A Modified Galvanic Cell Synthesis of Pd@Pt Core–Shell Nanowire Catalysts: Structural Insights and Enhanced ORR Performance

Abstract

One-dimensional nanostructures, specifically Pd@Pt core–shell nanowire catalysts, have garnered significant attention because of their potential to enhance the sluggish kinetics of the oxygen reduction reaction (ORR). However, fully realizing their potential depends on achieving consistent and uniform synthesis. In this study, we introduce an improved galvanic synthesis method for Pd@Pt core–shell nanowire catalysts (Pd-NW@Pt/C) that eliminates the need for electrochemical control or reducing agents, making it more accessible and efficient than the traditional Cu underpotential deposition (Cu-UPD) method. Our approach ensures a uniform Pt shell, resulting in superior ORR activity, with a mass activity of 1.06 A mg_Pt^–1 and a specific activity of 0.80 mA cm_Pt^–2. Detailed operando X-ray absorption spectroscopy (XAS) measurements, including high-energy resolution fluorescence detection (HERFD-XAS), revealed that Pd-NW@Pt/C catalysts with a fully covered Pt shell exhibit shorter Pt–Pt bond lengths and weaker oxygen binding energies compared to partially covered Pt shell nanowire catalysts (Pd-NW@Pt/C-ref) and nanoparticle catalysts (Pd-NP@Pt/C), leading to significantly enhanced ORR activity. This study demonstrates the effectiveness of a modified galvanic cell method for producing high-performance Pd@Pt core–shell nanowire catalysts, offering insights into their structural and electronic properties.