LOCALIZATION OF ELECTROCHEMICAL REACTIONS IN ELECTROCATALYTIC PROCESSES ON NANOCOMPOSITE ELECTRODES

A principle of reaction localization is proposed, which explains the catalytic properties of nanocomposites materials in the reaction under study. By changing the route of electrochemical reactions from the catalyst to the support or vice versa one can influence electrocatalytic properties. The catalytic activity can be judged from the difference in the electrochemical overpotential of separation of the reactant under investigation in a particular medium between the catalyst and the support, The action of this principle was demonstrated on the basis of oxygen reduction and hydrogen oxidation reactions for fuel cells and for the reaction of electrochemical hydrogen accumulation at a hydride electrode. For an oxygen electrode with carbon support in an alkaline medium, materials with high oxygen evolution overpotential are good catalysts. For a hydrogen electrode with carbon support in an alkaline medium, materials with low hydrogen evolution overpotential are good catalysts. In the case of electrochemical hydrogen accumulation at intermetallic compounds with low hydrogen evolution overpotential in an alkaline medium, catalysts with high hydrogen evolution overpotential must be used. Making use of this principle one can carry out goal-directed synthesis or select new organic or inorganic catalytic materials.