Surface diffusion of adsorbed gases on an energetically heterogeneous porous solid

Abstract A new model of surface diffusion based on an analogy with electrical conductivity in amorphous semiconductors is proposed. The adsorption sites are considered to be connected by resistances with randomly distributed values. The energetic heterogeneity of the solid surface and other aspects of the system are explicitly taken into account. An expression for the surface diffusion coefficient that quantifies these aspects and the surface coverage dependence is obtained. The model fits experimental data well for a variety of gas-solid systems.