bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Dynamics Simulation Reveals the Transport Mechanism of Molten Alkali Metal Amides
Authors: Kiyobayashi Tetsu , Kubota Keigo , Kiyohara Kenji 
Published: December 2024

The ionic conductivity of molten LiFSA, LiFTA and LiTFSA is peculiarly lower than that of other alkali metal counterparts, where FSA = bis(fluorosulfonyl)amide, FTA = fluorosulfonyl(trifluoromethylsulfonyl)-amide, TFSA = bis(trifluoromethylsulfonyl)amide. Another peculiarity of these lithium amides is that their ionic conductivity, σ, exceeds the Nernst-Einstein conductivity, σNE, a hypothetical conductivity that would be observed if ions were moving without correlating each other. Because the correlations between ions tend to impede their movement, σ < σNE for many cases including not only molten salts, ionic liquids but also electrolyte solutions. The present molecular dynamics (MD) simulation attempts to solve these mysteries in the transport mechanism of AFSA, AFTA and ATFSA (A = Li, Na, K, Rb, Cs).
We adopted the Lennard-Jones potential and the Yukawa potential (∝ exp(-κr)/r) for the intermolecular interactions of MD. The screening parameter, κ, of the Yukawa potential implicitly introduces the effect of induced polarization into the electrostatic interaction. We treated κ as an empirical parameter and determined it so as the simulated σ to reproduce the experimental results. The ionic conductivity σ was calculated by the time integral of the microscopic current correlations in the framework of the Green-Kubo formulation. The calculated σ can be divided into five terms, where the subscripts + and - stand for the cation and the anion, respectively:
σ = σ+ + σ++ + σ- + σ-- + 2σ+-

where σ±, σ±± and 2σ+- respectively represent the contribution to σ from the auto-correlation of each ions (σNE = σ+ + σ-), the cross-correlation between ions of the identical sign, and the cross-correlation between ions of the opposite sign.
The simulation results suggest that, for K, Rb and Cs-salts, σ±± < 0, which is understandable because the ions of the identical sign repel each other to attenuate the microscopic current and hence their correlations negatively contribute to σ. However, for Li-salts, σ-- < 0, but σ++ > 0, which is the proximate cause of bringing σ > σNE. The simulation also suggests that σ- + σ-- ～ 0 for Li-salts; i.e., anions little contribute to the total conductivity as if these salts were solid electrolytes of Li. In the presentation, we will dig deeper into the issues by hypothetical questions, such as "What if Li were bigger?", "What if Li were lighter/heavier?", etc.

Figure 1
Experimental and Theoretical Studies of the Solid-State Performance Ofelectrodeposited Yb2O3/As2Se3 Nanocomposite Films
Authors: Alshoaibi Adil 
Published: December 2024

The influence of the rare-earth oxide (Yb2O3) on arsenic selenide (AseSe) host is currently investigated
and documented in this study. Nanocomposite films were grown using the electrodeposition (ED)
technique with the addition of 1 e 4 mol% Yb2O3. The film’s optical structural, optical, morphological,
and electronic features were studied. The host matrix presents the monoclinic structure whereas the
composite films present two phases ecubic and orthorhombic crystal structure. Crystallites within nano
sizes (36.2 nm) were recorded for the pristine film while the composite films showed sizes ranging from
37.2 to 48.1 nm. Moreover, the Raman spectra revealed low energy Raman phonons characteristic of Se8
rings, As4Se4 cages, AseSe hetero-polar bonds whose cleavage was due to the diffusion of the Yb ions
into the host matrix as shown by the Raman shift. More so, the refractive index peaked at n ¼ 2.66 in the
l interval of 350e600 nm, while the SEM images showed nano-balls and nanoclusters which are fairly
homogeneous. PL studies exhibited multimode emission bands spanning the UVeViseNIR regions. Firstprinciples
calculations were employed to investigate the structural properties and electronic structure of
the pristine (AseSe) film, as well as Yb contribution. It was found that Yb addition leads to reduce the
bandgap energy and consequently the lone pair p-states of Se contribute nearby to Fermi energy level.
Hence, the experimental and theoretical results of films afford potential applications in phase-change
memory (PCM) and downconverting solar cell window layer.
(Invited) All-Solid-State Photoelectric Conversion Cells Employing the Combination of Metal Nanoparticle and p-Type Semiconductors for Plasmon-Induced Charge Separation
Authors: Takahashi Yukina 
Published: December 2024

Metal nanoparticles, such as gold and silver nanoparticles, can localize light energy to the nanospace near the particle surface by localized surface plasmon resonance (LSPR) under light irradiation at resonant wavelengths. In addition, by controlling parameters, such as shape and size of the metallic nanoparticles, it is possible to control the light absorption properties at any wavelength in the range from visible to near-infrared. Therefore, LSPR of metal nanoparticles is attracting attention as a technology for effective use of sunlight. When metal nanoparticles combined with semiconductors are irradiated with light at resonant wavelengths, charge is transferred from the metal nanoparticles to the semiconductors. This is called plasmon-induced charge separation (PICS) (Fig. 1(a)), and is expected to be applied to photoelectric conversion, photocatalysis, and sensing using light in the visible to near-infrared region.
Conventionally, the semiconductors to be combined are mainly n-type such as TiO2. In conventional systems, a positive charge is generated on the metal nanoparticle side, causing oxidative dissolution into the electrolyte, so the only practical options for metal nanoparticles were Au (or Ag with improved stability). In the case of all-solid-state systems that do not use an electrolyte, the counter electrode must be made of a material with a low work function, such as Al or In, which has an ohmic contact at the interface with the n-type semiconductor, resulting in air oxidation and low long-term device stability (Fig. 1(c)) [1].
In this study, we fabricated all-solid-state cells using p-type semiconductors as the semiconductor combined with metal nanoparticles (ITO/metal nanoparticles/p-type semiconductor/Au) (Fig. 1(d)). In this system, it was found that Ag and Cu can also be used as metal species because negative charges are generated on the metal nanoparticle side (Fig. 1(b)). In addition, Au, which makes ohmic contact with p-type semiconductors, could be used as the counter electrode, which dramatically improves the long-term stability of the device in air [2].
The all-solid-state photovoltaic cells composed of p-type semiconductors and metal nanoparticles realized in this study is expected to be applied as a cost-effective solar cell with a simple structure and high stability, as well as in various other applications, such as sensing and photocatalytic systems.
[1] Y. Takahashi, T. Tatsuma, Appl. Phys. Lett., 99, 182110(1 – 3) (2011).
[2] Y. Takahashi, Y. Yamadori, T. Murayama, S. Shingo, S. Yamada, in preparation.

Figure 1
(Invited) Metal and Compound Nanostructures Fabricated Via Photoelectrochemical Reactions
Authors: Nishi Hiroyasu 
Published: December 2024

Metal and compound nanoparticles or nanostructures have unique properties that are different from bulk materials. For instance, metal nanoparticles exhibit light absorption and scattering due to localized surface plasmon resonance (LSPR) while compound nanoparticles such as CdS emit photoluminescence because of quantum size effects. The optical and photoelectrochemical properties of nanomaterials are significantly dependent on their size, shape, orientation, periodicity, and combination with other materials. Therefore, nanofabrication methods to control these factors are of critical importance for photovoltaic, photocatalytic, and other applications.
We have successfully demonstrated photoelectrochemical techniques to fabricate different nanostructures composed of metal and/or metal oxide. Au-PbO2[1,2] and Au-Ag[3] hetero-nanostructures were fabricated via plasmon-induced charge separation (PICS)[4,5] in the presence of Pb2+ and Ag+ ions, respectively. Site-selective oxidative or reductive deposition took place at the resonance sites under excitation of LSPR of Au nanoparticles, that are in contact with a semiconductor such as TiO2 or a potential-controlled electrode. The reaction site can be controlled only by changing the irradiation wavelength. PbO2 deposited on the Au nanoparticles was galvanically replaced with MnO2 as a cocatalyst of photocatalytic reaction based on PICS[6]. Recently, we fabricated PbO2 periodic nanostructures by irradiating incoherent linearly polarized visible light to a potential-controlled bare indium-tin oxide electrode in the presence of Pb2+ ions[7] (see the image below). These photoelectrochemical approaches allow us to fabricate a variety of nanostructures with sizes beyond or comparable to the diffraction limit of light.

References

[1] H. Nishi, M. Sakamoto, T. Tatsuma, Chem. Commun.
2018, 54, 11741.
[2] H. Nishi, T. Tatsuma, Nanoscale
2019, 11, 19455.
[3] H. Nishi, Y. Zuo, Y. Kuroiwa, T. Tatsuma, in preparation.
[4] Y. Tian, T. Tatsuma, J. Am. Chem. Soc.
2005, 127, 7632.
[5] T. Tatsuma, H. Nishi, T. Ishida, Chem. Sci.
2017, 8, 3325.
[6] K. Kim, H. Nishi, T. Tatsuma, J. Chem. Phys.
2022, 157, 111101.
[7] H. Nishi, H. Tojo, A. Kawai, T. Tatsuma, ACS Appl. Nano Mater.
2024, 7, 5426.

Figure 1
Photo-Electro-Upcycling of Biomass via Dye-Sensitized Photoanode with Passivation Effect
Authors: Lee Jeong Kyeong , Kwon Tae_Hyuk 
Published: December 2024

Solar valuable chemical conversion is being actively studied for a sustainable environment. Organic dyesensitized semiconductor systems are suitable due to their easy band gap tuning, broad absorption spectrum, facile fabrication, and relatively low priced compared to metal complexes to convert light to valuable substances effectively and stably. However, charge transfer from biomass to oxidized organic dye is relatively slow in typical dye-sensitized photoelectrochemical cells, resulting in remarkably low
current density, unlike photovoltaics. Hence, the holes can be extracted from organic dye-sensitized photovoltaic system with passivation effect enhancing its efficiency and they can directly oxidize biomass. Organic dyes are researched to generate high current and voltage related to conversion yield and selectivity, so we designed IDT-1−4 organic dyes. Significantly, the methyl functional group is introduced to the acceptor unit to prevent loss of the photovoltage through slow recombination from TiO2 to oxidized organic dyes. This study shows that biomass can be oxidized and degraded with low applied bias and relatively short time.
Synthesis of Near-IR-Responsive Ag-Au-Te Quantum Dots with a Heating-up Method
Authors: Kikkawa Atsushi , Miyamae Chie , Akiyoshi Kazutaka , Kameyama Tatsuya , Sato Hiroki , Ohshima Yusuke , Torimoto Tsukasa 
Published: December 2024

Quantum dots (QDs) exhibit optoelectronic properties different from bulk materials due to the quantum size effect. Recently, near-IR-responsive QDs have attracted significant attention for developing highly efficient solar energy conversion systems and novel luminescent probes for in vivo bio-imaging. We previously reported that I-III-VI-based QDs of less toxicity, such as Ag(In,Ga)Se2, exhibited a sharp bandedge PL peak, the wavelength of which was controllable with their composition.(1) Here, we report the solution-phase synthesis of Ag-Au-Te QDs with low toxicity and evaluate their photoresponse in near-IR wavelength region.
Ag-Au-Te QDs were prepared by reacting corresponding metal complexes and Te compounds in a hot organic solvent. After cooling to room temperature with continuous stirring, the Ag-Au-Te QDs were isolated from the solution by adding ethanol, followed by dispersing in chloroform. The composition of the resulting QDs varied by changing the Ag/Au ratio in the precursors. TEM observation revealed that obtained Ag-Au-Te QDs with the average size of ca. 4 nm. With measurements of XRD patterns and EDX analysis, it was found that the obtained particles were Ag2Te QDs doped with Au. Absorption spectra demonstrated that thus-obtained Ag-Au-Te QDs absorbed light from the visible to the near-infrared wavelength ranges, with an absorption onset wavelength of approximately 1600 nm. Ag-Au-Te QDs exhibited a broad PL peak due to the defect-site emission with a PL quantum yield (PLQY) of 0.8%, which was slightly higher than that of Ag2Te QDs, 0.2%. In conclusion, we successfully synthesized Ag-Au-Te QDs showing near-IR photoresponse, holding promise for applications in photovoltaics and bio-imaging.

Reference

(1) T. Kameyama, et al., ACS Appl.
Nano Master., 2020, 3, 3275.
Modeling the Effects of Local Species Concentrations on the Selectivity of a Modified Cobalt Phthalocyanine Catalyst for CO2 Reduction to Produce Methanol
Authors: Silcox Rachel , Yao Libo , Rivera Cruz Kevin Enrique , McCrory Charles , Singh Nirala , Bala Chandran Rohini 
Published: December 2024

Methanol is a desirable end-product from CO2 reduction as it serves as a drop-in renewable fuel for the current fuel and transportation economy. Cobalt Phthalocyanine (CoPc) is an effective electrocatalyst to convert CO2 into methanol by preventing C-C coupling. In prior work with gas-fed CO2 electrolyzers, it has been shown that methanol production is suppressed when the relative concentration of CO2 to CO increases, as reaction sites for CO to methanol are blocked [1]. Therefore, having knowledge of the local concentrations of CO2 and CO can be significant to improve understanding and interpretation of experimental data. To probe these effects of mass-transfer in a gas-fed CO2 flow cell, we develop a three-dimensional computational model of the gas flow adjacent to the gas diffusion electrode. Different flow rates (1-30 ml/min) and partial pressure of the feed CO2 gas (0.02 - 1 atm) are modeled concurrently with inputs of experimentally measured partial current densities for methanol, carbon monoxide, and hydrogen formation. Model predictions determine space-time variations in the concentrations of all relevant reactant and product species. These are correlated with the relative concentrations of CO2 and CO on the measured reaction rates and selectivity. Results highlight that methanol production only occurs at sufficiently low mass flow rates or partial pressures of CO2 reactant gas, leading to low relative CO2 to CO concentrations. The value of the companion model developed is that it identifies the maximum value of the relative CO2 to CO concentration in the reactor that still yields methanol. Future predictive modeling studies can harness these local CO2:CO concentrations to relate to methanol productivity. Additionally, the modeling framework developed is applicable to probe and identify CO2 electrolyzer design/operating conditions that can enhance the relative concentration of CO as compared to CO2.
[1] Yao et al. (2024) Electrochemical CO2 Reduction to Methanol by Cobalt Phthalocyanine: Quantifying CO2 and CO Binding Strengths and Their Influence on Methanol Production. ACS Catalysis DOI:10.1021/acscatal.3c04957
(Invited) Coherent X-ray Studies of Electrode Nanoparticles and Surfaces
Authors: You Hoydoo , Kawaguchi Tomoya , Komanicky Vladimir 
Published: December 2024

Coherent X-rays provide a unique structural and dynamical viewpoint of electrode surfaces and nanoparticles. Using the coherent X-ray techniques, we have been studying several electrochemical phenomena such as electrochemical dissolution reactions of silver surfaces and nanoparticles, oxygen reduction/evolution reactions of platinum and platinum alloy nanoparticles, and the surface reconstruction dynamics of gold surfaces and nanoparticles. The coherent X-ray techniques are typically developed for real-space images and real-time dynamics. For imaging techniques, X-ray imaging such as Bragg Coherent Diffraction Imaging (BCDI) is used to image nanoparticles, and X-ray Ptychography is used to image electrode surfaces, and X-ray photon correlation spectroscopy (XPCS) is used to monitor the electrode surface dynamics.
In this talk, we will present a broad overview of the examples based on our previous studies and provide each example with an emphasis on the uniqueness of the coherent X-ray techniques and the structural and dynamical aspects of the electrodes, unavailable in traditional X-ray techniques. We will also provide a perspective of the coherent X-ray techniques using the more powerful and brilliant coherent X-rays becoming available in the newest generation X-ray photon sources such as upgraded Advanced Photon Source (APS-U).
Method Development and Applications of Online Inductively Coupled Plasma-Mass Spectrometry for Investigating Cathodic Degradation
Authors: Yan Katherine , Lee Sang-Won , Yap Kyra M. K. , Mule Aniket Sandip S. , Hannagan Ryan Travis , Matthews Jesse E. , Lee Dong Un , Burke Stevens Michaela , Nielander Adam C , Jaramillo Thomas F. 
Published: December 2024

Online inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool for investigating degradation behavior of electrochemical systems in situ. By coupling a potentiostat to an ICP-MS, one can simultaneously probe material degradation and reaction kinetics of electrochemical systems. High instrument sensitivity allows for quantifying trace amounts of degradation down to the parts per trillion range, including non-traditional mechanisms such as nanoparticle loss from bulk materials. In this study, online ICP-MS was used to investigate Au and Cu catalyst degradation via nanoparticle loss in situ during electrochemical CO2 reduction (CO2R). We created a model system to develop the experimental framework and evaluate the strengths and limitations of the technique. This framework was further developed to compare degradation behavior across multiple CO2R catalysts.
Au foil as a CO2R catalyst was used to create a model system. Under CO2R operating conditions in 0.1 M potassium bicarbonate, Au degraded in the form of potential-driven nanoparticle loss. To verify the use of ICP-MS for quantifying nanoparticle detachment, sizes of Au nanoparticle standards were measured by ex-situ ICP-MS, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The size distributions exhibit significant overlap between the three methods. For in-situ degradation experiments, a custom flow-cell design was used to ensure that degradation data was obtained at relevant current densities. We found that under CO2R operating conditions, nanoparticle loss from the Au foil can be induced through pulsing the applied potential. When such a procedure was tested on a Cu foil, both nanoparticle loss and dissolution occurred. In addition to distinguishing between different types of degradation, we used the framework to further probe the degradation mechanisms by modifying the gas environment. The developed experimental framework can be expanded to survey degradation of other electrocatalysts, determine the effects of real-world feedstocks for CO2R on electrocatalyst degradation, and investigate photocorrosion of photoelectrochemical systems.
Insights into the Electrochemical Reduction of Nitrate on Metal Surfaces
Authors: Zagalskaya Alexandra , Akhade Sneha A , Feaster Jeremy 
Published: December 2024

Electrochemical nitrate reduction to ammonia (NO3RR) emerges as a dual-purpose solution, addressing the environmental challenge of wastewater decontamination by removing harmful nitrates and providing a sustainable method for ammonia (NH3) production. This approach offers a viable and green alternative to producing NH3 compared to the traditional energy- and carbon-intensive Haber-Bosch process. However, electrocatalytic conversion of nitrate to ammonia involves a complex 8-electron process, leading to a variety of byproducts, including nitrogen and its oxides. Non-noble transition metals exhibit great potential for this reaction due to their affordability and catalytic activity. In this study, we explore the reaction mechanisms occurring on the surfaces of several face-centered cubic (fcc) transition metals. Our findings indicate that the *NO3 exhibits the strongest binding affinity to the (110) facet, followed by the (100) and (111) facets. In addition, the presence of alkali metal cations in the vicinity of electrode surface plays a crucial role in *NO3 stabilization. Combining density functional theory (DFT) calculations, ab initio molecular dynamics (AIMD) and enhanced sampling methods, we investigate the thermodynamics and kinetics of the NO3RR reaction mechanisms. Specifically, we present a favorable alternative pathway for converting *NO3 to *NO, indicating that the further reduction of *NO is likely the rate-limiting step. The obtained computational results are discussed in the light of the existing experimental data, emphasizing the significance of the combined influence of the electrode and electrolyte in advancing electrochemical nitrate reduction to ammonia.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Tuning Hydrogen Evolution and Oxidation Electrocatalysis through Interfacial Hydrogen Bonds
Authors: Zhang Yirui , Huang Botao , Aggarwal Abhishek , Leverick Graham , Shao-Horn Yang 
Published: December 2024

Designing electrochemical water splitting and its reverse process is crucial for fuel cells to achieve high efficiency. Conventional design of catalysts has focused on tuning the surface electronic structures and binding strength of intermediates, while recent studies show that changing electrolyte compositions, such as cations and pH, can also significantly alter catalytic activity, highlighting new opportunities in tuning noncovalent interactions in the electrolytes to control activities. Yet, the mechanistic role of electrolytes and their structures at the electrochemical double-layer remain poorly understood. Challenges arise in characterizing the interface and understanding the reaction mechanisms under operando processes.
In this talk, we tailor non-covalent hydrogen bonding interactions at the electrified interface to control electrochemical proton-coupled electron transfer reactions, and uncover the interfacial molecular mechanisms. We investigate hydrogen evolution and oxidation reactions (HER/HOR) by systematically confining water in organic matrixes. Tuning the hydrogen-bonding networks by changing the water concentration and altering the donor number of organic solvents shifted the onset potentials. High donor number solvents, such as DMSO, suppress HER more significantly due to its stabilization effect of isolated water, while the enhancement effect of HER with low donor number solvents, such as acetonitrile, is due to the promotion of interfacial hydrogen-bonded water. In situ surface-enhanced infrared absorption spectroscopy (SEIRAS) measurements and molecular dynamics simulations provide further support to the changes in interfacial hydrogen bonding during the reactions. These findings provide design principles for electrolytes and open up immense opportunities for using non-covalent hydrogen bonding interactions at the electrified interface to control the kinetics. The understanding would also be impactful across other reactions involving proton-coupled electron transfer that are crucial for energy storage, such as CO2 reduction and aqueous batteries.