Nodal PtNi Nanowires with Pt Skin and Controllable Near-Surface Composition for Enhanced Oxygen Reduction Electrocatalysis in Fuel Cells

Abstract The oxygen reduction reaction (ORR) takes place on the surface of catalyst, and the precise control of surface component at atomic scale has been an important factor to effectively improve the performance of catalysts. Herein, a highly active and stable catalyst is designed by constructing Pt skin and controllable near-surface atomic distribution of PtNi alloy nanowires (NWs). It is found that the d-band center of Pt-skin down-shifts with Pt ratio in the surface/near-surface of PtNi alloy decreasing, and correspondingly the adsorption energy of atomic oxygen (ΔEO) on PtNi alloys weakens, confirmed by experimental results and theoretical calculations. The optimum PtNi/C-NH3 NWs exhibit the enhanced mass activity (1.02 A mgPt−1) and specific activity (3.86 mA cm−2) for ORR, which are 5.7-fold and 11.4-fold higher than those of commercial Pt/C, respectively. Moreover, the H2/air fuel cell of PtNi/C-NH3 NWs exhibits a current density of 308 mA cm-2 at 0.8 V, which is superior to that of the 2020 target of the U.S. Department of Energy (DOE). Our study provides a new perspective and approach in promoting the electrocatalysis on alloy nanomaterials for ORR.