Evidences of CO spillover at a Pt/Pd bimetallic interface during the formic acid oxidation reaction

Abstract

The surface diffusion (spillover) through the intermetallic Pt/Pd junction of adsorbed CO (CO ad ) during the formic acid electrooxidation reaction (FAO) was analyzed on a bimetallic Pt/Pd electrode by chronoamperometry followed by stripping voltammetry. An ordered matrix of equally spaced square palladium islands on a platinum substrate was prepared by the Mask-Assisted E-Beam (MAEB) method in order to have a large interface length/area relationship. Potential steps were applied in 0.5 M HCOOH + 0.5 M H 2 SO 4 solution (0.2 V ≤ E s vs. RHE ≤ 0.5 V) during times t ≤ 500 s in a flow cell. After changing solution to 0.5 M H 2 SO 4 , the amount of CO ad on Pt and Pd were measured by voltammetric stripping. Under these experimental conditions, the pure metals show the presence of CO ad on Pt but not on Pd. The results obtained on the bimetallic electrode demonstrate the CO ad spillover from Pt towards Pd through the heterometallic junction.