Chemisorption

About: Chemisorption is a research topic. Over the lifetime, 16298 publications have been published within this topic receiving 554989 citations.

Contribution to Adsorption of Aromatic Amines on Mild Steel Surface from HCl Solutions by Impedance, UV, and Raman Spectroscopy

Abstract: Generally, aromatic amines are regarded as effective inhibitors for pickling and acid cleaning of mild steel in hydrochloric acid. Most previous studies advocate the view that the inhibition is a result of adsorption of the π-electron cloud of the aromatic ring on the iron and steel surface through vacant dπ orbital of iron. Later studies indicate a possible electrostatic adsorption or chemisorption due to synergistic action between halide ion and amine molecules as responsible for inhibition. In this paper, an attempt is made to study the mechanism of adsorption by using the concept of π-scale of potential as proposed by Antropov. The potential of zero charge (PZC) of mild steel is studied by two different techniques, and the mechanism of adsorption thus predicted has been found to corroborate the results of in situ Raman scattering study.

On the nature of spilt-over hydrogen

Abstract: Various experimental results on hydrogen spillover which have been obtained since the first evidence for this phenomenon are discussed concerning the nature of the activated hydrogen species. It will be demonstrated that the physical nature of the spilt-over species, especially their charge, can only be described by considering their interaction with the solid. A new model is proposed which is based on the description of spilt-over hydrogen as electron donor located at the surface. Consequently, H+ ions and H atoms coexist on the surface of the catalyst as also stated experimentally. Their ratio is determined by the electronic properties of the adsorbate/solid system. Considering atomic and recombinative desorption of spilt-over hydrogen, the adsorption isotherms are calculated exemplary for titania. The model is applied to interpret some experimental results related to hydrogen spillover, especially the partial electron transfer from the hydrogen species to the solid.

Room-Temperature Hydrogen Uptake by TiO2 Nanotubes

Abstract: TiO(2) nanotubes can reproducibly store up to approximately 2 wt % H(2) at room temperature and 6 MPa. However, only about 75% of this stored hydrogen can be released when the hydrogen pressure is lowered to ambient conditions, suggesting that both physisorption and chemisorption are responsible for the hydrogen uptake. FTIR spectroscopy, temperature-programmed desorption (TPD), and pressure-composition (P-C) isotherms suggest that 75% of the H(2) is physisorbed and can be reversibly released upon pressure reduction. Approximately 13% is weakly chemisorbed and can be released at 70 degrees C as H(2), and approximately 12% is bonded to oxide ions and released only at temperatures above 120 degrees C as H(2)O.

Chemisorption of Hydrogen on Tungsten (100)

Abstract: The interaction of hydrogen with a single‐crystal tungsten (100) surface has been studied, using LEED in conjunction with flash‐desorption and surface‐potential measurements. As hydrogen is adsorbed at room temperature a sequence of LEED patterns is observed, consisting of the formation of ``extra'' ½ ½ spots, splitting and eventual disappearance of these spots with simultaneous formation of ¼‐order spots, and finally, at saturation, the disappearance of all extra diffraction features. The possibility that these LEED patterns are caused by diffraction in the adlayer rather than in a reconstructed tungsten lattice is discussed in some detail.The initial adsorption is found to occur with a sticking probability of 0.65 and is accompanied by dissociation of the hydrogen molecules. At saturation there are two hydrogen atoms per surface tungsten atom. The surface potential decreases approximately linearly with coverage and at saturation the total change is about −0.9 V.For coverages above 0.25 the adsorption pr...