Structural effects in electrocatalysis

Structural effects in electrocatalytic reactions have been demonstrated on examples of the oxidation of HCOOH on Pt and the O2 reduction on Au. Catalytic effects of foreign metal adatoms on these reactions have been studied on single-crystal surfaces. Hypothetical superlattice structures of foreign adatoms have been considered in explaining the coverage effect on the kinetics of the HCOOH oxidation. The OH chemisorption on Au in alkaline solution is strongly dependent on the crystallographic orientation of the electrode surface which is the origin of the structural dependence of the O2 reduction. Thallium adsorbates at small overpotentials inhibit the O2 reduction on the Au(100) plane, but catalyse it at the Au(111) and the Au(110) faces. At higher overpotentials a four-electron reduction is observed with all three planes covered with thallium adatoms.