Please do not adjust margins Please do not adjust margins negatively charged. These calculations used graphite as a support instead of CB to reduce computational costs and employed the TEMobserved structure of Pt17NCs as the initial configuration, which was then optimized. To obtain insights into the HER mechanisms on Pt17/graphite, we optimized the structures of reaction intermediates for the HER. In the calculation, four pairs of Pt atoms (Fig. ) were selected as potential adsorption sites for hydrogen atoms (Hads) on the Pt17/graphite surface, referred to as Pt17(X)/graphite (X = i, ii, iii, or iv). The reaction intermediates (Hads/Pt17(X)/graphite) were then obtained by adsorbing Hads onto Pt17(X)/graphite (X = i, ii, iii, or iv). In the calculation of the intermediates, we also found another structure in which the pair of Hads is on the identical Pt atom (I = 11), referred to as Pt17(v)/graphite.