Electrocatalysis of the Ethylene glycol oxidation reaction and in situ Fourier-transform infared study on PtMo/C electrocatalysts in alkaline and acid media

International audiencePtMo/C (Pt:Mo atomic ratios of 1:1, 2:1 and 3:1) and Pt/C electrocatalysts synthesized by the formic acid method are investigated for the ethylene glycol oxidation reaction (EGOR) in alkaline and acid media. From XRD measurements, the crystallite sizes are between 2.5 and 4.3 nm. Electrochemical characterization of the EGOR on the electrocatalysts shows that the PtMo/C series exhibit higher electrocatalytic activity. When comparing the two electrolytes, the mass current densities obtained in alkaline media are significantly higher than in the acid counterpart. Among the bimetallic anodes, Pt1Mo1/C delivered a high performance in both media. In situ FTIR spectroscopy analysis has been performed to study the pathway of the EGOR. In alkaline media, the PtMo/C electrocatalysts have a higher selectivity for the C2 pathway resulting in the formation of species such as glycolate, glyoxal and glyoxylate. On the other hand, in acid electrolyte, the PtMo/C anodes show a preferential C1 pathway at high potentials and the main intermediate is identified as glycolic acid. The results indicate that the higher catalytic activity of PtMo/C electrocatalysts towards the EGOR may be attributed to the bifunctional mechanism and also to an electronic effect because of the incorporation of Mo atoms into the catalysts structure