Mechanism of glycerol oxidation reaction on silver-modified palladium electrode in alkaline medium

The silver-modified Pd (Ag/Pd) electrode was prepared by underpotential deposition of Cu adatoms, followed by galvanic displacement with Ag atoms to investigate the effect of silver modification on the catalysis and mechanism for glycerol oxidation reaction (GOR) of Pd. Cyclic voltammograms in alkaline glycerol solution exhibited that the Ag/Pd electrode had ca. 100 mV less positive onset potential of the GOR current density and higher peak current density than the Pd electrode, indicating that the GOR activity of Pd was enhanced by surface modification with Ag atoms. In potentiostatic electrolysis at −0.1 V vs. Hg/HgO, GOR mainly began with the oxidation of a terminal OH group for both electrodes, and glycerate and glycolate were major products. The glycolate production was more active for the Ag/Pd electrode. The in situ infrared reflectance-absorption spectra (IRAS) exhibited that GOR products with one or two carbons were detected at lower potentials for the Ag/Pd electrode, indicating that the CC bond cleavage was facilitated by the Ag modification.