigated to obtain quantitative insight into how sodium and water ions’ rotational movements occur in the absence and presence of other competing seawater cations such as potassium. Room temperature spectra and spin-lattice relaxation times indicated the presence of both mobile and rigidly held ionic species in the membrane at different levels of relative humidity. The concentration and temperature dependence of relaxation times and chemical shifts have been investigated. NMR relaxation measurements detect how the water rotation is modified by sodium and potassium cations in the membrane. Results show that at low relative humidity and in the presence of competing ions, there are sodium ion resonances for crystalline sodium ions and rigidly held sodium ions on the surface. With increasing relative humidity and decreasing competing ions, the resonance suggests solution-like dynamic rotational movements of sodium ions in polyamide. The results confirm the change in activation energy barrier for sodium and hydrogen ion permeation in polyamide upon the presence of potassium ions.
(Invited) Battphase – a Convergent, Non-Oscillatory, Efficient Algorithm and Code for Predicting Shape Changes in Lithium Metal Batteries Using Phase-Field Models
Authors: Jang Taejin , Mishra Lubhani , Roberts Scott A. , Subramaniam Akshay , Uppaluri Maitri , Gururajan Mogadalai P. , Zhang Ji-Guang , Subramanian Venkat R.
Published: November 2022

Electrochemical models at different scales and varying levels of complexity have been used in the literature to study the evolution of the anode surface in lithium metal batteries. This includes continuum, mesoscale (phase-field approaches), and multiscale models.1-5 Thermodynamics-based equations have been used to study phase changes in lithium batteries using phase-field approaches. However, grid convergence studies and the effect of additional parameters needed to simulate these models are not well-documented in the literature. In this talk, using a motivating example of a moving boundary model in one- and two-dimensions, we show how one can properly formulate phase-field models using the immersed interface/domain approach, implement robust and efficient algorithms for the same and analyze the results (Figure 1). An open-access code with no restrictions is provided as well. The talk concludes with some thoughts on the computational efficiency of phase-field models for simulating dendritic growth.

Acknowledgements

The authors would like to express gratitude to Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the DOE through the Advanced Battery Material Research (BMR) Program (Battery500 consortium). This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. Supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525. VS acknowledges interactions with Dr. Srikanth Vedantam from IIT Madras, India and Dr. Daniel Wheeler from National Institute of Standards and Technology for early discussions on phase-field and level-set methods. VS also acknowledges Richard Braatz from Massachusetts Institute of Technology for pointing out the poor results from standard algorithms because of the convective nature of the models.

References

1. Q. Wang, G. Zhang, Y. Li, Z. Hong, D. Wang and S. Shi, NPJ Comput. Mater., 6, 176 (2020).

2. Z. Hong and V. Viswanathan, ACS Energy Lett., 3, 1737 (2018).

3. L. Liang and L.-Q. Chen, Appl. Phys. Lett., 105, 263903 (2014).

4. D. A. Cogswell and M. Z. Bazant, ACS Nano, 6, 2215 (2012).

5. Y. Zeng and M. Z. Bazant, SIAM J. Appl. Math., 74, 980 (2014).

Figure 1
Triple-Phase Pore Network for Oxygen and Proton Transport Model in the Cathode Catalyst Layer of Proton Exchange Membrane Fuel Cells
Authors: Ince Alper Can , Serincan Mustafa Fazil , Holby Edward F. , Spendelow Jacob S. , Pasaogullari Ugur , Kort-Kamp Wilton
Published: November 2022

Improvement in the mass transport overpotentials of the oxygen reduction reaction provides a pathway for reducing the high cost associated to platinum group metal loading as well as enhancing the lifetime of electrodes in proton exchange membrane fuel cells (PEMFCs). State-of-the-art PEMFCs typically have Pt loadings of the order of 0.3 mgPtcm-2, which is the main part of the estimated stack cost of $55/kW. Understanding transport phenomena at triple phase boundaries that consist of a (solid) electrocatalyst, ionomer, and (gas-phase) oxygen, where the electrochemical reactions occur has gained importance to improve electrocatalyst accessibility. Mathematical models that address transport of electrons, protons, and oxygen in the cathode is critical for an effective catalyst layer design. Modeling of this multiphysics phenomena is further complicated due to multiscale effects. Pore network model (PNM) is a promising technique to tackle these challenges because of its capability of resolving porous networks locally in greater detail. Moreover, improvements in microscopic imaging techniques (e.g., SEM, TEM, and nano CT) enable the generation of realistic pore networks of the catalyst layers that can be directly integrated into PNM. Most modeling studies to date focus on single networks for oxygen transport in the open pore space, or transport of oxygen and water. A pore network that describes oxygen, proton, and electron transport simultaneously remains uncharted. Here, we construct a triple-phase pore network model using nano CT images of heterogeneous porous catalyst layers. Binary images of solid-open pore space and ionomer-catalyst support are generated, which are then overlapped to create ternary images. Pores and throats are then fit to these

images to create pore-networks that describe open-pores for oxygen and water transport, ionomer pores for proton transport, and a solid network for electron transport. A schematic of the approach is shown in Figure 1.

The study offers a new method that constructs a triple pore network for a porous material in which two levels of open space porosity (micro and macro) exist in connection with solid and ionomer networks. Therefore, a

realistic pore network is obtained to be further modeled through the approach presented.

Figure 1
Model Development for Temperature-Dependent Degradation in Large Format Lithium-Ion Batteries
Authors: Mishra Lubhani , Subramaniam Akshay , Jang Taejin , Garrick Taylor R. , Subramanian Venkat R.
Published: November 2022

Large-format cells are achieving increasing popularity for Electric Vehicle (EV) applications to maximize volumetric and gravimetric energy densities. These large batteries are often characterized by spatial non-uniformities in temperature and resulting difficulties in maintaining uniform temperature distribution. This poor thermal management is a primary reason for the inefficient performance and safety risks associated with these large format batteries and battery packs. Further, there have been several reported degradation mechanisms which are responsible for the capacity fade within Lithium-ion (Li-ion) batteries over multiple charge/discharge cycles. In particular, the presence of thermal gradients and consequent non-uniformities greatly exacerbates degradation, and poses serious safety risks. Thus, it is imperative to identify and study the degradation mechanisms coupled with the thermal effects by incorporating detailed physics-based models to characterize the cell-level phenomena.

This work aims to perform a detailed model-based study on the combined effects of battery degradation and temperature inhomogeneities within large-format Li-ion cells and battery packs. This simultaneous analysis for temperature-dependent degradation will be performed with a state-of-the-art electrochemical model like the classic pseudo-two-dimensional (p2D) model to be able to present a comprehensive analysis of the battery performance parameters. These models will be augmented to include thermal effects and various degradation mechanisms for Solid Electrolyte Interphase (SEI) formation and Lithium plating. The proposed numerical framework will be validated with experimental data for the loss in battery capacity over cycles. In addition, the model development, especially the weak form for model equations and their implementation in a finite-element solver, COMSOL Multiphysics, will be discussed in detail.

This study primarily focusses on certain important aspects of temperature-dependent degradation, viz., (a) cell-to-cell temperature variation, (b) operating conditions for current, (c) topology for the cell arrangement within the battery module, and (d) choice of the degradation mechanism. The delineation of the effects of these complex factors on the cell-level signatures will be of significant utility in monitoring and identifying the performance limitations of individual cells, and thereby help maximize the performance of large format cells and battery packs.

The ultimate goal is the design of a simple yet efficient numerical model with fast and robust simulations for the analysis of the temperature-dependent degradation of the Li-ion battery packs over a wide range of operating and design conditions. The proposed model will be developed to be computationally feasible for an adoption and implementation in a battery thermal management system.
Enhanced Multi-Carbon Selectivity Via Tandem CO2 Electroreduction
Authors: Xia Rong , Jiao Feng
Published: November 2022

Electrifying chemical production is a potential approach to decarbonizing the chemical industry. Currently, 21% of the global greenhouse gas emissions come from the industry sector, while chemical manufacturing accounts for the largest share of industrial carbon emissions1. The electrochemical processes, when powered by renewable electricity, have lower carbon footprints than conventional thermochemical routes. The rapid development of renewable energy provides opportunities for electrifying chemical production and decarbonizing the chemical industry. Among these, electrochemical CO2 reduction reaction (CO2RR) attracted much attention as a potential pathway for carbon utilization and sustainable chemical production. In this presentation, I would like to present a tandem CO2 electroreduction scheme for multicarbon production. A molecular tuning strategy is applied to tune the intermediate binding energy and thus enhance the CO selectivity in the first step2. Then CO2 and CO electroreduction to C2+ products in alkaline conditions are compared, with particular emphasis on carbonate formation and carbon efficiency (i.e., the amount of carbon ended in the desired products divided by the total amount of CO2 consumed)3. The conclusion is that CORR shows specific advantages over CO2RR in the aspects of C2+ selectivity, stability, carbon efficiency, and single-pass conversion. Then oxide-derived Cu plates are chosen for the second step in tandem reduction, which shows a C2+ Faradaic efficiency of 83% at -0.59 V vs RHE. Lastly, we further extend our tandem system to electrocatalytic–thermocatalytic reaction for CO2 conversion to C3 oxygenate4. A 25 cm2 membrane electrode assembly device is coupled with a thermochemical hydroformylation reactor to produce 1-propanol and propanal. A total C3 oxygenate selectivity of ~18% is achieved in the tandem reaction.

References:

Xia, R.; Overa, S.; Jiao, F., Emerging Electrochemical Processes to Decarbonize the Chemical Industry. JACS Au 2022, 2 (5), 1054-1070.

Xia, R.; Zhang, S.; Ma, X.; Jiao, F., Surface-functionalized palladium catalysts for electrochemical CO2
J. Mater. Chem. A 2020, 8 (31), 15884-15890.

Xia, R.; Lv, J.; Ma X.; Jiao, F., Enhanced multi-carbon selectivity via CO electroreduction approach. Catal. 2021, 398, 185-191.

Biswas, A. N.; Xie, Z.; Xia, R.; Overa, S.; Jiao, F.; Chen, J. G., Tandem Electrocatalytic–Thermocatalytic Reaction Scheme for CO2 Conversion to C3
ACS Energy Letters 2022, 2904-2910.
Novel Ni-V-Y Electrocatalysts for Hydrogen Evolution Reaction
Authors: Storimans Emma Adriana , Thorpe Steven
Published: November 2022

Generation of renewable energy is improving globally, the ability to store generated energy remains an issue. A new class of water electrolysers that utilize anion exchange membranes (AEMs) are effective at converting water to hydrogen gas which can be used as fuel. Novel electrocatalysts are required for AEMs to be active, stable, and cost effective when used in AEM water electrolysers. Previously, S. Ghobrial investigated the Ni-Nb-Y alloy system as an electrocatalyst for the hydrogen evolution reaction, with Ni and Y components contributed to electrocatalytic activity [1]. Nb phase did not contribute to electrochemical activity and behaved only as a glass former. For the second-generation alloy, V replaced Nb to create a Ni-V-Y alloy. Thermodynamic modelling via FactSage was used to develop the amorphous alloy system. To create the amorphous alloys, a two-step ball milling process was used. Elemental powders were mechanically alloyed and amorphized under cryogenic conditions. The micron sized alloyed powder was size reduced to nanoparticles suitable for use as electrocatalysts via surfactant assisted high energy ball milling (SA-HEBM). Both micron powders and nanoparticles were structurally characterized using X-ray diffraction and SEM. The catalytic activity of the electrocatalysts were electrochemically characterized using steady state polarization to determine Tafel slopes and exchange current densities. A Ni-V-Y alloy was successfully produced via cryomilling and SA-HEBM. The combination of the NiVY amorphous phase + Ni3V + Ni5Y phases in the micron and nanopowders improved activity relative to the intermetallics alone via the spillover effect. The surfactant used in SA-HEBM is not completely removed by the current centrifugation process leading to lower-than-expected activity and marginal spillover enhancement in nanoparticles. With an improved cleaning process, it is predicted the nanoparticles will have higher activities than their micron powder counterparts.

[1] - S. Ghobrial, Amorphous Ni-Nb-Y Alloys as Hydrogen Evolution Electrocatalysts, Toronto: University of Toronto, 2019.
Coupling Quantification of Pulverization with Galvanostatic Cycling of Bulk Film Alloy-Type Anodes
Authors: Otten Rhys A. , Nieto Kelly , Prieto Amy L
Published: November 2022

Alloy-type anodes, such as metallic antimony, demonstrate promise as alternative electrode materials for lithium-ion battery systems due to their high theoretical capacity of 660 mAh/g. However, antimony undergoes anisotropic volume expansion and multiple crystallographic phase transformations upon lithiation and delithiation, which often leads to fracture. This fracture can result in loss of electrical contact and poor cycling stability. These pulverization phenomena are often observed, primarily during delithiation, but are not quantified in terms of physical bulk material lost. To quantify the mass, size, volume, and density of pulverized regions in a bulk antimony film in a lithium system, we have developed a cell that enables the use of optical microscopy to capture videos of lithiation and delithiation. Using ImageJ and MATLAB® scripts developed for analysis, we have begun to quantify the amount of material lost as a function of deposition parameters.
(Invited) Surface Modification to Control Wetting and Adhesion of Aqueous Solutions
Authors: Hess Dennis W.
Published: November 2022

rf plasmas and electrochemical treatments have been used extensively for thin film deposition and etching in the fabrication of microelectronic and photonic devices. These methods can be applied to non-traditional substrates (e.g., paper and stainless steel) to alter surface and bulk properties to create (i) paper-based analytical devices with application to microfluidic devices, and (ii) antibacterial structures on stainless steel. Two examples will be described. First, the effects of plasma-based oxygen etching of cellulose surfaces followed by plasma-enhanced fluorocarbon film deposition will be described and shown to control wetting and adhesion of water droplets. These process steps can also be used to form fully enclosed hydrophilic channels in bulk paper and thereby allow microfluidic device fabrication on inexpensive and renewable substrates. Electrochemical etching of stainless steel creates micro- and nano-structures on stainless steel surfaces that repel water and bacteria. These surfaces have potential applications in orthopedic implants and consumer metal products prone to bacterial contamination.
(Invited) Chemistry Effects on the Electrodeposition of Re, Co, and Alloys
Authors: Huang Qiang
Published: November 2022

Electrodeposition has been adopted in various metallization processes. It allows conformal and super-conformal deposition on curved and recessed substrates, enables the fabrication of metals and alloys with well controlled composition, impurity, and grain structure, and provides fast growth rate, high throughput, and low cost of ownership. Organic additives have been used in electrolytes to tune not only the growth behavior, but also the impurity and grain structure of the deposited material. The most well-known cases are those used for magnetic alloy plating[1,2] in storage and MEMS industry and for damascene copper plating[3,4] in microelectronic industry. On the other hand, the electrolyte itself has largely remained aqueous for most cases. Organic solvents, room temperature ionic liquids, and deep eutectic systems have been widely studied with, however, relatively limited success in large scale adoption.

The first part of this talk will introduce some studies on the electrodeposition of Cobalt as an alternative metal for semiconductor interconnect applications. Organic additives that tailor the deposition rate of cobalt are used to enable the Co filling in sub-micron structures. The effect of such additives on the impurity incorporation and film grain structure will be discussed. The second part of the talk will discuss some recent studies on the electrodeposition from “water-in-salt” electrolytes, where the hydration of a super high concentration of supporting salt depletes the free water molecules in the aqueous solution, thus limiting the hydrogen evolution reaction. The discussion will be in a context of Re and ReCo alloy deposition for superconducting connector applications for quantum devices.

REFERENCES

T. Osaka, M. Takai, K. Hayashi, K. Ohashi, M. Saito, and K. Yamada, A soft magnetic CoNiFe film with high saturation magnetic flux density and low coercivity, Nature, 1998, 392(6678), 796.

E.I. Cooper, C. Bonhôte, J. Heidmann, Y. Hsu, P. Kern, J.W. Lam, M. Ramasubramanian, N. Robertson, L.T. Romankiw, and H. Xu, Recent developments in high-moment electroplated materials for recording heads, IBM Journal of Research and Development, 2005, 49(1), 103.

P. Andricacos, C. Uzoh, J. Dukovic, J. Horkans, and H. Deligianni, Damascene copper electroplating for chip interconnections, IBM Journal of Research and Development, 1998, 42(5), 567.

T.P. Moffat, J.E. Bonevich, W.H. Huber, A. Stanishevsky, D.R. Kelly, G.R. Stafford, and D. Josell, Superconformal Electrodeposition of Copper in 500–90 nm Features, Journal of The Electrochemical Society, 2000, 147, 4524.
(Invited) Understanding Residual Stress in Thin Films through a Kinetic Model
Authors: Chason Eric
Published: November 2022

Stress in thin films is a critical issue that affects the performance and lifetime of coatings. Multiple parameters have been shown to affect the stress evolution, including the growth rate, temperature, grain size and gas pressure. In addition, the deposition method (e.g., evaporation, electrodeposition, sputtering) is known to have an influence. To develop a unified picture of the processes controlling stress, a kinetic model has been developed that includes the role of different processing parameters and the microstructural evolution. Results are shown from applying the model to numerous published results for transition metals deposited by different methods. Trends in the fitting parameters are discussed in terms of the values expected from the physical mechanisms included in the model.
(Invited) In-Situ Observation of Copper Electroplating with Additives Using Micofluidic Devices
Authors: Hayase Masanori , Akita Takanori
Published: November 2022

Recent advances in integrated circuit have been driven by packaging technology. 3D packaging using TSV (Through-Silicon Via) is becoming common in commercial products. TSVs are formed by filling deep holes with a conductive material. Copper is widely used as the conductive material, since filling the deep holes with copper is enabled by bottom-up electrodeposition using a combination of several additives. Suppressors, levelers, and accelerators are well known categories of additive to acid copper sulfate plating solutions. Bottom-up deposition is realized by various additive formulas. Using leveler alone as additive, extreme bottom-up filling has been demonstrated, and levelers are considered to be essential for bottom-up deposition. But the mechanism is not yet clear with multiple additives addition.

Therefore, understanding of additive behaviors is important. Cyclic voltammetry using a rotational disk electrode has been widely used in additive studies, but interpretation of the results is not easy because adsorption occurs simultaneously with deactivation. The history of additive supply onto the plating surface also influences the hysteretic behavior. Recently, we constructed a microfluidic device in which flow cell experiments and rapid switching of the plating solution are enabled. Using the device, characteristic behavior of leveler, strong suppression and rapid deactivation, was directly observed optical microscopically and electrochemically, and difference with levelers and suppressors was clarified. Further, a TSV-like structure with similar dimensions to real TSVs was constructed in a microchannel, and real-time optical observation of bottom-up deposition was demonstrated.

References

T. Akita, et al., J. Electrochem. Soc., 166(1), D3058 (2019)

M. Tomie, et al., J. Electrochem. Soc., 167, 082513 (2020)

T. Akita, Y. Otsuka, M. Hayase, J. Electrochem. Soc., 167, 162515 (2020)
(Invited) Investigation of Pt-Alloy and Strained Pt As Electrocatalysts
Authors: McKeown Cian , Rhen Fernando M. F.
Published: November 2022

The need to replace conventional sources of energy has driven the development of fuel cell technology. The polymer electrolyte membrane fuel cells (PEMFCs) show high performance and are important power sources for hydrogen fuel cell vehicles due to the fact that the cells can operate at relatively low temperatures (50 - 90 oC) , has high energy efficiency and only emits water as a byproduct. Furthermore, the direct methanol fuel cell emerge as an important technology for the green energy transition with the use methanol fuel. The most important electrocatalyst for the fuel cells is platinum and efforts are made to enhance its performance and reduce its requirement by alloying with other metals. Therefore, novel approaches are required to develop electrocatalysts for the oxygen reduction reaction (ORR) and methanol oxidation using reduced amounts of Pt for use at PEMFC cathodes with high electrocatalytic activity.

Investigation of alloying Pt with transition metals (Ni, Co, Fe) has demonstrated increased electrocatalytic activity and is attributed to changes in the Pt-Pt atomic interaction distances. The electrocatalytic activity is linked to the adsorption of molecular oxygen to the electrocatalytic sites, which is a process enhanced by creating favorable Pt-Pt distances at the electrocatalyst. It is also understood that Pt-alloys have an increased density of d-band vacancies, resulting in stronger binding of OH species to catalyst surfaces. Furthermore, the use of alloying metals causes distortions in the atomic lattice, resulting in compressive strain in the lattice, which increases orbital overlap, widens the d-band, lowers the d-band centre and affects electrocatalytic performance. In addition, enhanced methanol oxidation on strained pure Pt platinum was recently demonstrated and is associated with the preferential absorption of reactant at optimum Pt-Pt interatomic distances.

Here, we show results of electrocatalytic activity for oxygen reduction reaction of Fe-Pt alloy with a range of iron content (0 to 80%), the electrocatalytic activity of highly ordered array of Pt nanotubes for methanol oxidation and the effect of strained Pt on methanol oxidation. Structural and electrochemical data of the catalysts will be presented including rotating disk electrode (RDE) voltammetry and SEM images.
(Invited) Electrochemical Metallization For Semiconductor Applications
Authors: Ahmed Shafaat
Published: November 2022

Initially after the invention of electroplating in 1805 it was mostly for used decorative applications and making printing press plates. But the introduction of copper as a replacement for aluminum as a CMOS interconnect material in 1997 by IBM (1) was a breakthrough in silicon chip manufacturing. The replacement of aluminum by copper not only has the benefit of lower interconnect resistance, but also has enabled improved interconnect reliability. Cu is expected to show better reliability because it has a high melting temperature and much lower grain boundary- and lattice diffusivity than aluminum (2). since electroplating is a low-cost and reliable technique, the method is being used for a wide variety of metal deposition applications in the semiconductor industry that includes interconnect & packaging metallization, and compound semiconductor fabrication for low-cost solar cells. Since the late 1990's, after IBM introduced copper interconnects, the development of the copper damascene process (1,3) and the implementation of the copper-based interconnect has had a considerable impact in the electrochemical society and semiconductor industries. Copper metallization technology has become critical for CMOS back-end interconnect, embedded multi-chip interconnect bridges, and interposers for 2.5D and 3D applications.

In this presentation, after a brief discussion of the history of metallization by electrochemistry for semiconductor applications, the development of Copper, Gallium, and Cobalt Metallization will be discussed with their application in the semiconductor technology. The discussion will focus on initial issues that arose and the various directions followed to properly address them. The presentation will then focus on the challenge of barrier and seed step coverage and their impact on defects in Cu damascene metallization. Topics of discussion will include the effect of additives, current density, bath aging, shelf life and their implication on product reliability.

References

R, Liu, C. Pai and E Martinez " Interconnect Technology Trend for Microelectronics", Solid state Electron. 43, 1003(1999)

S. Hau-Riege and C. V. Thomson, " Electromigration in copper interconnects with very different grain structures" Appl. Phys. Lett. 78, 3451 (2001)

K. Broadbent, E. J. McInerney, L. A. Gochberg, and R. L. Jackson, " Experimental and Analytical study of seed layer resistance for copper damascene electroplating" J Vac. Sci. Techonl. B17, 2584(1999)
(Invited) Mixed Redox-Active Molecules for High-Energy-Density and Stable Organic-Based Redox Flow Batteries
Authors: Amini Kiana , Jing Yan , Gao Jinxu , Aziz Michael
Published: November 2022

The intermittency of wind and solar electricity limits their penetration into our energy mix. Safe, cost-effective, large-scale electrical energy storage could solve this problem. Redox flow batteries (RFBs) are emerging energy storage technologies that are expected to have an increasing market size due to their scalability, safety, and system flexibility. Aqueous organic-based RFBs have gained attention due to their potential low cost and the possibility of tailoring the redox properties by modifying the organic chemical structure. To date, significant progress has been made in improving the stability and consequently the lifetime of organic-based RFBs [1-4]. Increased energy density is also desirable but is constrained by limited organic solubility. In this work, we discuss strategies for enhancing the energy density of organic-based RFBs by utilizing mixtures of redox-active organic molecules. In particular, we demonstrate an anthraquinone-based flow battery in which utilization of multiple tailor-made anthraquinones yields a 40% increase in the volumetric capacity, from 26.8 Ah/L to 37.5 Ah/L, without sacrificing the capacity fade rate of the system. The required principles for designing a mixed redox-active organic-based RFB and the possible trade-offs and opportunities will be discussed. These findings provide a pathway for enhancing the competitiveness of RFBs for practical applications.

[1] Kwabi, David G., Yunlong Ji, and Michael J. Aziz. "Electrolyte lifetime in aqueous organic redox flow batteries: a critical review." Chemical Reviews 120, no. 14 (2020): 6467-6489.

[2] Jin, Shijian, Eric M. Fell, Lucia Vina‐Lopez, Yan Jing, P. Winston Michalak, Roy G. Gordon, and Michael J. Aziz. "Near neutral pH redox flow battery with low permeability and long‐lifetime phosphonated viologen active species." Advanced Energy Materials 10, no. 20 (2020): 2000100.

[3] Wu, Min, Yan Jing, Andrew A. Wong, Eric M. Fell, Shijian Jin, Zhijiang Tang, Roy G. Gordon, and Michael J. Aziz. "Extremely stable anthraquinone negolytes synthesized from common precursors." Chem 6, no. 6 (2020): 1432-1442.

[4] Wu, Min, Meisam Bahari, Yan Jing, Kiana Amini, Eric Fell, Thomas George, Roy Gordon, and Michael Aziz. "Highly Stable, Low Redox Potential Quinone for Aqueous Flow Batteries." Batteries and Supercaps (2022).
(Invited) Effects of Halide Anion Type and Alkyl Chain Length on Hydrogen Bonding in Eutectic Solvent System
Authors: Shen Xiaochen , Sinclair Nicholas Scott , Wainright Jesse S. , Savinell Robert F.
Published: November 2022

Deep eutectic solvent (DES), formed by the intermolecular hydrogen bonding between its components of an H–bond acceptor (HBA) and an H–bond donor (HBD), has been extensively studied in the area of material synthesis, catalysis, electrochemistry, etc. The properties of DES including melting point, color, density, viscosity, conductivity, etc. are closely related to the H-bond network. Establishing an understanding of the H-bond structure offers an opportunity to fine-tune these properties.

Hence, in this study, we systematically investigated the effects of halide anion type and alkyl chain length on the hydrogen bond network of a series of eutectic solvent systems and attempted to establish an unambiguous H-bond correlation with the conductivity. We varied the halide anion from Cl− to I− (Cl−, Br−, I−) and the alkyl chain length from methyl to butyl (n
c = 1, 2, 4), and performed FTIR and conductivity measurements. Results show that the OH stretching peak exhibits a blue shift with the halide anion varies in the order of Cl−, Br−, I− when compared with the neat ethylene glycol (Figure 1a), indicating an increase in H-bond strength. A similar trend can be found with the increasing alkyl chain length as well. A stronger H-bond network inhibits the mobility of these halide anions in the eutectic system, as a result, the conductivity will decrease as shown in Figure 1b. Further probing the H-bond network with ultrafast spectroscopy is currently underway.

Figure 1. (a) FTIR spectrum of neat EG and TBAX:EG(1:10) sample, X= Cl−, Br−,I−. (b) Trend between the OH stretching peak shift (vs. neat EG) and conductivity of these investigated samples.

Acknowledgememts

This work was supported as part of the Breakthrough Electrolytes for Energy Storage (BEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0019409

Figure 1
(Invited) Radiation Damage in the Ultra Wide Bandgap Semiconductor Ga2O3
Authors: Xia Xinyi , Li Jian-Sian , Sharma Ribhu , Ren Fan , Rasel Md Abu Jafar , Stepanoff Sergei , Al-Mamun Nahid , Haque Amanul , Wolfe Douglas , Modak Sushrut , Chernyak Leonid , Law Mark , Khachatrian Ani , Pearton Stephen J
Published: November 2022

β-Ga2O3 is attractive for high temperature applications in harsh environments that cannot be tolerated by conventional electronics. Its wide bandgap allows operation at elevated temperatures, while it is also radiation hard. Radiation tolerance is an important factor while fabricating microelectronics and typical radiation damage suffered includes total dose effects, displacement damage, and single event effects. Ga2O3 appears to be more resistant to displacement damage than GaN and SiC, as expected from a consideration of their average bond strengths. EPR results of neutron irradiated, bulk samples suggested that octahedral gallium monovacancy defects were the main defects produced. Proton irradiation introduces two main paramagnetic defects in Ga2O3, which are stable at room temperature. Charge carrier removal can be explained by Fermi-level pinning far from the conduction band minimum due to gallium interstitials (Ga
i
), vacancies (VG
a), and antisites (GaO). While there are no experimental or simulation results for single event effects in Ga2O3 to this point, it has become worryingly apparent that while other wide bandgap semiconductors like SiC and GaN are robust against displacement damage and total ionizing dose, they display significant vulnerability to single event effects at high Linear Energy Transfer (LET) and at much lower biases than expected. We have also analyzed the transient response of β-Ga2O3 SBDs to heavy-ion strikes via TCAD simulations to understand the effect of various structural parameters. Using field metal rings has been reported to improve the breakdown voltage of these devices and biasing those rings can help control the breakdown voltage of the device. We find that such biased rings help in the removal of the charge deposited by the ion strike.
(Invited) Single Atom Co-Catalysts in Photocatalytic H2 Generation
Authors: Schmuki Patrik
Published: November 2022

Photocatalytic H2 generation has been a highly investigated topic ever since Fujishima und Honda (1972) reported on the use of TiO2 as a solar-illuminated semiconductor for the splitting of water into H2 and O2. Generally, in a fully photocatalytic setting (when photogenerated electron and hole are transferred from a solution-suspended TiO2 nanoparticle to an aqueous electrolyte), a reasonable electron transfer rate can only be established when a noble metal co-catalyst is attached to the TiO2. Mostly this is a Pt nanoparticle that is deposited onto the TiO2 by various reductive treatments.

Over the years numerous efforts have been devoted to the shrinkage of the particle to enhance the usage of the noble metal. Evidently the most extreme case shrinkage is the use of an insulated single atom of Pt. The use of such isolated atoms as a co-catalyst in photocatalysis has in recent years attracted strong interest, not only because the single atom state represents a maximized surface to volume efficiency, but also because single atom reactivity allows for unprecedented reaction pathways.

In the presentation we discuss the use of Pt dispersed and anchored as single atoms on TiO2 nanocrystallites, powders and nanotubes as a co-catalyst in photocatalytic H2 generation.

We discuss various trapping and stabilization approaches of SAs on photocatalysts and report on a SA-Pt photocatalyst with a higher photocatalytic activity than observed for classic arrangements of co-catalyst on the semiconductive substrate. Moreover, we show that a small fraction of the totally deposited Pt that is stably trapped SAs provides virtually all photocatalytic reactivity of a Pt decorated catalyst.
Atomic Layer Deposition for Memory Applications
Authors: Illiberi Andrea , Givens Michael , Leonhardt Alessandra , Surman Matthew , Ramachandran Ranjith , Popovici Mihaela
Published: November 2022

The semiconductor industry has continuously adopted more complex architectures and 3D geometries, while simultaneously down scaling the critical dimensions of the devices. This presentation will briefly review the evolution of the memory device architectures, their impact on material/processing requirements, and outline how atomic scale processing has helped to overcome integration challenges. We will first present some key atomic scale processes which have enabled the fabrication of 3D memory devices, with particular focus on V-NAND and DRAM. Next, we will introduce new atomic scale processes, their implementation in emerging memory concepts and the related challenges on the path to productization. We will present the recent advances in ALD of ferroelectric materials, showing how a precise control of film composition, dopant incorporation and morphology are key to control ferroelectricity in doped HfZrO.
Characterization of the Local Atomic Structure of ALD Coated Interfaces
Authors: Young Matthias J. , Paranamana Nikhila C , Gettler Ryan C , Koenig Henry D , He Xiaoqing
Published: November 2022

To accelerate technological innovations using atomic layer deposition (ALD) coatings, we need to establish better understanding of structure-property relationships for ALD films. Historically, the ALD community has had difficulty connecting the atomic structure of ALD films with their performance, largely because of the significant challenge in determining the atomic-scale structure of ultrathin ALD films that are often amorphous, polycrystalline, or defective. In this work, we describe a series of recent efforts that collectively aim to improve understanding of the atomic structure of ALD coatings and inform structure-property understanding. These efforts employ experimental measurements including (a) inert-transfer XPS, (b) in-situ synchrotron high energy X-ray diffraction, and (c) cryogenic electron diffraction. Of particular focus in this talk is the use of X-ray and electron diffraction measurements in combination with pair distribution function (PDF) analysis and reverse Monte Carlo (RMC) structural modeling. We describe a newly developed approach employing alternating RMC and molecular statics steps (RMC-MS) that improves the physical accuracy of model structures derived from experimental diffraction data with minimal additional computational cost over conventional RMC modeling. We also describe efforts using localized cryogenic electron diffraction and PDF analysis (cryo-ePDF) with a ≤ 5 nm spot size to measure atomic structure at ALD interfaces. Together, these advances allow us to quantify differences in the atomic structure as a function of position through the depth of ALD films. A simple two-phase model comprised of bulk and interfacial layers with distinct atomic structure features is consistent with our measurements for both aluminum oxide and zinc oxide ALD coatings. The approaches we report yield atomic structure models that can be used to inform computational studies of the properties if ALD films and will aid in the selection and modification of ALD coating chemistries to address technological needs.
Characterization of Novel ALD Process for the Synthesis of CaO for 12CaO·7Al2O3
electride Applications
Authors: Amoah Papa K. , Baumgart Helmut , Jin Eric , Wheeler Virginia D. , McDonald Michael , Hunt Charles
Published: November 2022

In this work we report on a novel CaO ALD process development with a little used solid ALD precursor for Calcium. This forms part of a larger effort to synthesize 12CaO·7Al2O3 [C12A7], which is a new electronic oxide compound with very low work function and applications potentials in displays and Field-Emission (FE) Cathodes. Currently there are no existing thin film technologies for the conformal deposition of C12A7 electride films on complex device surfaces with nanoscale precision. Use of ALD to obtain precise nanoscale interleaving of CaO and Al2O3 layers over Micro-Hollow Cathode Discharge devices MHCD or FE devices allows conversion to correct alloying of C12A7 in the desired nano-layers. Success in reproducibly obtaining these layers will significantly benefit applications using cathodes, such as light sources, nano-sat thrusters, vacuum electronics and small-format microwave amplifiers. For the final C12A7 film, the challenge is to develop two ALD processes for two binary films in this case CaO and Al2O3
which must be synthesized as alternating nanolaminates in the correct stoichiometric ratio and are subsequently reacted under high temperature annealing. Since ALD of Al2O3 is already a well-known established ALD process, we had to focus on developing an ALD process for CaO. For this study we decided to utilize the relatively novel solid ALD precursor Bis(N,N-di-iso-propylformamidinato)calcium(II) dimer [Ca(famd)2], which is a low vapor pressure solid Ca amidinate precursor and which has to be reacted with ozone or DI H2O vapors. The chemical structure of the Calcium precursor is shown schematically in Fig. 1. The Al2O3 binary compound will be synthesized with trimethylaluminum (TMA) and DI water vapor. The low vapor pressure of Ca amidinate precursor Ca(famd)2 in solid form constitutes a major technical challenge and cannot be reacted by ALD in vapor draw mode but necessitated as new hardware a 150mL booster bubbler with dip tube for bubbling the molten precursor and the installation of a Low Vapor Pressure Delivery (LVPD) kit with bypass. For this presentation we will report the physical characterization of the ALD CaO film with FE-SEM surface morphology studies, SEM EDS elemental analysis of the final composition, X-ray diffraction XRD analysis and atomic force microscopy AFM.

Fig. 1: Schematic of chemical structure of the novel solid ALD Ca amidinate precursor Bis(N,N-di-iso-propylformamidinato)calcium(II) dimer [Ca(famd)2]

Figure 1