Peroxodisulfate reduction on platinum stepped surfaces vicinal to the (110) and (100) poles

Abstract

The reduction of peroxodisulfate anion at stepped platinum single crystal electrodes vicinal to the (110) and (100) poles has been investigated using cyclic voltammetry. Particular emphasis is made in understanding the effect of the cooling atmosphere used after the flame annealing. Two cooling atmospheres have been used: H2/Ar and CO. The cooling procedure has a significant influence on the reactivity obtained with the stepped surfaces belonging to both crystallographic zones. For the surfaces composed of (110) terraces and (111) or (100) steps cooled in H2/Ar, only one peroxodisulfate reduction peak is observed. On the contrary, for the same surfaces cooled in CO, more than one peak is observed for wide terraces. For surfaces vicinal to the pole (100), the cooling in CO atmosphere seems to produce a surface with higher order than those cooled in H2/Ar. The implications of the results on the understanding of the local distribution of charges at heterogeneous surfaces are discussed, identifying local values of the potential of zero charge. Those results are compared, when possible, with results obtained with other techniques.