Mei-Ling Zhang

A First Principles Study of H2 Adsorption on LaNiO3(001) Surfaces

The adsorption of H2 on LaNiO3 was investigated using density functional theory (DFT) calculations. The adsorption sites, adsorption energy, and electronic structure of LaNiO3(001)/H2 systems were calculated and indicated through the calculated surface energy that the (001) surface was the most stable surface. By looking at optimized structure, adsorption energy and dissociation energy, we found that there were three types of adsorption on the surface. First, H2 molecules completely dissociate and then tend to bind with the O atoms, forming two –OH bonds. Second, H2 molecules partially dissociate with the H atoms bonding to the same O atom to form one H2O molecule. These two types are chemical adsorption modes; however, the physical adsorption of H2 molecules can also occur. When analyzing the electron structure of the H2O molecule formed by the partial dissociation of the H2 molecule and the surface O atom, we found that the interaction between H2O and the (001) surface was weaker, thus, H2O was easier to separate from the surface to create an O vacancy. On the (001) surface, a supercell was constructed to accurately study the most stable adsorption site. The results from analyses of the charge population; electron localization function; and density of the states indicated that the dissociated H and O atoms form a typical covalent bond and that the interaction between the H2 molecule and surface is mainly due to the overlap-hybridization among the H 1s, O 2s, and O 2p states. Therefore, the conductivity of LaNiO3(001)/H2 is stronger after adsorption and furthermore, the conductivity of the LaNiO3 surface is better than that of the LaFeO3 surface.

A first-principles study of gas molecule adsorption on borophene

Borophene, a new two-dimensional material, was recently synthesized. The unique anisotropic structure and excellent properties of borophene have attracted considerable research interest. This paper presents a first-principles study of the adsorption of gas molecules (CO, CO2, NH3, NO, NO2 and CH4) on borophene. The adsorption configurations, adsorption energies and electronic properties of the gas molecules absorpted on borophene are determined, and the mechanisms of the interactions between the gas molecules and borophene are evaluated. We find that CO, CO2, NH3, NO and NO2 are chemisorbed on borophene, while CH4 is physisorbed on borophene. Furthermore, our calculation also indicate that CO and CO2 are chemisorbed on borophene with moderate adsorption energy and NO, NO2 and NH3 are chemisorbed on borophene via strong covalent bonds. Moreover, CO is found as an electron donor, while CO2 an electron acceptor. The chemisorption of CO and CO2 on borophene increases the electrical conductivity, so It seems t...

Sc-Decorated Porous Graphene for High-Capacity Hydrogen Storage: First-Principles Calculations

The generalized gradient approximation (GGA) function based on density functional theory is adopted to investigate the optimized geometrical structure, electron structure and hydrogen storage performance of Sc modified porous graphene (PG). It is found that the carbon ring center is the most stable adsorbed position for a single Sc atom on PG, and the maximum number of adsorbed H2 molecules is four with the average adsorption energy of −0.429 eV/H2. By adding a second Sc atom on the other side of the system, the hydrogen storage capacity of the system can be improved effectively. Two Sc atoms located on opposite sides of the PG carbon ring center hole is the most suitable hydrogen storage structure, and the hydrogen storage capacity reach a maximum 9.09 wt % at the average adsorption energy of −0.296 eV/H2. The adsorption of H2 molecules in the PG system is mainly attributed to orbital hybridization among H, Sc, and C atoms, and Coulomb attraction between negatively charged H2 molecules and positively charged Sc atoms.

The role of electronic donor moieties in porphyrin dye sensitizers for solar cells: Electronic structures and excitation related properties

The development and synthesis of novel dye sensitizers are important for improving the power conversion efficiency of dye-sensitized solar cells (DSSCs) in terms of the role of dye sensitizers in photon to electricity energy conversion processes. How the different moieties tune the electronic structures and related properties is the fundamental issue in designing dye sensitizers. Here, the geometries, electronic structures, excitation properties, and free energy variations for electron injection (EI) and dye regeneration (DR) of porphyrin dye sensitizers SM315, GY50, FA, and KS, containing bulky bis(2′,4′-bis(hexyloxy)-[1,1′-biphenyl]-4-yl)amine, diarylamino group with two hexyl chains, quinolizinoacridine, and triazatruxene as electron donors, respectively, were investigated. The Q bands absorption spectra of FA and KS exhibit a blue-shift relative to those of SM315 and GY50, resulting from weak conjugation effects. The transition configurations and molecular orbital analysis suggest that the electron do...

First-Principle study of H 2 adsorption on LaFeO 3 (110) surface

The adsorption of H2 molecule on LaFeO3(110) surface was studied by first-principle calculations. Based on the adsorption sites, adsorption energies, and electronic structures, it can be found that one H atom can be adsorbed on O atom and form –OH with the O atom, which is the most stable structure. One H atom can be adsorbed on one Fe atom, which makes Fe3

Li-Decorated β12-Borophene as Potential Candidates for Hydrogen Storage: A First-Principle Study

The hydrogen storage properties of pristine β12-borophene and Li-decorated β12-borophene are systemically investigated by means of first-principles calculations based on density functional theory. The adsorption sites, adsorption energies, electronic structures, and hydrogen storage performance of pristine β12-borophene/H2 and Li-β12-borophene/H2 systems are discussed in detail. The results show that H2 is dissociated into Two H atoms that are then chemisorbed on β12-borophene via strong covalent bonds. Then, we use Li atom to improve the hydrogen storage performance and modify the hydrogen storage capacity of β12-borophene. Our numerical calculation shows that Li-β12-borophene system can adsorb up to 7 H2 molecules; while 2Li-β12-borophene system can adsorb up to 14 H2 molecules and the hydrogen storage capacity up to 10.85 wt %.

First-Principle Study of H2Adsorption on LaFeO3(110) Surface

The adsorption of H2 molecule on LaFeO3(110) surface was studied by first-principle calculations. Based on the adsorption sites, adsorption energies, and electronic structures, it can be found that one H atom can be adsorbed on O atom and form –OH with the O atom, which is the most stable structure. One H atom can be adsorbed on one Fe atom, which makes Fe3

First-Principle Study of H2 Adsorption on LaFeO3(110) Surface

The adsorption of H2 molecule on LaFeO3(110) surface was studied by first-principle calculations. Based on the adsorption sites, adsorption energies, and electronic structures, it can be found that one H atom can be adsorbed on O atom and form –OH with the O atom, which is the most stable structure. One H atom can be adsorbed on one Fe atom, which makes Fe3

Density Functional Theory Study on Organic Dye Sensitizers Containing Bis-dimethylfluorenyl Amino Benzofuran

The geometries, electronic structures, polarizabilities and hyperpolarizabilities, as well as the UV-Vis spectra of the two organic dye sensitizers containing bis-dimethylfluorenyl amino benzofuran were studied via density functional theory (DFT) and time-dependent DFT. The features of electronic absorption spectra were assigned on account of the agreement between the experiment and the calculations. The absorption bands in visible region are related to photoinduced electron transfer processes, and the dimethylfluorenyl amino benzo[b]furan groups are major chromophore that contributed to the sensitization of photo-to-current conversion. The role of vinylene group in geometry, electronic structure and spectra property is analyzed according to the comparative study of the dyes.