Enhanced Oxygen Reduction Activity of Size-selected Platinum Subnanocluster Catalysts: Ptn (n = 3–9)Akira Ohnuma & Koki Takahashi & Hironori Tsunoyama & Tomoya Inoue & Pei Zhao & Archana Velloth & Masahiro Ehara & Nobuyuki Ichikuni & Masao Tabuchi & Atsushi NakajimaPDF