An FTIR Study of the Electrooxidation of C-2 and C-3 Alcohols on Carbon-Supported PdxRhy in Alkaline Medium

We have investigated the promoting effect of Rh addition to Pd-based materials in the electrooxidation of ethanol and glycerol. Physicochemical characterizations (XRD, EDX, TEM, and XPS) of the PdxRhy/C materials, prepared by bromide anion exchange (BAE), showed that the experimental bimetallic compositions were close to the targeted ones. PdxRhy/C particle sizes ranged from 2.2 to 3.8 nm. The ethanol oxidation reaction (EOR) on the PdxRhy/C catalysts yielded four times larger carbonate (CO32-) amount. As for the glycerol oxidation reaction (GOR), the onset potential on the Pd50Rh50/C catalyst occurred at lower potentials. Chromatographic analysis combined with in situ Fourier transform infrared (FTIR) spectroscopy showed that GOR on the Pd50Rh50/C catalyst selectively and quantitatively produced glycerate and tartronate. The outstanding ability of the Pd50Rh50/C catalyst toward EOR and GOR was correlated to the electronic effect expressed by a negative potential shift (200 mV) and the 47 % alloying degree in the Pd50Rh50/C structure.