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Energetics and electronic structures of polymeric all-benzene hollow-cages and planar networks
摘要： We studied the energetics and electronic structure of polymerized benzene hollow-cages and sheet using the density functional theory with the generalized gradient approximation. The energetics and electronic structure of the polymeric benzene cages and sheet depend on their size and dimensionality. Because of the symmetric network topology as well as the constituent benzene units, the cages possess highly bunched states around the Fermi level. The energy gap between the highest occupied and the lowest unoccupied states of the cages is approximately proportional to their curvature, owing to the decrease of the strain. The polymerized benzene sheet is a direct gap semiconductor with the gap of 2.4 eV between the less dispersive states of the highest branch of the valence and the lowest branch of the conduction bands.
关键词： density functional theory,electronic structure,planar networks,polymerized benzene,hollow-cages
更新于2025-09-10 09:29:36
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Effect of multiorbital contributions to strong-field ionization of benzene derivatives
摘要： Strong-?eld ionization of benzene, ?uorobenzene, benzonitrile, and 1-chloro-2-?uorobenzene is studied within the framework of real-space and real-time time-dependent density functional theory. Analysis of the ionization rates as a function of the molecule orientation reveals a signi?cant contribution from multiple inner Kohn-Sham orbitals that depends on the electronic structure and on the orbital symmetries of the molecule, as well as on the polarization and intensity of the external laser ?eld. Calculated photoelectron angular distributions at different molecular orientations and in response to laser ?elds with different degrees of ellipticity further demonstrate the spatial dependency of the orbital ionization rates.
关键词： orbital symmetries,time-dependent density functional theory,strong-?eld ionization,benzene derivatives,photoelectron angular distributions
更新于2025-09-10 09:29:36
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Enhanced Electron Separation on in-Plane Benzene-Ring Doped g-C3N4 Nanosheets for Visible Light Photocatalytic Hydrogen Evolution
摘要： Solar-to-chemical energy conversion by photocatalytic hydrogen evolution (PHE) is critical for reduction of the pollution and storage of clean energy. To improve the solar conversion efficiency, it is highly imperative to accelerate the photocarrier separation and transportation through materials design. Herein, we describe a highly effective PHE catalyst based on in-plane benzene-ring doped g-C3N4 nanosheets heterostructure through the thermal co-polymerization of urea and 4, 4'-sulfonyldiphenol (BPS) followed by a controlled heat-etching step. The solid-state 13C NMR confirms the existence of benzene-ring structure in g-C3N4 nanosheets. Experimental results and theoretical calculations show that the energy and electronic structure of the catalyst are optimally regulated, inducing increased light absorption and effectively accelerated separation of the photo-driven charge carriers. It exhibits enhanced photocatalytic hydrogen evolution efficiency with a PHE rate of 12.3 mmol h-1 g-1 (almost 12 times higher than that of pure g-C3N4 nanosheets) and the quantum efficiency of 17.7 % at 420 nm.
关键词： g-C3N4,hydrogen evolution,in-plane,benzene-ring doping,photocatalysis
更新于2025-09-10 09:29:36
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Pure and M-doped (M=Zn, Cu, Ni, Co) cadmium oxide nanosheets, novel adsorbents for the adsorption of ethyl benzene and ortho, meta, para xylene: a theoretical study
摘要： The electronic and structural properties investigation of pure and zinc, copper, nickel, cobalt doped cadmium oxide nanosheets (CdONS) and the adsorption of ethyl benzene (EB) and ortho- meta- para xylene (OX, MX, PX) on these nanosheets were studied by density functional theory calculations. The adsorption energy, charge transfer, energy gap, spatial distribution of HOMO and LUMO orbitals and electron density scheme of ethyl benzene and ortho, meta, para xylene molecules on pure and doped CdONS are calculated. The obtained results show that the adsorption energy value increases after doping Zn, Cu, Ni and Co atoms in oxygen substituted state, especially in NiOCdONS and CoOCdONS. The adsorption energy of EB, OX, MX and PX on NiOCdONS and CoOCdONS is about ? 260?kJ/mol whereas its value on pure CdONS is approximately ? 100?kJ/mol. In comparison with pure CdONS, the adsorption energy of the molecules on MCdCdONS, decreases except in NiCdCdONS. The adsorption energy of OX, MX and PX on NiCdCdONS is ? 263.12, ? 150.94 and ? 151.85?kJ/mol, respectively. Also, the results show that the value of energy gap increases after the adsorption of EB, OX, MX and PX on CoOCdONS, therefore, CoOCdONS can be proposed as proper adsorbent and sensor for these molecules.
关键词： Adsorption,Ethyl benzene,Xylene,Cadmium oxide nanosheet,Density functional theory
更新于2025-09-10 09:29:36
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Metal-free photocatalytic aerobic hydroxylation of benzene catalyzed by the commercially available quinoline sulfate
摘要： Metal- free photocatalytic aerobic hydroxylation of benzene to phenol is achieved by using the low-cost commercially available quinoline sulfate (QuH2SO4) as the photocatalyst. The reaction conditions are optimized and a high phenol yield of 11.3% is obtained under the optimal reaction conditions. It is found that the [QuH]+ cation is the catalytic active species and its planar structure is crucial for its effect interaction with benzene. Moreover, the influence of the coupled anion on the photocatalytic activity of the [QuH]+ cation is investigated and discussed.
关键词： Metal- free,Photocatalysis,Hydroxylation of benzene,Phenol,Quinoline sulfate
更新于2025-09-04 15:30:14
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Improving the rectifying performance of the pyrene-benzene system by optimizing its hydrocarbon bridge: A first-principles investigation
摘要： We report a computational study on enhancing the rectification ratio (RR) of the pyrene-benzene junction by modifying the structure of its acyclic aliphatic hydrocarbon bridge. The RR values for a series of pyrene-benzene systems with different types of bridges are determined. Notably, the maximum RR of the pyrene-(CH)3-(CH2)3-(CH)3-benzene system is 93.8, and the same hydrocarbon bridge increases the RR of the organic photovoltaic materials pyrene-DMA (N,N-dimethylaniline) and pyrene-DCNB (p-dicyanobenzene) by 10 times and limits reverse current during photo-induced electron transfer. These findings are particularly important for the design of molecular devices where both a high RR and conductivity are desirable. Moreover, they provide new insight into phenomena that indirectly affects the photo-electric conversion efficiency viz. enhancing the RR of the materials.
关键词： molecular electronics,hydrocarbon bridge,photovoltaic materials,pyrene-benzene system,rectification ratio
更新于2025-09-04 15:30:14
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Modern Purification Methods for Liquid Scintillators Intended for Recording Rare Events
摘要： Chromato-mass-spectrometry and UV/VIS spectroscopy are used to study the composition and properties of linear alkyl benzene (LAB) produced in Russia as the basic solvent for production of low-background liquid scintillators. The efficiency of LAB purification by reducing intrinsic radioactivity (U, Th) via water extraction (with addition of a strong chelate, dimethylaminomethylendiphosphonic acid) and sorption on Al2O3 in silica gel is studied. The purification method for removing potassium from scintillation fluors (PPO, BPO, p-terphenyl) is developed. It is shown that U and Th can be efficiently extracted from NdCl3 water solutions with 0.1 M TOPO solution in pseudocumene.
关键词： NdCl3 water solutions,liquid scintillators,purification methods,sorption,potassium removal,radioactivity,linear alkyl benzene,water extraction
更新于2025-09-04 15:30:14
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Valence ππ* Excitations in Benzene Studied by Multiconfiguration Pair-Density Functional Theory
摘要： We explore the valence singlet and triplet ππ* excitations of benzene with complete active space self-consistent field (CASSCF) theory, complete active space perturbation theory (CASPT2), and multiconfiguration pair-density functional theory (MC-PDFT) for four different choices of active space. We propose a new way to quantify the covalent and ionic character of the electronic states in terms of the components of the total electronic energy. We also explore the effect of scaling the exchange and correlation components of the on-top density functional used in MC-PDFT; we observe that increasing the exchange contribution improves the MC-PDFT excitation energies for benzene.
关键词： CASSCF,MC-PDFT,benzene,CASPT2,valence excitations,multiconfiguration pair-density functional theory
更新于2025-09-04 15:30:14