Chemical Physics最新文献

Copper-based catalysts are regarded as highly promising catalysts for the oxidation of hydrogen chloride (HCl) to chlorine. This study involved the preparation of a range of copper-based catalysts via impregnation. The aim was to investigate the impact of Sr loading on the conversion rate of HCl in Cu/Y zeolite catalysts, through experimental analysis. The physicochemical properties of the catalyst were investigated using a series of characterization techniques. The experiment validated that the addition of Sr could improve the catalytic activity of Cu/Y zeolite catalyst and reduce the catalytic reaction temperature. The HCl conversion rate exceeded 89 %, with a spatial–temporal yield of approximately 2.75 ${g_{{Cl}_2}{g}_{cat}}^{-1}{h}^{-1}$ when the Sr loading amount was 1.5 %. The characterization results indicated that the addition of Sr further increased the proportion of highly dispersed copper. Additionally, molecular simulation techniques were employed to investigate the interaction between the reactants and the catalyst. Monte Carlo simulation showed that the adsorption capacity of zeolite for HCl was further enhanced by the addition of Sr. Molecular dynamics simulation showed that the addition of Sr reduced the diffusion of reactants in the catalyst support channel and promoted the catalytic reaction.

This paper investigates the effects of methyl substitution on the valence orbital momentum distributions of adamantane. Kinematically complete electron-impact ionization experiments on 1,3-dimethyladamantane are performed at an incident electron energy of 1.2 keV, and the resulting electron momentum profiles are compared with those of pristine adamantane. Moreover, the influences of molecular vibration and distorted-wave effects on the electron momentum profiles are examined. The highest occupied molecular orbital (HOMO) of adamantane, 7t₂, is split into the 10b₁, 18a₁, and 12b₂ orbitals in 1,3-dimethyladamantane. It is revealed that the momentum profile for the sum of the 10b₁, 18a₁, and 12b₂ orbitals exhibits a markedly higher intensity at low momentum than that of the 7t₂ parent orbital. This strongly suggests that the HOMO is spatially more extended when surface hydrogens are replaced with methyl groups, which causes an increase in the absorption cross section of the 3 s Rydberg excitation.

The investigation of stevia-surfactant systems is of significant importance for the extraction process of steviol molecules as well as for the formulation of food products. The present study investigates the electrical conductivity of aqueous solutions containing a sugar substitute and surfactant over a temperature range of 25–50 °C. The sugar-substitute, Stevia Rebaudiana, concentration C_s (g/mL), is ranged from 0.047 to 0.6. The surfactant, Sodium bis(2-ethylhexyl) sulfosuccinate (AOT), has a concentration range of 1.4 ≤C_AOT (g/L)≤ 6. The degree of ionization in ionic micelles, $\alpha$, is determined by examining the conductivity of AOT in Stevia-free water, where complete micelle dissociation is observed. In the presence of Stevia Rebaudiana, a significant exponential decay in system conductivity with respect to the concentration of the sugar substitute is observed. Empirical equations were introduced to describe this behavior. The temperature dependence of conductivity is modeled using an Arrhenius equation. We postulate the formation of pseudo-micelles arising from interactions between the sugar substitute and surfactant, characterized by an effective degree of ionization in ionic micelles, α_e.

Two-dimensional (2D) materials holding appropriate bandgaps, high carrier mobility, and long carrier lifetime require to be urgently explored as electronic devices such as field effect transistors (FETs) become more and more miniaturized. Herein, single-layer (SL) InGeS is thoroughly investigated using first-principles calculations. Theoretical results confirm SL InGeS has nice thermal and dynamical stability at 300 K. SL InGeS holds a direct bandgap of 1.28 eV by HSE06, and its electrons and holes are inherently located at different atomic regions. In the visible range, SL InGeS displays a maximum optical absorption of ∼ 5 × 10⁵ cm⁻¹, surpassing that of most known 2D materials. Furthermore, SL InGeS possesses high electron mobility (∼11100 cm² V⁻¹ s⁻¹) and relatively low hole mobility (∼1000 cm² V⁻¹ s⁻¹), and its carrier lifetime is as long as 4.99 ns. In addition, an Ohmic contact is designed in the graphene/InGeS heterojunction, implying small current resistance. In brief, all these scientific findings promise SL InGeS is a hopeful candidate in ultrathin FET devices.

Recently, a new type of high-energy explosive (TNTNB) has been synthesized. Before fully understanding its detonation performance and safety features, it is necessary to conduct certain studies on its basic physical properties. For this purpose, we have employed first-principles methods to investigate the structural, electronic, vibrational, and thermal properties of TNTNB. The optimized lattice parameters of TNTNB crystals differ from the experimental values by less than 2 %. The electronic properties calculation results show that TNTNB has an indirect bandgap of 2.1508 eV. The phonon dispersion and density of phonon states indicate that its phonon bath modes region is 0–245 cm⁻¹, and the doorway modes region is 245–735 cm⁻¹. Additionally, the calculated energy transfer rate is $3.460$ × 10¹² J/K/mol, and the phonon-vibration coupling coefficient is 3.31. The zero-point energy calculated from the density of phonon states is 1669.06 kJ/mol, and the isochoric heat capacity at 300 K is 1441.48 J/K/mol.

A new ZnO/NiCo₂O₄ photocatalyst was synthesized to develop systems for removing pharmaceutical pollutants. Various properties of the synthesized nanocomposite such as crystal structure, morphology, optical activity, chemical composition, electrochemical functions, and energy band structure were investigated. The study on tetracycline removal showed that the catalytic activity of the ZnO/NiCo₂O₄ nanocomposite (0.0426 min⁻¹) is significantly higher compared to ZnO and NiCo₂O₄ individually. Morphology images confirmed the creation of a heterojunction between rice-shaped ZnO and NiCo₂O₄ nanoparticles. In photoluminescence and electrochemical impedance analyses, the nanocomposite displayed the weakest signal among its components, suggesting effective control of recombination and charge carrier transfer. The combination of NiCo₂O₄ with ZnO resulted in increased light absorption in the visible spectrum, contributing to its photocatalytic performance. The energy band structure of ZnO and NiCo₂O₄ was examined, presenting a detailed explanation of the most likely mechanism for the improved photocatalytic activity.

In this contribution, based on density Functional Theory, we focus on studying the structural and dynamic stability of octahedral and icosahedral beryllium nitride (Be₃N₂)_x fullerenes and their symmetry equivalent carbon molecules. The icosahedron structure of beryllium nitride and carbon-based fullerenes shows hybrid features, between a sphere and a polyhedron. Nevertheless, the cohesive energies of carbon fullerenes are slightly lower than those of beryllium nitride based on Be₃N₂ units. Although icosahedral I_h (1,1) and I_h (2,2) (Be₃N₂)₃₀ and (Be₃N₂)₁₂₀ are energetically slightly less favorable than their corresponding carbon fullerenes, they showed chemically stable structures. IR & Raman spectra are also simulated using a coupled-perturbed KS/HF scheme permitting their identification. Importantly, no imaginary frequency is recorded in their vibrational spectra which confirms an inherent dynamic stability. These results provide valuable insights that can be extrapolated to other noncarbon nanostructures containing pentagonal rings or pentagonal defects.

The trigonal prismatic MnO₆ is a basic structural unit of Mn-based compound which has been seldom explored in theoretical and experimental studies. In this paper, the diffusion potential energy surfaces of Li⁺, Na⁺, K⁺, Mg²⁺, Al³⁺, and NH₄⁺ ion in trigonal prismatic 1H-MnO₂ are presented, which give an intuitionistic picture of the Jahn-Teller effect on the diffusion process. Based on the nudged elastic band method, it is found that the diffusion of ions in trigonal prismatic MnO₂ is accompanied by consecutive structural distortion. The low diffusion barriers indicate trigonal prismatic MnO₂ is a fast ion conductor. Band structure calculations show the semimetal characteristic of the intercalated compound, which is fit for high electrochemical performance. The details of the diffusion process are also highlighted. Our theoretical study provides an in-depth understanding and research on the fundamentals of the diffusion process in the special configuration in MnO₂ and helps to develop novel high-performance electrodes.

The standard lead-free double perovskite X₂NaIO₆ has become a viable alternative for lead-based perovskites due to its remarkable optoelectronic capabilities, high stability, non-toxicity, and multifunctionality. This study is presented to evaluate the structural, electronic, optical, and mechanical properties of X₂NaIO₆ (X=Sr, Ba) by applying a first-principles method based on density functional theory (DFT). These investigations were carried out at the level of the generalized gradient approximation (GGA) for the exchange–correlation functional, parameterized by Perdew Burke and Erenzerhof (PBE) within the CASTEP code. The tolerance factors (τ) for Sr₂NaIO₆ and Ba₂NaIO₆ are 0.98 and 1.0, confirming the cubic nature of both compounds. Both compounds Sr₂NaIO₆ and Ba₂NaIO₆ have direct narrow bandgap values of 1.57 eV and 1.42 eV, respectively. We also presented a comprehensive study of their optical properties. Shear modulus (G), Poisson’s ratio (v), elastic coefficient (C_ij), anisotropy (A), bulk moduli (B), Young’s modulus (Y), and Pugh’s ratio (B/G) are computed. The combined electronic, optical, and mechanical investigations show that both materials are suitable for optoelectronic, photovoltaic, and solar cell applications.

Highly crystalline Zn_1-xNi_xO [x = 0, 0.5 & 1.0 wt%] nanoparticles were successfully synthesized by chemical and green synthesis routes at different doping concentrations. XRD, FE-SEM, EDS, UV, FTIR and VSM characterized the obtained nanoparticles from both routes for micro-structural, morphological, compositional, optical and magnetic properties respectively. X-ray diffraction confirms the formation of hexagonal wurtzite structure with an average crystallite size lies in the range 14–35 nm. FESEM analysis reported well-distinguished small bricks like grains were observed for green synthesized samples, whereas, chemically synthesized samples possess spherical grains.The EDS study confirms the presence of Ni, O and Zn elements closely to the stoichiometric amount. The optical Eg was found to be reduced with Ni doping and minimum bandgap of 2.4 eV for green synthesized and 2.2 eV for chemically synthesized samples has been observed. The photocatalytic performance of methylene blue dye was studied and resulted in the highest degradation efficiency of 88.8 % is achieved at 150 min of sunlight exposure. The obtained magnetic results revealed that the presence of Ni doping introduced ferromagnetism behaviour in ZnO nanoparticles and makes them suitable material for spintronic device application.