Chemical Physics Letters最新文献

The effect of a static electric field ionization on the neutral hydrogen molecule H₂ confined in a spherical potential well is studied, as a simple model for the chemical activation of molecular species in a medium. Quantum diffusion Monte Carlo is employed with complete account of electron correlation. Field-induced ionization and dissociation are discussed, for different values of the confinement radius and electric field strength. This study allows to highlight the mechanism of electric field initiation of chemical reactions in fluids at different pressures, without the details of a specific chemical environment.

We combined Moment Tensor Potential (MTP) and Ring Polymer Molecular Dynamics (RPMD) for calculating the thermal rate constants of the OH + HBr system. We used the active learning (AL) algorithm for constructing a training set during RPMD. We compared the obtained RPMD-AL-MTP rate constants with the ones previously calculated using the quasi-classical trajectories (QCT) and the POTLIB potential energy surface, and with the experimental ones. We demonstrated that the RPMD rate constants were systematically closer to the experimental rate constants than the QCT ones at 200 K, 300 K, and 500 K.

An efficient electrocatalytic hydrogen storage system using CuCo₂O₄ supported by Ni foam (CuCo₂O₄/NF) as a bifunctional electrocatalyst and quinoxaline as a hydrogen storage carrier was developed. Electrochemical tests were conducted at room temperature and atmospheric pressure. The results showed that the conversion and selectivity of hydrogenation reached 93 % and 99 %, respectively, within 3 h at −0.18 V (vs. RHE). Meanwhile, the conversion and selectivity of dehydrogenation both reached 100 % within 20 min at 1.30 V (vs. RHE). Moreover, due to the excellent durability of CuCo₂O₄/NF, the hydrogenation conversion remained as high as 89 % after 8 cycles.

Despite platinum group metal have been widely used in catalytic converters, high cost and reaction temperature hindered their application. Inspired by the single-atom catalysts and confinement effect, selected PGM confined on the boron nitride nanotube with vacancy defects for CO oxidation have been systematically investigated. For PGM–BNNT catalysts, CO oxidation would proceed competitively in Eley–Rideal and Langmuir–Hinshelwood pathways. With N vacancy, Pd/Pt-BNNT(6,6) needs 0.33 and 0.28 eV to overcome the reaction barriers through the LH mechanism. The internal of BNNT will provide a more favorable nano-confinement environment than exterior surface, with the more activated adsorbed gases and electron transfer.

In this paper, the photochromic mechanism of different colors of sodalite and the changes in polysulfide radicals after photochromism were investigated. The results show that the substitution of chlorine by polysulfide radicals forms the basis for photochromism, and two structural defects—chlorine vacancies and oxygen hole centers are involved in the photochromism of sodalite. The decrease in the concentration of polysulfide radical S₂⁻ after photochromism leads to reduction in fluorescence intensity. This study explores the reasons for the change in fluorescence intensity caused by the alteration of polysulfide radicals after photochromism, and identifies the types of structural defects within sodalite.

The structural evolution and dynamic properties of liquid Ag₈₉Si₁₁ eutectic alloy during rapid cooling were explored by ab initio molecular dynamics. The calculated pair distribution functions and structure factors at 1173 K agree well with the experimental reference data. The comprehensive analyses including Honeycutt-Andersen index, Voronoi tessellation, and atomistic cluster alignment reveal a gradual enhancement of chemical short-range order with the decreasing temperature and a dominant structural shifting towards perfect and distorted icosahedra. Additionally, the dynamic properties of liquid Ag₈₉Si₁₁ eutectic alloy were obtained and the diffusion coefficients follow Arrhenius relationship.

The structural stability and electronic properties of CH₃NH₃PbI₃/ZnO heterojunctions were investigated using first-principles method. Our results show that the interfacial termination of CH₃NH₃PbI₃ influences the orientational order of C–N bonds and structural stability of heterojunction. For the first time, it was confirmed that the ionic polarization of CH₃NH₃PbI₃ material in CH₃NH₃PbI₃/ZnO induced by interfacial electrostatic interaction plays an important role in high efficient separation and transport of photo-generated carriers, which is a new physical mechanism. This study could provide an in-depth understanding of the properties of CH₃NH₃PbI₃/ZnO, and improve the stability and performance of perovskite solar cells.