On the concept of synergetic systems of composite or modified materials and their electrocatalytic properties: (1) General approach

The general concept of synergetic materials and their electrocatalytic activity, which is governed by the active-sites for the reactions, are presented. Electrocatalytic properties related to synergetic materials are defined. Based on the equations of the equilibrium between different types of active-sites, the effect of the active-site concentrations on the electrocatalytic properties for the HER and ORR is analysed. The equations related to the variation of the rate of reactions with the active-site concentration are presented. The dependence of the active-site concentration on the physical parameters of the support, the dispersive elements and the composite materials are indicated and the corresponding expressions are shown. The improvement in the electrocatalytic properties for the HER composite materials was then studied using the concept of surface active-sites and their related expressions. The dependence of the electrocatalytic properties of composite materials on active-site concentration, the energy levels of the supports the dispersive elements and the reaction rate is analysed. (C) 2001 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.