The ability of certain surface-bound species to significantly reduce or prevent activity on catalyst surfaces is well established. However, it was recently discovered that disulfide (S^2–) bound to a Pt (111) surface could promote the oxygen reduction reaction (ORR). Despite this important observation, the mechanism by which it takes place remains unclear. As the ORR plays a critical role in areas such energy conversion, understanding some or all of the mechanistic steps in this process should be of great value in producing improved OOR catalysts and in understanding promotion effects of surface-bound species.

In this talk, periodic planewave calculations of the ORR on a Pt(111) catalyst surface with varying coverages of disulfide will be discussed. Comparison of computed and experimental IR spectra of intermediate species will be used to validate the computational methodology. The results of the calculations will be used in a mean-field microkinetic model to better understand the origin of the promotion effect due to the presence of the disulfide.