Impact of water adsorbates on the acetaldehyde oxidation reaction on Pt- and Rh-based multimetallic electrocatalysts

By Delpeuch, Antoine Bach; Cremers, Carsten; Chatenet, Marian
Published in Electrochimica Acta NULL 2016

Abstract

Abstract The influence of water adsorbates on the acetaldehyde oxidation reaction (AOR) was studied on 20 wt.% Pt/C, Rh/C, Pt-Rh/C and Pt-Rh-SnO2/C electrocatalysts by means of differential electrochemical mass spectrometry (DEMS) in an electrochemical flow cell. A polyol method was employed to synthesize the home-made electrocatalysts, the physical proprieties of which were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The investigation by cyclic voltammetry of the {AOR} was performed after potentiostatic formation of hydrogen- (Had) and oxygen-like (OHad, Oad) adsorbates on the electrocatalysts surface at Ead = 0.05 and 1 V vs. {RHE} respectively. For comparison, another pre-treatment was achieved at Ead = 0.3 V vs. RHE, in the double layer region, where neither H+ nor OH? adsorption prevails. Comparing the {CVs} demonstrates that Had formation slows down the {AOR} initiation on Pt/C. The study on Rh/C reveals that water adsorbates are displaced by acetaldehyde species during their adsorption, owing to their stronger polarity. Acetaldehyde adsorption occurs quantitatively at potential as low as E = 0.05 V vs. {RHE} on Pt-based electrocatalysts. The reaction pathway leading to the formation of {CO2} is promoted during the {AOR} on Rh-based electrocatalysts (Rh/C, Pt-Rh/C and Pt-Rh-SnO2/C). The lowest {AOR} onset potential was recorded on Pt-Rh/C. The present results on the {AOR} are discussed in the light of a previous similar study on the EOR.

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