Low-Temperature Oxidation of Nitrided Iron Surfaces

Torres, J.; Perry, Christopher C.; Bransfield, Stephen J.; Fairbrother, D. Howard

doi:10.1021/jp027802w

Cited by 79 publications

(71 citation statements)

References 49 publications

(115 reference statements)

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“…Each of the latter shows a similar marked trend as a function of R, that is, a marked drop in the intensity in the low N1s energy region of the spectra (396 eV-398 eV) when R decreases. The literature indicates that this low energy region corresponds to iron nitrides or nitrided iron surfaces [26][27][28][29]. For each material collection, the spectra recorded for low R are quite similar.…”

Section: As-prepared Materialsmentioning

confidence: 79%

Synthesis and Characterization of Carbon/Nitrogen/Iron Based Nanoparticles by Laser Pyrolysis as Non-Noble Metal Electrocatalysts for Oxygen Reduction

Pérez

Jorda

Bonville

et al. 2018

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This paper reports original results on the synthesis of Carbon/Nitrogen/Iron-based Oxygen Reduction Reaction (ORR) electrocatalysts by CO 2 laser pyrolysis. Precursors consisted of two different liquid mixtures containing FeOOH nanoparticles or iron III acetylacetonate as iron precursors, being fed to the reactor as an aerosol of liquid droplets. Carbon and nitrogen were brought by pyridine or a mixture of pyridine and ethanol depending on the iron precursor involved. The use of ammonia as laser energy transfer agent also provided a potential nitrogen source. For each liquid precursor mixture, several syntheses were conducted through the step-by-step modification of NH 3 flow volume fraction, so-called R parameter. We found that various feature such as the synthesis production yield or the nanomaterial iron and carbon content, showed identical trends as a function of R for each liquid precursor mixture. The obtained nanomaterials consisted in composite nanostructures in which iron based nanoparticles are, to varying degrees, encapsulated by a presumably nitrogen doped carbon shell. Combining X-ray diffraction and Mossbauer spectroscopy with acid leaching treatment and extensive XPS surface analysis allowed the difficult question of the nature of the formed iron phases to be addressed. Besides metal and carbide iron phases, data suggest the formation of iron nitride phase at high R values. Interestingly, electrochemical measurements reveal that the higher R the higher the onset potential for the ORR, what suggests the need of iron-nitride phase existence for the formation of active sites towards the ORR.

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Section: As-prepared Materialsmentioning

confidence: 79%

Synthesis and Characterization of Carbon/Nitrogen/Iron Based Nanoparticles by Laser Pyrolysis as Non-Noble Metal Electrocatalysts for Oxygen Reduction

Pérez

Jorda

Bonville

et al. 2018

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“…The ionic character of the N-Fe bond is enhanced by the formation of an Fe-O bond. As a result, the binding energy of N 1s decreased through charge transfer from Fe to N. [15] High binding energies were also observed at approximately 399 and 402 eV; they can be attributed to the presence of nitrosonium ions (NO + ) and nitrite (NO 2 − ) species, respectively. Thus, the oxide layer observed by means of AES, as shown in Fig.…”

Section: Aes Depth-profile Analysis Of the Surface Nitride Layermentioning

confidence: 99%

“…These peaks can be attributed to structural features on the basis of previous studies on the oxidation behavior of metallic nitrides. [15,16] The peak at 397.4 eV corresponds to the intuitive N-Fe bond in iron nitrides. The distinct peak at approximately 396.0 eV, which is a lower binding energy of the N-Fe bond, can be attributed to the formation of iron oxynitrides (N x -Fe y -O) by the oxidation of parent iron nitrides.…”

Section: Aes Depth-profile Analysis Of the Surface Nitride Layermentioning

confidence: 99%

Surface analysis of nitride layers formed on Fe‐based alloys through plasma nitride process

Sato

Omori

Araki

et al. 2009

Surface & Interface Analysis

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Nitriding phenomena that occur on the surfaces of pure Fe and Fe-Cr alloy (16 wt% Cr) samples were investigated. An Ar + N 2 mixture-gas glow-discharge plasma was used so that surface nitriding could occur on a clean surface etched by Ar + ion sputtering. In addition, the metal substrates were kept at a low temperature to suppress the diffusion of nitrogen. These plasmanitriding conditions enabled us to characterize the surface reaction between nitrogen radicals and the metal substrates. The emission characteristics of the band heads of the nitrogen molecule ion (N 2 + ) and nitrogen molecule from the glow-discharge plasma suggest that the active nitrogen molecule is probably the major nitriding reactant. AES and angle-resolved XPS were used to characterize the thickness of the nitride layer and the concentration of elements and chemical species in the nitride layer. The thickness of the nitride layer did not depend on the metal substrate type. An oxide layer with a thickness of a few nanometers was formed on the top of the nitride layer during the nitriding process. The oxide layer consisted of several species of N x -Fe y -O, NO + , and NO 2 − . In the Fe-Cr alloy sample, these oxide species could be reduced because chromium is preferentially nitrided.

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“…8. A small peak at 394.7 eV is assignable to the Me-N related the bond (Me-N) [37]. The Me-N type N comprises only a very small portion (0.21-0.25 at%) of total surface N species (Table. 2), so it is difficult to evaluate the effect of Me-N in this case.…”

Section: Resultsmentioning

confidence: 99%

One-step synthesis of dual-transition metal substitution on ionic liquid based N-doped mesoporous carbon for oxygen reduction reaction

Byambasuren

Jeon

et al. 2016

Carbon letters

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Nitrogen (N)-doped ordered mesoporous carbons (OMCs) with a dual transition metal system were synthesized as non-Pt catalysts for the ORR. The highly nitrogen doped OMCs were prepared by the precursor of ionic liquid (3-methyl-1-butylpyridine dicyanamide) for N/C species and a mesoporous silica template for the physical structure. Mostly, N-doped carbons are promoted by a single transition metal to improve catalytic activity for ORR in PEMFCs. In this study, our N-doped mesoporous carbons were promoted by the dual transition metals of iron and cobalt (Fe, Co), which were incorporated into the N-doped carbons lattice by subsequently heat treatments. All the prepared carbons were characterized by via transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). To evaluate the activities of synthesized doped carbons, linear sweep was recorded in an acidic solution to compare the ORR catalytic activities values for the use in the PEMFC system. The dual transition metal promotion improved the ORR activity compared with the single transition metal promotion, due to the increase in the quaternary nitrogen species from the structural change by the dual metals. The effect of different ratio of the dual metals into the N doped carbon were examined to evaluate the activities of the oxygen reduction reaction.

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Low-Temperature Oxidation of Nitrided Iron Surfaces

Cited by 79 publications

References 49 publications

Synthesis and Characterization of Carbon/Nitrogen/Iron Based Nanoparticles by Laser Pyrolysis as Non-Noble Metal Electrocatalysts for Oxygen Reduction

Synthesis and Characterization of Carbon/Nitrogen/Iron Based Nanoparticles by Laser Pyrolysis as Non-Noble Metal Electrocatalysts for Oxygen Reduction

Surface analysis of nitride layers formed on Fe‐based alloys through plasma nitride process

One-step synthesis of dual-transition metal substitution on ionic liquid based N-doped mesoporous carbon for oxygen reduction reaction

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