Insight into both coverage and surface structure dependent CO adsorption and activation on different Ni surfaces from DFT and atomistic thermodynamics

2016 ◽  
Vol 18 (26) ◽  
pp. 17606-17618 ◽  
Author(s):  
Xiaobin Hao ◽  
Baojun Wang ◽  
Qiang Wang ◽  
Riguang Zhang ◽  
Debao Li
Keyword(s):  
Surface Structure ◽  
Co Adsorption ◽  
Ni Catalyst ◽  
High Coverage ◽  
Atomistic Thermodynamics ◽  
Insight Into

CO adsorption and activation from low to high coverage on Ni catalyst.

High coverage adsorption and co-adsorption of CO and H2 on Ru(0001) from DFT and thermodynamics

2015 ◽  
Vol 17 (29) ◽  
pp. 19446-19456 ◽  
Author(s):  
Peng Zhao ◽  
Yurong He ◽  
Dong-Bo Cao ◽  
Xiaodong Wen ◽  
Hongwei Xiang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Co Adsorption ◽  
High Coverage ◽  
Functional Theory ◽  
Adsorption Of Co ◽  
Atomistic Thermodynamics

The adsorption and co-adsorption of CO and H2 at different coverages on p(4 × 4) Ru(0001) have been computed using periodic density functional theory (GGA-RPBE) and atomistic thermodynamics.

Nano-sized nickel catalyst for deep hydrogenation of lignin monomers and first-principles insight into the catalyst preparation

2017 ◽  
Vol 5 (8) ◽  
pp. 3948-3965 ◽  
Author(s):  
Shi-Chao Qi ◽  
Lu Zhang ◽  
Hisahiro Einaga ◽  
Shinji Kudo ◽  
Koyo Norinaga ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Full Range ◽  
Catalyst Preparation ◽  
Ni Catalyst ◽  
Borohydride Reduction ◽  
Functional Theory ◽  
Pyridine Complex ◽  
Insight Into

A type of nano-sized Ni catalyst supported by ZSM-5 zeolite for the deep hydrogenation of lignin monomers is prepared by borohydride reduction of a Ni2+–pyridine complex in ethanol. The mechanism of the borohydride reduction over the full range from Ni2+ to Ni0 is calculated by applying density functional theory.

scholarly journals Aquatic flora in two Indian ponds near Kolkata, West Bengal: Implications for conservation

1970 ◽  
Vol 14 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Gautam Mukhopadhyay ◽  
Sourav Sengupta ◽  
Anjana Dewanji
Keyword(s):  
Chemical Constituents ◽  
Positive Association ◽  
Alternanthera Philoxeroides ◽  
Cladophora Glomerata ◽  
High Coverage ◽  
Hydrodictyon Reticulatum ◽  
Aquatic Flora ◽  
Plant Taxon ◽  
Negative Impacts ◽  
Insight Into

Occurrence, coverage and chemical constituents of aquatic flora were studied in two Indian ponds over a period of 39-month in order to gain an insight into their associations and infestation for implications in conservation and management. Species diversity was recorded in presence of two invasive species (Alternanthera philoxeroides (Martius) Griseb. and Lemna aequinoctialis Welwitsch). These species should be managed in view of their beneficial uses. Nymphaea pubescens Willd, a threatened species, was recorded. Positive association of Nymphoides hydrophylla (Loureiro) O. Kuntze with Alternanthera philoxeroides and Vallisneria spiralis L. showed that spatially separated habitats are useful for conservation. Azolla pinnata R. Brown, an useful species and Rotala rotundifolia (F. Hamilton ex Roxburgh) Koehne, an uncommon species, were able to produce high coverage in their brief occurrence - important for their conservation. Similar feature as observed in Cladophora glomerata (L.) Kütz and Hydrodictyon reticulatum (L.) Lagerh. is useful for management of these species due to their negative impacts. Key words: Aquatic flora, Species composition, Occurrence, Coverage, Nitrogen, Phosphorus, Management DOI: 10.3329/bjpt.v14i1.519 Bangladesh J. Plant Taxon. 14(1): 13-24, 2007 (June)

Chiral nanoscale pores created during the surface explosion of tartaric acid on Cu(111)

2016 ◽  
Vol 52 (99) ◽  
pp. 14282-14285 ◽  
Author(s):  
A. J. Therrien ◽  
T. J. Lawton ◽  
B. Mernoff ◽  
F. R. Lucci ◽  
V. V. Pushkarev ◽  
...  
Keyword(s):  
Surface Structure ◽  
Tartaric Acid ◽  
Autocatalytic Decomposition ◽  
High Coverage ◽  
Surface Explosion

The autocatalytic decomposition of tartaric acid on Cu(111) exhibits unique kinetics, which are linked to a hexagonal surface structure adopted at high coverage.

Active sites and states in the heterogeneous catalysis of carbon–hydrogen bonds

2005 ◽  
Vol 363 (1829) ◽  
pp. 879-900 ◽  
Author(s):  
Gabor A Somorjai ◽  
Anderson L Marsh
Keyword(s):  
Surface Structure ◽  
Active Sites ◽  
High Pressures ◽  
Bond Activation ◽  
Co Adsorption ◽  
Molecular Rearrangement ◽  
Platinum Surface ◽  
Bond Dissociation ◽  
Surface Mobility ◽  
Structure Sensitive

C–H bond activation for several alkenes (ethylene, propylene, isobutene, cyclohexene and 1-hexene) and alkanes (methane, ethane, n -hexane, 2-methylpentane and 3-methylpentane) has been studied on the (111) crystal face of platinum as a function of temperature at low (<10 −6  Torr) and high (≥1 Torr) pressures in the absence and presence of hydrogen pressures (≥10 Torr). Sum frequency generation (SFG) vibrational spectroscopy has been used to characterize the adsorbate structures and high pressure scanning tunnelling microscopy (HP-STM) has been used to monitor their surface mobility under reaction conditions during hydrogenation, dehydrogenation and CO poisoning. C–H bond dissociation occurs at low temperatures, approximately 250 K, for all of these molecules, although only at high pressures for the weakly bound alkanes because of their low desorption temperatures. Bond dissociation is known to be surface structure sensitive and we find that it is also accompanied by the restructuring of the metal surface. The presence of hydrogen slows down dehydrogenation and for some of the molecules it influences the molecular rearrangement, thus altering reaction selectivity. Surface mobility of adsorbates is essential to produce catalytic activity. When surface diffusion is inhibited by CO adsorption, ordered surface structures form and the reaction is poisoned. Ethylene hydrogenation is surface structure insensitive, while cyclohexene hydrogenation and dehydrogenation are structure sensitive. n -Hexane and other C 6 alkanes form either upright or flat-lying molecules on the platinum surface which react to produce branched isomers or benzene, respectively.

Mechanistic Insight into H2S Adsorption and Dissociation on MoP(010): A Density Functional Investigation

2017 ◽  
Vol 1142 ◽  
pp. 300-305
Author(s):  
Gui Xia Li ◽  
Hou Yu Zhu ◽  
Lian Ming Zhao ◽  
Wen Yue Guo ◽  
Xiao Qing Lu ◽  
...  
Keyword(s):  
Density Functional ◽  
Co Adsorption ◽  
Adsorbed Species ◽  
Functional Theory ◽  
Mechanistic Insight ◽  
Structure Sensitive ◽  
Bond Scission ◽  
Functional Investigation ◽  
Adsorption And Dissociation ◽  
Insight Into

H2S adsorption and dissociation on MoP(010) were investigated using density functional theory (DFT) together with periodic slab models. Several different possibilities for H2S, SH, S and H adsorption were considered. Our results show that the H2S, SH and H prefer to adsorb at bridge site, while S adsorbs preferentially at hcp and bridge sites. Additionally, the optimum co-adsorption configurations for SH/H and S/H were determined. The results indicate that the co-adsorbed species repel each other slightly on MoP(010) surface. Finally, the potential energy profile of H2S dissociation on MoP(010) surface was given out. The dissociation energy barriers of the S–H bond scission exhibit that H2S prefers to dissociate on MoP(010) surface. When compared with MoP(001) surface, the obvious differences in H2S decomposition arise demonstrate that the MoP-based catalysts are structure-sensitive.

scholarly journals Coordination chemistry of Ca sites at the surface of nanosized hydroxyapatite: interaction with H 2 O and CO

2012 ◽  
Vol 370 (1963) ◽  
pp. 1313-1336 ◽  
Author(s):  
Vera Bolis ◽  
Claudia Busco ◽  
Gianmario Martra ◽  
Luca Bertinetti ◽  
Yuriy Sakhno ◽  
...  
Keyword(s):  
Preparation Method ◽  
Co Adsorption ◽  
Specimen Preparation ◽  
High Coverage ◽  
Mild Conditions ◽  
Specific Effects ◽  
Vapour Adsorption ◽  
Co Probe ◽  
Ir Spectroscopic ◽  
Selection Of

The affinity towards water of a selection of well-defined, nanostructured hydroxyapatite (HA) samples was investigated by H 2 O vapour adsorption microcalorimetry and infrared (IR) spectroscopy. A large hydrophilicity of all investigated materials was confirmed. The surface features of hydrated HA were investigated on the as-synthesized samples pre-treated in mild conditions at T =303 K, whereas dehydrated HA features were characterized on samples activated at T =573 K. The relatively large hydrophilicity of the hydrated surface (−Δ ads H∼100–50 kJ mol −1 ) was due to the interaction of water with the highly polarized H 2 O molecules strongly coordinated to the surface Ca 2+ cations. At the dehydrated surface, exposing coordinatively unsaturated ( cus ) Ca 2+ cations, H 2 O was still molecularly adsorbed but more strongly (−Δ ads H∼120–90 kJ mol −1 ). The use of CO adsorption to quantify the Lewis acidic strength of HA surface sites revealed only a moderate strength of cus Ca 2+ cations, as confirmed by both microcalorimetric and IR spectroscopic measurements and ab initio calculations. This result implies that the large HA/H 2 O interaction energy is due to the interplay between cus Ca 2+ sites and nearby hydrophilic PO 4 groups, not revealed by the CO probe. The lower density of cus Ca 2+ cations at the 573 K activated HA surface with respect to the pristine one did not affect the whole hydrophilicity of the surface, as the polarizing effect of Ca sites is so strong to extend up to the fourth hydrated layer, as confirmed by both high-coverage microcalorimetric and IR spectroscopic data. No specific effects due to the investigated specimen preparation method and/or different morphology were observed.

scholarly journals New Insight into the Surface Structure of Lignin Nanoparticles Revealed by 1H Liquid-State NMR Spectroscopy

2020 ◽  
Vol 8 (36) ◽  
pp. 13805-13812
Author(s):  
Ievgen V. Pylypchuk ◽  
Pär A. Lindén ◽  
Mikael E. Lindström ◽  
Olena Sevastyanova
Keyword(s):  
Nmr Spectroscopy ◽  
Surface Structure ◽  
Liquid State ◽  
Insight Into

Surface structure and energetics of oxygen and CO adsorption on α-Mo2C(0001)

2005 ◽  
Vol 596 (1-3) ◽  
pp. 212-221 ◽  
Author(s):  
Jun Ren ◽  
Chun-Fang Huo ◽  
Jianguo Wang ◽  
Yong-Wang Li ◽  
Haijun Jiao
Keyword(s):  
Surface Structure ◽  
Co Adsorption

Surface structure and phase transition of K adsorption on Au(111): By ab initio atomistic thermodynamics

2012 ◽  
Vol 136 (4) ◽  
pp. 044510 ◽  
Author(s):  
Li-Yong Gan ◽  
Ren-Yu Tian ◽  
Xiao-Bao Yang ◽  
Yu-Jun Zhao
Keyword(s):  
Phase Transition ◽  
Ab Initio ◽  
Surface Structure ◽  
Atomistic Thermodynamics
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