Characterization of hydroxylated oxide film on iron surfaces and its acid–base properties using XPS

Kurbatov, G. G.; Darque-Ceretti, Évelyne; Aucouturier, Marc

doi:10.1002/sia.740181206

Cited by 51 publications

(38 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This indicates that a hydroxylated film is formed on the Fe surface as soon as it is contacted with an aqueous solution and that the protons on the -OH groups readily exchange with Pd ions that are present in solution. A similar cation exchange phenomenon has been observed previously where the protons on the -OH groups on an Fe surface exchange with K' ions in solution (Kurbatov et al 1992). …”

Section: -9supporting

confidence: 55%

In situ treatment of mixed contaminants in groundwater: Application of zero-valence iron and palladized iron for treatment of groundwater contaminated with trichloroethene and technetium-99

Korte¹,

Muck²,

Zutman³

et al. 1997

View full text Add to dashboard Cite

1This report has been reproduced directly from the best available copy. 4-7(a) Binding energies of the Pd 3d3,2 and the Pd3d, peaks in the x-ray photoelectron spectrum of elemental Pd deposited on the iron surf-ace. 4.8. 4.9.5.1. 5.2.5.3.6.1. 7-4Tc (pCi/g) distribution in Fe columns 580,000 gal of water treated . . . 7-6 Number of times influent TCE concentration was reduced by % as it passed through the Pd/Fe treatment columns. Laboratory research conducted at ORNL and the UofA led to the discovery that zero-valence iron treated with a trace of palladium (pd) (nominally 0.05%) rapidly dechlorinated a wide range of hydrocarbons. Other research at ORNL and elsewhere has shown that many metals and radionuclides either precipitate or are adsorbed by zero-valence iron. Technetium (Tc) is particularly amenable to treatment of this type. Consequently, a combined approach using zero-valence iron for Tc and palladized iron (Pd/Fe) for trichloroethene (TCE) was applied to a groundwater waste stream at the PORTS facility.Laboratory research preparatory to the field tests demonstrated that Pd/Fe dechlorinated TCE one to two orders of magnitude faster than untreated iron. Further studies examined the nature of the Pd/Fe surface and evaluated the reaction mechanism. Work with x-ray photoelectron spectroscopy demonstrated that Pd attaches to the iron surface in a two-step process whereby a Pd-oxygen bond forms first with Pd in the +2 oxidation state. The Pd is then rapidly fbrther reduced to the elemental state as it plates on the Fe surface.Mechanistic studies have demonstrated that Pd/Fe reduces chlorinated hydrocarbons by hydrogenation. Hydrogen gas, formed because of the corrosion of Fe, is absorbed by the Pd. The chlorinated hydrocarbon adsorbs to the iron and is then reduced by hydrogen at the Pd/Fe interface.Laboratory studies with zero-valence iron revealed a very high capacity for immobilization of Tc. In a column study, approximately an order of magnitude more Tccontaminated water could be treated by the iron as compared to a conventional ion xiii exchange resin. The primary removal mechanism is believed to be reductive precipitation.In the field test, approximately 600,000 gal of water were treated. Treatment was straightfonvard and completely effective for Tc. The influent concentration of Tc was lower than anticipated (<20 pCi/L). Nevertheless, all of the Tc contained in the treated water was adsorbed by approximately 12 in. of a coarse zero-valence iron.

show abstract

Section: -9supporting

confidence: 55%

In situ treatment of mixed contaminants in groundwater: Application of zero-valence iron and palladized iron for treatment of groundwater contaminated with trichloroethene and technetium-99

Korte¹,

Muck²,

Zutman³

et al. 1997

View full text Add to dashboard Cite

show abstract

“…4 for oxide-covered metals have been obtained using contact angle meaurements as a function of the pH of the wetting liquid 21 or from exchange measurements in conjunction with XPS. 32 The data for oxide-covered metals in Fig. 4 display some scatter around the data for bulk metal oxides, but the trend is the same for both bulk oxides and oxide films.…”

Section: Resultsmentioning

confidence: 80%

“…4, which is for bulk oxides, we have added data for several oxide-covered metals. 21,32 The linear correlation shown in Fig. 4 is for the data given by Delamar 31 for bulk metal oxides.…”

Section: Resultsmentioning

confidence: 98%

Surface Properties of Hydroxyl Groups in the Air‐Formed Oxide Film on Titanium

McCafferty

Wightman

Cromer

1999

J. Electrochem. Soc.

View full text Add to dashboard Cite

The air-formed oxide film on titanium and the nature of the surface hydroxyls are important in a number of surface phenomena, such as localized corrosion, 1 adhesion of polymers, 2 adsorption, 3-5 catalysis, 6 photoelectrolysis, 7 and the behavior of biomedical implants. 4,8 For example, in the adhesion of polymers on various surfaces, Fowkes et al. 9 has emphasized the importance of acid-base (i.e., electron acceptor/donor) interactions at the interface. In a recent study on oxide-covered metals, it has been observed that the peel strength of an acidic pressure-sensitive adhesive on various oxide-covered metals, including titanium, increased with the basicity of the oxide surface. 10 The acid/base nature of the oxide surface in turn depends on the character of the hydroxyl groups contained in the oxide film.There have been a number of analytical surface studies on the composition of oxide films on titanium formed by controlled oxidation of clean surfaces, 11-13 by electrochemical anodization, 14-16 or by special techniques such as reactive sputtering, 17 ion beam mixing, 18 or ion beam enhanced deposition. 19 However, there appear to have been few studies heretofore on titanium surfaces dealing with the nature of the native incipient air-formed oxide film formed by exposure to the ambient environment. The purpose of this communication is to present our recent work on such incipient air-formed oxide films on titanium.This communication (i) presents data obtained from variable angle X-ray photoelectron spectroscopy (VAXPS) and from secondary ion mass spectrometry (SIMS) to show that the outermost layer of the oxide film on titanium is hydroxylated, and uses X-ray photoelectron spectroscopy (XPS) to determine (ii) the surface isoelectric point of the air-formed oxide film on titanium, and (iii) the surface concentration of hydroxyl groups in the oxide film on titanium. ExperimentalFoils of titanium of 0.25 mm thickness and 99.99% purity were obtained from Johnson Matthey. Samples were usually analyzed in the as-received condition, i.e., without any surface treatment, although with selected samples two cleaning procedures were used to reduce the thickness of the overlayer of carbon contamination. 20,21 These were ultrasonic cleaning or argon plasma treatment. Ultrasonic cleaning involved 5 min in acetone followed by 5 min in methanol, after which the samples were dried in a stream of argon gas. Argon plasma treatment was done using a March Instruments Plasmod ® unit, using conditions described previously. 20,21 XPS surface analysis was performed using a Perkin-Elmer PHI 5400 spectrometer employing a Mg K␣ (1253.6 eV) X-ray source operated at 14 kV and 400 W. The takeoff angle was generally 45Њ although one set of experiments was performed using variable angle XPS in which the takeoff angle was varied from 15 to 90Њ (measured with respect to the surface of the sample). Typical operating pressures were approximately 1 ϫ 10 Ϫ8 Torr. If either ultrasonic cleaning or argon plasma treatment was employed, the metal sample...

show abstract

“…47 By performing isobaric and/or isothermal measurements to access a range of relative humidities, the oxygen spectra of model oxide surfaces have been deconvoluted into hydroxyls (OH − ), oxy-carbonaceous species such as carbonate (CO3 2− ), bulk oxygen, and adsorbed water (H2O). Using a multilayer electron attenuation model, [48][49][50] the coverage of each species can be deduced. In the case of TiO2, the relation between the coverage of OH − and Ti 3+ sites suggests hydroxylation of the surface proceeds by dissociation of water molecules, where the OH − group fills an O 2− vacancy and the remaining H + binds to a bridging O 2− , forming a second OH − group.…”

Section: The Oxide/h2o Vapor Interfacementioning

confidence: 99%

Insights into Electrochemical Reactions from Ambient Pressure Photoelectron Spectroscopy

et al. 2015

View full text Add to dashboard Cite

ConspectusThe understanding of fundamental processes in the bulk and at the interfaces of electrochemical devices is a prerequisite for the development of new technologies with higher efficiency and improved performance. One energy storage scheme of great interest is splitting water to form hydrogen and oxygen gas, and converting back to electrical energy by their subsequent recombination with only water as a by-product. However, kinetic limitations to the rate of oxygen-based electrochemical reactions hamper the efficiency in technologies such as solar fuels, fuel cells, and electrolyzers. For these reactions, the use of metal oxides as electrocatalysts is prevalent due to their stability, low cost, and ability to store oxygen within the lattice. However, due to the inherently convoluted nature of electrochemical and chemical processes in electrochemical systems, it is difficult to isolate and study individual electrochemical processes in a complex system. Therefore in situ characterization tools are required for observing related physical and chemical processes directly at the places where and while they occur, and can help elucidate the mechanisms of charge separation and charge transfer at electrochemical interfaces.X-ray photoelectron spectroscopy (XPS), also known as ESCA (electron spectroscopy for chemical analysis) has been used as a quantitative spectroscopic technique that measures the elemental composition, as well as chemical and electronic state of a material. Building from extensive ex situ characterization of electrochemical systems, initial in situ studies were conducted at (near) UHV conditions (≤10 −6 Torr) to probe solid-state electrochemical systems. However through the integration of differential-pumping stages, XPS can now operate at pressures in the Torr range, comprising a technique called ambient pressure XPS (AP-XPS).In this Account, we briefly review the working principles and current status of AP-XPS. We use several recent in situ studies on model electrochemical components as well as operando studies performed by our groups at the Advanced Light Source (ALS) at Lawrence Berkeley National Lab to illustrate that AP-XPS is both a chemically and electrically specific tool since photoelectrons carry information on both the local chemistry and electrical potentials. The applications of AP-XPS to oxygen electrocatalysis shown in this Account span well defined studies of (1) the oxide/oxygen gas interface, (2) the oxide/water vapor interface, and (3) operando measurements of half and full electrochemical cells. Using 2 specially designed model devices, we can expose and isolate the electrode or interface of interest to the incident X-ray beam and AP-XPS analyzer to relate the electrical potentials to the composition/chemical state of the key components and interfaces. We conclude with an outlook on new developments of AP-XPS endstations, which may provide significant improvement in the observation of dynamics over a wide range of time scale, higher spatial resolution, and improved characteri...

show abstract

Characterization of hydroxylated oxide film on iron surfaces and its acid–base properties using XPS

Cited by 51 publications

References 38 publications

In situ treatment of mixed contaminants in groundwater: Application of zero-valence iron and palladized iron for treatment of groundwater contaminated with trichloroethene and technetium-99

In situ treatment of mixed contaminants in groundwater: Application of zero-valence iron and palladized iron for treatment of groundwater contaminated with trichloroethene and technetium-99

Surface Properties of Hydroxyl Groups in the Air‐Formed Oxide Film on Titanium

Insights into Electrochemical Reactions from Ambient Pressure Photoelectron Spectroscopy

Contact Info

Product

Resources

About