Electronic Configuration Research Articles

Selective Ions Exchange Reactions Endow Defective Heterovalent Copper‐Based Selenides With Enhanced Dielectric Polarization Response

AbstractDefective heterovalent selenides provide a spacious arena for creating emergent electromagnetic (EM) phenomena that are unattainable in the conventional constituent counterparts. However, there are still synthetic methodological challenges, and in‐depth understanding of the EM properties, particularly correlation between tailored polarization sites and dielectric polarization response, are significantly inadequate. Herein, a selective ions exchange strategy driven by concentration‐regulated (Case 1) and time‐evoked (Case 2) approaches, is innovatively proposed to design series of defective heterovalent copper‐based selenides. The controllable phase evolution tailored by concentration‐regulated mixed cation/anion exchange is responsible for heterointerfaces levels (Case 1), while Cu+/Cu2+ electronic configurations controlled by time‐evoked cation exchange accounted for further manipulating heterointerfaces/defects levels and enriching polarization sites (Case 2). The coupling of nonstoichiometric Cu2−xSe‐containing heterointerfaces, unsaturated Se vacancies and multi‐valence configurations, rather than themselves alone even at a higher level, imparted abundant polarization sites to trigger boosted polarization response for defective heterovalent selenides. Consequently, this designed defective heterovalent selenide (ZnSe/CuSe/Cu2‐xSe) deliveres a broad bandwidth of 6.89 GHz compare to parent ZnSe without dielectric response, outperforming most reported metal selenides until now. This innovative strategy overcame the bottlenecks of conventional synthetic methodology, providing a paradigm for fabricating sophisticated defective heterovalent materials for versatile applications beyond EM absorption.

N-Doped Zigzag-Type Aromatic Truncated Cone Belts.

Zigzag aromatic hydrocarbon belts, ultrashort segments of zigzag carbon nanotubes, have been fascinating in the chemistry community for more than a half century because of their aesthetically appealing molecular nanostructures and tantalizing applications. Precise introduction of heteroatoms of distinct electronegativity and electronic configuration can create various heterocyclic aromatic nanobelts with novel physical and chemical properties. Here, we report the synthesis of unprecedented N-doped zigzag-type aromatic belts, belt[n]pyrrole[n]pyridines (n = 6-8), from multiple intramolecular Caryl-Caryl homocoupling reactions of readily available azacalix[n](3,5-dibromopyridine)s. These compounds adopt globally π-conjugated belt structures and display unique photophysical and electrochemical properties. The truncated cone cavity of belt[8]pyrrole[8]pyridine was used as the outstanding host to form very stable 2:1 encapsulation complexes with fullerenes. This work opens a new avenue to the rational design and efficient synthesis of aromatic belts of distinct topological structures and tailor-made properties, which are invaluable in applications in materials and supramolecular chemistry.

Unraveling 3d Transition Metal (Ni, Co, Mn, Fe, Cr, V) Ions Migration in Layered Oxide Cathodes: A Pathway to Superior Li-Ion and Na-Ion Battery Cathodes.

Li-ion and Na-ion batteries are promising systems for powering electric vehicles and grid storage. Layered 3d transition metal oxides AxTMO2 (A = Li, Na; TM = 3d transition metals; 0<x≤2) have drawn extensive attention as cathode materials due to their exceptional energy densities. However, they suffer from several technical challenges caused by crystal structure degradation associated with TM ions migration, such as poor cycling stability, inferior rate capability, significant voltage hysteresis, and serious voltage decay. Aiming to tackle these challenges, this review provides an in-depth discussion and comprehensive understanding of the TM ions migration behaviors in AxTMO2. First, the key thermodynamics and kinetics that impact TM ions migration are discussed, covering ionic radius, electronic configuration, crystal structure arrangement, and migration energy barrier. In particular, details are provided regarding the universal and specific migration characteristics of Ni, Co, Mn, Fe, Cr, and V ions in layered cathode materials. Subsequently, the impacts of these migrations on electrochemical performance are emphasized in terms of the fundamental science behind technical issues, and strategies to modulate TM ions migration for advanced cathode materials development are summarized. Besides, characterization techniques for probing the TM ions migration are present, like neutron diffraction (ND), scanning transmission electron microscopy (STEM), nuclear magnetic resonance (NMR), and others. Finally, future directions in this regard are comprehensively concluded. This review offers valuable insights into the basic design of advanced layered oxide cathode materials for Li-ion and Na-ion batteries.

Exploring molecule-surface interactions of urania via IR spectroscopy and density functional theory.

Within the framework of surface-adsorbate interactions relevant to chemical reactions of spent nuclear fuel, the study of actinide oxide systems remains one of the most challenging tasks at both the experimental and computational levels. Consequently, our understanding of the effect of their unique electronic configurations on surface reactions lags behind that of d-block oxides. To investigate the surface properties of this system, we present the first infrared spectroscopy analysis of carbon monoxide (CO) interaction with a monocrystalline actinide oxide, UO2(111). Using a monocrystalline form largely avoids issues related to super-stoichiometries (UO2+x) and makes the experimental data suitable for further theoretical studies. Our findings reveal that CO adsorbs molecularly and shows a pronounced blue shift of the vibrational frequency to 2160 cm-1 relative to the gas-phase value. Interpreted through density functional theory (DFT) at different levels of computation, results indicate that to accurately describe the interaction between the CO molecule and the surface, it is essential to consider hybrid functionals, the non-collinearity of uranium's local magnetic moments, and spin-orbit coupling. Moreover, an intense IR absorption band at 978 cm-1 emerged upon CO adsorption, tentatively attributed to the frequency shift of the O-U-O asymmetric stretch of the UO2(111) surface in the presence of adsorbed oxygen. This new band, together with the observation of the importance of the relativistic effects in determining the nature of the chemical bonding of CO, is poised to broaden our understanding of actinide surface reactions.

Decoupling many-body interactions in the CeO2(111) oxygen vacancy structure with statistical learning and cluster expansion.

Oxygen vacancies (VO's) are of paramount importance in influencing the properties and applications of ceria (CeO2). Yet, comprehending the distribution and nature of VO's poses a significant challenge due to the vast number of electronic configurations and intricate many-body interactions among VO's and polarons (Ce3+ ions). In this study, we established a cluster expansion model based on first-principles calculations and statistical learning to decouple the interactions among the Ce3+ ions and VO's, thereby circumventing the limitations associated with sampling electronic configurations. By separating these interactions, we identified specific electronic configurations characterized by the most favorable VO-Ce3+ attractions and the least favorable Ce3+-Ce3+/VO-VO repulsions, which are crucial in determining the stability of vacancy structures. Through more than 108 Metropolis Monte Carlo samplings of VO's and Ce3+ ions in the near surface of CeO2(111), we explored potential configurations within an 8 × 8 supercell. Our findings revealed that oxygen vacancies tend to aggregate and are abundant in the third oxygen layer with an elevated VO concentration primarily due to extensive geometric relaxation, an aspect previously overlooked. This work introduces a novel theoretical framework for unraveling the complex vacancy structures in metal oxides, with potential applications in redox and catalytic chemistry.

Controlling orbital ordering of intergrowth structures with flat [Ag(II)F2] layers to mimic oxocuprates(II).

Based on density functional theory calculations, we propose a new pathway toward compounds featuring flat [AgF2] layers which mimic [CuO2] layers in high-temperature oxocuprate superconductor precursors. Calculations predict the dynamic (phonon) and energetic stability of the new phases over diverse substrates. For some compounds with ferro orbital ordering, we find a gigantic intrasheet superexchange constant of up to -211 meV (DFT+U) and -256 meV (SCAN), calculated for hypothetical (CsMgF3)2KAgF3 intergrowth. Semiempirical calculations show that at optimum doping, the expected superconducting critical temperature should reach 200 K. The partial substitution of K+ with Ba2+ leads to noticeable electron doping of the [AgF2] sublattice, as revealed by progressive population of the upper-Hubbard band. On the other hand, modest 10-15% hole-doping through partial substitution of Mg2+ with Li+, primarily leads to the depopulation of p(z) orbitals of apical F atoms. We also find structures with an undesired antiferrodistortive structural ordering and discuss the structural factors that determine the transition from buckled to flat planes and from different types of orbital ordering using the Landau theory of phase transitions.

Duality of electron localization and configuration admixing for d/f electrons in two ordered cerium-nickel intermetallic compounds: Density functional theory merged with a two-impurity model

Duality of electron localization and configuration admixing for d/f electrons in two ordered cerium-nickel intermetallic compounds: Density functional theory merged with a two-impurity model

Ru2Ptx/AC catalysts with tunable electronic configurations for in-situ hydrogenolysis of glycerol

Ru2Ptx/AC catalysts with tunable electronic configurations for in-situ hydrogenolysis of glycerol

Rocksalt-type heavy rare earth monoxides TbO, DyO, and ErO exhibiting metallic electronic states and ferromagnetism.

Solid-phase rare earth monoxides have been recently synthesized via thin film epitaxy. However, it has been difficult to synthesize heavy rare earth monoxides owing to their severe chemical instability. In this study, rocksalt-type heavy rare earth monoxides REOs (RE = Tb, Dy, Er) were synthesized for the first time, as single-phase epitaxial thin films. The REOs were characterized by hard X-ray photoemission spectroscopy, X-ray absorption spectroscopy, resonant photoemission spectroscopy, and magnetization measurements. These REOs showed metallic electronic states with the almost localized 4f states, indicating the 4fn5d1 electronic configurations of Tb, Dy, and Er ions. X-ray magnetic circular dichroism measurements of TbO evidenced the magnetic ordering of the 4f spins below the Curie temperature (TC). The TC was evaluated to be 233 K for TbO, 142 K for DyO, and 88 K for ErO, where the TC decreased with the 4f electron number, approximately proportional to the de Gennes factor.

Unveiling the molecular mechanism of Mn and Zn-catalyzed Ullmann-type C-O cross-coupling reactions.

A detailed theoretical study delving into the molecular mechanisms of the Ullmann-type O-arylation reactions catalyzed by manganese and zinc metal ions has been investigated with the aid of the density functional theory (DFT) method. In contrast to the redox-active mechanisms proposed for classical Ullmann-type condensation reaction, a redox-neutral mechanism involving σ-bond metathesis emerged as the most appealing pathway for the investigated high-valent Mn(II) and Zn(II)-catalyzed O-arylation reactions. The mechanism remains invariant with respect to the nature of the central metal, ligand, base, etc. This unusuality in the mechanism has been dissected by considering three cases: ligand-free and ligand-assisted Mn(II)-catalyzed O-arylation reaction and ligand-assisted Zn(II)-catalyzed O-arylation reactions. In each class, a metal phenoxide species was identified as the active catalyst. The unusual mechanistic trends observed in these C-O cross-coupling reactions could be attributed to the stable electronic configurations (d5, d10) combined with the higher oxidation states of the catalytic metal centers (Mn(II), Zn(II)). The exploration into the electronic effects of functional groups in controlling the reaction feasibility within each metal variant disclosed a consistent trend irrespective of the transition metal catalyst involved in the reaction. It was found that the introduction of electron-withdrawing groups at the para-position of organic halide lowers the energy of their lowest unoccupied molecular orbitals (LUMO), thereby lowering the HOMO-LUMO gap between the coupling partners. This study thereby revealed a comprehensive understanding of the fundamental mechanisms exhibited by high-valent first-row transition metal catalysts that could foster the development of eco-friendly protocols for preparing biaryl ether moieties.

Enhancing electrocatalytic hydrogen evolution via engineering unsaturated electronic structures in MoS2.

The search for efficient, earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) has identified unsaturated molybdenum disulfide (MoS2) as a leading candidate. This review synthesises recent advancements in the engineering of MoS2 to enhance its electrocatalytic properties. It focuses on strategies for designing an unsaturated electronic structure on metal catalytic centers and their role in boosting the efficiency of the hydrogen evolution reaction (HER). It also considers how to optimize the electronic structures of unsaturated MoS2 for enhanced catalytic performance. This review commences with an examination of the fundamental crystal structure of MoS2; it elucidates the classical unsaturated electron configurations and the intrinsic factors that contribute to such electronic structures. Furthermore, it introduces popular strategies for constructing unsaturated electronic structures at the atomic level, such as nanostructure engineering, surface chemical modification and interlayer coupling engineering. It also discusses the challenges and future research directions in the study of MoS2 electronic structures, with the aim of broadening their application in sustainable hydrogen production.

Erratum to “The mechanism of surface activation in sphalerite by metal ions with d10 electronic configurations: Experimental and DFT study” [Appl. Surf. Sci. 649 (2024) 159181

Erratum to “The mechanism of surface activation in sphalerite by metal ions with d10 electronic configurations: Experimental and DFT study” [Appl. Surf. Sci. 649 (2024) 159181

B92: a complete coating icosahedral B12 core-shell structure.

Using first-principles calculations, this study unveils a spherically aromatic core-shell B12@B80 structure featuring a B12 icosahedral core, which is the smallest complete coating icosahedral B12 core-shell Bn cluster to date. Detailed orbital and bonding analyses reveal that the icosahedral B12 core exhibits prominent superatomic behavior with the electronic configuration 1S21P61D101F8.

Exploring graphene's impact on graphite/PANI matrix composites: high-pressure fabrication and enhanced thermal-electrical properties.

This study investigates the effects of the graphene content and applied pressure on the electrical and thermal conductivities of graphite/polyaniline (GP) and graphite/graphene/polyaniline (GGP) composites produced via direct mixing method. Based on the electrical and thermal conductivity results, 14 wt% graphene content was found to be the crucial threshold, beyond which extra graphene additions exhibited different behaviors in pressed and unpressed samples. While the electrical conductivity of the unpressed samples increased up to 14 wt% graphene addition, the thermal conductivity increased further after 14 wt% graphene addition. The addition of graphene induced notable changes in the electronic configurations of quinoid and benzenoid rings, as evidenced by ATR-FT-IR spectroscopy. Based on XPS data, the addition of graphene to the graphite/PANI-CSA matrix affected the electronic distribution and charge transfer mechanisms within the GGP composites, particularly showing the impact of graphene addition on the electronic structure of PANI-CSA in the GGP-14 527 MPa sample. Importantly, the interlocking of graphene and graphite layers observed in the GGP-14 sample pressed at 527 MPa (according to Raman and XRD data) led to enhanced thermal (2253 W m-1 K-1) and electrical (210 S cm-1) conductivity. The interlocked configuration of graphene and graphite in GGP-14 527 MPa facilitated efficient electron and phonon flow throughout the hexagonal CC rings and partially charged nitrogen and oxygen atoms of PANI-CSA. In future work, the concept of interlocked graphene and graphite layers can be used to further enhance the thermal and electrical properties in thermoelectric material applications.

Cascade Selenization Regulated the Electronic Structure and Interface Effect of Transition Metal Sulfides for Enhanced Sodium Storage

The utilization of cobalt‐based sulfides is constrained by their inherently low conductivity and slow sodium ion diffusion kinetics. Modifying the electronic configuration and constructing heterostructures are promising strategies to enhance intrinsic conductivity and expedite the sodium ion diffusion process. In this study, heterogeneous nanoparticles of Se‐substituted CoS2/CoSe2, embedded within heteroatom‐modified carbon nanosheet, were synthesized using metal molten salt‐assisted dimensionality reduction alongside concurrent sulfurization and selenization techniques. The incorporation of Se into CoS2 markedly enhances its intrinsic conductivity, thereby significantly improving its rate performance. The elongated Co‐S bonds and the formation of CoSe2 species contribute to the acceleration of dynamics and facilitate the construction of the CoS2/CoSe2 heterointerface. In‐situ Raman spectroscopy, in conjunction with theoretical calculations, has elucidated the sodium storage mechanism of the Se‐CoS2/CoSe2 and the underlying factors contributing to its enhanced performance. The synergistic effects of electronic structure engineering, have resulted in the optimized Se‐CoS2/CoSe2 demonstrating exceptional rate performance, achieving 442 mAh g−1 at 10 A g−1, and a prolonged cycle lifespan, maintaining 409.3 mAh g−1 at 5 A g−1 over 2100 cycles and 262.5 mAh g−1 after 7000 cycles at 10 A g−1. This study presents a viable strategy for integrating electronic structure engineering with interface engineering.

Structure of the Se4 Isomers─An Ab Initio Study.

This study investigates the equilibrium geometries of four different Se4 isomers using the coupled cluster single and double perturbative (CCSD(T)) method, extrapolating to the complete basis sets. The ground-state geometry of the Se4 isomer with the C2v structure (2.8715 Å, 2.1750 Å, and 88.4°) is found to be very close to other theoretical values (2.910 Å, 2.224 Å, and 90.0°) for the Se═Se and Se-Se bond lengths and valence angle. Additionally, the adiabatic electron affinity, vertical electron affinity, and vertical ionization energy are calculated. The multireference configuration interaction method was used to calculate transitions from the singlet ground state to some excited counterparts, including the vertical excitation energy, oscillator strength, and main electronic configuration. The predicted wavelengths of electronic transitions to 11Bu, 11Au with C2h symmetry, and 11B1 state with the C2V symmetry could match the experimental NIR absorption band at 710-850 nm. These transitions and electronic properties may provide insights into the role of selenium in astrophysical environments, where 74Se in the solar system has been confirmed to originate from the supernova explosion process. The theoretical results offer a deeper understanding of Se4 electronic and geometric structures while also providing crucial spectroscopic data that could aid in the identification of selenium-containing molecules in extraterrestrial environments.

Cascade Selenization Regulated the Electronic Structure and Interface Effect of Transition Metal Sulfides for Enhanced Sodium Storage.

The utilization of cobalt-based sulfides is constrained by their inherently low conductivity and slow sodium ion diffusion kinetics. Modifying the electronic configuration and constructing heterostructures are promising strategies to enhance intrinsic conductivity and expedite the sodium ion diffusion process. In this study, heterogeneous nanoparticles of Se-substituted CoS2/CoSe2, embedded within heteroatom-modified carbon nanosheet, were synthesized using metal molten salt-assisted dimensionality reduction alongside concurrent sulfurization and selenization techniques. The incorporation of Se into CoS2 markedly enhances its intrinsic conductivity, thereby significantly improving its rate performance. The elongated Co-S bonds and the formation of CoSe2 species contribute to the acceleration of dynamics and facilitate the construction of the CoS2/CoSe2 heterointerface. In situ Raman spectroscopy, in conjunction with theoretical calculations, has elucidated the sodium storage mechanism of the Se-CoS2/CoSe2 and the underlying factors contributing to its enhanced performance. The synergistic effects of interface engineering and electronic structure engineering, have resulted in the optimized Se-CoS2/CoSe2 demonstrating exceptional rate performance, achieving 442 mAh g-1 at 10 A g-1, and a prolonged cycle lifespan, maintaining 409.3 mAh g-1 at 5 A g-1 over 2100 cycles and 262.5 mAh g-1 after 7000 cycles at 10 A g-1. This study presents a viable strategy for integrating electronic structure engineering with interface engineering.

Upgrading the Bioinspired Iron-Polyporphyrin Structures by Abiological Metals Toward New-Generation Reactive Oxygen Biocatalysts.

Developing artificial enzymes based on organic molecules or polymers for reactive oxygen biocatalysis has broad applicability. Here, inspired by heme-based enzyme systems, we construct the abiological iron group metal-based polyporphyrin (Ru/Os-coordinated porphyrin-based biocatalyst, Ru/Os-PorBC) to serve as a new generation of efficient and versatile reactive oxygen species (ROS)-related biocatalyst. Due to the structural benefits, including excellent electron configuration, appropriate bandgap, and optimized adsorption and activation of reaction intermediates, Ru/Os-PorBC shows unparalleled ROS-production activities regarding maximum reaction rate and turnover numbers, which also demonstrates superior pH and temperature adaptability compared to natural enzymes. Impressively, the Os-PorBC manifests the most efficacious ROS-production capabilities, surpassing not only Ru/Fe-PorBC but also the existing state-of-the-art ROS-related biocatalyst. Our findings provide a pivotal direction for developing next-generation polyporphyrin-based biocatalysts, setting the stage for a new era of upgrading the artificial metalloenzymes by abiological metals.

Strain Effects in Carbon Dioxide Electroreduction

AbstractAs a frontier method for adjusting the electronic and geometric configurations of metal sites, lattice strain engineering plays a key role in regulating the interaction between catalytic surface and adsorbed molecules. Here, the research progress of strain effects in electrochemical carbon dioxide reduction (CO2RR) is reviewed. Starting from the basic principles of strain effects in the CO2RR, the advanced in situ characterization techniques are summarized. The key effect of strain on the structure–activity relationship in CO2RR is comprehensively discussed. Subsequently, the electrocatalysts with different properties rich in strain are classified, including core–shell structure catalysts, alloys, transition metal compounds, and single‐atom catalysts. Finally, the obstacles encountered in the practical application of strain effect are proposed, and the future research direction of this emerging field is prospected.

Organosilicon Polymeric Acetylene Derivatives: X-Ray Spectral Study and Quantum-Chemical Calculations

The atomic and electronic structure of two organosilicon polymers [–Ph2Si–(C≡C)2–]n (P1) and [–Ph2Si–(C≡C–C≡C)2–]m (P2) (where Ph — is phenyl group) of acetylene and diacetylene types by methods of density functional theory and X-ray emission spectroscopy. The interpretation of X-ray emission SiKβ1-spectra of these polymers was carried out based on an analysis of the distribution of partial electronic states obtained from quantum chemical calculations. Quantitative characteristics of the parameters of the chemical interaction of atoms, such as populations, natural charges, and electronic configurations in the studied polymers, were obtained based on the analysis of hybrid natural bond orbitals. The obtained values of the natural bond orbitals polarization coefficients indicate that the electron density is localized predominantly on carbon atoms. The electronic configurations for carbon atoms in different fragments differ significantly. For C atoms of ethynyl (diethynyl) fragments, they are close to linear σ-bond with sp1.03 (P1) and sp0.95 (P2) configurations, while for C atoms of phenyl fragments it is sp2.42, intermediate between sp2 and sp3 configurations. The natural charges on Si in both polymers are almost the same: +1.58e, +1.59e, while the natural charges on the carbon atoms of the diethynyl group decrease in comparison with the charge on the carbon atom of the ethynyl group from –0.42e to –0.36e.