Influence of the thickness of sputter-deposited platinum films on the electrochemical promotion of propane combustion

Billard, Alain; Vernoux, P.

doi:10.1007/bf02430411

Cited by 8 publications

(11 citation statements)

References 12 publications

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“…When the current was stopped, the conversion returned to its initial value. The rapid response of activity with applied overpotential is characteristic of sputtered catalytic thin films as already shown in a previous paper [25]. These results confirm the inhibiting effect of ionic species on propene conversion.…”

Section: Light-off Curvessupporting

confidence: 87%

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Towards a new definition of EPOC parameters for anionic electrochemical catalysts: case of propene combustion

et al. 2008

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The electrochemical promotion of catalysis (EPOC) of propene combustion was investigated using Pt sputtered thin film on an O 2-conductor, 8 mol% Y 2 O 3 -stabilized-ZrO 2 (YSZ). In order to separate the influence of the thermal migration of the O 2-oxide ions from the electrolyte to the catalyst surface and the impact of an electrical polarization on the catalytic activity, several lightoff experiments (cool down and heat up procedures) were successively performed under different polarizations, i.e. OCV, +2 and -2 V. These experiments have clearly shown that the presence of O 2-(thermally or electrochemically induced) inhibits the catalytic activity of the platinum for the propene deep oxidation. These results demonstrate the importance to define a normalized rate enhancement ratio, q n , from a reference value of the catalytic rate corresponding to a Pt surface state free of O 2-ions.

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Section: Light-off Curvessupporting

confidence: 87%

“…This technique creates reproducible and dense films for EPOC applications [24]. Propene oxidation was investigated in lean-burn conditions (large excess of oxygen) and at low temperatures (260°C) in order to simulate the operating conditions of a real Diesel exhaust gas [25,26].…”

Section: Introductionmentioning

confidence: 99%

Towards a new definition of EPOC parameters for anionic electrochemical catalysts: case of propene combustion

et al. 2008

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“…In our study, thin films of Pt were sputter-deposited by magnetron sputtering of a Pt target on two different solid electrolytes: 8 mol% Y 2 O 3 -stabilized ZrO 2 (YSZ), an O 2) ionic conductor and Na 3 Zr 2 Si 2 PO 12 (NASICON), a Na + one. We have shown in previous studies [11,12] that magnetron sputtering is a suitable technique for synthesis of catalyst coatings. The development of electrochemical catalysts composed of a very thin layer of sputtered catalyst onto a solid electrolyte can considerably reduced the Pt loading.…”

Section: Introductionmentioning

confidence: 98%

Electrochemical catalysts for hydrocarbon combustion

Billard¹,

Vernoux

2007

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International audienceTwo series of electrochemical catalysts were prepared from sputtered Pt thin films onto two kinds of electrolyte membranes, 8 mol% Y2O3-stabilized ZrO2 (YSZ), an O2− conducting oxide and Na3Zr2Si2PO12 (NASICON), a Na+ one; respectively. The thickness of the Pt films varied from 8 to 120 nm. Therefore, the Pt loading was extremely low. The catalytic activity of Pt/YSZ and Pt/NASICON systems has been investigated between 200 and 500 °C for propane and propene, respectively. In spite of the low Pt loading, the Pt/YSZ electrochemical catalysts exhibited high activity for propane combustion. Furthermore, the catalytic activity can be in-situ controlled by applying electrical polarisation with high Faradaic efficiency (103). The catalytic rate of propene deep oxidation on Pt/NASICON electrochemical catalyst was found to be limited by the number of active sites, which is low on very thin Pt films. Moreover, initial anodic polarisation indicate that Na+ ions are already present on the top surface of Pt, probably proceeding from the preliminary stabilisation treatment of Pt in the reactive mixture. Nevertheless, polarisation allows the tuning of the catalytic activity of the electrochemical catalysts for propene oxidation. Finally, for both kinds of electrochemical catalysts, our results have evidenced that the measurement of the open-circuit voltage during catalytic process can be an indicator of the hydrocarbon conversion

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“…The results were in good qualitative agreement with the model predictions [84] describing the diffusion and reaction of the backspillover O 2-species, which causes the EP. In previous study [85] the influence of the thickness of sputter-deposited Platinum films on the Electrochemical Promotion of propane combustion was studied by Billard and Vernoux. They found that the catalytic activity does not follow a linear evolution with the film thickness while NEMCA measurements performed at 337°C and 400°C indicate that a minimal thickness of about 15 nm is required in order to allow the bias of the whole Pt surface.…”

Section: Electrochemical Promotion Of Reactions With Environmental Anmentioning

confidence: 99%

Recent developments and trends in the electrochemical promotion of catalysis (EPOC)

Katsaounis

2009

J Appl Electrochem

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Electrochemical Promotion of Catalysis (EPOC or NEMCA effect) is one of the most exciting discoveries in Electrochemistry with great impact on many catalytic and electrocatalytic processes. According to the words of John O'M. Bockris, EPOC is a triumph, and the latest in a series of advances in electrochemistry which have come about in the last 30 years. It has been shown with more than 80 different catalytic systems that the catalytic activity and selectivity of conductive catalysts deposited on solid electrolytes can be altered in a very pronounced, reversible and, to some extent, predictable manner by applying electrical currents or potentials (typically up to ±2 V) between the catalyst and a second electronic conductor (counter electrode) also deposited on the solid electrolyte. The induced steady-state change in catalytic rate can be up to 135 9 10 3 % higher than the normal (open-circuit) catalytic rate and up to 3 9 10 5 higher than the steady-state rate of ion supply. EPOC studies in the last 7 years mainly focus on the following four areas: Catalytic reactions with environmental impact (such as reduction of NO x and oxidation of light hydrocarbons), mechanistic studies on the origin of EPOC (using mainly oxygen ion conductors), scale-up pf EPOC reactors for potential commercialization via development of novel compact monolithic reactors and application of EPOC in high or low temperature fuel cells via introduction of the concept of triode fuel cell. The most recent EPOC studies in these areas are discussed in the present review and some of the future trends and aims of EPOC research are presented.

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Influence of the thickness of sputter-deposited platinum films on the electrochemical promotion of propane combustion

Cited by 8 publications

References 12 publications

Towards a new definition of EPOC parameters for anionic electrochemical catalysts: case of propene combustion

Towards a new definition of EPOC parameters for anionic electrochemical catalysts: case of propene combustion

Electrochemical catalysts for hydrocarbon combustion

Recent developments and trends in the electrochemical promotion of catalysis (EPOC)

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