Three‐Dimensional Assembly of PtNi Alloy Nanosticks with Enhanced Electrocatalytic Activity and Ultrahigh Stability for the Oxygen Reduction Reaction

A three‐dimensional (3D) assembly of PtNi alloy nanosticks (NSA) is synthesized through an effective organic solvothermal approach to enhance the specific activity and long‐term durability for the oxygen reduction reaction (ORR). The 3D PtNi NSA is composed of interconnected nanosticks with an average diameter of approximately 5 nm, which are confirmed to be of high crystallinity with ordered atomic arrangement of ORR‐favorable PtNi (111). After an electrochemical dealloying process, the surface of the nanosticks becomes rough with a large quantity of step‐like nanostructures, which are verified to effectively improve the ORR activity. The electrochemical results of half‐cell tests demonstrate that the 3D PtNi alloy NSA exhibits a 4.5 times higher mass activity than the Pt/C (20 wt%, JM) catalyst (0.58 A/mg) and a 5.1 times higher specific activity (742 μA/cm2). Most importantly, after the accelerated deterioration test, the 3D PtNi alloy NSA catalyst shows almost no activity decrease, both in half‐ and single‐cell tests. The 3D PtNi alloy NSA prepared here is indeed a promising electrocatalyst for practical electrocatalytic applications.