Electrochemical and in situ FTIR study of the ethanol oxidation reaction on PtMo/C nanomaterials in alkaline media

- PtMo/C catalysts have been synthesized by the formic acid method.
- PtMo/C alloys show higher catalytic activity for the EOR than Pt/C in 0.5 M KOH.
- Pt3Mo1/C has shown the highest catalytic activity.
- The alloys oxidize CO at more negative potentials relative to Pt/C.
- The alloys promote the EOR in the alkaline media mostly through a 4e− route.

In this work, the catalytic activity of PtMo/C catalysts for the Ethanol Oxidation Reaction (EOR) in 0.5 mol L−1 KOH electrolyte was evaluated by electrochemical and in situ Fourier Transform Infrared Spectroscopy (FTIR) measurements. The alloys having 1:1, 2:1 and 3:1 Pt:Mo atomic ratios were synthesized by the formic acid method. X-ray diffraction analyses (XRD) showed the crystalline features of the catalysts, with crystallite sizes between 2.5 and 3.2 nm. Cyclic voltammograms (CVs) indicated the alloys mass catalytic activity in the order: Pt1Mo1/C > Pt3Mo1/C > Pt2Mo1/C, in all cases higher that Pt/C. For specific catalytic activity, the performance was in the order Pt3Mo1/C > Pt1Mo1/C-Pt/C > Pt2Mo1/C. Two CO-like species namely COadsI and COadsII were evidenced from CO-stripping measurements on the alloys. In situ FTIR characterization showed that the alloys promote the oxidation of ethanol in the alkaline media mainly through a 4 electrons transfer route. CO2 was produced probably from the break-up of the CC bond and the oxidation of C1 species. Pt3Mo1/C produced moreCOadsI, followed by Pt1Mo1/C, oxidizing carbon monoxide more easily. These two alloys also had a higher CO2/CH3CHO ratio, due to a high efficiency for oxidizing C2 and C1 species to CO2. Such capabilities promoted a higher catalytic activity of Pt1Mo1/C and Pt3Mo1/C for the EOR, related to the other catalysts.

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