Theoretical investigation on coadsorption effect of O2 and H2O on Pt(111) surface
8
Citation
34
Reference
10
Related Paper
Citation Trend
Keywords:
Chemisorption
Physisorption
Adsorption mode of corrosion inhibitors is often determined by criteria based on the standard free energy of adsorption, with values greater than −20 kJ/mol attributed to physisorption and values smaller than −40 kJ/mol attributed to chemisorption. Several arguments are presented herein to show that these are not very reliable criteria to distinguish between physisorption and chemisorption. The most notable among them is that chemisorption may involve bond-breaking and bond-making that result in a rather "weak" standard adsorption free energy (or enthalpy). For this reason, more reliable criteria are recommended that are readily available in first-principle computational modeling studies. The strong molecule–surface interaction, involved in chemisorption, should also be detectable by spectroscopy.
Cite
Citations (213)
The TiC monolayer sheet, a new two-dimensional structure, is proposed as a promising hydrogen storage material because of its high specific surface area and the large number of exposed Ti ions on the surface. First principles calculations showed that both chemisorption and physisorption of H2 can take place on the TiC sheet surface, with adsorption energies of 0.36 and 0.09 eV per H2, respectively. For 1 and 1/4 monolayer(ML) coverages, the dissociation barriers of H2 on the TiC sheet surface were calculated to be 1.12 and 0.33 eV, respectively. Thus, as well as physisorption and chemisorption, there were dissociated H atoms on the TiC sheet surface. The maximum H2 storage capacity was calculated to be up to 7.69%(mass fraction).The capacities were 1.54%, 3.07%, and 3.07% for dissociated H atoms, and chemisorption and physisorption of H2, respectively. Considering only Kubas adsorption, the hydrogen storage capacity was 3.07%. The adsorption energy for H2 chemisorption on the TiC sheet surface only slightly changed at different coverages,which benefits the storage and release of H2.
Physisorption
Chemisorption
Cite
Citations (0)
Physisorption
Chemisorption
Cite
Citations (10)
We resolve a thermodynamic inconsistency in previous theoretical descriptions of the free energy of chemisorption (charge regulation) under conditions where nonelectrostatic physisorption is included, as applied to surface forces and particle-particle interactions. We clarify the role of nonelectrostatic ion physisorption energies and show that a term previously thought to represent physisorbed ion concentrations (activities) should instead be interpreted as a "partial ion activity" based solely on the electrostatic physisorption energy and bulk concentration, or alternatively on the nonelectrostatic physisorption energy and surface concentration. Second, the chemisorption energy must be understood as the change in chemical potential after subtracting the electrostatic energy, not subtracting the physisorption energy. Consequently, a previously reported specific ion nonelectrostatic physisorption contribution to the chemisorption free energy is annulled. We also report a correction to the calculation of surface charge. The distinction in "partial ion activity" evaluated from bulk concentration or from surface concentration opens a way to study nonequilibrium forces where chemisorption is in equilibrium with physisorbed ions but not in equilibrium with bulk ions, e.g., by a jump in ion concentrations.
Physisorption
Chemisorption
Cite
Citations (16)
Physisorption
Chemisorption
Cite
Citations (25)
Physisorption
Chemisorption
Cite
Citations (17)
A description of the physisorption and subsequent chemisorption of water on silica glass surfaces is presented that combines electronic structure calculations with classical molecular dynamics simulations. The method associates the strength of the physisorption sites with the gradient of the electrostatic potential, and the chemical reactivity with the chemical hardness of the surface. The physisorption results are compared with those of more classical physisorption energy mappings, and to ab initio calculations of water molecules physisorbing at specific sites. The chemisorption reactivity index is compared with calculated chemisorption energy barriers. The techniques are applied to two types of silica glass surfaces: a fracture surface with high energy coordination defects and a low energy defect-free ``melt surface.'' The mappings show that the strongest sites for physisorption are network coordination defects, but that a high physisorption energy is not necessarily an indicator of a reactive site. The physisorption and chemisorption mappings were converted to energy distributions and reactivity distributions for a direct comparison between the melt and fracture surfaces. Altogether, this approach combines the efficiency of classical molecular dynamics for structural determinations, with the chemical degrees of freedom provided by electronic structure calculations, to yield a semiquantitative map of chemical reactivity across a surface.
Physisorption
Chemisorption
Cite
Citations (47)
Chemisorption and physisorption of water onto the {0001}, {1011}, {1120}, and {2243} surfaces of alpha‐alumina have been studied via atomistic simulation techniques, using potentials that have been verified against the structures of hydrated ß‐alumina and diaspore. Both physisorption and chemisorption of all surfaces are energetically favorable, especially the hydroxylation of dipolar oxygen‐terminated planes. The equilibrium morphology is calculated, as a way to assess the change in surface energies, and the equilibrium morphologies agree with the experimentally observed crystal morphologies. The calculated energies of both physisorption and chemisorption agree well with experimentally obtained hydration energies.
Physisorption
Chemisorption
Cite
Citations (88)
Chemisorption
Physisorption
Cite
Citations (8)
Physisorption
Chemisorption
Hysteresis
Cite
Citations (101)