Synthesis of CO-tolerant Ni-Pt Rhombic Dodecahedra Bimetallic Electrocatalytic Nanoparticles

Abstract

Developing scalable synthetic routes for fabricating low-cost CO-tolerant and highly active electrocatalysts have significant relevance for fuel cell applications. Here, we report a novel and rapid single step synthesis of Ni enriched bimetallic core-shell (Ni−Pt) rhombic dodecahedra nanoparticles (NPs) via the thermal decomposition of precursor in the presence of oleylamine. Electrochemical dealloying in acidic medium (0.1 M HClO4) subjecting NPs to different potential cycles is employed to vary the chemical composition and morphologies of parent bimetallic core-shell NPs. As a result, rhombic dodecahedra NPs transform to different morphologies such as concave, nanocage (open structure), and squeezed nanocage. Our results reveal that concave rhombic dodecahedra shaped electrocatalysts show high resistance to CO poisoning compare to core-shell, nanocage, and squeezed nanocage morphologies as well as commercial Pt/C electrocatalysts. The improved CO tolerant of concave rhombic dodecahedra bimetallic NPs results from the presence of optimal content of Ni along with Pt content at the surface. We also demonstrate that CO tolerance of concave bimetallic NPs can be changed by electrochemical parameters such as the scan rate and CO adsorption potential. Overall, the present study presents a conceptual strategy for achieving improved CO tolerance by change in the composition and morphologies of bimetallic core-shell NPs.