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 mu A/cm(2)). 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.