Highly stable one-dimensional Pt nanowires with modulated structural disorder towards the oxygen reduction reaction

Developing stable nanocatalysts with high activity for the oxygen reduction reaction (ORR) remains a great challenge in the field of clean energy. Herein, a highly stable and active nanocatalyst is designed by an efficient dealloying of Pt-Ni nanowires in an oxygen saturated solution. It is found that Ni atoms can be removed almost completely in an oxygen atmosphere (D-O₂-Pt NWs) instead of an Ar environment, confirmed by a combination of X-ray diffraction, X-ray photoelectron spectroscopy and surface-sensitive electrochemical characterization methods. As a result, the D-O₂-Pt NWs exhibit an enhanced mass (0.86 A mg_Pt^-1) and specific (0.99 mA cm_Pt^-2) activity compared to commercial Pt/C for the ORR by a factor of 5 and 5.8, respectively. These catalysts also show an increased power density (30%) and polarization current density (50%) at 0.5 V of real H₂/air PEMFCs with respect to commercial Pt/C. In addition, in contrast to the 60% activity loss of Pt/C after accelerated degradation tests (ADTs) for 50 000 potential cycles, the D-O₂-Pt NWs show an extremely stable behavior with only 17% performance loss. The high activity and extreme stability of D-O₂-Pt NWs are rationalized by the structural effects, confirmed by the combination of quantitative analysis using X-ray absorption fine structure (XAFS), high resolution-transmission electron microscopy (HR-TEM) and average adsorbed CO oxidation potential (μCO1). This work illustrates a new class of Pt based nanocatalysts with high activity and stability for the ORR.