Step sites for HER have already been thoroughly treated in literature and will not be discussed here. In addition, these sites are not necessarily inherent Finally, we present GCDFT energies of reactions relating to the stability of *S/*OH on Ni (111) in Figure . The adsorption of S was computed using H2S (g) and H2 (g) as references and without using an electron transfer term. S adsorption is very favorable and not a function of potential biasing. In contrast, OH adsorption is a function of potential, with significant grand canonical effects originating from a shift in PZC upon adsorption.