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Nicole, Jacques; Comninellis, Ch.

doi:10.1023/a:1003295112211

Cited by 41 publications

(11 citation statements)

References 6 publications

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“…The slope of this relationship was 0.5. This persistent electrochemical promotion (p-EPOC) is due to the stored oxygen ions in PdO x that act as sacrificial promoters when the electrical circuit is open [27]. To confirm PdOx formation and oxygen storage effect on p-EPOC, the catalyst was polarized for a different duration 3, 6 and 10 h. As seen in Figure 6, the closed-circuit catalytic rate was continuously increasing with time under constant current (40 μA for 3 h) and potential (0.5 V for 6 and 10 h) application.…”

Section: Resultsmentioning

confidence: 99%

“…The slope of this relationship was 0.5. This persistent electrochemical promotion (p-EPOC) is due to the stored oxygen ions in PdOx that act as sacrificial promoters when the electrical circuit is open [27]. This indicates that during the positive polarization two parallel processes take place: i. Migration of O δ− promoters to the gas exposed catalyst surface and ii PdOx formation at the three-phase boundary (tpb) according to the electrochemical reaction:…”

Section: Resultsmentioning

confidence: 99%

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Electrochemical Promotion of Nanostructured Palladium Catalyst for Complete Methane Oxidation

2019

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Electrochemical promotion of catalysis (EPOC) was investigated for methane complete oxidation over palladium nano-structured catalysts deposited on yttria-stabilized zirconia (YSZ) solid electrolyte. The catalytic rate was evaluated at different temperatures (400, 425 and 450 °C), reactant ratios and polarization values. The electrophobic behavior of the catalyst, i.e., reaction rate increase upon anodic polarization was observed for all temperatures and gas compositions with an apparent Faradaic efficiency as high as 3000 (a current application as low as 1 μA) and maximum rate enhancement ratio up to 2.7. Temperature increase resulted in higher enhancement ratios under closed-circuit conditions. Electrochemical promotion experiments showed persistent behavior, where the catalyst remained in the promoted state upon current or potential interruption for a long period of time. An increase in the polarization time resulted in a longer-lasting persistent promotion (p-EPOC) and required more time for the reaction rate to reach its initial open-circuit value. This was attributed to continuous promotion by the stored oxygen in palladium oxide, which was formed during the anodic polarization in agreement with p-EPOC mechanism reported earlier.

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Section: Resultsmentioning

confidence: 99%

“…The slope of this relationship was 0.5. This persistent electrochemical promotion (p-EPOC) is due to the stored oxygen ions in PdOx that act as sacrificial promoters when the electrical circuit is open [27]. This indicates that during the positive polarization two parallel processes take place: i. Migration of O δ− promoters to the gas exposed catalyst surface and ii PdOx formation at the three-phase boundary (tpb) according to the electrochemical reaction:…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Promotion of Nanostructured Palladium Catalyst for Complete Methane Oxidation

2019

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“…This phenomenon has been studied extensively over the last 20 years by Vayenas and co-workers [1] and a number of other groups [2][3][4][5][6][7][8][9][10][11]. Based on their results, it is generally accepted that EPOC grounds on the electrochemical generation (pumping/spillover) of promoting surface species at electroactive surface sites (three-phase boundary) [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

In situ imaging of electrode processes on solid electrolytes by photoelectron microscopy and microspectroscopy – the role of the three-phase boundary

et al. 2007

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The electrochemical polarisation of metal catalyst films on solid electrolyte substrates can basically lead to three different effects: (a) the generation of mobile surface species (spillover) which spread over the catalyst surface and modify the catalytic activity, (b) potential-controlled segregation of impurities in the catalyst and (c) potential-dependent surface energy (electrocapillarity). The generation of spillover species occurs at the three-phase boundary between metal, solid electrolyte and gas phase and is highly localized. The spreading occurs via diffusion and leads to time-dependent and inhomogeneous surface concentrations. The kinetics of the spillover process can only be observed with in situ surface-analytical techniques in combination with electrochemical methods which offer sufficient resolution in space and time. Model experiments with UV and X-ray photoelectron emission microscopy (PEEM and SPEM) are summarized and discussed with respect to their relevance for the better understanding of electrochemical promotion in catalysis.

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“…The example is the combustion of ethylene with oxygen at 375 °C over RuO 2 catalyst interfaced with yttria-stabilized zirconia (YSZ) solid electrolyte, which is an O 2conductor at this temperature. This irreversibility, first reported from our laboratory [4] and called permanent promotion, is attributed to current-assisted chemical modification of the catalyst surface. As seen in Fig.…”

Section: Introductionmentioning

confidence: 69%

Electrochemical Promotion of Catalysis

Fóti¹,

Bolzonella²,

Eaves³

et al. 2002

Chimia

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Recent progress made in our laboratory in the field of electrochemical promotion of heterogeneous catalytic gas reactions is presented. The phenomenon consists of non-Faradaic modification of the catalytic reaction rate as the result of electrochemical polarization of the interface between the catalyst and the solid electrolyte support. Two main aspects are addressed, the description of the phenomenon and the development of bipolar cell configurations suitable for practical applications. It is shown that the necessary condition to achieve electrochemical promotion is the formation of a double layer at the catalyst/gas interface by mechanism of ion backspillover from the solid electrolyte support. Electrochemical promotion is only feasible in an adequate temperature range, limited by the mobility and the lifetime of the promoting ion, and it is favored by high porosity and low film thickness of the catalyst. On the application side, two new cell designs have been developed, a ring-shaped and a multiple-channel configuration, both operated in bipolar polarization mode. The ring-shaped cell is shown to be almost free of current bypass. Feasibility of electrochemical promotion is successfully demonstrated with both configurations. Realization of efficient bipolar cell configurations for electrochemical promotion is very promising in view of future applications in dispersed catalytic systems.

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Cited by 41 publications

References 6 publications

Electrochemical Promotion of Nanostructured Palladium Catalyst for Complete Methane Oxidation

Electrochemical Promotion of Nanostructured Palladium Catalyst for Complete Methane Oxidation

In situ imaging of electrode processes on solid electrolytes by photoelectron microscopy and microspectroscopy – the role of the three-phase boundary

Electrochemical Promotion of Catalysis

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