One-Pot Water-Based Synthesis of Pt–Pd Alloy Nanoflowers and Their Superior Electrocatalytic Activity for the Oxygen Reduction Reaction and Remarkable Methanol-Tolerant Ability in Acid Media

Well-defined and strikingly monomorphic Pt–Pd alloy nanoflowers (Pt–Pd ANFs) with dominant {111} facets were successfully synthesized through a facile cochemical reduction method in a poly(allylamine hydrochloride) (PAH) based aqueous solution. The detailed morphology, composition, and structure of the Pt–Pd ANFs were investigated by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), energy dispersive spectrum (EDS), nitrogen adsorption–desorption isotherms (SADI), EDS mapping, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), demonstrating the Pt–Pd ANFs were highly porous and a self-supported structure. The formation mechanism of the Pt–Pd ANFs were investigated by TEM and Fourier transform infrared (FT-IR), indicating that the existence of PAH and rapid growth of crystal nuclei were essential for the formation of the Pt–Pd ANFs. The electrocatalytic activity and stability of the Pt–Pd ANFs for the oxygen reduction reaction (ORR) were investigated by rotating disk electrode voltammetry in 0.1 M HClO 4 solution. The electrochemical tests indicated the {111}-enclosed Pt–Pd ANFs exhibited superior ORR activity along with satisfactory stability and methanol-tolerant ability under acidic conditions, which made them promising electrocatalysts for the future.