scholarly journals Understanding Catalytic Activity Trends of Electrochemical Ammonia Oxidation Reaction using Density Functional Theory Calculations and Microkinetic Modeling

2021 ◽  
Author(s):  
Ho Yeon Jang ◽  
Seoin Back
Keyword(s):  
Density Functional Theory ◽  
Catalytic Activity ◽  
Oxidation Reaction ◽  
Density Functional ◽  
Ammonia Oxidation ◽  
Bond Formation ◽  
Catalyst Design ◽  
Binding Energies ◽  
Pt Catalyst ◽  
Functional Theory

Electrochemical ammonia oxidation reaction (AOR) is promising as an alternative anodic reaction to oxygen evolution in water electrolysis system. Herein, we develop a microkinetic model based on density functional theory (DFT) calculations for all possible reaction pathways considering both thermochemical and electrochemical N-N bond formation processes. From the microkinetic analysis, we discover that Faradaic bond formation contributes to AOR more significantly than non-Faradaic counterpart and we observe good agreements with the experimental results. We then construct a kinetic volcano plot using binding energies of two reaction intermediates as descriptors, which suggests a catalyst design strategy. Following this strategy, we enumerate numerous alloy combinations and identify a few promising candidates with higher catalytic activity than the most active monometallic Pt catalyst.

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

STRUCTURES, ELECTRONIC AND MAGNETIC PROPERTIES OF C20 FULLERENES DOPED TRANSITION METAL ATOMS M@C20 (M = Fe, Co, Ti, V)

2010 ◽  
Vol 21 (12) ◽  
pp. 1469-1477 ◽  
Author(s):  
M. SAMAH ◽  
B. BOUGHIDEN
Keyword(s):  
Density Functional Theory ◽  
Magnetic Moment ◽  
Density Functional ◽  
Binding Energies ◽  
Functional Theory ◽  
Magnetic Dipoles ◽  
Metal Atoms ◽  
Transition Metal Atoms ◽  
Semiconductor Behavior ◽  
Co Doped

Structures, binding energies, magnetic and electronic properties endohedrally doped C 20 fullerenes by metallic atoms ( Fe , Co , Ti and V ) have been obtained by pseudopotential density functional theory. All M @ C 20, except Co @ C 20, are more stable than the undoped C 20 cage. The magnetic moment values are 1 and 2μB. These values and semiconductor behavior give to these compounds interesting feature in several technological applications. Titanium doped C 20 has a same magnetic moment than the isolated Ti atom. Hybridization process in the Co doped C 20 fullerene is most strong than in other doped cages. Electrical and magnetic dipoles calculated in the iron doped C 20 are very strong compared with other clusters.

Research Optical Characteristics of H2S Molecule Adsorption on Agn (n=2,4,6) Clusters

2013 ◽  
Vol 321-324 ◽  
pp. 499-502
Author(s):  
Hong Zhou ◽  
Jun Feng Wang ◽  
Jun Qing Wen ◽  
Wei Bin Cheng ◽  
Jun Fei Wang
Keyword(s):  
Density Functional Theory ◽  
Infrared Spectrum ◽  
Density Functional ◽  
Global Minimum ◽  
Electronic States ◽  
Binding Energies ◽  
Optical Characteristics ◽  
Functional Theory ◽  
Calculation Results ◽  
Planar Geometries

Density-functional theory has been used to calculate the energetically global-minimum geometries and electronic states of AgnH2S (n=2, 4, 6) clusters. The lowest-energy structures of Ag2, Ag4, Ag6, Ag2H2S, Ag4H2S and Ag6H2S clusters were obtained, respectively. The calculation results show that the lowest-energy structures of Ag2, Ag4and Ag6clusters are planar geometries. The binding energies of Agn(n=2, 4, 6) clusters are gradually increasing in our calculations. Compare the infrared spectrum peaks of Ag4cluster with that of Ag6cluster, which show that the peaks shift to shortwave. After adsorption, we found that the peaks shift to shortwave by comparison.

The effect of defects on the catalytic activity of single Au atom supported carbon nanotubes and reaction mechanism for CO oxidation

2017 ◽  
Vol 19 (33) ◽  
pp. 22344-22354 ◽  
Author(s):  
Sajjad Ali ◽  
Tian Fu Liu ◽  
Zan Lian ◽  
Bo Li ◽  
Dang Sheng Su
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional Theory ◽  
Catalytic Activity ◽  
Carbon Nanotube ◽  
Reaction Mechanism ◽  
Co Oxidation ◽  
Density Functional ◽  
Functional Theory ◽  
Single Walled Carbon Nanotube ◽  
Wales Defect

The mechanism of CO oxidation by O2 on a single Au atom supported on pristine, mono atom vacancy (m), di atom vacancy (di) and the Stone Wales defect (SW) on single walled carbon nanotube (SWCNT) surface is systematically investigated theoretically using density functional theory.

scholarly journals Covalent Functionalization of Nickel Phosphide Nanocrystals with Aryl-Diazonium Salts

2021 ◽  
Author(s):  
Ian Murphy ◽  
Peter Rice ◽  
Madison Monahan ◽  
Leo Zasada ◽  
Elisa Miller ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Binding Energies ◽  
Diazonium Salts ◽  
Surface Functional Group ◽  
Covalent Functionalization ◽  
Substitution Pattern ◽  
Core Electron ◽  
Functional Theory

Covalent functionalization of Ni2P nanocrystals was demonstrated using aryl-diazonium salts. Spontaneous adsorption of aryl functional groups was observed, with surface coverages ranging from 20-96% depending on the native reactivity of the salt as determined by the aryl substitution pattern. Increased coverage was possible for low reactivity species using a sacrificial reductant. Functionalization was confirmed using thermogravimetric analysis, FTIR and X-ray photoelectron spectroscopy. The structure and energetics of this nanocrystal electrocatalyst system, as a function of ligand coverage, was explored with density functional theory calculations. The Hammett parameter of the surface functional group was found to linearly correlate with the change in Ni and P core-electron binding energies and the nanocrystal’s experimentally and computationally determined work-function. The electrocatalytic activity and stability of the functionalized nanocrystals for hydrogen evolution were also improved when compared to the unfunctionalized material, but a simple trend based on electrostatics was not evident. We used density functional theory to understand this discrepancy and found that H adsorption energies on the covalently functionalized Ni2P also do not follow the electrostatic trend and are predictive descriptors of the experimental results.

scholarly journals A Density Functional Theory Investigation of the Reaction of Water with Ce2O-

2020 ◽  
Author(s):  
Hassan Harb ◽  
Hrant Hratchian
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Function Theory ◽  
Practical Importance ◽  
Density Function Theory ◽  
Catalyst Design ◽  
Reaction Pathways ◽  
Spin States ◽  
Functional Theory ◽  
Energy Science

<div>Cerium suboxide clusters have been shown to react with water to yield H<sub>2</sub>. Since reactions of metal oxides with water are of great fundamental and practical importance in energy science, detailed study of this reaction can provide new key knowledge for future catalyst design. Using density function theory calculations, we identified and report complete reaction pathways for two spin-states of Ce<sub>2</sub>O<sup>–</sup> reacting with H<sub>2</sub>O. Additionally, examining the molecular orbitals of initial and final cerium oxide clusters, we found that metal d electrons facilitate the reduction of water. This work provides new understanding of this reaction and insights to the reactivity enhancements for cerium-doped surfaces.</div>

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