The role of TiO2 layers deposited on YSZ on the electrochemical promotion of C2H4 oxidation on Pt

Abstract

The electrochemical promotion of Pt/YSZ and Pt/TiO 2 /YSZ catalyst-electrodes has been investigated for the model reaction of C 2 H 4 oxidation in an atmospheric pressure single chamber reactor, under oxygen excess between 280 and 375°C. It has been found that the presence of a dispersed TiO 2 thin layer between the catalyst electrode and the solid electrolyte (YSZ), results in a significant increase of the magnitude of the electrochemical promotion of catalysis (EPOC) effect. The rate enhancement ratio upon current application and the faradaic efficiency values, were found to be a factor of 2.5 and 4 respectively, higher than those in absence of TiO 2 . This significantly enhanced EPOC effect via the addition of TiO 2 suggests that the presence of the porous TiO 2 layer enhances the transport of promoting O 2-species onto the Pt catalyst surface. This enhancement may be partly due to morphological factors, such as increased Pt dispersion and three-phase-boundary length in presence of the TiO 2 porous layer, but appears to be mainly caused by the mixed ionic-electronic conductivity of the TiO 2 layer which results to enhanced O 2-transport to the Pt surface via a self-driven electrochemical promotion O 2-transport mechanism.

Ionically Conducting Ceramics as Active Catalyst Supports

“…More recently, the effect of a TiO 2 interlayer was examined by Papaioannou et al 354 on the catalytic activity and EPOC behavior of C 2 H 4 oxidation on Pt by comparing a Pt/YSZ catalyst electrode and a Pt/TiO 2 /YSZ catalyst electrode under similar operating conditions in O 2 excess. It has been found that the presence of the dispersed TiO 2 interlayer results in a very significant increase in the magnitude of the electrochemical promotion effect upon anodic polarizations.…”

Theoretical insight into the origin of the electrochemical promotion of ethylene oxidation on ruthenium oxide

“…Herein, we rely on the model reaction of ethylene oxidation 31,32,[34][35][36][47][48][49][50] to demonstrate, using ab-initio computations, the effect of electrochemical potential on the surface reactivity. We will elucidate on the one hand the impact of the electrochemical potential on the surface state compared to thermal catalysis and on the other hand, the impact of the potential generated electric field on the reactivity of ethylene and oxygen activation.…”

Investigation of Heterogeneous Catalysts by an Electrochemical Method: Ceria and Titania-Supported Iridium Nanoparticles for Ethylene Oxidation

“…Typically, EPOC studies have been performed over continuous-film catalysts 4,5 ; however, recent studies have been implementing the use of nanocatalysts by supporting them on MIEC material 6 (i.e., CeO 2 7 and TiO 2 8 ). The use of nanoparticles allows for the reduction in the amount of noble metal required as a catalyst 9,10 .…”