ANION-SURFACE INTERACTIONS .3. N2O REDUCTION AS A CHEMICAL PROBE OF THE LOCAL POTENTIAL OF ZERO TOTAL CHARGE

A detailed study of the reduction of N2O on a variety of single-crystal electrode surfaces is reported. By comparison with previous experimental determinations of the potential of zero total charge E(Q=0), it is shown that there is a direct correspondence between E(Q=0) and the maximum rate of N2O reduction. The importance of the local value of E(Q=0) is emphasized, particularly with respect to reconstructive metal surfaces such as Pt(100) and Pt(110) which can be prepared in a variety of crystallographic states. It is proposed that the sensitivity of N2O reduction to E(Q=0)(local) is derived from the blocking of N2O adsorption by ionic solution species whose surface concentrations are a function of the local charged state of the electrode surface.