Fig. 1. (A) Cyclic voltammograms of Pt(111), Pt(221), Pt(331) and Pt(775) in 0.1 M HClO4, dU/dt = 50 mV s–1, and (B) the integrated anodic parts of the voltammograms in which it is shown that the *OH adsorption energies for the stepped surfaces are lower with respect to Pt(111). (C) ORR-activity enhancement of Pt(221), Pt(331) and Pt(775) with respect to Pt(111) at 0.9V RHE; the inset shows a comparison of Pt(221) and Pt(331) with the most active Pt alloys reported in the literature. (D) Activity “volcano” plot for pristine Pt(111) (circle), stepped Pt[n(111) × (111)] (triangles) and Pt[n(111) × (100)] (squares) surfaces from ref. 39 and references therein are provided; data from this work (Pt(331) in blue, Pt(221) in green and Pt(775) in red) are also provided. The atomic length of the 111-terraces (n) is provided in each case. The data in (C) and (D) and their sources appear in Table S1.† .
