Effect of modifying impurities on magnetocatalytic and magnetoadsorption effects
Based on the theory of the s-d-exchange interaction in ferromagnetics, the relation between the magnetic state of a metal and the modifying action of impurities on chemisorption and catalysis was discussed. The experimental data were analyzed by using estimates of changes in the surface electron density of the metal performed with the use of statistical-thermodynamic and quantum-chemical models. The conditions of appearance of the magnetocatalytic and magnetoadsorption effects during the adsorption of gases on nickel and its alloys with copper and silver and also under the action of small amounts of modifiers, such as chemisorbed O2, H2S, CO, C2H4, and C6H6, were determined. It was found that the magnetic transition causes the modifier charge sign to change, whereas chemisorption results in changes in the parameters characterizing the exchange interaction between the s- and d-electron systems of the metal. It is shown that the magnetocatalytic effect depends on the nature of the surface modifier: it can disappear, appear, enhance, or decrease in their presence. For the H2 + CO and H2 + Ochem reactions, as an example, the change in the reaction mechanism caused by the magnetic transition in the presence of modifiers was found.