Synthesis of Branched Platinum Nanoparticles and Their Catalytic Activities for the Oxygen Reduction Reaction (Supporting Information)

<div>Here we report the synthesis of branched platinum nanoparticles (Pt NPs) and the evaluation of their performance as a catalyst for the oxygen reduction reaction (ORR). The morphology of the branched Pt NPs could be easily controlled from one dimensional (1D) to three dimensional (3D) by the concentration of L(+)-ascorbic acid (AA) used for the synthesis. The surface-specific activities of the product prepared at 8.0 mmol L⁻¹ AA was four times higher than that of a commercial standard catalyst. Our method could be extended to the development of higher efficient Pt NP catalysts for the ORR including photoelectrochemical systems.</div>