Issue 33, 2010

Origin of non-Faradayicity in electrochemical promotion of catalyticethyleneoxidation

Abstract

The electrochemical promotion of catalytic C2H4 oxidation has been investigated under low pressure conditions (p ≈ 10−6–10−4 mbar) with a Pt film on yttrium stabilized zirconia (YSZ) as catalyst. All measurements were conducted with a UHV system with a differentially pumped quadruple mass spectrometer (QMS) for rate measurements and a photoelectron emission microscope (PEEM) for spatially resolved measurements. A pronounced rate hysteresis upon cyclic variation of p(C2H4) was observed under open circuit conditions which is attributed to carbonaceous CHx adlayer inhibiting O2 adsorption and hence poisoning the reaction. Application of a positive potential causes a partial removal of the inhibiting CHx adlayer by spillover oxygen thus triggering a transition from thus poisoned state of the surface to an active state with reduced carbon coverage. The ignition effect and therefore also the electrochemical promotion effect are linked to the presence of a carbon adlayer on the surface. The non-Faradayicity which is observed in this reaction system is explained as an ignition effect.

Graphical abstract: Origin of non-Faradayicity in electrochemical promotion of catalytic ethylene oxidation

Supplementary files

Article information

Article type
Paper
Submitted
10 Feb 2010
Accepted
06 May 2010
First published
01 Jul 2010

Phys. Chem. Chem. Phys., 2010,12, 9811-9815

Origin of non-Faradayicity in electrochemical promotion of catalytic ethylene oxidation

A. Toghan, L. M. Rösken and R. Imbihl, Phys. Chem. Chem. Phys., 2010, 12, 9811 DOI: 10.1039/C002912B

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