Chemical Physics Letters最新文献

The electronic structure and the magnetic properties are performed on Co doped MoS₂ (MoS₂-Co) and Co doped MoS₂/graphene (MoS₂/Gr-Co) systems based on the first principles calculations. When two Mo atoms are substituted by two Co atoms, the magnetic moments of two Co co-doped MoS₂ (MoS₂-2Co) and MoS₂/Gr (MoS₂/Gr-2Co) are 5.96 µ_B and 6.40 µ_B. The magnetic moment of MoS₂-2Co increases by 0.44 µ_B and the transition from half-metal to metal occurs after introducing the graphene layer. Further introducing an O atom in MoS₂-2Co and MoS₂/Gr-2Co, the hybridization between Co-3d and O-2p is significantly stronger than that between Co-3d and S-3p.

Benzotrithiophene and its derivatives obtained by fusing the aromatic rings at the peripheral sites are modelled using density functional methods for exploring their optoelectronic properties. The studies showed that absorption maximum shifted towards higher wavelengths with the extension of rings, irrespective of the functional used. The above molecules adopt anti-parallel orientations in their stacked dimer. The analysis of the stacked dimers revealed that they interact via van der Waals forces. The charge transport properties are found to vary with the orientation of the molecules. The studies showed that the designed molecules act as electron transporters in their anti-parallel orientation.

This paper investigates the role of carbon-containing impurities (i.e. C, C + H, CH, and CH + H) playing in hydrogen diffusion into Pd(1 0 0) subsurface. Energetics and structures for adsorptions and absorptions of hydrogen were explored with variational coverages and locations of adsorbates by density functional theory, and then minimum energy pathways were cautiously searched out by climbing image nudged elastic band method. Surface relaxation and reconstruction effects were also concerned. Quantum simulations reveal that C and CH strongly bond to hollow site and lead to charge density redistribution and structural change of Pd(1 0 0) surface, and thus predominantly affect hydrogen penetration behavior.

Molecular dynamics simulations were performed on water droplets containing fewer than 400 molecules, exploring both, bulk and surface regions. The droplet model was evaluated using two order parameters: tetrahedrality, as defined by Errington et al., and g₅, as defined by Cuthbertson et al. Comparisons were made with bulk water. Our findings revealed negative tetrahedrality for surface water molecules. Additionally, the correlation between the distance from the droplet center and g₅ indicated a decrease in the surface density of the droplet.

The DFT/PBE functional and coupled-cluster theory CCSD(T) computations were used to explore properties of the isovalent B₁₂H₂, B₁₁SiH and B₁₀Si₂ clusters. Diverse approaches for analysing quasi-degenerate isomers pointed out that while the ribbon-like isomer achieves aromaticity, its spatial effects diminish it with increasing ribbon size. Doping of two H atoms into B₁₂ does not reduce the σ aromaticity of B₁₂H₁₂. Remarkably, the lowest-lying isomer of B₁₀Si₂ exhibits a novel 3D structure whose shape and electrons can be simulated by a rectangular cuboid. The spectrum of the whole set of valence electron of this 3D B₁₀Si₂ was elucidated by this model.

Atomically dispersed single metal on defective boron nitride nanotubes (BNNTs) show promising potential for CO₂ electrocatalytic reduction reaction (CO₂ERR). Using density functional theory calculations, we explore the CO₂ERR mechanism on single-atom catalysts (SACs) supported on BNNTs as well as assess their electrocatalytic performance of these catalysts. Boron or nitrogen vacancies in BNNTs are doped with palladium, platinum, or rhodium atoms to form three-coordinated metal centers, denoted as M@BNNT-V (M = Pt, Rh, Pd; V = B vacancy or N vacancy). Pt@BNNT with boron vacancies (Pt@BNNT-B_vac) demonstrates a tendency to facilitate multi-electron reduction processes leading to the formation of complex molecules such as CH₂O, CH₃OH, and CH₄ with a limiting potential (U_L) of −0.36 V. Conversely, Rh@BNNT-B_vac and Pd@BNWNT-B_vac show significantly lower limiting potentials of −0.06 V and −0.12 V, respectively, for the reduction to formic acid (HCOOH), with Rh@BNNT-B_vac exhibiting enhanced activity and selectivity. Additionally, the deep reduction to other hydrocarbons or oxygenates, which typically requires potentials of −0.72 V and −0.60 V, appears less likely on both Rh and Pd doped BNNT-B_vac, further delineating the nuanced performance differences induced by metal type and coordination environment within the BNNT structure.

The study investigated the behavior of N-nitropyrazole (1-NP, C₃H₃N₃O₂) under high pressure using a diamond anvil cell, Raman spectroscopy, and simulation calculations. The pressure–volume relationship of the sample, molecular interactions, and changes in optical Raman were analyzed. The Raman experiments revealed abnormal vibration intensities and a discontinuity in peak position at 2.2 GPa. For instance, the C-H stretching vibration produces a new vibration peak under pressure, and the NO₂ torsion mode continues to red shift beyond 2.2 GPa. These observations suggest that the crystal’s phase transition results from the distortion of its hydrogen-bonded network structure. The pressure relief experiment confirms the reversibility of the phase transition.

The global need of energy is raising day by day. To meet this demand double perovskites (DPs) can play a vital role for energy conversion devices. In this letter, we formulated and examined lead-free defect perovskites using a combination of tellurium and tin, denoted as Cs₂Sn_1-xTe_xI₆ (0, 0.25), utilizing density functional theory which include structural, optical and thermal behavior. Both the optimized volume and lattice parameter exhibit a linear increase with the Te content in Cs₂Sn_1-xTe_xI₆ (CsSnTeI). The negative value of formation energy for both pure and doped materials along with their Poisson and Pugh ratio confirm the stability of these materials. The band structure analysis reveals its semiconducting behavior, with the band gap expanding proportionally to the increased Te concentration with band gap value of pure (1.20 eV) and doped 91.43 eV) double perovskites. Optical characteristics, including the dielectric function and absorption coefficient, were also analyzed. To expose their potential use of Cs₂Sn_1-xTe_xI₆ (0, 0.25) in thermoelectric devices, temperature dependent thermoelectric features are investigated reveal that suitability of these materials for energy conversion purposes.

Notable strides have been made in membrane technology, yet challenges persist in separating complex oily wastewater. Thus, developing an advanced, high-flux filtration membrane that resists oil and degrades organic pollutants is vital. Herein, we developed a novel TiO₂-MX@PVDF ESM with unique cauliflower-like structures, imparting superwetting behaviour for effective water capture and oil droplet repulsion, thereby improving oil/water separation. Additionally, it exhibits excellent oil-fouling resistance despite multiple separation cycles. Furthermore, its light-trapping ability and unique band structure degrade the malachite green dye. Thus, this work introduces an achievable approach for designing dual-functional membranes to address challenging oily wastewater.

Simple theoretical equation of state has been derived to study the dependency of size, shape and temperature of the nanostructures. Qi and Wang model of equation of state (EoS) is extended to study the size and shape dependent compression ratio for Se nanoparticle. The compression ratio (V/V₀) increases with temperature across nanoparticles of various sizes. The computed data for volume compression ratio are compared with available experimental data and found in good agreement. A good agreement between theoretically calculated and experimental result proves the usefulness of the model to study the thermal properties of nanoparticles.