Structural effects of the oxygen reduction reaction on the high index planes of Pt3Fe

Abstract

In this study, the oxygen reduction reaction (ORR) on n(111)–(111), n(111)–(100), and n(100)–(111) series of Pt3Fe in 0.1 M HClO4 was studied. The specific activity of the ORR (jk) at 0.90 V(RHE) reached an upper limit at 4 ≤ n on the n(111)–(111) series. This tendency differed from those observed for the same series of Pt, Pt3Co, and Pt3Ni. In the n(111)–(100) series, Pt, Pt3Co, and Pt3Ni plots, as well as the values of jk plotted against step atom density (dS), exhibited a volcano-shape: Pt3Fe(544) n = 9 provided the maximum activity. In the n(100)–(111) series, the values of jk were constant regardless of dS, as occurred for the same series of Pt, Pt3Co, and Pt3Ni. The ORR activity of Pt3Fe(544) = 9(111)–(100) was 5.8 times higher than that of Pt(331) = 3(111)–(111), which has the highest activity among single-crystal Pt electrodes.