High-Index Faceted Pt Nanoflower Catalysts with Ultra-Low Overpotential and Superb Cyclic Retention for Rechargeable Li-O2 Batteries

Surface structure of noble metal catalysts has been regarded as an important factor to determine the catalytic activities in various applications. For oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in the cathode of Li-O₂ batteries, however, the structure sensitive catalytic activities are still poorly understood. We here report the preparation of anisotropic structure of Pt nanoflowers and its catalytic properties in rechargeable Li-O₂ batteries. As for the ORR properties, the Pt nanoflowers exhibit high capacity (12,985 mAh/g_carbon), excellent rate capability and a good cycle performance up to 70 cycles (with a curtaining capacity of 1,000 mAh/g_carbon). In addition, the Pt nanoflowers demonstrate a low OER potential of 3.1 V, providing the highest round trip efficiency of ~87% at a current density of 200 mA/g_carbon. These greatly enhanced ORR and OER performances of the Pt nanoflower-incorporated cathode compared to that of commercial Pt/C catalyst can be attributed to the exposed high-index {411} facets on their anisotropic structure.