The double-layer approach to promotion, electrocatalysis, electrochemical promotion, and metal-support interactions

Recent progress in understanding and modeling promotion, electrocatalysis, electrochemical promotion, and metal-support interactions is surveyed. It is shown that via the action of spillover and via the concept of the sacrificial promoter, the phenomena of promotion, electrochemical promotion, and metal-support interactions are functionally identical and only operationally different, as they all correspond to catalysis in presence of a controllable double layer. This is then utilized to derive adsorption isotherms and kinetic expressions which account explicitly for the electrostatic interactions between the double layer and the adsorbed reactants, intermediates, and products. The resulting analytical expressions are shown to be in excellent semiquantitative agreement with experiment and with the recently established promotional rules. (C) 2003 Elsevier Science (USA). All rights reserved.