Nguyen Ngoc Ha

Theoretical study on the adsorption of phenol on activated carbon using density functional theory

Density functional theory (DFT) calculations performed at the PBE/DZP level using the DFT-D2 method were utilized to investigate the adsorption of phenol on pristine activated carbon (AC) and on activated carbon functionalized with OH, CHO, or COOH groups. Over the pristine AC, the phenol molecule undergoes weak physical adsorption due to van der Waals interactions between the aromatic part of the phenol and the basal planes of the AC. Among the three functional groups used to functionalize the AC, the carboxylic group was found to interact most strongly with the hydroxyl group of phenol. These results suggest that functionalized AC-COOH has great potential for use in environmental applications as an adsorbent of phenol molecules in aqueous phases.

Theoretical study on the adsorption of carbon dioxide on individual and alkali-metal doped MOF-5s

Density functional theory (DFT) calculations were performed to investigate the adsorption of carbon dioxide (CO2) on metal-organic framework (MOF-5) and alkali-metal (Li, K, Na) doped MOF-5s. The adsorption energy calculation showed that metal atom adsorption is exothermic in MOF-5 system. Moreover, alkali-metal doping can significantly improve the adsorption ability of carbon dioxide on MOF-5. The best influence is observed for Li-doping.

Electronic properties of the polypyrrole-dopant anions ClO 4 − and MoO 4 2− : a density functional theory study

The conductive properties of polypyrrole chains doped with ClO4− or MoO42− anions and the existence of polarons and bipolarons in these doped polypyrrole chains were investigated by performing computational calculations based on density functional theory (DFT). Doping with these anions was found to decrease the band gap of the polypyrrole. Theoretical calculations revealed that changing the type of oxidative agent applied does not affect the conversion of polypyrrole into a conducting polymer, but the conductivity of the doped polypyrrole does depend on the ratio of oxidant to polypyrrole.

Synthesis of Cu\(^+\)/bipyridyl Based Complex Towards Dye Sensitized Solar Cell Application

This study aims to synthesize the Cu + /bipyridyl-based complex using Sonogashira cross coupling. The structure of the ligand and the complex were investigated by nuclear magnetic resonance spectroscopy; by single crystal X-ray diffraction and by UV-VIS absorption spectroscopy. The obtained experimental results were in good agreement with the theoretical calculations. The complex is a potential candidate to be the photo sensitizer in dye-sensitized solar cells.

Low resistivity molybdenum thin film towards the back contact of dye-sensitized solar cell

This paper reports the optimization of the molybdenum thin film electrode as the back contact of dye-sensitized solar cell (DSSC). The molybdenum thin film was grown on the glass substrate by direct current sputtering techniques of which the sputtering power was 150 W at 18 sccm flow rate of Ar. At such sputtering parameters, the Mo film can reach the lowest resistivity of 1.28E −6 Ω cm at 400 nm thick. And the reflection of Mo membrane was 82%. This value is considered as a very good result for preparation of the back contact of DSSC.

Effect of organic substituents on the adsorption of carbon dioxide on a metal–organic framework

The adsorption of carbon dioxide on the MOF-5 metal–organic framework and modifications of it obtained by replacing the hydrogen atoms in the organic ligands with electron donor (–CH3,–OCH3) or electron acceptor groups (–CN,–NO2) is investigated using the grand canonical Monte Carlo (GCMC) method and density functional theory (DFT). It is shown that the adsorption of carbon dioxide molecules on the structures of metal–organic frameworks is most likely on Zn4O clusters, and that the adsorption of carbon dioxide is of a physical nature. The presence of substituents–CH3,–OCH3,–CN in metal–organic frameworks increases their capacity to adsorb carbon dioxide, while that of nitro groups (–NO2) has the opposite effect.

The theoretical study of temperature- and pressure-dependent reactions kinetic for unimolecular isomerization reactions of C2H5O radical

Minimum energies for the C 2 H 5 O radical, products and transition states of reactions on the potential energy surface were obtained at the MP2/6-311++G(3df,2pd) high level of theory, and single-point energies were refined at the CCSD(T)/6-311++G(3df,2pd) level of theory for all stationary points. Isomerization reactions of C 2 H 5 O radical take place via two proton migration mechanisms: C 2 H 5 O → CH 3 CHOH (1,2-H shift) (1) and C 2 H 5 O → CH 2 CH 2 OH (1,3-H shift) (2) . Temperature and pressure-dependent rate constants of the two reactions (1) and (2) were calculated by using transitional state theory (TST) and Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Obtained results show that the reaction rate constants were: k ∞ TST (T) (1) = 1.978.10 10 .T 0.428 exp(-13530.4/T), k ∞ TST (T) (2) = 3.077.10 10 .T 0.403 exp(-14347.2/T); k ∞ RRKM (T) (1) = 1.664.10 12 .T 0.204 exp(-15465.0/T), k ∞ RRKM (T) (2) = 1.183.10 12 .T 0.147 exp(-15927.1/T) using TST and RRKM theory, respectively. The pressure-dependent rate constants of isomerization reactions being analysed and solved by RRKM theory and master equation (ME) method were k(T,P) (1) = 9.110.10 7 .P 0.815 exp(-4959.3/T) and k(T,P) (2) = 1.382.10 7 .P 0.850 exp(-5009.5/T). Our results suggest that, rate constants of both (1) and (2) depend linearly on pressure in the low-temperature and pressure ranges, or in the high-temperature range. Conversely, rate constants of both (1) and (2) are nearly not depending on pressure in the low-temperature and high-pressure ranges. Keywords. Potential energies surface, isomerization reactions, Rice-Ramsperger-Kassel-Marcus theory.

Theoretical Study on Ru2+, Cu+, and Fe2+ Complexes Toward the Application in Dye Sensitized Solar Cell

This paper reports the application of the Ru2+, Cu+, and Fe2+ complexes in form of RuL2(SCN)2, CuL2(SCN)2− for dye-sensitized solar cell (DSSC) development. The calculation results, given by quantum chemistry, demonstrated that the complex containing copper is more suitable than the one containing iron. The modification of Cu(I) complex by using various numbers of ligands enhanced photon absorption capacity as well as the absorption range. The addition of an organic ligand such as an electron attraction group to the benzene ring gave a better result as compared to the inorganic ones. Based on the analysis conducted, CuM2(SCN)2− is considered as potential material for N3 replacement.

Theoretical study of electronic structure, chemical bonding, and X-ray absorption near edge spectroscopy in niobium and niobium monoxide

In this work, we calculate band structures, the density of state and chemical bonding of the metallic niobium (Nb) and its mono-oxide (NbO) crystals in their solid states using the Density Functional Theory and X-ray Absorption Near Edge Spectroscopy. The electronic properties of Nb and NbO are investigated using the Finite Difference Method. These theoretical results are found in good agreement with the most recent experimental data. Our calculations reveal that the NbO crystal behaves like a superconductor.

Oxidative Dehydrogenation of n-Butane over LaV Catalysts Supported on TiO2

The catalytic performance of vanadia catalysts with 15 wt% V supported on TiO2 and (15 wt% V