Induced adsorption of gases on metals and oxide semiconductors

Using a two-dimensional electron gas model, it was shown that reversible adsorption of gases on metal and semiconductor surfaces can be increased by changing the electron density. The adsorption of H2, Ar, Kr, N 2, CO, CO2, and n-C6H14 on films, ultrafine-grain powders, metal-like graphitized carbon black and bulk metals (Rh, Ni, Ta, Ag) and the adsorption of CO and CO2 on Ta 2O5 oxide semiconductor powder were considered. Two effects were found: (1) an increase in the adsorbate amount because of the surface modification by irreversible adsorption (chemisorption) and (2) a surface inhomogeneity induced in the course of reversible adsorption, which is responsible for deviations of the adsorption isotherm from the Henry equation. Copyright © 2005 by Pleiades Publishing. Inc.