Facile Preparation of Hollow Pt- and PtIr-Nanostructures with Spiky Surface for the Electro-Oxidation of Ammonia

Abstract

In this paper, we described the facile preparation of Pt- and PtIr-based hollow nanostructures (Pt–Am and PtIr–Am), which could be achieved through a co-reduction of precious metal complexes with ammine ligands and Ni ions that were reduced to form an in situ sacrificial template. For a comparative study, other types of Pt and Ir precursors with chloride ligands, i.e., Pt–Cl and PtIr–Cl, were also employed for the preparation of Pt and PtIr-based nanostructures. In constrast to Pt–Am and PtIr–Am, both Pt–Cl and PtIr–Cl showed typical aggregated small particles. The surface composition and element distribution were also affected by the type of metal precursors employed. Owing to a dilution effect of Ir or Ni on the surface of the Pt, Pt–Cl and PtIr–Cl showed a lower electrochemically active surface area and poor catalytic performance in the electro-oxidation of ammonia. Owing to a high EAS combined with the synergic effect of Ir, PtIr–Am delivered the highest oxidation current among the catalysts studied in this work. Hollow Pt and PtIr nanostructures with an urchin-type surface can be easily prepared through the co-reduction of the Pt, Ir, and Ni precursor followed by a leaching of the Ni component. The prepared hollow Pt and PtIr nanostructures showed a large electrochemically active surface area and Pt-rich surface, which resulted in a better catalytic performance than commercial Pt black and aggregated particles composed of Pt and PtIr in the electro-oxidation of ammonia.