Oxidation of formic acid on bulk and nanosized Pt-Co alloys

Abstract

Bulk Pt3Co and nanosized Pt3Co and PtCo alloys supported on XC-72 high area carbon were investigated as the electrocatalysts for the oxidation of formic acid. Cyclic voltammetry in 0.1 M HClO4 and stripping voltammetry of COads in the same electrolyte show a small difference in the potentials of Pt-oxide formation and reduction and COads oxidation. Based on these results, we concluded that electronic modification of Pt by Co atoms, which was theoretically predicted and experimentally proved on solid/gas interface, is exhibited in the electrochemical environment. Promotion of HCOOH oxidation rate on bimetallic Pt-Co surfaces with respect to pure Pt was found to be up to factor of eight in the case of PtCo/XC-72 catalyst. This moderate increase of the reaction rate is ascribed mostly to the ensemble effect, because partial leaching of Co increased Pt:Co ratio at the bimetallic surfaces, diminishing the efficiency of the ensemble effect.