Influence of Protein Surface Coverage on Anomalously Strong Adsorption Sites

2015 ◽  
Vol 8 (1) ◽  
pp. 511-520 ◽  
Author(s):  
Yu Cai ◽  
Daniel K. Schwartz
Keyword(s):  
Surface Coverage ◽  
Protein Surface ◽  
Adsorption Sites ◽  
Strong Adsorption

Dissociation of H2O molecule adsorbed on Si (001) 2×1 surface: a theoretical study

2008 ◽  
Vol 1145 ◽  
Author(s):  
Hyun-Chul Oh ◽  
Hwa-Il Seo ◽  
Yeong-Cheol Kim
Keyword(s):  
Water Molecule ◽  
Room Temperature ◽  
Surface Coverage ◽  
Theoretical Study ◽  
Surface Model ◽  
Water Molecules ◽  
First Principles Calculations ◽  
Adsorption Sites ◽  
Adsorption Surface ◽  
Adsorption And Dissociation

AbstractThe adsorption and dissociation behavior of water molecule below and above the critical dissociation temperatures were studied by first principles calculations. We found that water-molecule adsorption (surface coverage, θ=0.25) on the down Si atom of a Si dimer in two dimers surface model was 0.26 eV more favorable than that on the up Si atom. The activation energies of water molecule on the down Si atom for interdimer and intradimer dissociations were 0.17 eV and 0.20 eV, respectively. Due to the lower activation energy, the water molecule splits into H and OH immediately once it adsorbs on down Si atom of the Si (001) surface at room temperature. There were three different adsorption sites among four sites of the two dimers for the second water molecule (θ=0.5): one was preoccupied by OH of the first water molecule; up Si atom of the same-dimer with 76.3 % probability, up Si atom of the adjacent-dimer with 23.6 % probability, and down Si atom of the adjacent-dimer with 0.1 % probability. Thus, ½ monolayer of OH sites on the Si (001) surface are irregularly distributed when water molecules are adsorbed and dissociated at room temperature.

Hydrogenation of 2-phenyl-1-propene on platinum black modified with copper

1980 ◽  
Vol 45 (12) ◽  
pp. 3541-3545
Author(s):  
Ivo Paseka ◽  
Libor Červený ◽  
Josef Mach ◽  
Vlastimil Růžička
Keyword(s):  
Reaction Rate ◽  
Surface Coverage ◽  
Platinum Black ◽  
Hydrogenation Rate ◽  
Platinum Surface ◽  
Adsorption Sites ◽  
Pt Black

Copper deposited from a solution of copper(II) formate on Pt-black at surface coverage lower than unity is present on the platinum surface both in the form of ad-atoms and in the form of multiatomic layers. From the dependence of the hydrogenation rate on coverage by copper is followed that the reaction rate depended on the number of free pairs of the adsorption sites of platinum unoccupied by copper.

scholarly journals Smart adsorbents for CO2 capture: Making strong adsorption sites respond to visible light

2020 ◽  
Author(s):  
Qiu-Rong Wu ◽  
Peng Tan ◽  
Chen Gu ◽  
Rui Zhou ◽  
Shi-Chao Qi ◽  
...  
Keyword(s):  
Visible Light ◽  
Co2 Capture ◽  
Adsorption Sites ◽  
Strong Adsorption

scholarly journals Effect of aluminum and sodium on the sorption of water and methanol in microporous MFI-type zeolites and mesoporous SBA-15 materials

Adsorption ◽  
2020 ◽  
Author(s):  
Zheng Li ◽  
Carolin Rieg ◽  
Ann-Katrin Beurer ◽  
Michael Benz ◽  
Johannes Bender ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Acid Sites ◽  
Mas Nmr ◽  
Nmr Studies ◽  
Oh Groups ◽  
Adsorption Sites ◽  
Low Field ◽  
Strong Adsorption ◽  
Nmr Signals

Abstract The interaction and nature of surface sites for water and methanol sorption on MFI-type zeolites and mesoporous SBA-15 were investigated by solid-state NMR spectroscopy and correlated with the desorption enthalpies determined via TGA/DSC. For siliceous Silicalite-1, 29Si CPMAS NMR studies support stronger methanol than water interactions with SiOH groups of Q3-type. On siliceous SBA-15, SiOH groups of Q2-type are accompanied by an enhanced hydrophilicity. In aluminum-containing Na-ZSM-5, Na+ cations are strong adsorption sites for water and methanol as evidenced by 23Na MAS NMR in agreement with high desorption enthalpies of ΔH = 66–74 kJ/mol. Solid-state NMR of aluminum-containing Na-[Al]SBA-15, in contrast, has shown negligible water and methanol interactions with sodium and aluminum. Desorption enthalpies of ΔH = 44–60 kJ/mol hint at adsorption sites consisting of SiOH groups influenced by distant framework aluminum. On H-ZSM-5, Brønsted acidic OH groups are strong adsorption sites as indicated by partial protonation of water and methanol causing low-field shifts of their 1H MAS NMR signals and enhanced desorption enthalpies. Due to the small number of Brønsted acid sites in aluminum-containing H-[Al]SBA-15, water and methanol adsorption on this material is suggested to mainly occur at SiOH groups with distant framework aluminum species, as in the case of Na-[Al]SBA-15.

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