The breaking point is related to the place-exchange mechanism, identified to occur close to 1.06 V (N O /N Pt ≈ 1.0) where the d-band centers begin to stabilize but show increased standard deviation. This point marks where the reaction is greatly inhibited by site-blocking effects via the formation of stable oxide-like species. At this point, the electronic effect leaves the scalability regime, and the effects on ∆ ḠO become less clear, as shown in Figure .