scholarly journals Identifying Outstanding Transition-Metal-Alloy Heterogeneous Catalysts for the Oxygen Reduction and Evolution Reactions via Subgroup Discovery

2021 ◽  
Author(s):  
Lucas Foppa ◽  
Luca M. Ghiringhelli
Keyword(s):  
Transition Metal ◽  
Oxygen Reduction ◽  
Density Functional ◽  
Heterogeneous Catalysts ◽  
Adsorption Properties ◽  
Subgroup Discovery ◽  
Data Set ◽  
Transition Metal Alloy ◽  
Adsorption Sites ◽  
Adsorption Energies

AbstractIn order to estimate the reactivity of a large number of potentially complex heterogeneous catalysts while searching for novel and more efficient materials, physical as well as data-centric models have been developed for a faster evaluation of adsorption energies compared to first-principles calculations. However, global models designed to describe as many materials as possible might overlook the very few compounds that have the appropriate adsorption properties to be suitable for a given catalytic process. Here, the subgroup-discovery (SGD) local artificial-intelligence approach is used to identify the key descriptive parameters and constrains on their values, the so-called SG rules, which particularly describe transition-metal surfaces with outstanding adsorption properties for the oxygen-reduction and -evolution reactions. We start from a data set of 95 oxygen adsorption-energy values evaluated by density-functional-theory calculations for several monometallic surfaces along with 16 atomic, bulk and surface properties as candidate descriptive parameters. From this data set, SGD identifies constraints on the most relevant parameters describing materials and adsorption sites that (i) result in O adsorption energies within the Sabatier-optimal range required for the oxygen-reduction reaction and (ii) present the largest deviations from the linear-scaling relations between O and OH adsorption energies, which limit the catalyst performance in the oxygen-evolution reaction. The SG rules not only reflect the local underlying physicochemical phenomena that result in the desired adsorption properties, but also guide the challenging design of alloy catalysts.

Tuning Transition Metal Carbides Activity by Surface Metal Alloying: Case Study on CO2 Capture and Activation

2018 ◽  
Author(s):  
Marti Lopez ◽  
Luke Broderick ◽  
John J Carey ◽  
Francesc Vines ◽  
Michael Nolan ◽  
...  
Keyword(s):  
Transition Metal ◽  
Co2 Capture ◽  
Density Functional ◽  
Deep Understanding ◽  
Metal Carbides ◽  
Transition Metal Carbides ◽  
Adsorption Sites ◽  
Surface Metal ◽  
A Minor

<div>CO2 is one of the main actors in the greenhouse effect and its removal from the atmosphere is becoming an urgent need. Thus, CO2 capture and storage (CCS) and CO2 capture and usage (CCU) technologies are intensively investigated as technologies to decrease the concentration</div><div>of atmospheric CO2. Both CCS and CCU require appropriate materials to adsorb/release and adsorb/activate CO2, respectively. Recently, it has been theoretically and experimentally shown that transition metal carbides (TMC) are able to capture, store, and activate CO2. To further improve the adsorption capacity of these materials, a deep understanding of the atomic level processes involved is essential. In the present work, we theoretically investigate the possible effects of surface metal doping of these TMCs by taking TiC as a textbook case and Cr, Hf, Mo, Nb, Ta, V, W, and Zr as dopants. Using periodic slab models with large</div><div>supercells and state-of-the-art density functional theory based calculations we show that CO2 adsorption is enhanced by doping with metals down a group but worsened along the d series. Adsorption sites, dispersion and coverage appear to play a minor, secondary constant effect. The dopant-induced adsorption enhancement is highly biased by the charge rearrangement at the surface. In all cases, CO2 activation is found but doping can shift the desorption temperature by up to 135 K.</div>

scholarly journals Probing the activity of transition metal M and heteroatom N4 co-doped in vacancy fullerene (M–N4–C64, M = Fe, Co, and Ni) towards the oxygen reduction reaction by density functional theory

RSC Advances ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 3174-3182
Author(s):  
Siwei Yang ◽  
Chaoyu Zhao ◽  
Ruxin Qu ◽  
Yaxuan Cheng ◽  
Huiling Liu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Density Functional ◽  
Reduction Reaction ◽  
Functional Theory ◽  
Co Doped

In this study, a novel type oxygen reduction reaction (ORR) electrocatalyst is explored using density functional theory (DFT); the catalyst consists of transition metal M and heteroatom N4 co-doped in vacancy fullerene (M–N4–C64, M = Fe, Co, and Ni).

ADSORPTION SITES OF THE PRODUCTS OF GeH4 ON ASYMMETRIC Si(100)(2×1) SURFACE

2004 ◽  
Vol 18 (08) ◽  
pp. 1191-1202
Author(s):  
ŞENAY KATıRCıOĞLU
Keyword(s):  
Density Functional ◽  
Geometry Optimization ◽  
Density Functional Theory Method ◽  
Adsorption Model ◽  
Functional Theory ◽  
Adsorption Models ◽  
Adsorption Sites ◽  
Asymmetric Dimer ◽  
Adsorption Energies ◽  
Relative Adsorption

The decomposition of GeH 4 on Si (100)(2×1) was investigated on different adsorption models of fragments using density functional theory method. The most probable adsorption model of fragments corresponding to the growth steps of SiGe film has been obtained by geometry optimization and single value total energy calculations. The relative adsorption energies of GeH 3, GeH 2 and GeH have been found to be -5.6, -5.1, and -4.5 eV for their most probable adsorption models respectively. It has been found that, the asymmetric dimer bond rows of Ge on Si (100) surface can be constructed by following the adsorption models corresponding to the relative adsorption energies of GeH 3, GeH 2 and GeH .

scholarly journals Adsorption properties of NO molecules on the hexagonal LaCoO3 (0 0 1) surface: a density functional theory study

RSC Advances ◽  
2017 ◽  
Vol 7 (55) ◽  
pp. 34714-34721 ◽  
Author(s):  
Zhijie Liu ◽  
Yanxin Wang ◽  
Hongwei Gao
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Adsorption Properties ◽  
Density Functional Theory Study ◽  
No Adsorption ◽  
Functional Theory ◽  
Adsorption Sites

Six types of adsorption configurations, together with two different adsorption sites for NO adsorption on LaCoO3, were investigated via density functional theory.

scholarly journals Strategies and Software for Machine Learning Accelerated Discovery in Transition Metal Chemistry

2018 ◽  
Author(s):  
Aditya Nandy ◽  
Chenru Duan ◽  
Jon Paul Janet ◽  
Stefan Gugler ◽  
Heather Kulik
Keyword(s):  
Machine Learning ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Density Functional ◽  
Open Shell ◽  
Frontier Molecular Orbital ◽  
Data Set ◽  
Homo Level ◽  
Homo Lumo

<p>Machine learning the electronic structure of open shell transition metal complexes presents unique challenges, including robust and automated data set generation. Here, we introduce tools that simplify data acquisition from density functional theory (DFT) and validation of trained machine learning models using the molSimplify automatic design (mAD) workflow. We demonstrate this workflow by training and comparing the performance of LASSO, kernel ridge regression (KRR), and artificial neural network (ANN) models using heuristic, topological revised autocorrelation (RAC) descriptors we have recently introduced for machine learning inorganic chemistry. On a series of open shell transition metal complexes, we evaluate set aside test errors of these models for predicting the HOMO level and HOMO-LUMO gap. The best performing models are ANNs, which show 0.15 and 0.25 eV test set mean absolute errors on the HOMO level and HOMO-LUMO gap, respectively. Poor performing KRR models using the full 153-feature RAC set are improved to nearly the same performance as the ANNs when trained on down-selected subsets of 20-30 features. Analysis of the essential descriptors for HOMO and HOMO-LUMO gap prediction as well as comparison to subsets previously obtained for other properties reveals the paramount importance of non-local, steric properties in determining frontier molecular orbital energetics. We demonstrate our model performance on diverse complexes and in the discovery of molecules with target HOMO-LUMO gaps from a large 15,000 molecule design space in minutes rather than days that full DFT evaluation would require. </p>

scholarly journals Density Functional Theory Study Of The Interaction Of Hydroxyl Groups With Iron Surface

2015 ◽  
Vol 60 (2) ◽  
pp. 931-933 ◽  
Author(s):  
N. Nunomura ◽  
S. Sunada
Keyword(s):  
Density Functional Theory ◽  
Iron Atom ◽  
Density Functional ◽  
Lone Pair ◽  
Hydroxyl Groups ◽  
Electronic Interaction ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Surface Iron ◽  
Adsorption Energies

AbstractThe electronic interaction of hydroxyl groups with Fe(100) surface is modelled using a density functional theory (DFT) approach. The adsorption energies and structures of possible adsorption sites are calculated. According to our calculations of the adsorption energies, the interaction between oxygen atom of OH species and surface iron atom is shown to be strong. It is likely to be due to the interaction of the lone-pair electrons of oxygen and the 3dorbital electrons of iron atom. At low coverage (0.25ML), the most favorable adsorption sites are found to be two-fold bridge sites, and the orientation of the O-H bond is tilted to the surface normal. Further, the adsorption energy is found to be decreasing with the increasing OH group coverage.

scholarly journals Decoupling strain and ligand effects in ternary nanoparticles for improved ORR electrocatalysis

2016 ◽  
Vol 18 (35) ◽  
pp. 24737-24745 ◽  
Author(s):  
Paul C. Jennings ◽  
Steen Lysgaard ◽  
Heine A. Hansen ◽  
Tejs Vegge
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Oxygen Reduction Reaction ◽  
Density Functional ◽  
Pt Nanoparticles ◽  
Reduction Reaction ◽  
Functional Theory ◽  
Transition Metal Nanoparticles ◽  
Ligand Effects ◽  
Adsorption Energies

Ternary Pt–Au–M (M = 3d transition metal) nanoparticles show reduced OH adsorption energies and improved activity for the oxygen reduction reaction (ORR) compared to pure Pt nanoparticles, as obtained by density functional theory.

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