Supported Cu cluster on N-doped graphene: An efficient triatom catalyst for CO electroreduction to propanol at low potential.

Electroreduction of carbon monoxide into high-energy fuel is an excellent energy strategy for sustainable development, but the high yield of multi-carbon products remains a difficult challenge. Inspired by the successful synthesis of various trimer metal clusters and studies on electrocatalysis of CO to C3 products by Cu-based catalysts, Cu supported on N-doped graphene structures (Cu@NG) are investigated as electrocatalysts for CORR toward propanol in this paper. Due to the appropriate Cu-Cu bond length, the moderate charge of the Cu site, mild CO adsorption energy, and 100 % CO coverage, the absorbed 3*CO substance can form the critical *CO-CO-CO intermediate with a rather low kinetic barrier of 0.

Computational Discovery of High-Temperature Ferromagnetic Semiconductor Monolayer H-MnN.

In the past few years, two-dimensional (2D) high-temperature ferromagnetic semiconductor (FMS) materials with novelty and excellent properties have attracted much attention due to their potential in spintronics applications. In this work, using first-principles calculations, we predict that the H-MnN monolayer with the H-MoS-type structure is a stable intrinsic FMS with an indirect band gap of 0.79 eV and a high Curie temperature () of 380 K.

Immobilized triatomic CuB clusters on 2D carbon nitride: highly selective conversion of CO to ethanol at low potentials.

A promising pathway for carbon usage and energy storage is electrocatalytic reduction of CO to form high-value multi-carbon products. Herein, the d-p coupled triatomic catalyst CuB@g-CN with significant activity and selectivity for ethanol is presented for the first time. Density functional theory calculations elucidate that these spatially confined triatomic centers are capable of immobilizing multiple CO molecules, providing an exclusive reaction channel for direct C-C coupling.

A density functional theory study of a water gas shift reaction on Ag(111): potassium effect.

Density functional theory (DFT) calculations are executed to investigate the effect of a potassium (K) promoter on the activity of the water gas shift reaction (WGSR) over an Ag(111) surface. It is found that the WGSR proceeds mainly through the OH(O)-assisted carboxy pathway in which HO dehydrogenation is the rate-controlling step on both Ag(111) and K/Ag(111) surfaces. Energetic span model analysis shows that K addition can enhance the activity of the WGSR by reducing the apparent activation energy of the whole reaction since it can promote HO dissociation and stabilize the adsorption of the reactants (CO and HO).

Pd Nanoparticles Coupled to NiMoO-C Nanorods for Enhanced Electrocatalytic Ethanol Oxidation.

The interfacial interaction including chemical bonding or electron transfer and even physisorption in composite electrocatalysts has a considerable effect on electrocatalytic oxidation reaction. Herein, we report a tremendously enhanced catalytic activity and excellent durability for the ethanol electro-oxidation reaction in NiMoO-C-supported Pd composites (Pd/NiMoO-C) compared to the commercial Pd/C (10%) catalyst. The X-ray powder diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements disclose that the strong electron transfer between NiMoO nanorods and Pd nanoparticles likely induces the formation of more electrochemical active centers and improves the adsorption-desorption capacity of reactants and corresponding intermediates.

Multicenter electron-sharing σ-bonding in the AgFe(CO) complex.

The heterodinuclear silver tetracarbonyl-iron anion was generated in the gas phase and studied by joint photoelectron velocity map imaging spectroscopy and quantum chemical calculations. The AgFe(CO)4- anion is characterized to be an 18-electron complex with the silver atom covalently bonded to the anionic tetracarbonyl-iron, an isolobal analogue of the methyl radical. The bonding analyses using a range of state-of-the-art quantum chemistry methods revealed a peculiar decentralized bonding situation, where the silver atom is covalently bonded to both the iron center and the vicinal carbon atoms in the form of an electron-sharing σ bond.

Cooperative physisorption and chemisorption of hydrogen on vanadium-decorated benzene.

3d TM-decorated carbon composites have been proved to be a new generation of hydrogen storage materials. However, detailed hydrogen storage mechanisms are still unclear. Investigation of the H dissociation and H migration on the 3d TM-decorated six-membered carbocycles is very critical for better understanding the hydrogen storage mechanism.

Triply Carbonyl-Bridged Ni(CO) Featuring Triple Three-Center Two-Electron Ni-C-Ni Bonds Instead of Ni≡Ni Triple Bond.

Motivated by the predicted unusual short Ni-Ni bond length that is comparable to the intermetallic distance anticipated for the triple bond, the nature of Ni-Ni bonding interaction in the triply carbonyl-bridged geometry of the neutral Ni(CO) complex has been investigated using a range of state-of-the-art quantum chemistry methods. The elaborate analyses manifest that the tribridged Ni(CO) features triple three-center two-electron Ni-C-Ni bonds instead of Ni≡Ni triple bond. The electron pair donated by the bridging carbonyl ligand should be shared by both nickel centers to achieve the favored (18, 18) configuration.

The effect of group-substitution on the sensitization properties of alkynylrhenium(I) tricarbonyl diimine complexes adsorbed to TiO(101) film surface: a theoretical study.

A series of dyes are designed by adding the different electron-donating (-CH, -NH, -OH) and electron-withdrawing groups (-Br, -Cl, -NO) to the different ancillary ligands in the alkynylrhenium(I) tricarbonyl diimine complexes [Re(CO)(N^N){C≡C-CH-CH=C(CN)(COOH)}], where N^N = 1,10-phenanthroline (phen)(1) and then investigated the sensitization properties of dyes linked to the TiO(101) surface. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used to study the electronic structure, frontier molecular orbitals, and absorption spectral properties. The effect of group-substitution on sensitization properties is obvious.

Thermodynamics and Kinetics of Gas-Phase CO Oxidation on the Scandium Monoxide Carbonyl Complexes.

The CO chemisorption onto the ScO cation was investigated using infrared photodissociation spectroscopy combined with density functional theory calculations. The spectra were recorded in the CO stretching vibrational region for the OSc(CO) ( = 4-6) complex series. Comparisons of the experimental spectra with the simulated ones have established the geometries and present strong evidence that all of the CO ligands are chemisorbed, which could not be readily oxidized by scandium monoxide core into CO.

Dissociative adsorption modes of TATB on the Al (111) surface: a DFT investigation.

Herein, the adsorption modes and electronic structures of TATB/Al (111) systems were investigated using the density functional theory (DFT) approach. We found that chemical adsorption led to the decomposition of the TATB molecule on the Al surface by four adsorption modes. All the adsorption configurations were accompanied by fractures of the N-O bonds in the nitro groups.

A comparative theoretical study on the electrical and nonlinear optical properties of Li atom adsorbed on AlN and BN single-walled nanotubes.

The geometrical structures, electrical properties, and nonlinear optical (NLO) properties of AlNNT-Li and BNNT-Li nanotube systems were investigated by means of the density functional theory (DFT) method. Frontier molecular orbitals and density of states analyses show that adsorption of the Li atom can significantly narrow the wide HOMO-LUMO gaps of pure AlNNT and BNNT. The results reveal that AlNNT-Li and BNNT-Li systems containing diffuse excess electrons can be regarded as inorganic electrides.

Au (n = 1-16) clusters on the ZrO(111) surface: a DFT+U investigation.

The growth patterns and electronic structures of Au clusters (n = 1-16) supported on the monoclinic ZrO(111) surface were investigated using a DFT+U approach. We found that the supported Au clusters prefer quasi-planar structures and lay flat on the ZrO surface. This result agrees well with the experimental results.

Mechanistic investigation of palladium-catalyzed amidation of aryl halides.

A mechanistic investigation using Becke3LYP density functional theory (DFT) was carried out on the palladium-catalyzed amidition of bromobenzene and (t)Bu-isocyanide. The whole catalytic cycle consists of five steps: oxidative addition, migratory insertion, anion exchange, reductive elimination, and hydrogen migration. The rate-determining step is oxidative addition, with a small Gibbs free energy of 14.

Theoretical investigation of the mechanism for the cycloaddition of CO2 to epoxides catalyzed by a magnesium(II) porphyrin complex.

The cycloaddition of CO2 to epoxides, catalyzed by Mg(TPP)/TBAI (TPP = tetraphenylporphyrin; TBAI = tetrabutylammonium iodide), was investigated using DFT methods. Epoxides with various substituents were studied to explore steric and electronic effects on the reaction mechanism. Computational results show that the cycloaddition proceeds according to a much easier mechanism in the presence of Mg(TPP) and TBAI than the mechanism that takes place when Mg(TPP) is used as the catalyst.

A computational study on the insertion of CO2 into (PSiP)palladium allyl σ-bond.

The insertion of CO2 into the (PSiP)palladium-allyl bond has been investigated using DFT. Three possible modes of CO2 insertion into (PSiP)Pd-allyl bond have been calculated, that is, direct 1.2-insertion mode, metallo-ene mode, and SE2 mode.

Quantum dynamics study of H + DBr and D + HBr reaction.

Time-dependent quantum wave packet calculations have been performed for the H + DBr and D + HBr reaction using the recent diabatic potential energy surfaces. Reaction probabilities, integral cross sections, and rate constants are obtained. The results show that the isotopic effects have an influence on the nonadiabatic effect which is generally inversely proportional to the atom mass.

Density functional studies of the stepwise substitution of pyridine, pyridazine, pyrimidine, pyrazine, and 1,3,5-triazine with BCO.

The structures, stabilities, and aromaticities of a series of (BCO) n (CH)5-n N (n = 0-5), (BCO) n (CH)4-n N2 (n = 0-4), and 1,3,5-(BCO) n (CH)3-n N3 (n = 0-3) clusters were investigated at the B3LYP density functional level of theory. The most stable positional isomers of individual clusters were obtained. All of the calculated CO binding energies were positive, suggesting that the BCO-substituted species are stable.

Strain-free [N]ferrocenylenes and cyclo[10]ferrocenylene.

Calculated attraction: Trans-linear and cis-angular [N]ferrocenylenes, as well as cyclo[10]ferrocenylene, higher homologues of biferrocenylene, and analogues of [N]phenylenes, are demonstrated as strain-free.

Structures and stabilities of ScBn (n = 1-12) clusters: an ab initio investigation.

The geometries, stabilities, and electronic properties of ScBn (n = 1-12) clusters have been systematically investigated by using density functional theory B3LYP method and coupled-cluster theory CCSD(T) method. It is found that the ground state isomers of ScBn have planar or quasi-planar structure when n ≤ 6, which can be viewed as a B atom of the corresponding Bn+1 cluster is substituted by a Sc atom. From n ≥ 7, the ground state isomers favor nest-like structure, in which the Sc atom sits on a nest-like Bn cluster.

Density functional studies of the stepwise substitution of pyrrole, furan, and thiophene with BCO.

The structures, stabilities, and aromaticities of a series of (BCO) n (CH)₄-n NH (n = 0-4), (BCO) n (CH)₄-n O (n = 0-4), and (BCO) n (CH)₄-n S (n = 0-4) clusters were investigated at the B3LYP density functional level of theory. The most stable positional isomers of the individual clusters were obtained. All of the calculated CO binding energies were exothermic, suggesting that these BCO-substituted species are stable.

Computational studies on polynitropurines as potential high energy density materials.

As part of a search for high energy density materials (HEDMs), a series of purine derivatives with nitro groups were designed computationally. The relationship between the structures and the performances of these polynitropurines was studied. Density functional theory (DFT) at the B3LYP/6-311G** level was employed to evaluate the heats of formation (HOFs) of the polynitropurines by designing an isodesmic reaction method.

Theoretical investigation on detonation performances and thermodynamic stabilities of the prismane derivatives.

Based on DFT-B3LYP/6-311G** method, the molecular geometric structures of polynitramineprismanes are fully optimized. The detonation performances, energy gaps, strain energies, as well as their stability were investigated to look for high energy density compounds (HEDCs). Our results show that all polynitramineprismanes have high and positive heat of formation.

Looking for high energy density compounds among polynitraminecubanes.

Based on fully optimized geometric structures at DFT-B3LYP/6-311G** level, we calculated electronic structures, heats of formation, strain energies, bond dissociation energies and detonation performance (detonation velocity and detonation pressure) for a series of polynitraminecubanes. Our results have shown that energy gaps of cubane derivatives are much higher than that of triaminotrinitrobenzene (TATB), which means that cubane derivatives may be more sensitive than TATB. Polynitraminecubanes have high and positive heats of formation, and a good linear relationship between heats of formation and nitramine group numbers was presented.

The valence and Rydberg excited states of CH2: a theoretical exploration.

Using the completed active space second-order perturbation (CASPT2) method, valence and Rydberg excited states of CH(2) molecule are probed with the large atomic natural orbital (ANO-L) basis set. Five states are optimized and the geometric parameters are in good agreement with the available data in literatures, furthermore, the state of 2(1)B(1) is obtained for the first time. Valence and Rydberg excited states of CH(2) are also calculated for the vertical transitions with the ANO-L+ basis set that is constructed by adding a set of 1s1p1d Rydberg orbitals into the ANO-L basis set.