Single-and double transition metal atoms anchored C2N as a high-activity catalyst for CO oxidation: A first-principles study.

The oxidation of CO has attracted great interest in recent years due to its important role in enhancing the catalyst durability in fuel cells and solving the growing environmental problems caused by CO emissions. Consequently, the catalytic oxidation of CO at double non-noble metal atoms anchored C2N is investigated using density functional theory (DFT) computations. All the screened Ti@C2N and Ti2@C2N are thermodynamically stable based on their binding energy calculations. The electronic characteristics, the natural bond orbital analyses (NBO), Frontier orbital, statistical thermodynamics, projected densities of states (PDOS) characteristics, non-covalent interactions (NCI), and quantum theory of atoms in molecules (QTAIM) descriptors of these systems have been examined to analyze the interaction process. Our comparative study suggested that the newly predicted double-atom catalyst (Ti2@C2N) is highly active for CO oxidation, which is a useful guideline for further development. The calculated static first-order hyperpolarizability (ßo) illustrated that the double-atom catalyst under investigation can be considered a potential candidate for non-linear optical behavior and could be used for NLO applications. CO oxidation on Ti2@C2N along the Eley-Rideal (ER) mechanism with a low energy barrier of 0.16 eV, which is smaller than the maximum energy barrier (0.73 eV) of CO oxidation along the Langmuir-Hinshelwood (LH) mechanism. Consequently, the ER mechanism is more favorable both thermodynamically and dynamically. This work can provide useful insights and guidelines for future theoretical and experimental investigations to promote the design and development of highly effective and low-cost non-precious-metal Ti2@C2N nanocatalysts towards CO oxidation at ambient temperature.

DFT study of adsorbing SO2, NO2, and NH3 gases based on pristine and carbon-doped Al24N24 nanocages.

The adsorption of SO2, NO2, and NH3 toxic gases on Al24N24 and Al24N23C nanocages was investigated by using density functional theory (DFT) calculations. The adsorption energies, frontier orbitals, charge transfer using natural bonding orbital (NBO) analysis, dipole moment, the partial density of states (PDOS), thermodynamic relationships, non-covalent interaction (NCI), and quantum theory of atoms in molecules (QTAIM) were considered. The results reveal that carbon-doped Al24N24 nanocage increases the adsorption energies for SO2 and NO2 gases while decreasing the adsorption energy of NH3 gas. The ΔG for all configurations were negative except the configurations A1 and G2 confirming the weak adsorption of these two complexes. In conclusion, Al24N24 and Al24N23C nanocages are in general promising adsorbents for the removal of SO2, NO2, and NH3 toxic gases. The Al24N24 and Al24N23C nanocages are ideal electronic materials.

Investigation of the anticorrosion and adsorption properties of two polymer compounds on the corrosion of SABIC iron in 1 M HCl solution by practical and computational approaches.

The anticorrosion efficiency of two polymer compounds, namely polystyrene (PS), polybutylene terephthalate (PBT), against the corrosion of SABIC iron (S-Fe) in 1.0 M HCl solution was investigated. The anticorrosion efficiency was estimated by chemical and electrochemical measurements. The anticorrosion efficiency increased with the increase in the concentration of the polymer compounds and reduction in temperature. All the obtained corrosion data confirmed the anticorrosion strength in the presence of PS and PBT compounds, such as the decreasing values of the corrosion current density, capacity of the double layer, and weight reduction, while the values of the charge-transfer resistance increased. Also, the pitting potential values moved in the noble (+) direction. The anticorrosion efficiency of the PBT compound was higher than that of the PS compound, which was 95.98% at 500 ppm concentration for PBT while for PS it was 93.34% according to polarization measurements. The anticorrosion activity occurred by the adsorption of PS and PBT compounds on the surface of S-Fe according to the Langmuir isotherm. The polarization curves indicated that the PS and PBT compounds were mixed-type inhibitors. Density functional theory (DFT) and Monte Carlo simulation (MC) were performed for the two polymer compounds. The computational quantum functions were found to be in agreement with the experimental results.

Natural parsley oil as a green and safe inhibitor for corrosion of X80 carbon steel in 0.5 M H2SO4 solution: a chemical, electrochemical, DFT and MC simulation approach.

This work focuses on the use of natural parsley oil as a safe, eco-friendly and cost-effective inhibitor for dissolution of X80 carbon steel (X80CS) in 0.5 M H2SO4 solution. Electrochemical and chemical measurements and theoretical studies were utilized to determine the inhibitory vigor of parsley oil. The inhibition efficacy increases with an increase in the parsley oil concentration and a decrease in temperature. It reached 95.68% at 450 ppm of parsley oil. The inhibition process is explained by spontaneous adsorption of the oil on the X80CS. Adsorption is described by the Langmuir isotherm model. The polarization data demonstrate that parsley oil is categorized as a mixed inhibitor with a dominant control of the cathodic reaction. Parsley oil inhibits the pitting corrosion of X80CS in the presence of NaCl solution by moving the pitting potential to a more positive mode indicating protection against pitting attack. The thermodynamic parameters for activation and adsorption were computed and interpreted. The four chemical components in natural parsley oil were examined using density functional theory (DFT). Monte Carlo (MC) simulation was performed to study the adsorption of parsley oil on the X80CS surface. The outcomes confirmed that the Apiole molecule is the most effective in the inhibition process.

Enhancing the inhibition and adsorption performance of SABIC iron corrosion in sulfuric acid by expired vitamins. Experimental and computational approach.

The inhibition potency of expired thiamine or vitamin B1 (VB1) and riboflavin or vitamin B2 (VB2) against SABIC iron corrosion in 0.5 M H2SO4 solutions was investigated using chemical and electrochemical techniques. Theoretical studies such as DFT and MC simulations were performed on both VB1 and VB2 inhibitors to obtain information related to the experimental results. It has been found that the inhibition efficacy assigned from all measurements used increases with increasing concentration of the two expired vitamins and reduces at elevated temperatures. It reached 91.14% and 92.40% at 250 ppm of VB1 and VB2, respectively. The inhibition was explicated by the adsorption of the complex formed between expired vitamins and ferrous ions on the SABIC iron surface. The adsorption was found to obey the Langmuir isotherm model. Galvanostatic polarization demonstrated that the two expired vitamins act as an inhibitor of the mixed type. These expired vitamins have proven effective in inhibiting the pitting corrosion induced by the presence of Cl- ions. The pitting potential is transferred to the positive values showing resistance to pitting damage. The theoretical parameter values are consistent with experimental results.

Natural dye extracted from karkadah and its application in dye-sensitized solar cells: experimental and density functional theory study: publisher's note.

This note corrects an error in the math of [Appl. Opt.55, 838 (2016)APOPAI0003-693510.1364/AO.55.000838] and reports a deletion of text that should have occurred in production.

Natural dye extracted from karkadah and its application in dye-sensitized solar cells: experimental and density functional theory study.

This work presents an experimental and theoretical study of cyanidin natural dye as a sensitizer for ZnO dye-sensitized solar cells. ZnO nanoparticles were prepared using ammonia and oxalic acid as a capping agent. The calculated average size of the synthesized ZnO with different capping agents was found to be 32.1 nm. Electronic properties of cyanidin and delphinidin dye were studied using density functional theory (DFT) and time-dependent DFT with a B3LYP/6-31G(d,p) level. By comparing the theoretical results with the experimental data, the cyanidin dye can be used as a sensitizer in dye-sensitized solar cells. An efficiency of 0.006% under an AM-1.5 illumination at 100 mW/cm(2) was attained. The influence of dye adsorption time on the solar cell performance is discussed.

A comparative theoretical study of metal functionalized carbon nanocones and carbon nanocone sheets as potential hydrogen storage materials.

The hydrogen storage of Ti functionalized carbon nanocones and carbon nanocone sheets is investigated by using the state-of-the-art density functional theory calculations. The Ti atom prefers to bind at the hollow site of the hexagonal ring. The average adsorption energies corrected for dispersion forces are -0.54 and -0.39 eV per hydrogen molecule. With no metal clustering, the system gravimetric capacities are expected to be as large as 9.31 and 11.01 wt%. The hydrogen storage reactions are characterized in terms of simulated infrared spectra, projected densities of states, kinetics, and statistical thermodynamics. The free energies and enthalpies of the Ti functionalized carbon nanocone meet the ultimate targets of the Department of Energy for all temperatures and pressures. The closest reactions to zero free energy occur at 378.15 K/2.961 atm for carbon nanocones and 233.15 K/2.961 atm for carbon nanocone sheets. The translational component is found to exert a dominant effect on the total entropy change with temperature. More promising thermodynamics are assigned to the hydrogenation of Ti functionalized carbon nanocone sheets at 233.15 K. As the temperature is increased, the lifetimes of the hydrogen molecules adsorbed at the surface drop and the rate constants increase. At fixed pressure, the rate constants of hydrogenation of Ti functionalized carbon nanocones are smaller than those of Ti functionalized carbon nanocone sheets, while the lifetimes are greater.

Cloning, expression, and chromosomal localization of the rat mitochondrial capsule selenoprotein gene (MCS): the reading frame does not contain potential UGA selenocysteine codons.

The mitochondrial capsule selenoprotein (MCS) is a selenium-containing polypeptide. It is one of three proteins that are important for the maintenance and stabilization of the crescent structure of the sperm mitochondria. In this paper, we report the isolation and characterization of the rat MCS cDNA and gene. The cDNA contains a reading frame for a 145-amino-acid protein and it lacks the UGA codons, which have been found in the reading frame of the mouse MCS cDNA and have been presumed to encode the selenocysteine in the amino terminal of the deduced mouse amino acid sequence. The deduced amino acid sequence of the rat and mouse MCS shows a high level of homology (79%). The rat MCS gene contains two exons; the intron sequence interrupts the 5' untranslated sequence at the same position as in the mouse MCS gene. The transcription start site is located 184 bp upstream of the translation start site. Alignment of the 5'-flanking regions of the mouse and rat genes reveals that the first 400 nucleotides upstream of the transcription start site exhibit an overall sequence similarity of 73%. This conserved region contains no TATA or CAAT box motifs. Northern blot analysis indicates that the MCS mRNA is detectable only in the testis after day 30 of postnatal development. Moreover, in situ hybridization revealed that the rat MCS gene is mainly expressed in round spermatids. From the analysis of mouse-rat cell hybrids that segregate rat chromosomes, the MCS gene was assigned to rat chromosome 2.