Tribological properties of a series of carbon dots modified by ionic liquids with various anion species: experimental findings and density functional theory calculations

2021 ◽  
Author(s):  
Baogang Wang ◽  
Lilong Zhang ◽  
Na Wang ◽  
Wenmeng Duan ◽  
Weiwei Tang
Keyword(s):  
Ionic Liquids ◽  
Carbon Dots ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
One Pot ◽  
Functional Theory ◽  
Exchange Processes ◽  
The One ◽  
Experimental Findings ◽  
Anion Species

A series of carbon dots modified by ionic liquids with various anion species (CDs-ILs-X) were facile synthesized by the one-pot pyrolysis method and subsequent anion exchange processes, where the X-...

scholarly journals Thermal Stability and Decomposition Kinetics of 1-Alkyl-2,3-Dimethylimidazolium Nitrate Ionic Liquids: TGA and DFT Study

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2560
Author(s):  
Jianwen Meng ◽  
Yong Pan ◽  
Fan Yang ◽  
Yanjun Wang ◽  
Zhongyu Zheng ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Density Functional Theory ◽  
Ionic Liquids ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Nitrogen Atmosphere ◽  
Decomposition Kinetics ◽  
Heating Rates ◽  
Functional Theory ◽  
Kinetics Of

The thermal stability and decomposition kinetics analysis of 1-alkyl-2,3-dimethylimidazole nitrate ionic liquids with different alkyl chains (ethyl, butyl, hexyl, octyl and decyl) were investigated by using isothermal and nonisothermal thermogravimetric analysis combined with thermoanalytical kinetics calculations (Kissinger, Friedman and Flynn-Wall-Ozawa) and density functional theory (DFT) calculations. Isothermal experiments were performed in a nitrogen atmosphere at 240, 250, 260 and 270 °C. In addition, the nonisothermal experiments were carried out in nitrogen and air atmospheres from 30 to 600 °C with heating rates of 5, 10, 15, 20 and 25 °C/min. The results of two heating modes, three activation energy calculations and density functional theory calculations consistently showed that the thermal stability of 1-alkyl-2,3-dimethylimidazolium nitrate ionic liquids decreases with the increasing length of the alkyl chain of the substituent on the cation, and then the thermal hazard increases. This study could provide some guidance for the safety design and use of imidazolium nitrate ionic liquids for engineering.

Density Functional Theory Calculations of the Radical Scavenging Activity of Alkannin Derivatives

2012 ◽  
Vol 189 ◽  
pp. 225-231
Author(s):  
Xiang Peng Guo ◽  
Rui Fa Jin
Keyword(s):  
Density Functional ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Density Functional Theory Calculations ◽  
Hydrogen Atom Transfer ◽  
Scavenging Activity ◽  
Functional Theory ◽  
Hydrogen Bond Formation ◽  
Structural And Electronic Properties ◽  
The One

The structural and electronic properties of alkannin and its derivatives and their radicals were investigated at density functional level. It turned out that the presence of the dihydroxy functionality increases the radical stability through hydrogen bond formation. The hydrogen atom transfer for alkannin derivatives is difficult to occur compared with zero compound phenol. However, alkannin derivatives appear to be good candidates for the one-electron-transfer, particularly for alkannin derivatives with –OCOCH=CH(CH3)2 and –OCOCH2CH(CH3)2 groups. It suggests that 1–7 are expected to be the promising candidates for radical scavenging activity compounds because The ionization potential (IP) values of 1–7 are lower than that of the zero compound phenol.

scholarly journals Classical Polarizable Force Field to Study Hydrated Hectorite: Optimization on DFT Calculations and Validation against XRD Data

Minerals ◽  
2018 ◽  
Vol 8 (5) ◽  
pp. 205 ◽  
Author(s):  
Ragnhild Hånde ◽  
Vivien Ramothe ◽  
Stéphane Tesson ◽  
Baptiste Dazas ◽  
Eric Ferrage ◽  
...  
Keyword(s):  
Force Field ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
X Ray Diffraction ◽  
Electronic Density ◽  
Functional Theory ◽  
Polarizable Force Field ◽  
Xrd Patterns ◽  
The One ◽  
Dynamics Simulations

Following our previous works on dioctahedral clays, we extend the classical Polarizable Ion Model (PIM) to trioctahedral clays, by considering dry Na-, Cs-, Ca- and Sr-hectorites as well as hydrated Na-hectorite. The parameters of the force field are determined by optimizing the atomic forces and dipoles on density functional theory calculations. The simulation results are validated by comparison with experimental X-ray diffraction (XRD) data. The XRD patterns calculated from classical molecular dynamics simulations performed with the PIM force field are in very good agreement with experimental results. In the bihydrated state, the less structured electronic density profile obtained with PIM compared to the one from the state-of-the-art non-polarizable force field clayFF explains the slightly better agreement between the PIM results and experiments.

Theoretical Insights into the Role of Water Molecule in The Aqueous/Cu(111) Interface during Corrosion Pathway

2014 ◽  
Vol 19 (4) ◽  
pp. 235-240
Author(s):  
Jun Hu ◽  
Xiao-yong Fan ◽  
Chao-Ming Wang
Keyword(s):  
Water Molecule ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Adsorbed Water ◽  
Dipole Interaction ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Adsorbed Water Molecule ◽  
The One

The absorption and possible reaction paths during corrosion have been systematically identified at the molecular level by us-ing density functional theory calculations. The results show that the co-adsorbed water molecule has a two-fold impact on the corrosive kinetics process. The one is the solvation effect, where water molecule affects the various reactions through ion dipole interaction, without bond fracture and formation. Another is the H-transfer mediator, where the bond of co-adsorbed water molecule breaks and regenerates in order to transfer hydrogen atoms.

scholarly journals Electrical Conductivities and Interactions in Binary Mixtures of Imidazolium-Based Ionic Liquids with Acetonitrile and Dimethyl Sulfoxide

2020 ◽  
Vol 71 (2) ◽  
pp. 392-402
Author(s):  
Oana Ciocirlan ◽  
Amalia Stefaniu
Keyword(s):  
Electrical Conductivity ◽  
Ionic Liquids ◽  
Dimethyl Sulfoxide ◽  
Binary Mixtures ◽  
Density Functional ◽  
Binary Systems ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Electrical Conductivities ◽  
Anion Type

This paper reports experimental electrical conductivities data of eight binary systems of four ionic liquids: 1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF4], 1-hexyl-3-methylimidazolium tetrafluoroborate, [Hmim][BF4], 1-butyl-3-methylimidazolium hexafluorophosphate, [Bmim][PF6] and 1-butyl-2,3-dimethyl-imidazolium tetrafluoroborate, [Bmmim][BF4] with the organic solvents dimethyl sulfoxide (DMSO) and acetonitrile (ACN) at atmospheric pressure and temperatures from 298.15 to 328.15 K. It was found that conductivities in the investigated ionic liquids follow the order: [Bmim][BF4] ] [Bmim][PF6] ][Bmmim][BF4] ] [Hmim][BF4]. Experimental results demonstrate that the binary mixtures possess higher electrical conductivity compared with pure components. Electrical conductivity data were correlated using Casteel�Amis and Arrhenius equations. The molar conductivity was derived from experimental data and fitted to Walden rule. The influence of the cation structure and anion type on the conductivity was discussed, which help understanding the intermolecular interactions in the binary systems. A deeper understanding of the transport behavior of ILs is given by means of density functional theory calculations (DFT)

scholarly journals Relative Stability of Small Silver, Platinum, and Palladium Doped Gold Cluster Cations

2019 ◽  
Vol 9 (8) ◽  
pp. 1666 ◽  
Author(s):  
Piero Ferrari ◽  
Ewald Janssens
Keyword(s):  
Density Functional ◽  
Gold Cluster ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Local Maxima ◽  
Dissociation Energies ◽  
Valence Electrons ◽  
Pd Doping ◽  
The Stability ◽  
Experimental Findings

The stability patterns of single silver, platinum, and palladium atom doped gold cluster cations, MAuN−1+ (M = Ag, Pt, Pd; N = 3–6), are investigated by a combination of photofragmentation experiments and density functional theory calculations. The mass spectra of the photofragmented clusters reveal an odd-even pattern in the abundances of AgAuN−1+, with local maxima for clusters containing an even number of valence electrons, similarly to pure AuN+. The odd-even pattern, however, disappears upon Pt and Pd doping. Computed dissociation energies agree well with the experimental findings for the different doped clusters. The effect of Ag, Pt, and Pd doping is discussed on the basis of an analysis of the density of states of the N = 3–5 clusters. Whereas Ag delocalizes its 5s valence electron in all sizes, this process is size-specific for Pt and Pd.

Phenanthro[9,10-a]corannulene by one-step annulative π-extension of corannulene

2017 ◽  
Vol 95 (3) ◽  
pp. 329-333 ◽  
Author(s):  
Kenta Kato ◽  
Yasutomo Segawa ◽  
Kenichiro Itami
Keyword(s):  
Crystal Structure ◽  
Density Functional ◽  
Photophysical Properties ◽  
Coupling Reaction ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
X Ray ◽  
Palladium Catalyzed ◽  
One Step ◽  
The One

The one-step π-extension of corannulene was achieved using a palladium-catalyzed C–H coupling reaction. The X-ray crystal structure and photophysical properties of the thus formed phenanthro[9,10-a]corannulene (1) were investigated, and the structural properties of 1 were examined by density functional theory calculations. In contrast to dibenzo[g,p]chrysene, the most stable structure of 1 was a butterfly-shaped structure, resulting from the bowl-shaped distortion of the corannulene moiety.

scholarly journals What is the origin of macroscopic friction?

2018 ◽  
Vol 4 (12) ◽  
pp. eaav2268 ◽  
Author(s):  
H. Sakuma ◽  
K. Kawai ◽  
I. Katayama ◽  
S. Suehara
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Wear Particles ◽  
Shear Tests ◽  
Functional Theory ◽  
Direct Shear Tests ◽  
Sliding Direction ◽  
Frictional Forces ◽  
Experimental Findings ◽  
Molecular Friction

What is the origin of molecular friction, and how can macroscopic friction be explained in terms of molecular friction? To elucidate the origins of molecular and macroscopic friction, we conducted density functional theory calculations and double-direct shear tests at normal stresses ranging from 5 to 60 MPa for mica surfaces. Frictional forces between mica surfaces were theoretically predicted to oscillate periodically every 30° of sliding direction, in agreement with previous experimental findings. This result affirms that the potential energy roughness of mica under sliding is the origin of molecular friction, which depends on the normal stress and sliding direction. The discovered mechanism of molecular friction can quantitatively explain experimentally observed macroscopic friction of mica when the presence of wear particles is taken into consideration.

scholarly journals Structural model of silicene-like nanoribbons on a Pb-reconstructed Si(111) surface

2017 ◽  
Vol 8 ◽  
pp. 1836-1843 ◽  
Author(s):  
Agnieszka Stępniak-Dybala ◽  
Mariusz Krawiec
Keyword(s):  
Density Functional Theory ◽  
Surface Energy ◽  
First Principles ◽  
Density Functional ◽  
Structural Model ◽  
Density Functional Theory Calculations ◽  
Honeycomb Structure ◽  
Functional Theory ◽  
Substrate Interaction ◽  
Experimental Findings

A structural model of the recently observed silicene-like nanoribbons on a Pb-induced √3 × √3 reconstructed Si(111) surface is proposed. The model, which is based on first principles density functional theory calculations, features a deformed honeycomb structure directly bonded to the Si(111) surface underneath. Pb atoms stabilize the nanoribbons, as they passivate the uncovered substrate, thus lower the surface energy, and suppress the nanoribbon–substrate interaction. The proposed structural model reproduces well all the experimental findings.

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