scholarly journals Theoretical Study on V Atom Supported on N and P-Doped Defective Graphene for Electrocatalytic Nitrogen Reduction

2021 ◽  
Author(s):  
Wei Song ◽  
Ran Wang ◽  
Xiao Liu ◽  
Yongliang Guo ◽  
Ling Fu ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Carbon Dioxide Emissions ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Ambient Conditions ◽  
Nitrogen And Phosphorus ◽  
Nitrogen Reduction ◽  
Bosch Process ◽  
Defective Graphene

Abstract Ammonia (NH3) is one of the most extensively produced chemicals worldwide, and it plays an important and indispensable role in the global economy. At present NH3 is mainly produced by the traditional Haber-Bosch process operated at high pressure and temperature, which results in massive energy consumption and carbon dioxide emissions. The electrochemical nitrogen reduction reaction (NRR) can allow the production of NH3 from nitrogen and water under ambient conditions and is regarded as a sustainable alternative to the Haber–Bosch process because of its low energy consumption and limited environmental impact. In this study, using density functional theory calculations, we designed a monovacancy defective graphene (MVG) doped with various nitrogen and phosphorus atoms and a single vanadium atom (VN1–3@MVG and VP1–3@MVG) to be used as electrocatalysts. The results revealed that N- and P-doping are beneficial for N2 adsorption and activation and can effectively reduce the energy barrier of the NRR, especially for P-doping. Among the synthesized electrocatalysts, double P-doped V@MVG demonstrated the best catalytic activity with a low free energy barrier of 0.43 eV. This paper reports the development of an efficient catalyst for electrochemical NH3 synthesis and provides valuable insights on the design of electrocatalysts with high activity and stability.

scholarly journals Transition Metal Oxynitrides Catalysts for Electrochemical Reduction of Nitrogen to Ammonia

2021 ◽  
Author(s):  
Damilola Ologunagba ◽  
Shyam Kattel
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Dft Calculations ◽  
Electrochemical Reduction ◽  
Density Functional ◽  
Reduction Reaction ◽  
Ambient Conditions ◽  
Functional Theory ◽  
Nitrogen Reduction ◽  
Bosch Process

Electrochemical nitrogen reduction reaction (ENRR) at ambient conditions is beneficial compared to energy intensive thermochemical Haber-Bosch process for NH3 production. Here, periodic density functional theory (DFT) calculations are carried out...

DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

2018 ◽  
Vol 17 (08) ◽  
pp. 1850050 ◽  
Author(s):  
Qiuhan Luo ◽  
Gang Li ◽  
Junping Xiao ◽  
Chunhui Yin ◽  
Yahui He ◽  
...  
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Carbonyl Group ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Metsulfuron Methyl ◽  
Catalytic Role ◽  
Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

Electrochemical nitrogen reduction to ammonia at ambient conditions on nitrogen and phosphorus co-doped porous carbon

2019 ◽  
Vol 55 (5) ◽  
pp. 687-690 ◽  
Author(s):  
Pengfei Song ◽  
Hao Wang ◽  
Li Kang ◽  
Baocheng Ran ◽  
Honghong Song ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Porous Carbon ◽  
Ambient Conditions ◽  
Nitrogen And Phosphorus ◽  
Nitrogen Reduction ◽  
Highly Efficient ◽  
Co Doped

N,P co-doped porous carbon as a highly efficient electrocatalyst for N2 fixation in aqueous solution under ambient conditions.

THEORETICAL STUDY ON CUI-CATALYZED LIGAND-FREE N-ARYLATION OF IMIDAZOLE WITH BROMOBENZENE

2012 ◽  
Vol 11 (05) ◽  
pp. 1135-1147 ◽  
Author(s):  
HAN GUO ◽  
YING XUE
Keyword(s):  
Free Energy ◽  
Energy Barrier ◽  
Density Functional ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Free Energy Barrier ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Ligand Free ◽  
Rate Limiting

The density functional theory (DFT) is used to investigate the mechanism of ligand-free CuI -catalyzed N -arylation of imidazole with aryl halide. The oxidative addition/reductive elimination mechanism is adopted via two different pathways to form the same Cu(III) intermediate. Comparing two pathways, the path 1 in which the imidazolyl coordination occurs prior to the oxidative addition is more favorable, because the free energy barrier of the rate-limiting step of path 1 is lower than the barrier of the other. In addition, it leads to a relative stable intermediate which can promote the reaction to process via path 1. And the overall free energy barrier of oxidative addition to imidazole-ligated Cu(I) complex is not high enough when comparing with the diamine-promote process, which can further prove that the N -arylation of imidazole is feasible in the absence of additional ligands. Nucleophile coordination and reductive elimination steps are facile, while the oxidative addition is the rate-limiting step.

scholarly journals Mechanistic Insights into Selective Hydrogenation of C=C Bonds Catalyzed by CCC Cobalt Pincer Complexes: A DFT Study

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 168
Author(s):  
Zheng Zuo ◽  
Xinzheng Yang
Keyword(s):  
Energy Barrier ◽  
Density Functional ◽  
Pincer Complexes ◽  
Free Energy Barrier ◽  
Electronic Effects ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Hydrogenation Reactions ◽  
Catalytic Cycles ◽  
Hydrogenation Selectivity

The mechanistic insights into hydrogenations of hex-5-en-2-one, isoprene, and 4-vinylcyclohex-1-ene catalyzed by pincer (MesCCC)Co (Mes = bis(mesityl-benzimidazol-2-ylidene)phenyl) complexes are computationally investigated by using the density functional theory. Different from a previously proposed mechanism with a cobalt dihydrogen complex (MesCCC)Co-H2 as the catalyst, we found that its less stable dihydride isomer, (MesCCC)Co(H)2, is the real catalyst in those catalytic cycles. The generations of final products with H2 cleavages for the formations of C−H bonds are the turnover-limiting steps in all three hydrogenation reactions. We found that the hydrogenation selectivity of different C=C bonds in the same compound is dominated by the steric effects, while the hydrogenation selectivity of C=C and C=O bonds in the same compound could be primarily influenced by the electronic effects. In addition, the observed inhabition of the hydrogenation reactions by excessive addition of PPh3 could be explained by a 15.8 kcal/mol free energy barrier for the dissociation of PPh3 from the precatalyst.

scholarly journals Ensemble Effects of Explicit Solvation on Allylic Oxidation

2021 ◽  
Author(s):  
Hung Le ◽  
Mariano Guagliardo ◽  
Anne Gorden ◽  
Aurora Clark
Keyword(s):  
Gas Phase ◽  
Energy Barrier ◽  
Density Functional ◽  
Umbrella Sampling ◽  
Catalytic Cycle ◽  
Allylic Oxidation ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Ensemble Effects ◽  
Explicit Solvation

<div>Umbrella-sampling density functional theory molecular dynamics (DFT-MD) has been employed to study the full catalytic cycle of the allylic oxidation of cyclohexene</div><div>using a Cu(II) (E)-6-amino-7-((2-hydroxybenzylidene)amino)quinoxalin-2-ol complex in acetonitrile, which creates the desired cyclohexenone and H 2 O as products. In comparison to prior study using gas-phase DFT, a significant solvent effect is observed on the rate determining allylic H-atom abstraction step (which has a free energy barrier of 12.1 ± 0.2 kcal/mol). During the cycle, the explicit solvation and ensemble sampling of solvent configurations reveals an important dehydrogenation and re-hydrogenation step of the -NH 2 ligand that is essential to catalyst recovery. This work illustrates the importance of ensemble solvent configurational sampling to reveal the breadth of processes that underpin the full catalytic cycle.</div>

THE HYDROLYTIC DEAMINATION MECHANISM OF PROTONATED ADENINE: A DFT STUDY

2011 ◽  
Vol 10 (03) ◽  
pp. 309-320 ◽  
Author(s):  
XINLIN LIU ◽  
HUI ZENG ◽  
FANCUI MENG ◽  
JUNXIANG LIU
Keyword(s):  
Energy Barrier ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Density Functional Theory Method ◽  
Hydroxyl Group ◽  
Free Energy Barrier ◽  
Activation Energy Barrier ◽  
Functional Theory ◽  
Activation Free Energy ◽  
Hydrolytic Deamination

The hydrolytic deamination mechanism of protonated adenine has been studied using density functional theory method. There are five pathways according to adenine protonated at N1, N3 and N7, respectively. As for the N1 protonated adenine only one pathway has been found, while for N3 and N7 protonated adenine two pathways have been found. Pathway c2 is preferred due to lowest activation free energy barrier of 53.02 kcal/mol. In this pathway, the hydroxyl group of water attacks C6 atom and hydrogen atom attacks N10 atom to produce enol form of protonated hypoxanthine and ammonia, then hydrogen transfer occurs to cause enol-keto tautomerization of protonated hypoxanthine with the assistance of ammonia. Adenine deamination is easier to take place under acidic condition than under neutral condition owing to lower activation energy barrier.

scholarly journals Ensemble Effects of Explicit Solvation on Allylic Oxidation

2021 ◽  
Author(s):  
Hung Le ◽  
Mariano Guagliardo ◽  
Anne Gorden ◽  
Aurora Clark
Keyword(s):  
Gas Phase ◽  
Energy Barrier ◽  
Density Functional ◽  
Umbrella Sampling ◽  
Catalytic Cycle ◽  
Allylic Oxidation ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Ensemble Effects ◽  
Explicit Solvation

<div>Umbrella-sampling density functional theory molecular dynamics (DFT-MD) has been employed to study the full catalytic cycle of the allylic oxidation of cyclohexene</div><div>using a Cu(II) (E)-6-amino-7-((2-hydroxybenzylidene)amino)quinoxalin-2-ol complex in acetonitrile, which creates the desired cyclohexenone and H 2 O as products. In comparison to prior study using gas-phase DFT, a significant solvent effect is observed on the rate determining allylic H-atom abstraction step (which has a free energy barrier of 12.1 ± 0.2 kcal/mol). During the cycle, the explicit solvation and ensemble sampling of solvent configurations reveals an important dehydrogenation and re-hydrogenation step of the -NH 2 ligand that is essential to catalyst recovery. This work illustrates the importance of ensemble solvent configurational sampling to reveal the breadth of processes that underpin the full catalytic cycle.</div>

A two-dimensional Ru@MXene catalyst for highly selective ambient electrocatalytic nitrogen reduction

Nanoscale ◽  
2020 ◽  
Vol 12 (20) ◽  
pp. 10933-10938 ◽  
Author(s):  
Anmin Liu ◽  
Mengfan Gao ◽  
Xuefeng Ren ◽  
Fanning Meng ◽  
Yanan Yang ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Ammonia Synthesis ◽  
Low Energy ◽  
Two Dimensional ◽  
Pollution Potential ◽  
Nitrogen Reduction ◽  
Bosch Process ◽  
Low Energy Consumption

Compared with the traditional Haber–Bosch process, electrochemical ammonia synthesis has attracted much attention owing to its low energy consumption, low pollution potential, and sustainability.

High-efficiency electrochemical nitrite reduction to NH3 by Cu3P nanowire array under ambient conditions

2021 ◽  
Author(s):  
Jie Liang ◽  
Biao Deng ◽  
Qin Liu ◽  
Guilai Wen ◽  
Qian Liu ◽  
...  
Keyword(s):  
Significant Role ◽  
Large Scale ◽  
High Efficiency ◽  
Nanowire Array ◽  
Nitrite Reduction ◽  
Ambient Conditions ◽  
Nitrogen Reduction ◽  
Bosch Process

Ammonia (NH3) plays a significant role in agriculture and industry. Industrially, large-scale NH3 production mainly depends on the energy-intensive and environmentally unfriendly Haber-Bosch process. Electrochemical nitrogen reduction is regarded as...

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