0000000000039928
AUTHOR
Hong-xing Zhang
showing 13 related works from this author
Certain doping concentrations caused half-metallic graphene
2017
This work is supported by National Natural Science Foundation of China (Grant No. 21173096).
Nickel-catalyzed carboxylation of aryl zinc reagent with CO2: A theoretical and experimental study
2019
Abstract Two Ni-complexes with 1,1′-bis(diphenylphosphino)ferrocene (dppf) and tricyclohexylphosphine (PCy3) ligands were tested for the Ni-catalyzed cross-coupling of aryl zinc reagent with CO2 to form aryl carboxylic acid. Theoretical study with the aid of density functional theory (DFT) was carried out to understand the detailed reaction mechanism. The reasonable reaction pathway was deduced. The simulation results suggested that the free energy barrier of the rate-limiting step with (dppf)Ni is only 1.64 kcal mol−1 higher than the barrier with (PCy3)2Ni. However, our experiment provided an unexpectedly low yield by using (dppf)Ni complex as the catalyst. Further theoretical study ascrib…
Elastic, electronic and optical properties of boron- and nitrogen-doped 4,12,4-graphyne nanosheet
2020
Abstract The effects of boron (B) and nitrogen (N) dopants on 4,12,4-graphyne have been systematically investigated with density functional theory (DFT) calculations. The charge density analysis reveals that the N dopant at the sp-site destroys the acetylenic linkage in 4,12,4-graphyne, but instead tends to form a polar bond. The B- and N-doped 4,12,4-graphyne systems exhibit p- and n- semiconductor characters, respectively. Some obvious spin splitting polarizations can be observed in their band structures and DOS. Moreover, there is a giant difference in effective masses between electrons and electron holes, especially for B-doped 4,12,4-graphyne at C5 site. The directional electron and el…
Novel Carbon Nanotubes Rolled from 6,6,12-Graphyne: Double Dirac Points in 1D Material
2017
Two kinds of novel carbon nanotubes, namely, (N, 0) and (0, N) 6,6,12-graphyne nanotubes (6,6,12-GNTs), are constructed by rolling up the rectangular 6,6,12-graphyne sheets along two different sides into cylinders. The mechanical and electronic properties of 6,6,12-GNTs with varied N from 3 to 20 are investigated by using density functional theory. Unlike the single-wall carbon nanotubes, the Young’s moduli of 6,6,12-GNTs do not remain constant in the case of (N, 0), but the (0, N) tubes possess almost the same one around 0.32 TPa. The band structures and density of states are also exhibited in this work. When the tube sizes N are bigger than four, Dirac points appear at Fermi level in the …
First principles studies of the self trapped hole and the fluorine adsorption on the SrF2(111) surface
2013
Abstract By using density functional theory (DFT) with hybrid exchange potentials, namely DFT-B3PW, the ground states of self trapped hole and adsorbed fluorine atom on the strontium fluoride (1 1 1) surface are investigated. The self trapped hole at an interstitial anion site is denoted by H-center. In both the H-center and fluorine adsorption cases, the strong relaxations due to the surface effects are observed. In the H-center case, the unpaired electron distributes almost equally over two H-center atoms. This equivalent distribution of the unpaired electron is totally different from that of the bulk H-center [J. Phys. Chem. A 114 (2010) 8444]. The other case with an adsorbed fluorine at…
How does graphene enhance the photoelectric conversion efficiency of dye sensitized solar cells? An insight from a theoretical perspective
2019
The main goal of this work is to clearly answer the question from a theoretical perspective: how does graphene enhance the photoelectric conversion efficiency in the semiconducting layer of a dye sensitized solar cell? Several arrangements of the graphene layer between the dye molecule and the TiO2 (101) surface are carefully studied and discussed. The dynamic interfacial electron propagations are simulated with consideration of the underlying nuclear motion effect. Theoretical investigation shows that graphene can speed up the electron injection from the dye molecules to the semiconductor layer, only when the graphene sheet is bonded to the TiO2 surface via C–Ti bonds. The excited electron…
Novel 2D boron nitride with optimal direct band gap: A theoretical prediction
2022
Abstract A novel structurally stable 2D-boron nitride material, namely di-BN, is predicted by means of the first-principles simulations. This monolayer BN system is composed of the azo (N-N) and diboron (B-B) groups. Its in-plane stiffness is close to the monolayer h-BN. Usually, the boron nitride materials are semiconductors with large band gaps. However, the monolayer di-BN possesses a moderate direct band gap of 1.622 eV obtained from our HSE06 calculation. Although the GW correction enlarges the band gap to 2.446 eV, this value is still in the range of the visible light. The detailed investigation of its band arrangement reveals that this material is able to product hydrogen molecules i…
Theoretical study on hydrogen storage capacity of expanded h-BN systems
2017
In this work, the hydrogen storage capacity of the expanded hexagonal Boron Nitride (eh-BN) systems has been presented. We have employed a new equation of state (EOS) for hydrogen gas to figure out the hydrogen density distribution profiles in the eh-BN systems. In this regard, the environmental conditions (i.e., temperature and pressure) are considered in the prediction procedure using DFT single point calculations. The eh-BN systems with different layer spacings are studied by PBE method with consideration of the long range dispersion corrections. On account of the in-plane polar bonds, a series of adsorption positions are considered. Additionally, the adsorption energy and hydrogen densi…
A novel T-C3N and seawater desalination
2020
A structurally stable stacked multilayer carbonitride is predicted with the aid of ab initio calculations. This carbonitride consists of C3N tetrahedra, and is similar to T-carbon and thus named T-C3N. Its 2-dimensional (2D) monolayer is also carefully investigated in this work. The studies on electronic properties reveal that bulk and 2D T-C3N are insulators with a 5.542 eV indirect band gap and a 5.741 eV direct band gap, respectively. However, the monolayer T-C3N exhibits an excellent uniform porosity. Its 5.50 A pore size is perfect for water nanofiltration. The adsorption and permeation of water molecules on the monolayer T-C3N are investigated. Its promising potential application in h…
MD Simulation Investigation on the Binding Process of Smoke-Derived Germination Stimulants to Its Receptor
2019
Karrikins (KARs) are a class of smoke-derived seed germination stimulants with great significance in both agriculture and plant biology. By means of direct binding to the receptor protein KAI2, the compounds can initiate the KAR signal transduction pathway, hence triggering germination of the dormant seeds in the soil. In the research, several molecular dynamics (MD) simulation techniques were properly integrated to investigate the binding process of KAR1 to KAI2 and reveal the details of the whole binding event. The calculated binding free energy, -7.00 kcal/mol, is in good agreement with the experimental measurement, -6.83 kcal/mol. The obtained PMF profile indicates the existence of thre…
Dipoles in 4,12,4-graphyne
2021
Abstract In present work, B-N pairs as dipole source were introduced into 4,12,4-graphyne. According to the density functional theory (DFT) simulations, the electronic configurations of the doped 4,12,4-graphyne systems were significantly modified owing to the built-in electric fields caused by the B-N dipoles. Different B-N concentrations and arrangements can alter the electronic structure of 4,12,4-graphyne. Consequently, an obvious in-plane piezoelectricity can also be induced. Moreover, the direct band gap can be delicately modulated from 150 meV to 660 meV at PBE level. The B-N dipoles can also greatly enhance the light absorption instead of shifting the absorption region. According to…
Giant piezoelectricity in B/N doped 4,12,2-graphyne
2020
Abstract The effects of boron (B) and nitrogen (N) substitutions in 4,12,2-graphyne on its geometric structure and mechanical as well as electronic properties have been systematically investigated with the aid of density functional theory (DFT). The trend in the elastic properties of the substituted systems is determined by the doping positions and the type of the dopants. The Bader charge analysis reveals that the N dopant at the sp-site destroys the acetylenic linkage in 4,12,2-graphyne, but instead tends to form a polar bond, or even possibly a charge-shift bond. In particular, an obvious in-plane piezoelectricity is induced by foreign atom substitutions owing to the deformation of the p…
From determination of the fugacity coefficients to estimation of hydrogen storage capacity: A convenient theoretical method
2015
Abstract The equation of state (EOS) from virial expansion (VE) is used in this work to pave the way for determining the fugacity coefficients of the hydrogen fluid at arbitrary temperature and pressure. The fugacity coefficients from our VE method have more physical meanings than the empirical values. In this way, the hydrogen storage capacity of a novel material model can be estimated by using few density functional theory (DFT) calculations with the aid of a continuum model. The efficient continuum model can provide a more accurate estimation of the hydrogen storage capacity than the pure DFT calculations. Furthermore, the expensive grand canonical ensemble (μNT) simulations combining wi…