ELECTROSORPTION OF HYDROGEN AND SULFURIC-ACID ANIONS ON SINGLE-CRYSTAL PLATINUM STEPPED SURFACES .2. THE [110] ZONE

Hydrogen and bisulphate adsorption at platinum single crystal surfaces from the [110BAR] zone is strongly dependent on the crystallographic orientation of the electrode surface, which is similar to that found earlier for the [1101 zone. For the purposes of comparison, some experiments were performed with non-adsorbing perchlorate acid solutions. The multiple states of hydrogen adsorption can be correlated with symmetry of surface sites and the nature of the adsorbed oxi-anions. All stepped surfaces investigated from this zone have one sharp peak at -0.175 V which is due to a coupled desorption of bisulphate and hydrogen adsorption from the sites with the (110) symmetry. The surfaces of the n(110)-(111) type behave as the surfaces denoted (n-1)(110)-3(111) since the three atom long terrace is "seen" by bisulphate and hydrogen. Bisulphate anions are more strongly adsorbed at the steps than at the (III) oriented terraces. The latter process occurs at more positive potentials than the adsorption at steps and it is affected by anions at the step sites. The structure in the electrolyte solutions has been discussed.