Reconstruction phenomena at metal-electrolyte interfaces

For gold and platinum single-crystal electrodes in aqueous solutions surface reconstruction phenomena are observed which are very much the same as those known from respective investigations in ultra high vacuum. The current status of our knowledge on reconstructed electrode surfaces is summarized, placing emphasis on the more recent in-situ scanning tunneling microscopy studies. The presented data will focus on two topics which are of particular importance for electrochemistry. The first one describes the conditions under which reconstructed surfaces are stable in solution, and hence, represent the actual surface geometry. The second one deals with the so-called potential-induced reconstruction and the transitions between reconstructed and unreconstructed surfaces which can be controlled by the electrode potential, a feature unique to the electrochemical interface. The kinetics of such surface transitions are discussed in some detail. Finally, examples of electrochemical reactions are given, which can occur at both reconstructed and unreconstructed surfaces and which demonstrate the need for taking reconstruction phenomena into account.