Methanol electro-oxidation on carbon-supported Pt and Au@Pt nanoparticles with quasi-spherical and polyhedral forms in acid aqueous medium

In this work, monometallic Pt and bimetallic Au@Pt (core-shell) nanoparticles with different shapes are synthesized by adding Ag⁺ as a shape-modifying agent, polyhedral forms are obtained: Pt_0.02 (cubic form), bimetallic Au@Pt_0.1 (angulated polyhedral form), and Au@Pt_0.2 (polyhedral and cube forms). The nanoparticle’s shape depends on the amount of Ag⁺ used during synthesis (subindex indicates the Ag/Pt ratio in all cases). Without Ag⁺, quasi-spherical Pt and Au@Pt nanoparticles are obtained. The polyhedral and angulated shapes of Pt_0.02/C and Au@Pt_0.1/C are more active for methanol oxidation (0.5 M methanol + 0.5 M H₂SO₄), in comparison with the quasi-spherical Pt/C, Au@Pt/C and polyhedral/cubic Au@Pt_0.2/C nanoparticles. From these results, it is found that the electrochemical response of the tested catalysts varies not only due to the nature of the electrocatalyst (Pt/C or Au@Pt/C) but on the nanoparticle’s shape which is also associated with the dominant crystal plane on their surfaces.