scholarly journals A comparative analysis of the mechanisms of ammonia synthesis on various catalysts using density functional theory

2021 ◽  
Vol 8 (11) ◽  
Author(s):  
Constantinos D. Zeinalipour-Yazdi ◽  
Justin S. J. Hargreaves ◽  
Said Laassiri ◽  
C. Richard A. Catlow
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ammonia Synthesis ◽  
Supported Catalysts ◽  
Metal Nitrides ◽  
Dissociative Mechanism ◽  
Functional Theory ◽  
Associative Mechanism ◽  
Fe Catalyst ◽  
Nano Cluster

In this review, we present the recent progress in ammonia synthesis research using density functional theory (DFT) calculations on various industrial catalysts, metal nitrides and nano-cluster-supported catalysts. The mechanism of ammonia synthesis on the industrial Fe catalyst is generally accepted to be a dissociative mechanism . We have recently found, using DFT techniques, that on Co 3 Mo 3 N (111) surfaces, an associative mechanism in the synthesis of ammonia can offer a new low-energy pathway that was previously unknown. In particular, we have shown that metal nitrides that are also known to have high activity for ammonia synthesis can readily form nitrogen vacancies which can activate dinitrogen, thereby promoting the associative mechanism. These fundamental studies suggest that a promising route to the discovery of low-temperature ammonia synthesis catalysts will be to identify systems that proceed via the associative mechanism, which is closer to the nitrogen-fixation mechanism occurring in nitrogenases.

scholarly journals A density functional theory study of the oxygen reduction reaction on the (111) and (100) surfaces of cobalt(II) oxide

2019 ◽  
Vol 44 (2) ◽  
pp. 122-131
Author(s):  
Bangchang Qin ◽  
Yang Tian ◽  
Pengxiang Zhang ◽  
Zuoyin Yang ◽  
Guoxin Zhang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Free Energy ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Gibbs Free Energy ◽  
Density Functional ◽  
Rational Design ◽  
Reduction Reaction ◽  
Functional Theory ◽  
Associative Mechanism

Density functional theory calculations were employed to investigate the electrochemical oxygen reduction reaction on the (111) and (100) surfaces of cobalt(II) oxide. Different mechanisms were applied to evaluate the oxygen reduction reaction performance of cobalt(II) oxide structures in terms of the Gibbs free energy and density of states. A variety of intermediate structures based on associative and dissociative mechanisms were constructed and optimized. As a result, we estimated the catalytic activity by calculating the free energy of the intermediates and constructing free energy diagrams, which suggested that the oxygen reduction reaction Gibbs free energy on cobalt(II) oxide (111) and (100) surfaces based on the associative mechanism is smaller than that based on the dissociative mechanism, demonstrating that the associative mechanism should be more likely to be the oxygen reduction reaction pathway. Moreover, the theoretical oxygen reduction reaction activity on the cobalt(II) oxide (111) surface was found to be higher than that on the cobalt(II) oxide (100) surface. These results shed light on the rational design of high-performance cobalt(II) oxide oxygen reduction reaction catalysts.

Kinetics and mechanism of ligands substitution in the chromium(III) complex of tetraphenylporphin

2013 ◽  
Vol 17 (11) ◽  
pp. 1064-1072
Author(s):  
Vladimir A. Burmistrov ◽  
Irina P. Trifonova ◽  
Alexandr V. Zakharov ◽  
Oscar I. Koifman
Keyword(s):  
Density Functional Theory ◽  
Coordination Sphere ◽  
Hybrid Method ◽  
Density Functional ◽  
Dissociative Mechanism ◽  
Functional Theory ◽  
Dft Computations ◽  
Imidazole Derivatives ◽  
Axial Coordination ◽  
Two Stages

The reaction of axial coordination of imidazole derivatives by (X)CrTPP in amphiprotic media was studied. The reaction includes two stages: consecutive substitution of the two alcohols molecules, first in the outer coordination sphere, and then in the inner sphere. For the reaction of the intrasphere substitution the solvolytic associative-dissociative mechanism has been found. The molecule of (chloro)chromium(III) porphyrin and its derivatives have been studied by density functional theory (DFT) computations utilizing the B3LYP hybrid method.

scholarly journals Application of B-=SUB=-12-=/SUB=-N-=SUB=-12-=/SUB=- and B-=SUB=-12-=/SUB=-P-=SUB=-12-=/SUB=- as two fullerene-like semiconductors for adsorption of halomethane: density functional theory study

2017 ◽  
Vol 51 (1) ◽  
pp. 134
Author(s):  
Ali Shokuhi Rad
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Gap Energy ◽  
Adsorption Energies ◽  
Nano Cluster ◽  
Homo Lumo ◽  
Selective Sensor

We examined and discussed the interaction of two halomethanes (mono-chloromethane (MCM), and mono-fluoromethane (MFM) ) with B12N12 and B12P12 fullerene-like semiconductors based on density functional theory (DFT). We calculated adsorption energies and followed the changes in the electronic structure of semiconductors upon adsorption of MCM and MFM. We found that the adsorption on the B12N12 nano-cluster is energetically more favorable compared to B12P12 nano-cluster. Also for both systems we found higher values of adsorption energy for MFM than for MCM. We found that upon adsorption of above-mentioned species on these two fullerene-like semiconductors, the HOMO-LUMO distributions and also the gap energy for each system did not change significantly, which correspond to the physisorption process. As a result, B12N12 is a more appropriate nano-cluster to be used as a selective sensor for halomethanes, especially for MFM. DOI: 10.21883/FTP.2017.01.8191

Theoretical study on the structural, electronic and physical properties of layered alkaline-earth-group-4 transition-metal nitrides AEMN2

RSC Advances ◽  
2014 ◽  
Vol 4 (60) ◽  
pp. 31981-31987 ◽  
Author(s):  
Esther Orisakwe ◽  
Bruno Fontaine ◽  
Duncan H. Gregory ◽  
Régis Gautier ◽  
Jean-François Halet
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Density Functional ◽  
Alkaline Earth ◽  
Theoretical Study ◽  
Metal Nitrides ◽  
Transition Metal Nitrides ◽  
Functional Theory ◽  
Group 4 ◽  
Structural And Electronic Properties

Thermodynamic, structural, and electronic properties of the layered ternary nitrides AEMN2 (AE = alkaline-earth; M = group 4 transition metal) both with the KCoO2 and α-NaFeO2 structure-types are examined within density-functional theory.

Nitrogen electroreduction performance of transition metal dimers embedded into N-doped graphene: a theoretical prediction

2020 ◽  
Vol 8 (8) ◽  
pp. 4533-4543 ◽  
Author(s):  
Hongyan Li ◽  
Zhifeng Zhao ◽  
Qinghai Cai ◽  
Lichang Yin ◽  
Jingxiang Zhao
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Theoretical Prediction ◽  
Density Functional ◽  
Ammonia Synthesis ◽  
Functional Theory ◽  
Doped Graphene ◽  
Density Functional Theory Computations ◽  
Dual Atom

By means of comprehensive density functional theory computations, the FeRh dimer embedded in N-doped graphene was screened as a quite promising electrocatalyst with dual-atom centered sites for ammonia synthesis from N2 fixation.

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