Electron-electron Interaction Research Articles

Fixed-Point Atomic Regulation Engineered Low-Thickness Wideband Microwave Absorption.

Atomic doping is widely employed to fine-tune crystal structures, energy band structures, and the corresponding electrical properties. However, due to the difficulty in precisely regulating doping sites and concentrations, establishing a relationship between electricity properties and doping becomes a huge challenge. In this work, a modulation strategy on A-site cation dopant into spinel-phase metal sulfide Co9S8 lattice via Fe and Ni elements is developed to improve the microwave absorption (MA) properties. At the atomic scale, accurately controlling doped sites can introduce local lattice distortions and strain concentration. Tunned electron energy redistribution of the doped Co9S8 strengthens electron interactions, ultimately enhancing the high-frequency dielectric polarization (ɛ' from 10.5 to 12.5 at 12GHz). For the Fe-doped Co9S8, the effective absorption bandwidth (EAB) at 1.7mm increases by 5%, and the minimum reflection loss (RLmin) improves by 26% (EAB = 5.8GHz, RLmin = -46dB). The methodology of atomic-scale fixed-point doping presents a promising avenue for customizing the dielectric properties of nanomaterials, imparting invaluable insights for the design of cutting-edge high-performance microwave absorption materials.

Positive and Negative Effects under Light Illumination in Halide Perovskites

Metal halide perovskites (MHPs) have excellent characteristics and present great potential in a broad range of applications such as solar cells, light‐emitting diodes, and photodetectors. However, the light stability of devices remains an unresolved issue and has received great research attention. Under light illumination, MHPs exhibit various anomalous phenomena, such as photoluminescence (PL) enhancement, defect curing, PL blinking, and phase segregation. These phenomena are commonly considered intimately correlated with the performance and stability of MHP devices. In recent years, significant efforts have been made experimentally and theoretically toward understanding the physical origins of these anomalous effects. However, most research focuses on negative effects while the positive effects are mostly ignored. Herein, the positive effects and the negative effects of light soaking in MHPs are systematically discussed with a classification of the correlated physical mechanisms by specifically focusing on variation occurring in timescale from second to hour, corresponding to the unique ionic–electronic interaction. This intends to provide a new insight into ion effects on excellent properties of perovskites, and deep physical understanding of charge‐carrier and ion dynamics in perovskite, and theoretical guidelines for the fabrication of high‐quality and stability perovskite‐based photovoltaic and photoelectric devices.

S‐Scheme g‐C3N4/CdS Heterostructures Grafting Single Pd Atoms for Ultrafast Charge Transport and Efficient Visible‐Light‐Driven H2 Evolution

AbstractEmerging step‐scheme (S‐scheme) heterostructures hold unique superiority in steering directional charge transport and reinforcing redox capacity, yet rational modification of S‐scheme heterostructures by single atoms (SAs) for efficient photocatalytic H2 evolution is rarely reported. In this work, Pd SAs‐modulated organic–inorganic g‐C3N4/CdS S‐scheme heterostructures are designed and prepared by a one‐pot mechanochemical approach allowing for g‐C3N4 nanosheets/CdS nanoparticles to confine atomically dispersed Pd co‐catalysts. The g‐C3N4/CdS S‐scheme charge‐transfer pathway is corroborated by a combination of in situ irradiated X‐ray photoelectron spectroscopy, electron paramagnetic resonance, and Kelvin probe force microscopy. Density functional theory (DFT) calculations, high‐angle annular dark‐field scanning transmission electron microscopy, and X‐ray absorption fine structure identify Pd‐S3 and Pd‐N2 atomic moieties underpinned by the electronic interaction between Pd SAs and g‐C3N4/CdS heterostructures, in which the d‐band center of Pd SAs is optimized for proton adsorption thermodynamically. Further, the g‐C3N4/CdS S‐scheme heterostructures alongside Pd SAs in concert boost the rapid migration of photogenerated electrons (1.05 ps) via Pd─S and Pd─N bond‐derived channels. A maximal H2 evolution rate of 85.66 mmol h−1 g−1 is achieved by 1 wt% Pd‐20 wt% g‐C3N4/CdS hierarchical composites. This work may guide the design of high‐efficiency S‐scheme‐based photocatalysts for solar‐to‐H2 conversion and beyond.

Structural and electronic transport properties of Zn- and Ga-doped Bi2− x Sb x Te3− y Se y topological insulator single crystals

A comprehensive study of structural and magnetotransport properties of pristine Bi2−x Sb x Te3−y Se y (BSTS) single crystals and doped with Zn (BSTS:Zn) and Ga (BSTS:Ga) are presented here. Magnetic field dependent Hall resistivities of the single crystals indicate that the holes are the majority carriers. The field dependent resistivity curves at different temperatures of the crystals display cusp-like characteristics at low magnetic fields, attributed to two-dimensional (2D) weak antilocalization (WAL) effect. We fit the observed low-field WAL effects at low temperatures using 2D and three-dimensional (3D) Hikami-Larkin-Nagaoka (HLN) equations. The 2D HLN equation fits the data more closely than the 3D HLN equation, indicating a 2D nature. The 2D HLN equation fit to the low field WAL effects at various temperatures reveal a phase coherence length (l φ) that decreases as temperature increases. The variation of l φ with temperature follows T −0.41 power law for BSTS:Zn, suggesting that the dominant dephasing mechanism is a 2D electron–electron (e−e) interactions. For pristine BSTS and BSTS:Ga, l φ(T) is described by considering a coexistence of 2D e−e and electron–phonon (e−p) interactions in the single crystals. The temperature variation of the longitudinal resistance in BSTS:Ga is described by 3D Mott variable range hoping model. In contrast, the transport mechanisms of both pristine BSTS and BSTS:Zn are described by a combination of 2D WAL/EEI models and 3D WAL.

Quantum computational, charge density, optical, molecular reactivity and thermodynamical analysis of Di-Halogen substituted nicotinic acid derivatives

6-Chloro-3-fluoro-2-(trifluoromethyl) isonicotinic acid (6C3F2TINA) and 6-Chloro-5-fluoronicotinic acid (6C5FNA) are currently being studied using the DFT method for the detailed examination of structural and molecular character alterationsin gas as well as in several organic solvent media. Implementing electrostatic potential maps and Fukui functions analyses the reactive environment of compounds. The occurrence of the transfer of electrons and holes within the molecule is reported by a charge transfer study along with the heat maps. The orbital study investigates the electronic density and interactions within themolecules. Optical examination of compounds revealed an enhancement with the solvents. Thebonding typefound in molecules isdetermined by topographical investigation, which examines the concentration and localisationof electrons present in them. The UV–Vis spectra exhibit the absorption characteristics of these compounds. The thermodynamic investigation reveals the compound’s stability at various temperatures at 1 atm pressure.

Nonadiabatic dynamics of molecules interacting with metal surfaces: A quantum-classical approach based on Langevin dynamics and the hierarchical equations of motion.

A novel mixed quantum-classical approach to simulating nonadiabatic dynamics of molecules at metal surfaces is presented. The method combines the numerically exact hierarchical equations of motion approach for the quantum electronic degrees of freedom with Langevin dynamics for the classical degrees of freedom, namely, low-frequency vibrational modes within the molecule. The approach extends previous mixed quantum-classical methods based on Langevin equations to models containing strong electron-electron or quantum electronic-vibrational interactions, while maintaining a nonperturbative and non-Markovian treatment of the molecule-metal coupling. To demonstrate the approach, nonequilibrium transport observables are calculated for a molecular nanojunction containing strong interactions.

Interplay of Landau Quantization and Interminivalley Scatterings in a Weakly Coupled Moiré Superlattice.

Double-layer quantum systems are promising platforms for realizing novel quantum phases. Here, we report a study of quantum oscillations (QOs) in a weakly coupled double-layer system composed of a large-angle twisted-double-bilayer graphene (TDBG). We quantify the interlayer coupling strength by measuring the interlayer capacitance from the QOs pattern at low temperatures, revealing electron-hole asymmetry. At high temperatures when SdHOs are thermally smeared, we observe resistance peaks when Landau levels (LLs) from two moiré minivalleys are aligned, regardless of carrier density; eventually, it results in a 2-fold increase of oscillating frequency in D, serving as compelling evidence of the magneto-intersub-band oscillations (MISOs) in double-layer systems. The temperature dependence of MISOs suggests that electron-electron interactions play a crucial role and the scattering times obtained from MISO thermal damping are correlated with the interlayer coupling strength. Our study reveals intriguing interplays among Landau quantization, moiré band structure, and scatterings.

Preparation and electrocatalytic oxygen evolution of bimetallic phosphates (NiFe)2P/NF

Abstract The energy and environmental crisis pose a great challenge to human development in the 21st century. The design and development of clean and renewable energy and the solution for environmental pollution have become a hotspot in the current research. Based on the preparation of transition metal phosphates, transition metals were used as raw materials, Prussian blue-like NiFe(CN)6 as a precursor, which was in situ grown on nickel foam (NF) substrate. After low temperature phosphating treatment, a bimetallic phosphide electrocatalyst (NiFe)2P/NF was prepared on NF substrate. Using 1 mol·L−1 KOH solution as a basic electrolyte, based on the electrochemical workstation of a three-electrode system, the electrochemical catalytic oxygen evolution performance of the material was tested and evaluated. Experiments show that (NiFe)2P/NF catalyst has excellent oxygen evolution performance. In an alkaline medium, the overpotential required to obtain the catalytic current density of 10 mA·cm−2 is only 220 mV, and the Tafel slope is 67 mV·dec−1. This is largely due to: (1) (NiFe)2p/NF nanocatalysts were well dispersed on NF substrates, which increased the number of active sites exposed; (2) the hollow heterostructure of bimetallic phosphates promotes the electron interaction between (NiFe)2P and NF, increased the rate of charge transfer, and the electrical conductivity of the material is improved; and (3) theoretical calculations show that (NiFe)2P/NF hollow heterostructure can effectively reduce the dissociation barrier of water, promote the dissociation of water; furthermore, the kinetic reaction rate of electrocatalytic oxygen evolution is accelerated. Meanwhile, the catalyst still has high activity and high stability in 30 wt% concentrated alkali solution. Therefore, the construction of (NiFe)2P/NF electrocatalysts enriches the application of non-noble metal nanomaterials in the field of oxygen production from electrolytic water.

Metal-support interface engineering for stable and enhanced hydrogen evolution reaction

Hydrogen has emerged as a green and sustainable pathway towards achieving global decarbonization and net-zero emissions, intensely driving the need for efficient hydrogen production protocols. Electrocatalytic hydrogen evolution reaction (HER) holds great potential as a scalable, eco-friendly and safe avenue for efficient hydrogen production. However, the large-scale implementation of electrocatalytic HER is substantially challenged by the high-cost and unstable materials that are mainly fabricated from noble metals, e.g., Pt and Pd. Given this challenge, we adopted an interface engineering strategy to immobilize nanoscale Pt particles within the framework of nitrogen-doped CNTs, namely Pt@N-CNTs, where electronic metal-support interaction (EMSI) plays an important role in enabling orbital rehybridization and regulating the charge transfer through the metal-support interface, thereby considerably improving the electrocatalytic activity. With limited content of noble metals, our developed Pt@N-CNTs delivered superior HER performance with an ultralow overpotential of 5.8 mV at 10 mA cm−2 and demonstrated a high mass activity of 12.72 A mgPt−1 at an overpotential of 50 mV as well as excellent stability under harsh acidic conditions. At 500 mA cm−2, Pt@N-CNTs surprisingly exhibited an overpotential of 55.2 mV, outperforming that of commercial 20 wt% Pt/C catalysts (131.5 mV). Importantly, we established a straightforward, scalable, and time-saving microwave reduction strategy, alluding to its promising commercial viability. This work therefore sheds light on the development of high-performance electrocatalysts for hydrogen evolution and water electrolysis.

Structural and superconducting properties in the Te-doped spinel CuRh2Se4

In this paper, we discuss the impact of tellurium (Te) doping on the spinel superconductor CuRh2Se4. We conducted a comprehensive evaluation of the structural and superconducting properties of the system using various techniques, including X-ray diffraction (XRD), resistivity, magnetization, and specific heat measurements. Based on our XRD analysis, we found that the spinel superconductor CuRh2Se4-xTex (0 ≤ x ≤ 0.28) crystallizes in the space group Fd3̅m (227), while the layered compound CuRh2Se4-xTex (2.8 ≤ x ≤ 4.0) crystallizes in the space group P3̅m1 (164). The upper critical magnetic field can be increased from 0.95(2) T for CuRh2Se4 to 3.44(1) T for CuRh2Se3.72Te0.28 by doping with elemental Te. However, the layered compound CuRh2Se4-xTex (2.8 ≤ x ≤ 4.0) did not exhibit superconducting properties. Besides, the specific heat measurements of CuRh2Se4-xTex (x = 0, 0.1, 0.28) indicate that the Te element doping affects the electronic structure and interactions of the material and breaks the stability of the superconducting pairing, which leads to a decrease in the Tc. Finally, we show the electronic phase diagram of Tc with Te doping to summarise our findings.

A first-principles study of HfB2 anisotropic surface stability and its oxygen adsorption behavior

In this work, the HfB2 anisotropic surface stability, and the adsorption behavior of oxygen molecule on the most likely exposed HfB2 surface were investigated based on density functional theory. The study found that the HfB2(0001) surface terminated by Hf (labeled as: Hf-(0001)) is more stable, and more likely interact with oxygen. By rotating the oxygen molecule orientation and changing the adsorption site, all possible high and low-symmetry adsorption configurations are considered. The results show that the low symmetry structure is unstable, and eventually turn into the high symmetry ones. For the highly symmetric structures, oxygen molecule tends to be adsorbed in parallel, and the dissociated oxygen molecule tends to be located at the bridge and hollow site of the Hf-(0001) surface, and there is no energy barrier to this process. Charge density difference and partial density of states proved that oxygen absorbed structures present similar electronic interaction characteristics, and oxygen adsorption process mainly affects the Hf atom at the outmost layer of the Hf-(0001) plane. Oxygen atoms bind to the Hf-(0001) surface mainly in the form of ionic bonds and covalent bonds, originating from the orbital hybridization of O-p and Hf-d. The oxidation of HfB2 starts from the interaction between oxygen and Hf.

Stability, Chemical Bonding, and Electron Lone Pair Localization in AsN at High Pressure by Density Functional Theory Calculations.

The covalent bonding framework of crystalline single-bonded cubic AsN, recently synthesized under high pressure and high temperature conditions in a laser-heated diamond anvil cell, is here studied by means of density functional theory calculations and compared to single crystal X-ray diffraction data. The precise localization of the nonbonding electron lone pairs and the determination of their distances and orientations are related to the presence of characteristic structural motifs and space regions of the unit cell dominated by repulsive electronic interactions, with the relative orientation of the electron lone pairs playing a key role in minimizing the energy of the structure. We find that the vibrational modes associated with the expression of the lone pairs are strongly localized, an observation that may have implications for the thermal conductivity of the compound. The results indicate the thermodynamic stability of the experimentally observed structure of AsN above ∼17 GPa, provide a detailed insight into the nature of the chemical bonding network underlying the formation of this compound, and open new perspectives to the design and high pressure synthesis of new pnictogen-based advanced materials for potential applications of energetic and technological relevance.

Uncovering the origin of unique elemental distribution behaviors of Vanadium in high entropy alloys

Owing to the unique elemental character, Vanadium (V) has recently gained growing interest in the field of high entropy alloys. It is known that V benefits in the mechanical strength in alloys, accompanying by the unique elemental distribution behaviors. In this work, we concentrate on the mechanism of V's distribution characters in VFeCoNi, which is similar to that of Cr in CrFeCoNi, by evaluating element inherent electronegativity, charge transfer, atomic volume, Voronoi volume and the atomic stress resulting from the combined effects of these factors. Another unique character of electronic interaction in the t2g and eg orbitals has been observed, which contributed to the fluctuation of atomic volume, thus enhancing solid solution strengthening. The tensile stress-strain tests show that the chemical ordering of V enhanced mechanical strength, especially for the grain boundary. Our work will provide new insights into the nanoscale distribution of V elements and the related macroscopic mechanical effects.

TS-1 zeolite encapsulated Pt clusters with enhanced electronic metal-support interaction of Pt−O(H)−Ti for nearly-zero-carbon-emitting photocatalytic hydrogen production from methanol

Photocatalytic H2 production from methanol is sustainable, yet challenges remain in avoiding carbon-containing gaseous by-products. Titanium silicalite-1 (TS-1) zeolite possesses attractive photocatalytic performance, but lack of modification strategies due to its microporous framework. Herein, we developed a pre-anchoring strategy to confine ultra-small Pt clusters inside TS-1 with ultra-low loading (0.2mol%), in which Pt were anchored in Ti−OH nests by electronic metal-support interaction (EMSI). The optimal catalyst achieved a remarkable H2 generation rate of 63.2mmolg–1 h–1 in CH3OH solutions, along with the production of high-value chemical HCHO as the oxidation product with 96.9% selectivity. Investigations reveal that the EMSI between Pt and Ti facilitated the selective decomposition of CH3OH to H2 and HCHO, leading to a nearly zero-carbon-emission process. Accordingly, we propose a light-driven carbon-negative "CO2→CH3OH→H2" route, coupling CO2 utilization and green H2 production with CH3OH as the intermediate, therefore offering a new perspective for "liquid sunshine".

Accumulated charge density at the interface boosts the urea oxidation reaction activity of Ni3N/Ni3S2 heterointerface

Optimizing the adsorption strength of multiple intermediates at one single active site at the same time is rather difficult. Heterointerface engineering provides more than one type of active sites to function, which may dramatically enhance the intrinsic urea oxidation reaction (UOR) activity of catalysts. Herein, a Ni3N (110)/Ni3S2 (010) heterointerface was fabricated. The electronic interactions between the two phases generates an accumulated charge density heterointerface and endows the heterointerface with more enhanced density of states, which facilitates the adsorption and desorption of more UOR intermediates, thus lowering the theoretical reaction barriers for the rate-controlling step of *CONHN to *CONN. The nickel moieties on Ni3N side tends to bond carbonyl and the nickel moieties on Ni3S2 side preferentially bond amnio. The cooperation of both nickel moieties contributes to the superb intrinsic UOR activity of Ni3N (110)/Ni3S2 (010) heterointerface. As a consequence, Ni3N (110)/Ni3S2 (010) heterointerface showcases outstanding UOR activity, reaching 105.66 mA·cm−2 at 1.6 V. This work provides an excellent UOR catalyst and helps to better understand the cooperation mechanism of the active sites at the heterointerface.

Study of new p-tolylpiperidin-4-one as an anti-Parkinson agent: Synthesis, spectral, XRD-crystal, in silico study, electronic and intermolecular interaction investigations by the DFT method

This study thoroughly investigated the potential of using 3,3-dimethyl-2,6-di-p-tolylpiperidin-4-one, (DMeTP) as an anti-Parkinson medicine against Parkinson's disease. To accomplish this, DMeTP was synthesized and characterized by various spectral techniques such as FT-IR, NMR, and Mass. The Hirshfeld analysis and finger plot were used in this study to reveal important insights about the intermolecular relations of the compounds. The theoretical analyses of the compound was carried out using Density Functional Theory (DFT) at the level of theory B3LYP/6-311++G(**). The frontier orbital and the molecular electrostatic potential studies proved the chemical stability of the DMeTP structure. Then, weak interactions like hydrogen and Vdw interactions were investigated throughout the topological study (AIM, RDG). The alpha-synuclein protein was used in a molecular docking analysis to uncover inhibitory properties against Parkinson's disease. Additionally, the pharmacokinetic and physicochemical characteristics of the DMeTP molecule were examined using the SwissADME online program.

Electronic metal-support interactions for defect-induced Ru/Co-Sm2O3 mesosphere to achieve efficient NaBH4 hydrolysis activity

Crafting resilient catalysts that promote H2 production through the hydrolysis of hydrogen storage materials like sodium borohydride stands paramount for the impending hydrogen economy. In this study, we propose a versatile metal–organic framework (MOF)-assisted approach to systematically explore the impact of electron-metal support interaction (EMSI) of Ru-modified Co-Sm2O3 (Ru/Co-Sm2O3) on H2 evolution from NaBH4 hydrolysis. Strategic annealing at 800 °C induces cobalt vacancies on the Ru/Co-Sm2O3 surface, optimizing the exposure of active sites and amplifying mass-charge transfer efficiency. Consequently, the defect-enriched Ru/Co-Sm2O3 showcases an impressive hydrogen generation rate (HGR = 0.430 mol min−1 gcatalyst−1) and outstanding cycling resilience, eclipsing the performance of most contemporary catalysts. Experimental findings reveal that Sm can not only adjust the Ru lattice spacing to accommodate more BH4−, but also modulate the Co vacancy concentration, thus bolstering the charge transport and ameliorating the catalyst's electrical conductivity. DFT calculations confirm that the Michaelis-Menten/Eley-Rideal mechanism is more appropriate to explain the hydrolysis of NaBH4.

Mean force emission theory for classical bremsstrahlung in strongly coupled plasmas

This work presents mean force emission theory, which extends the classical theory of bremsstrahlung emission to strongly coupled plasmas. In the high-frequency limit, the theory reduces to solving for the electron trajectory during a binary collision, but where the electron–ion interactions occur through the potential of mean force. In the low-frequency limit, it uses an autocorrelation formalism that captures effects of multiple collisions and strongly correlated motion. The predictions are benchmarked by comparison with first-principles classical molecular dynamics simulations of a fully ionized hydrogen plasma in which all interactions are repulsive. The comparison shows good agreement up to Coulomb coupling strengths of Γ∼30. The theory improves upon traditional models by including strong coupling effects and systematically including the effect of multiple collisions. Furthermore, mean force emission theory provides evidence that the Drude correction factor commonly used in quantum calculations of optical quantities may not be adequate at strong coupling.

Effect of bonding description and strain regulation on the conductive transition of Bi semimetal

Due to the differences in the treatment methods of the electron–ion interaction and the critical strain mode of the transition from semimetals to semiconductors, the corresponding strain modulation mechanism in layered bismuth (Bi) crystals remains elusive. In this work, the effects of van der Waals (vdW) correction on the crystal structure and electrical properties of Bi in an equilibrium/strained state are comparatively studied based on the density functional theory. It is found that vdW corrections can better describe the layered crystal and bandgap structure of Bi under equilibrium/strain conditions. With the vdW modification, bismuth can be converted from a semimetal to a semiconductor within a small compression range that is experimentally available. This transition is induced by the transfer of the conduction band minimum and the valence band maximum and is related to the competition of the near-band edge energy state near the Fermi level of bismuth. The present results not only provide guidance for the accurate study of the crystal structure and electronic properties of complex model systems, such as Bi or Bi-based inherently nanostructured materials, but also reveal strain regulation mechanism of Bi and predict its potential application in the semiconductor electronic devices.

Self-supported Ru-Fe-Ox nanospheres as efficient electrocatalyst to boost overall water-splitting in acid and alkaline media

Developing electrocatalysts with high activity and durability for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in both acidic and alkaline electrolytes remains challenging. In this study, we synthesize a self-supported ruthenium-iron oxide on carbon cloth (Ru-Fe-Ox/CC) using solvothermal methods followed by air calcination. The morphology of the nanoparticle exposes numerous active sites vital for electrocatalysis. Additionally, the strong electronic interaction between Ru and Fe enhances electrocatalytic kinetics optimization. The porous structure of the carbon cloth matrix facilitates mass transport, improving electrolyte penetration and bubble release. Consequently, Ru-Fe-Ox/CC demonstrates excellent catalytic performance, achieving low overpotentials of 32 mV and 28 mV for HER and 216 mV and 228 mV for OER in acidic and alkaline electrolytes, respectively. Notably, only 1.48 V and 1.46 V are required to reach 10 mA cm−2 for efficient water-splitting in both mediums, exhibiting remarkable stability. This research offers insights into designing versatile, highly efficient catalysts suitable for varied pH conditions.