STM observation of the origin of electrochemical promotion on metal catalyst-electrodes interfaced with YSZ and β″-Al2O3

Archonta, D.; Frantzis, A.; Tsiplakides, D.; Vayenas, C.G.

doi:10.1016/j.ssi.2006.02.026

Cited by 11 publications

(8 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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. Very interesting results on the origin of EPOC were reported also using the technique of STM under atmospheric pressure and ambient conditions [73,74]. The surface of a Pt(111) single crystal well attached with YSZ (O 2-conductor) [73,74] and b 00 -Al 2 O 3 (Na ?…”

Section: Electrochemical Promotion Of Reactions With Environmental Anmentioning

confidence: 92%

“…Very interesting results on the origin of EPOC were reported also using the technique of STM under atmospheric pressure and ambient conditions [73,74]. The surface of a Pt(111) single crystal well attached with YSZ (O 2-conductor) [73,74] and b 00 -Al 2 O 3 (Na ? conductor) [74] was investigated both under open circuit, cathodic and anodic polarization.…”

Section: Electrochemical Promotion Of Reactions With Environmental Anmentioning

confidence: 92%

“…Besides the results which have been already reported in the literature till 2001 and reviewed by Professor Vayenas et al in the ''Electrochemical Promotion of Catalysis'' book [28] several new studies have been reported till the end of 2008 using various techniques and methods such as TPD [29,30,32,47,72], TPR [29], CV [21], FTIR [21], SEM-EDX [21], AC impedance spectroscopy [39], STM [73,74], work function measurements and theoretical considerations [18,75,76], transients experiments and kinetic studies [34,35], quantum mechanical calculations and Monte Carlo simulations [77] and general thermodynamic considerations [18,78,79]. The use of oxygen temperature programmed desorption both under UHV and atmospheric pressure conditions has proven [29,30] the existence of two different and distinct oxygen adsorption states on the catalyst surface when oxygen ion conductors used like YSZ.…”

Section: Electrochemical Promotion Of Reactions With Environmental Anmentioning

confidence: 99%

“…The surface of a Pt(111) single crystal well attached with YSZ (O 2-conductor) [73,74] and b 00 -Al 2 O 3 (Na ? conductor) [74] was investigated both under open circuit, cathodic and anodic polarization. The results confirm the reversible electrochemically controlled backspillover of sodium and of O 2-between the solid electrolyte and the Pt(111) surface but also the mechanism of EP and MSI.…”

Section: Electrochemical Promotion Of Reactions With Environmental Anmentioning

confidence: 99%

See 3 more Smart Citations

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

Katsaounis

2009

J Appl Electrochem

View full text Add to dashboard Cite

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.

show abstract

Section: Electrochemical Promotion Of Reactions With Environmental Anmentioning

confidence: 92%

Section: Electrochemical Promotion Of Reactions With Environmental Anmentioning

confidence: 92%

Section: Electrochemical Promotion Of Reactions With Environmental Anmentioning

confidence: 99%

Section: Electrochemical Promotion Of Reactions With Environmental Anmentioning

confidence: 99%

See 2 more Smart Citations

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

Katsaounis

2009

J Appl Electrochem

View full text Add to dashboard Cite

show abstract

“…The origin of electrochemical promotion has been investigated using a variety of techniques including STM [51][52][53], XPS [54], SERS , TPD [56][57][58][59][60][61], UPS [62] and the Kelvin probe method [26,63,64]. A key step in the elucidation of the origin of NEMCA was the experimental discovery [26,27,62] and theoretical confirmation [25] that solid electrolyte cells with metal electrodes are both work function probes and work function controllers for the gas-exposed surfaces of their electrodes.…”

Section: Electrochemical Promotion Of Catalysis (Epoc)mentioning

confidence: 99%

Temperature programmed desorption of oxygen from Pd films interfaced with Y2O3-doped ZrO2

Katsaounis

2008

J Appl Electrochem

View full text Add to dashboard Cite

The origin of the effect of non-faradaic electrochemical modification of catalytic activity (NEMCA) or Electrochemical Promotion was investigated via temperature-programmed-desorption (TPD) of oxygen, from polycrystalline Pd films deposited on 8 mol%Y 2 O 3 -stabilized-ZrO 2 (YSZ), an O 2-conductor, under high-vacuum conditions and temperatures between 50 and 250°C. Oxygen was adsorbed both via the gas phase and electrochemically, as O 2-, via electrical current application between the Pd catalyst film and a Au counter electrode. Gaseous oxygen adsorption gives two adsorbed atomic oxygen species desorbing at about 300°C (state b 1 ) and 340-500°C (state b 2 ). The creation of the low temperature peak is favored at high exposure times (exposure [1 kL) and low adsorption temperatures (T ads \ 200°C). The decrease of the open circuit potential (or catalyst work function) during the adsorption at high exposure times, indicates the formation of subsurface oxygen species which desorbs at higher temperatures (above 450°C). The desorption peak of this subsurface oxygen is not clear due to the wide peaks of the TPD spectra. The TPD spectra after electrochemical O 2-pumping to the Pd catalyst film show two peaks (at 350 and 430°C) corresponding to spillover O ads and O dÀ ads according to the reaction:The formation of the spillover O dÀ ads oxygen species is an intermediate stage before the formation of the atomic adsorbed oxygen, O ads . Mixed gaseous and electrochemical adsorption was carried out in order to simulate the Electrochemical Promotion conditions. The initial surface coverage with oxygen from the gas phase plays a very important role on the high or low effect of polarization. In general mixed adsorption leads to much higher oxygen coverages compare with that observed either under gaseous or electrochemical adsorption. The binding strength of the atomic adsorbed oxygen (state b 2 ) was investigated as a function of applied potential. It was found that the binding energy decreases linearly with increasing catalyst potential and work function. Similar behavior has been observed for oxygen adsorption on Pt, Ag and Au deposited on YSZ in previous studies.Keywords Temperature programmed desorption Á Oxygen adsorption on Pd Á Electrochemical promotion Á Electrochemical adsorption Á Palladium supported catalyst Á Spillover-backspillover of oxygen Á NEMCA effect 1 Introduction

show abstract

EPOC with Alkaline Conductors: Implementations in Emission Control Catalysis

Yentekakis

Vernoux²,

Caravaca³

2022

Modern Aspects of Electrochemistry

View full text Add to dashboard Cite

STM observation of the origin of electrochemical promotion on metal catalyst-electrodes interfaced with YSZ and β″-Al2O3

Cited by 11 publications

References 14 publications

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

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

Temperature programmed desorption of oxygen from Pd films interfaced with Y2O3-doped ZrO2

EPOC with Alkaline Conductors: Implementations in Emission Control Catalysis

Contact Info

Product

Resources

About