bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Ultrafast Excited Electron Relaxation in Triply Fused Ni(II) Porphyrin-Nanographene Conjugates for Energy Conversion
Authors: Cabanillas Gonzalez Juan Ramon
Published: August 2024

Porphyrins are appealing building blocks for solar energy applications, although their photosensitization capability is limited by their large optical energy gap, resulting in a mismatch in absorption for efficient harvesting of the solar spectrum. Porphyrin π-extension by edge-fusing with nanographenes can be employed to narrow their optical energy gap, enabling the development of porphyrin-based panchromatic dyes with an optimized energy onset for solar energy conversion in dye-sensitized solar fuel and solar cell configurations. Metalloporphyrin-nanographene conjugates based on open-shell transition metals, such as Ni(II), exhibit panchromatic absporption covering the entire visible and part of the near-IR spectral range. Dispite this interesting property, they exhibit fast excited-state electronic relaxation across the Ni d levels, which hampers harnessing photoexcited electrons to trigger photophysical or photochemical reactions. In this work, we shed light into the underlying mechanism behind fast non-radiative relaxation in these systems. Variable temperature transient absorption and global fit analysis are combined with time-dependent density functional theory to produce a picture of the relevant excited states and underlying relaxation pathways in the conjugates. At room temperature, photoexcitation to the lowest S1* energy level is followed by vibrational cooling in 1-2 ps, and intersystem crossing in > 10 ps, setting a short temporal window wherein a small fraction of relaxed singlets decay to the ground state. Following intersystem crossing and triplet internal conversion, triplets relax rapidly to the ground state (S0) in few tens of picoseconds. By performing measurements at low temperature, we provide evidences for the interplay of a lowest terminal triplet level with > 1 ns lifetime which acts as a bottleneck, and a sloped conical intersection to S0* which is thermally accessible at room temperature from the former energy level. The overall triplet decay is dictated by the contributions that fall along these two photophysical branches. This observation bears significance in understanding how nanographene functionalization leads to a profound effect, opening avenues for potential applications in Optoelectronics and related fields.

[1] Garcia-Orrit, S., Vega-Mayoral, V., Chen, Q., Serra, G., Paternò, G. M., Cánovas, E., Narita, A., Müllen, K., Tommasini, M., Cabanillas-González, J., Nanographene-Based Decoration as a Panchromatic Antenna for Metalloporphyrin Conjugates. Small 2023, 19, 2301596.

[2] Garcia-Orrit, S. et al., in preparation

Figure 1
(Invited) Density Functional Theory Study on Molecular Structures of Polyhydroxy Fullerenes
Authors: Xu Yue , Krishna Vijay
Published: August 2024

Polyhydroxy fullerenes (PHF), also known as fullerenols or fullerols, are water-soluble fullerenes that are being studied for several applications. PHF is usually synthesized by acid or alkali method and is assumed to have only hydroxyl groups. These approaches use uncontrolled oxidation method and it is possible to have unintended functionalization. In fact, few studies have proposed presence of hemi-ketal and carbonyl groups based on NMR, XPS and FTIR studies. However, a complete understanding of their molecular structures is still lacking. Theoretical quantum chemical calculations based on density functional theory (DFT) are commonly used to predict and corroborate vibrational spectrum of molecules. Interestingly, in silico studies thus far have considered fullerenes with only hydroxyl groups with a big mismatch in their calculated vibrational energies and experimental FTIR spectrum.

In this study, we investigated the presence of carbonyl and hemi-ketal functional groups on hydroxylated fullerenes using DFT. We also evaluated the influence of counterions on oxygen-containing functional groups. All DFT calculations were carried out on Gaussian19 with hybrid B3LYP functional and 6-31G(d,p) basis set. By bridging the gap between theoretical calculations and experimental measurements, we offer an alternative interpretation for the characteristic peaks observed in the FTIR spectrum. Furthermore, our theoretical calculations suggest a dynamic nature inherent in these oxygen-containing functional groups residing on the carbon cage of the fullerene structure.
(Invited) Disentangling the Nonequilibrium Dynamics of Excitations in 2D Material Interfaces Under Bias: Leveraging Theory, Electrochemistry, and Time-Resolved Spectroscopy
Authors: Sayer Thomas , Farah Yusef , Austin Rachelle , Sambur Justin , Krummel Amber , Montoya-Castillo Andres
Published: August 2024

A fundamental challenge in elucidating, controlling, and exploiting nonequilibrium relaxation in condensed phase systems is the ability to find and employ physically transparent models. Through such models, one can develop a compelling assignment and interpretation of the spectral signatures of processes spanning charge and energy transfer, quasiparticle formation, and even chemical reactivity. Two-dimensional materials, such as transition metal dichalcogenides (TMDs), offer one such challenge, especially under applied fields. In this talk, I will describe our recent work combining theory, electrochemical measurements, and ultrafast spectroscopy to demonstrate hot carrier extraction in photoelectrochemical cells composed of monolayer MoS2 on an ITO electrode exposed to electrolyte solution. In addition, I will discuss our critical assessment of the ability of a physically intuitive Hamiltonian, consisting of an infinitely heavy exciton immersed in a fermi sea of conduction band electrons, to capture and offer an interpretation of the spectral features in the linear and transient absorption optical signals of this material under an applied bias. Importantly, we leverage our analysis to identify, physically, how trion formation moves, broadens, and resizes the “A exciton” absorption of our working device. We further unify the interpretation over various sources of such TMD spectral shifts: applied bias, fluence, and (TA) delay time. Our work thus demonstrates hot carrier extraction in 2D photoelectrochemical cells, outlines a path to exploit this phenomenon in semiconductor devices, delineates open questions that are only now becoming possible to address with theory and experiment, and identifies the underlying physical process responsible for previously misidentified spectral features in 2D materials that changed with applied voltage, fluence, and time.
(Invited) Long-Term Sustainability through Carbon Dioxide Capture and Conversion: The Methanol Economy
Authors: Prakash G. K. Surya G. K.
Published: August 2024

Renewable methanol synthesized from carbon dioxide capture and conversion using water and renewable energies such as solar, wind, geothermal, atomic, etc., is a simple solution in the long run to a complex climate change carbon conundrum. Liquid methanol is a versatile high octane, clean burning automotive and marine fuel (to replace gasoline and diesel), a fuel for direct oxidation methanol fuel cell, chemical feedstock to make ethylene, propylene and myriad of other chemicals and a convenient hydrogen storage medium that can replace fossil fuels in almost all applications without inflicting major changes to the existing infrastructure. For a one carbon global CO2 problem, renewable CH3OH is a one carbonglobalsolution.
Electrochemical Analysis Comparison of Nitrogen Undoped and Doped Ti3C2Tx/Co3O4 Hybrid Composites on Carbon Cloth for Application as Electrode in Supercapacitor
Authors: Adnan Ali
Published: August 2024

Supercapacitor provides great potential for good energy storage devices application, compared with other energy storage such as rechargeable batteries, fuel cell, dielectric capacitors and so on. Freestanding and flexible electrodes are vital for the development of flexible and wearable devices that store energy. But the significant trade-off between mechanical flexibility and electrode electrochemical performance limits the fabrication of efficient energy storage systems. In this research, we report the synthesis of a 2D material Ti3C2Tx
and Co NPs on carbon cloth (CC) substrate. Co NPs was synthesized by microplasma reactors which eliminate harmful reducing agents and are efficient and cost-effective. And the Co NPs/Ti3C2Tx were synthesized by hydrothermal method for supercapacitor. These materials were characterized by scanning electron microscopy (SEM) Energy Dispersive Spectroscopy and X-Ray Diffraction for morphology and phases analysis. Besides these Transmission electron microscopies (TEM) and X-ray Photoelectron spectroscopy (XPS) were also done. For electrochemical analysis these materials were applied on the 2.25 cm2 carbon cloth as active material (working electrode) by various electrochemical techniques in 1 M H2SO4 electrolyte. The Co NPs/Ti3C2Tx electrode had a maximum gravimetric capacity of 52 mAh g-1, specific capacitance of 580 mF cm-2 and 240 F g-1 at the current density of 1 mA cm-2.

Figure 1
(Invited) Diverse Strategies for Pseudocapacitance in 2D Materials and Beyond
Authors: Lukatskaya Maria
Published: August 2024

As electronic technology advances, the need in safe and long-lasting energy storage devices that occupy minimum volume arises. Short charging times of several seconds to minutes, with energy densities comparable to those of batteries, can be achieved in pseudocapacitors. These are sub-class of supercapacitors, where capacitance is mediated by fast redox reactions and can enable at least an order of magnitude more energy to be stored than in typical electrical double layer capacitors. Transition metal oxides (e.g. RuO2, MnO2) and conducting polymers (e.g. polyaniline) serve as typical examples. However, these materials are often high in cost and/or suffer from low cycling stability. As a result, the search for new pseudocapacitive materials constitutes an important direction today.

In my talk, I will discuss various strategies to improve the performance metrics of pseudocapacitors, specifically focusing on enhancing capacitance and charging rates. I will primarily discuss the electrochemical behavior of layered materials, such as 2D transition metal carbides (MXenes) and 2D pi-conjugated conductive metal-organic frameworks, with a strong emphasis on understanding the mechanisms of charge storage and the various factors influencing electrochemical performance. Additionally, I will explore the role of cation intercalation in layered MXenes as a means to finely tune their electrochemical responses.
(Invited) Single-Molecule Electroluminescence Triggered by Field-Driven Tunneling Electrons
Authors: Kimura Kensuke , Imada Hiroshi , Katayama Ikufumi , Takeda Jun , Kim Yousoo
Published: August 2024

Exciton dynamics governs versatile functions of molecules such as photon emission, photovoltaic and photo chemical reactions. For clarifying the dynamics of excitons in a molecule, an optical measurement with high spatiotemporal resolution is required because the excitons have short lifetimes and their behavior in the local region is important for optical properties. Luminescence spectroscopy based on a scanning tunneling microscope (STM) enable to investigate optical properties with sub-nanometer spatial resolution[1-2]. In this method, scanning tunneling luminescence (STL) spectroscopy, a molecule is excited by the tunneling current of an STM, which can be controlled with atomic spatial resolution. In contrast, the time resolution of STL spectroscopy is limited, because the tunnel current is controlled by electrical circuits. Therefore, this method cannot be used to track the picosecond dynamics of excitons. For overcoming the time-resolution of STL, we have combined a single-cycle terahertz (THz) pulse with STL spectroscopy. By coupling the THz pulse to a tip of an STM, the photoelectric field of THz pulse with sub picosecond time width is confined to the tip apex, which enables to manipulate the tunneling electrons with high spatiotemporal resolutions[4-9]. In this work, we succeeded in forming an exciton in a single molecule by using THz-field-driven current and clarifying the mechanism of the exciton formation.

Single-cycle THz pulses were generated by using optical rectification of near infrared (NIR) laser pulses from a Yb fiber laser using a tilted-pulse-front configuration (Fig. 1a). The generated THz pulses were guided into the STM chamber and focused by using a lens near the tip. We prepared a clean Ag(111) surface and deposited NaCl films. Then, we deposited Pd phthalocyanine (PdPc) molecules on the NaCl/Ag(111) surface. Figure 1b shows THz-STL spectra of a PdPc on NaCl/Ag(111). Several sharp peaks appeared at around 1.9 eV in the red spectrum (with THz irradiation) and no peak appeared in the gray spectrum (without THz). The peak energy of the main peak is identical to the fluorescence peak of a PdPc measured by conventional STL[3], thus we concluded that the singlet excited state was formed by THz-field-driven tunneling. In this presentation, we would like to discuss the detailed mechanism for the exciton formation in a molecule by THz-field-driven electrons.

[1] H. Imada et al., Nature 538, 364 (2016). [2] K. Kimura et al., Nature 570, 210 (2019). [3] S. Cao et al., Nat. Chem. 13, 766 (2021). [4] T. L. Cocker et al., Nat. Photon. 7, 620 (2013). [5] K. Yoshioka et al., Nat. Photon. 10, 762 (2016). [6] V. Jelic et al., Nature Physics 13, 591 (2017). [7] D. Peller et al., Nature 585, 58 (2020). [8] L. Wang 376, 401 (2022). [9] K. Kimura et al., ACS photon. 8, 982 (2021).

Figure 1
Metal Doped-MoS2/g-C3N4 Nanocomposites for Antibiotics Degradation with Photo-Fenton Reaction Process: Defect Engineering, Synergistic Effects, and Degradation Mechanisms
Authors: Zelekew Osman Ahmed , Wu Yi-nan
Published: August 2024

Currently, the energy crisis and environmental pollutions due to the growth of industrialization and urbanization become gradually a prominent and serious issue. Due to these reasons, we aimed to design photoactive metal-doped MoS2/g-C3N4 nanocomposites photocatalysts for the degradation of antibiotics. The degradation of organic pollutants with photocatalysis is considered as green, ecofriendly, economical, and promising methods. Herein, ultrathin g-C3N4 was prepared with simple method and combined with metal-doped MoS2 (Mg-doped MoS2) with varying the amounts of dopants. The prepared photocatalyst materials were tested for the degradation of ciprofloxacin in the photo-Fenton reaction process. The optimum amount of metal-doped MoS2/g-C3N4 nanocomposites photocatalysts showed enhanced catalytic performance and degrades 72% of ciprofloxacin while 52 and 48 % of degradations were achieved with MoS2 and g-C3N4 catalysts, respectively. Here, the key significant problems of the individual components were solved via synergistic effects in the photocatalytic degradation system. The results also offer an opportunity to enhance the electronic structures of the crystalline materials. Moreover, the metal-doping will also create defects on the MoS2 and improves the charge transfer ability of the photocatalyst. The results proved that the metal-doped MoS2/g-C3N4 nanocomposites photocatalysts could be a promising photo-Fenton catalyst system in the environmental remediation.
A Novel Cancer Therapy Using Proton Beam: An Integrated Proton-Dynamic Therapy, iPDT
Authors: Matsui Hirofumi
Published: August 2024

[Background and Aims]

A super-aged society, the prime example of which is Japan, is being flooded with increasing in numerous numbers of aged cancer patients, who often take anti-coagulant medicines to prevent the attacks of ischemic heart diseases and/ or strokes. Since they show bleeding tendency induced by the medicines, it’s hard for them to receive surgical operations. Thus, low invasive cancer treatments without bleedings are abundantly desired. In this study, the applicant will establish a new proton therapy, in which a resonance nuclear reaction (RNR) induced by collision of a proton with a stable nitrogen isotope (15N), can be a clue to injure cancer-cells specifically. The LET of the product ions (12C6+, 4He2+) of the 15N RNR is above 50 times in comparison with the LET of proton. To establish the cancer-specific 15N delivery, 15N-aminolevulinic acid (15N-ALA) will be used. This reagent has been already used and obtained regulatory approvals as a diagnostic medicine for the location of the glioblastoma in Japan.

[Methods]

In this study, a pair of rat gastric epithelial cells, one is normal cell RGM1, and another is cancerous characteristics cells RGK1 were used. The authors treated these cells with both 1mM 15N-ALA and 14N-ALA. Thereafter, we measured and compared porphyrin fluorescent intensity of these cells. Moreover, these cells will be irradiated with 4 nc proton beam generated by an electrostatic accelerator, then 4.43 MeV gamma-rays will be measured to demonstrate the amount of 15N collected specifically in the tumour cells. After these proton irradiations, cells were stained with hoechest33258 and dapi to observe cellular apoptosis.

[Results] Cancer cells accumulated 9 folds of 15N in comparison with normal epithelial cells. After 3hours of proton irradiation, both cancer cells and normal cells were not injured. However, almost all cancer cells were died with apoptosis while normal cells showed few cellular injuries after 24 hours.

[Conclusions] Cancer cells were completely killed by RNR involved with imM 15N-ALA and 4nc proton irradiation whereas this dose of proton showed few effects of ionizing radiation on normal cells. Thus, iPDT should be an ideal treatment for cancer. Moreover, the quantitative analysis of 15N in the tumour cells can be a new pre-diagnosis for iPDT.
Sensitized Singlet Fission in Pentacene-Subphthalocyanine Conjugates
Authors: Guldi Dirk Michael
Published: August 2024

The goal of harnessing the theoretical potential of singlet fission (SF), a process in which one singlet excited state is split into two triplet excited states, has become a central challenge in solar energy research. Covalently-linked dimers provide crucial models for understanding the role of chromophore arrangement and coupling in SF. Sensitizers can be integrated into these systems to expand the absorption bandwidth through which singlet fission can be accessed. Here, we define the role of the sensitizer-chromophore geometry in sensitized singlet fission model systems. To this end, several conjugates have been synthesized consisting of a pentacene dimer (SF motif) connected via a rigid alkynyl bridge to subphthalocyanines (the sensitizer motif). Steady-state and time-resolved photophysical measurements are used to confirm that both conjugates operate as per design, displaying near unity energy transfer efficiencies and high triplet quantum yields from SF.
Metallophthalocyanines as Outstanding Hole Transporting Materials in Perovskite Solar Cells
Authors: Sastre-Santos Angela
Published: August 2024

Perovskite solar cells (PSCs) are promising candidates to reach the market to complement the current offer of photovoltaic cells although for such a thing they still have to overcome some challenges such as long-term stability. The hole transporting layer (HTL) is a crucial component in n-i-p PSC, since it must favor an adequate movement of charges and protect the perovskite layer from environmental conditions. In this sense, the commonly used HTL, spiro-OMeTAD, does not provide PSCs with sufficient stability and is too expensive. Cheaper molecular materials such as metallophthalocyanines are proving to be a good alternative, as they provide greater stability.[1]

In this communication, we will present novel ZnPcs and CuPcs monomers[2] (see as examples Figure 1), among others, as efficient, stable, and low cost HTMs in PSCs. The MPcs are substituted with functional groups that possesses a very good solubility in a wide range of organic solvents, adequate HOMO LUMO levels and their photovoltaics performance as high stable solution processing in a wide range of perovskite solar cell devices.

References

[1] a) D. Molina, J. Follana, Á. Sastre-Santos, J. Mater. C 10, 11975–11982 (2023). b) P. Huang, A. Hernández, J. Follana-Berná, S. Kazim, J. Ortíz, Á. Sastre-Santos, S. Ahmad, ACS Appl. Energy Mater. 4, 9, 10124–10135 (2021).

[2] a) A. Hernández, N. H. Hemasir, S. Kazim, J. Ortiz, S. Ahmad and Ángela Sastre-Santos 11, 8243-8253, (2023).

Figure 1
The Next Industrial Revolution: Rendering Steel, Aluminum, and Copper Obsolete with Carbon Nanotube Materials
Authors: Hassin Bryan Guido
Published: August 2024

In this presentation, we explore the groundbreaking advancements and commercial applications of DexMat's Galvorn carbon nanotube-based materials. Galvorn harnesses the unique properties of carbon nanotubes to offer an unparalleled combination of strength, light weight, conductivity, and sustainability. We delve into the science behind Galvorn's properties and properties improvement, which make it an ideal candidate for diverse industrial applications. The talk highlights the material's significant impact in sectors such as aerospace and defense, demonstrating its role in lightweighting, energy efficiency, and high-performance. Special attention is given to the scalability of production and climate impact considerations, underscoring Galvorn's potential as a sustainable material for the future. Through case studies and current research, this presentation aims to illuminate the transformative potential of carbon nanotube technology in driving the next industrial revolution: displacing emissive materials such as steel, aluminum, and copper, and ushering humanity into the carbon age.

Figure 1
(Keynote) High-Performance Carbon Nanotube Transistors for Logic Platform
Authors: Li Shengman , Gilardi Carlo , Zeevi Gilad , Mitra Subhasish , Wong H.-S. Philip
Published: August 2024

Low-dimensional 1D and 2D materials hold promise as candidate channel materials for highly scaled and high-performance transistors beyond the limits of silicon-based transistors. This talk will first motivate transistors built on low-dimensional channels due to the significant speed, energy efficiency, and transistor density benefits enabled by their electronic and physical properties. This talk will focus on 1D carbon nanotube (CNT) semiconductors and describe the advanced device component process modules that have been demonstrated, explaining both the fundamental mechanisms of operation and device-level performance objectives. Single-CNT FET experimental studies give insight into the quality of (1) low resistance N- and P- contacts down to 10 nm contact length, (2) high-capacitance gate dielectrics optimized for deposition on SP2 carbon surfaces, and (3) controlled N- and P- remote dielectric doping. To achieve high current density each transistor must contain multiple CNTs, therefore we will review state-of-the-art strategies to assemble densely aligned arrays of CNT with controlled CNT spacing between 2-10 nm and uniform electronic bandgap. The final portion of the talk will highlight recent advances from our team and others to integrate the best device components together to demonstrate high-performance carbon nanotube MOSFETs. We will elaborate on the remaining challenges and provide a summary of device design tradeoffs that will help guide future studies.

We are grateful for support and collaboration from TSMC Corporate Research, DoD, Stanford SystemX Alliance, Stanford Nanofabrication Facility, Stanford Nano Shared Facility, and the University of California at San Diego.
Exploring the Surface Stability of Non-Benzenoid and Non-Planar High-Membered Rings
Authors: Sánchez Carlos
Published: August 2024

The synthesis of carbon-based nanomaterials has experienced an enormous advance in the last 15 years, in part motivated by the advent of On-surface Synthesis (OSS).1 This young field, based on the synthesis of carbon-based nanostructures directly on surfaces thanks to their unique catalytic properties, has allowed the formation of otherwise unattainable extended pi-conjugated systems, like atomically precise graphene nanoribbons,which turned out to be an excellent workbench to explore new physico-chemical properties at the atomic and molecular level.2

Once it was shown the feasibility to use this bottom-up approach to induce organic chemical reactions between tailored precursor monomers, the field evolved toward adding increasing complexity to the final products, either by modifying the dimensionality, edge structure and shape or by including heteroatoms or defects. All these approaches resulted in new intriguing properties as modified band structures or topological states. Of particular recent interest is the effect of non-benzenoid rings in the emergence of pi-magnetism, so far mainly focused on pentagonal rings.3 However, if we want to increase the versatility of the field and explore new possible functionalities associated to the presence of non-benzenoid rings in the nanostructures, it is mandatory to study their stability on surfaces.

In this talk, we will discuss the thermal stability of different high-membered non-benzenoid rings, specifically heptagons and octogons, when included into graphene-based nanostructures, paying special attention to the reaction mechanisms involved.

References

(1) Gourdon, A. On-Surface Covalent Coupling in Ultrahigh Vacuum. Angew. Chem. Int. Ed.
2008, 47 (37), 6950–6953. https://doi.org/10.1002/anie.200802229.

(2) Clair, S.; de Oteyza, D. G. Controlling a Chemical Coupling Reaction on a Surface: Tools and Strategies for On-Surface Synthesis. Chem. Rev.
2019, 119 (7), 4717–4776. https://doi.org/10.1021/acs.chemrev.8b00601.

(3) Oteyza, D. G. de; Frederiksen, T. Carbon-Based Nanostructures as a Versatile Platform for Tunable π-Magnetism. J. Phys. Condens. Matter
2022, 34 (44), 443001. https://doi.org/10.1088/1361-648X/ac8a7f.
Tetraphenylethyelne (TPE)-Based Macrocycles Exhibiting (anti) Aromaticity
Authors: Li En , Lin Nian
Published: August 2024

I will present the synthesis of four-, six- and eight-membered tetraphenylethylene (TPE)-based macrocycles on Ag(111) via on-surface Ullmann coupling reactions. Their unique chemical and physical properties, such as intrinsic inner cavities and aromaticity/antiaromaticity make these systems appealing building blocks for functional supramolecular materials. The as-synthesized macrocycles are spontaneously segregated on the surface and self-assemble as large-area two-dimensional mono-component supramolecular crystals. Combined in-situ characterized by scanning tunneling spectroscopic and computational analysis evidence that the macrocycles undergo structural and orbital symmetry breaking due to extended conjugation in the macrocycles.
Multi-Scale Development and Integration of Granular Activated Carbon Electrodes in Multiphase Electrochemical Systems
Authors: Taqieddin Amir , Alshawabkeh Akram N
Published: August 2024

Providing clean water remains a significant challenge in underserved areas that lack access to public water systems or are affected by extreme natural events like hurricanes. Electrochemical technologies show promise for developing affordable and effective water treatment systems due to their ability to efficiently oxidize contaminants. Particularly, the electrochemical synthesis of in-situ reagents, such as H2O2, systems can oxidize contaminants over the full range of pH with high oxidation potential, leaving only water and oxygen at the end of process, making it a safe and effective method for water treatment. This study is focused on integrating carbon-based electrodes into electrochemical water treatment systems emphasizing their scalability, cost effectiveness, and the efficient generation of reactive oxygen species (ROS). By employing multiscale computational approaches, we develop a comprehensive mechanistic understanding and optimization of ROS generation at the surface of granular activated carbon (GAC) electrodes. Using reactive molecular dynamics simulations, the thermodynamic and transport properties of water-based electrolyte (e.g., adsorption, viscosity, and diffusion) are investigated as a function of the GAC particle size and chemistry. The obtained results show that tuning the GAC particle structure at nanoscale can improve the local diffusion rates by three times. Subsequently, multiphase continuum simulations are used to integrate the GAC electrodes in full electrochemical systems through optimizing the dispersion and the solid-liquid-gas interactions in a reactive environment. The computational findings reveal that higher production of H2O2 and are observed at optimized electrode porosity values when the GAC electrodes are integrated at the system level. These observations are linked to the complex reactive solid-fluid interactions. Specifically, the electrochemical oxygen bubble splitting and coalescence are minimized by optimizing the electrode porosity, which improves the dispersion mass transfer processes by at least one order of magnitude. This leads to higher generation rates of ROS and enhanced degradation of water contaminants. These mechanistic observations will help in designing and scaling up carbon-based electrodes for developing efficient and cost-effective electrochemical water treatment reactors.
Corrosion of Copper-Nickel Alloys in Seawater-Based Electrolytes
Authors: Anderson Rachel M. , Kinee WIlliam J , Policastro Steven A
Published: August 2024

Copper nickel materials are used for their corrosion resistance due to the protective film that forms in seawater. The development of this film over time depends on the exposure condition, and it is critically important to understand the aging process for CuNi components used in marine systems to ensure passivity under sulfide contaminated conditions. Here we study the formation of the protective film over time and its effect on corrosion performance. Electrochemical impedance spectroscopy (EIS) measurements during exposure are used to develop a model of film growth on CuNi 70/30 alloys. These electrochemical measurements are coupled with surface analytical techniques such as glow discharge-optical emission spectroscopy (GD-OES) and X-ray photoelectron spectroscopy (XPS) to characterize the composition of the surface oxide. GD-OES results show that as the protective layer forms, nickel mainly remains at the metal surface and the outer layers are copper enriched oxides and chlorides. There is also incorporation of various elements from the seawater within the film. The rate of this film growth is correlated to the resulting decrease in corrosion rate. Different exposure conditions, such as under flow, are investigated.

The translation of these protective film mechanisms to additively manufactured CuNi materials is also of interest, to ensure similar performance with these materials. Evaluating corrosion performance of these newly developed materials involves careful comparison to existing knowledge of film growth and potential for breakdown.
(Invited) Thermo-Electrochemical Stability of Solid-State Batteries
Authors: Mukherjee Partha P. , Vishnugopi Bairav Sabarish
Published: August 2024

Solid-state batteries (SSBs) are promising due to higher energy density and improved safety. While interface instability due to electrochemical-mechanics interaction, transport and morphological dynamics at solid-solid interfaces has been identified as a critical determinant of failure modes, the role of thermo-electrochemical effect is still elusive. A wide range of factors, such as, high reactivity of lithium, propensity for hotspot formation (e.g., at solid/solid point contacts), and cathode instability may affect thermo-electrochemical signature of solid-state architectures. In addition, spatio-temporal evolution of thermal and reaction heterogeneities and the occurrence of failure mechanisms such as lithium filament growth can be critical. In this presentation, the important role of internal thermal signature and mechanistic origin of thermo-electrochemical instability in solid-state battery architectures will be discussed.
Corrosion of Waste Heat Boiler Tubes in Methanol Plant
Authors: Al-Sahli Abdulmohsen , Al-Meshari Abdulaziz
Published: August 2024

A thorough failure investigation was conducted into a failure of waste heat boiler tubes in a methanol plant to determine the failure mechanism, and contributing factors. The investigation was performed utilizing different characterization techniques, including optical light microscopy, scanning electron microscopy, mechanical testing and chemical analysis techniques. The investigation findings showed that the tubes failure is attributed to corrosion under deposit. Details of the failure’s contributing factors, and recommendations to avoid similar failures, are discussed in this article.
Design for Passivity in Engineering Alloys
Authors: Al-Sahli Abdulmohsen , Macdonald Digby D.
Published: August 2024

The solute‐vacancy interaction model (SVIM), which is an extension of the point‐defect model, has been utilized to investigate the effect of minor alloying on passivity breakdown. Experimental data of nickel binary alloys, aluminum binary alloys and Fe-Cr steels were used to calculate various SVIM parameters, and compare SVIM predictions to experimental observations. We found that the SVIM is capable to predict the effect of minor alloying on passivity breakdown potential for different alloying systems. Some systems showed an increase in pitting potential beyond the SVIM prediction, especially at high concentrations. This observation points to a different mechanism at higher concentrations, e.g., the formation of stable molybdates is a possible mechanism when the alloying concentration exceeds minor alloying, i.e., 3% wt. However, for lower concentrations, we postulate that the effect of the solute-vacancy interaction to be the most dominant.
The Strategy to Tune Li Stripping/Plating Behavior in Li Alloy Anode
Authors: Zhu Yunguang , Yao Eric , You Haoxuan , Meng Yongtao , Bugga Ratnakumar , Favors Zach , Mikolajczak Celina
Published: August 2024

Li metal anode is the most promising anode for high-energy-density batteries due to its high specific capacity (3860 mAh/g) and highest oxidation potential. However, the high reactivity of Li metal with electrolytes and the resultant formation of Li dendrites restrict its practical applications. To tune the reactivity and Li deposition behavior, Li alloys were widely studied and demonstrated to perform better than Li in Li metal batteries.1-4 Here, we studied the electrochemical behavior of one solid-solution phase Li alloy. In this work, the phase transition in the Li stripping process and phase separation after Li plating were observed, which can be attributed to the sluggish Li diffusion in the solid-solution phase of the alloy. To unlock the Li stripping capacity without phase transition, we designed a bi-phase Li composite anode by introducing Li+ conductive materials. Due to the reduced diffusion length, Li can diffuse into the Li solid-solution phase after plating back on the bi-phase Li composite anode, resulting in uniform Li deposition morphology. Accordingly, the bi-phase Li composite anodes showed much better rate performance than the Li alloy or pristine Li. With these findings, it is expected that the new bi-phase Li composite anodes are a promising direction for long-life, high-power, and high-energy Li metal batteries, including Li-S batteries.
A Review on CMP Challenges in HWB and Wafer Level Packaging
Authors: Basim G. Bahar
Published: August 2024

Chemical mechanical planarization/polishing process faces new challenges in multiple new dimensions as hybrid wafer bonding (HWB) and flip-chip technologies evolve to enable innovative integration forms in semiconductor applications. The advanced capabilities of (i) manufacturing the CMOS independent of the memory array through HWB and, (ii) selecting the fully functional chiplets at the die level for heterogenous components for flip-chip bonding, drive cost-effective and high-performance integration.

This paper is a review of the CMP challenges as these new technologies demand additional capabilities such as bonding surface planarization in addition to TSV exposure and polishing ability for backside metallization, edge trimming as well as backside thinning. The toolsets and current capabilities are reviewed in addition to the forthcoming trends of manufacturing ultrathin wafers.
Enhancing Methylated Amorphous Silicon Anode Performances in Li-Ion Batteries By Boron Doping
Authors: Phung Tram Ngoc , Feng Yue , Poupardin Théodore , Rosso Michel , Henry-de-Villeneuve Catherine , Ozanam Francois
Published: August 2024

Methylated amorphous silicon has already demonstrated some advantages as compared to silicon in terms of mechanical properties and cyclability for Li-ion batteries (LIB) [1]. However, the conductivity of methylated amorphous silicon drops by several orders of magnitude when increasing the methyl content in the material, which prevents investigating methyl contents higher than 10%. It is well known that doping significantly improves the conductivity of crystalline or amorphous silicon, and has sometimes been reported to improve the material cyclability when used as a LiB anode [2].

Here, boron-doped methylated amorphous silicon electrodes with different methyl contents were investigated as anodes for LiB in half-cell configuration. Boron doped methylated silicon thin films (100nm thick) with various methyl content were cycled in the range 0.025V – 1V at C/2 rate (electrolyte: LP30 with 5%FEC). 10% methylated amorphous silicon with 2% boron doping performs a capacity retention of 77% after 1000 cycles (exhibiting a capacity around 1800 mAh.g-1) of full lithiation/delithiation. Figure 1a shows a clearly improved performance as compared to the undoped material. The stability upon cycling of higher methyl contents (15% and 20%) electrodes is further increased, with a capacity retention exceeding 80% over 1000 cycles of full lithiation/delithiation.

The evolution of the SEI thickness can be quantitatively determined from IR spectra during cycling. The thickness in the delithiated state is found to increase from cycle to cycle, but with a lower rate for the doped 10% methylated electrodes (thickness lower than 25 nm after 40 cycles and 30 nm after 80 cycles) than for the undoped ones (thickness larger than 35 nm after 40 cycles), see Figure 1b. The SEI evolution upon cycling for higher methyl content is currently under investigation. Reference

[1]

L. Touahir, A. Cheriet, D. A. D. Corte, J.-N. Chazalviel, C. H. Villeneuve, F. Ozanam, I. Solomon, A. Keffous, N. Gabouze et M. Rosso, «Methylated silicon: A longer cycle-life material for Li-ion batteries,» Journal of Power Sources, vol. 240, pp. 551-557, 10 2013.

[2]

M. Salah, C. Hall, P. Murphy, C. Francis, R. Kerr, B. Stoehr, S. Rudd et M. Fabretto, «Doped and reactive silicon thin film anodes for lithium ion batteries: A review,» Journal of Power Sources, vol. 506, p. 230194, 9 2021.

Figure 1
The Effect of Structural Disorder on Li-Ion Transport in the Inorganic Components of the Electrode-Electrolyte Interfaces of Li-Ion Batteries
Authors: Adelstein Nicole , Jeong Wonseok , Weitzner Stephen Eric , Wan Liwen
Published: August 2024

Conventional organic electrolytes in Li-ion batteries have an electrochemical window that is too narrow, leading to a decomposition at the cathode and anode surfaces, especially at high voltages. The breakdown of the electrolyte leads to the formation of cathode-electrolyte interphase (CEI) and solid-electrolyte interface (SEI) at the anode. These interfaces are a multicomponent, 3-dimensional heterogeneous structures that span from a few nanometers to micrometers. To understand the atomic-scale impact of the interfaces’ structure and chemistry on function we have run molecular dynamics simulations of the Li-ion diffusivity in the most likely components: LiF, Li2CO3, and Li2O. Our work focuses on identifying the effect of local chemistry and lattice structure in disordered or amorphous component materials on Li-diffusivity. We extract Li-ion diffusivity and the activation energy for Li-ion transport from both machine learning force fields and ab-initio molecular dynamics from the individual components of the interface and explicit interfaces. Post analysis establishes the local correlation between atomic structure, chemistry, and Li-ion migration. If well designed, the SEI and CEI can protect the electrolyte and cathode to prevent further degradation during cycling and thus optimization of battery performance.

This work was sponsored by the Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office and was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
(Invited) Photoluminescence Dynamics in PbS/CdS Core/Shell Nanocrystal Films: Carrier Recombination and Energy Transfer
Authors: Tsybeskov Leonid , Ko Dong-Kyun , Islam Rakina
Published: August 2024

Colloidal semiconductor nanocrystals (NCs) exhibit highly controllable size-dependent optical properties due to the quantum confinement effect. Among other semiconductor NCs, the lead chalcogenides, especially PbS, are one of the most studied and promising NC systems. They are the material of choice for studies of fundamental phenomena as well as for the development of solution processed infrared optoelectronic devices including LEDs, lasers, solar cells, and photodetectors. Compared to organically passivated NCs, the core-shell approach (more specifically PbS/CdS core-shell NCs) offers not only the improved stability and higher photoluminescence (PL) quantum efficiency but also an opportunity of the core/shell interface nano-engineering resulting in suppression of Auger recombination, reduction of the exciton radiative lifetime and an improved lasing threshold. However, despite more than a decade of detailed studies there are conflicting reports on PL dynamics in PbS/CdS core-shell NCs, and there is no accepted model explaining the observed PL lifetimes ranging from hundred nanoseconds to tens of microseconds. In this work we use time-resolved PL measurements and demonstrate that low-temperature PL dynamics in PbS/CdS core shell NCs show strong dependence on the PL detection wavelengths. The presented experimental results allow us to distinguish between processes of energy transfer and exciton recombination. We propose a model, which considers energy transfer between NCs and various mechanisms of exciton recombination (non-radiative, radiative, spin-flip, diffusion limited, etc.).
Suppressing Ti Reduction Via Multiple Doping in Nasicon-Type Solid Electrolyte
Authors: Lu Wen-Hsuan , Chen Han-Yi
Published: August 2024

The NASICON-type solid electrolyte emerges as a promising candidate for lithium-ion batteries due to its notable ionic conductivity and stability in ambient conditions. However, the LiTi2(PO4)3 and LiGe2(PO4)3 series encounter a reduction of Ti and Ge upon contact with lithium metal, limiting their use in all-solid-state lithium-ion batteries. To address this challenge, we propose a solution by introducing multi-doped NASICON-type oxides. Following the doping process, the material demonstrates electrochemical stability when in contact with lithium metal, as evidenced by cyclic voltammetry measurements. Moreover, the material achieves a noteworthy ionic conductivity of ca. 1.3 × 10-4 S/cm, rendering it suitable for integration into lithium-ion batteries. By resolving the reduction issue of Ti in the material, it becomes feasible to employ it in all-solid-state lithium-ion batteries without the need for a protective layer between lithium metal and the solid electrolyte. This absence of an additional layer reduces interfacial resistance within the device, thereby anticipating improved battery performance.
High-Valence Ion Doped Compositionally Partitioned Li[Ni0.78Co0.10Mn0.12]O2 Cathode for Advanced Lithium-Ion Batteries
Authors: Kim Myoung-Chan , Park Geon-Tae , Sun Yang-Kook
Published: August 2024

Numerous approaches have been employed to reduce the intrinsic instability of Ni-rich cathodes. Among them, the introduction of concentration gradient (CG), i.e., a strategy to protect the labile Ni-enriched compartment with a chemically protective Mn-rich shell, has proven successful in commercial applications.1 However, because the segmentation of transition metal (TM) constituents and the formation of unique geometric configurations are characteristics inherited from the CG hydroxide precursor; it is crucial to select the optimal calcination temperature and precisely control it.2 Excessive thermal energy input can result in concentration planarization because the CG of the hydroxide precursor is intrinsically susceptible to the interdiffusion of TM elements during lithiation. Moreover, the immoderate coarsening of the primary particles can eliminate the advantageous features of the CG design by producing equiaxed primary particles.2 In this study, we propose a strategy that can effectively ameliorate the deterioration of Ni-rich CG cathodes resulting from excessive thermal energy input and remarkably improve their electrochemical cycling performance. It was revealed that a trace amount of tungsten incorporation during the cathode calcination can effectively mitigate the high-temperature-induced cathode degeneration and maintain outstanding product quality over a wide range of temperatures. Thus, the proposed strategy opens new avenues for the facile synthesis of long-life Ni-rich CG cathodes.

Reference
s
:

[1] Y.-K. Sun, S.-T. Myung, B.-C. Park, J. Prakash, I. Belharouak, K. Amine, Nat. Mater. 8 (2009) 320-324.

[2] G.-T. Park, H.-H. Ryu, T.-C. Noh, G.-C. Kang, Y.-K. Sun, Mater. Today 52 (2022) 9-18.