DRIFTS Study of the Surface Structure and Nitridation Process of Mixed Galloaluminophosphate Oxynitride (AlGaPON) Catalysts

Delsarte, Stéphanie; Grange, Paul

doi:10.1021/jp990699z

Cited by 16 publications

(4 citation statements)

References 54 publications

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“…Based on the spectra of the oxide-terminated particles, we assign the peak at 1225 cm -1 to Ga 2 O and the peaks at 635 and 800 cm -1 to contamination from As 2 O 3 in either the Claudetite or amorphous phase. It should also be noted that Ga−N vibrational modes have been observed in diffuse reflectance IR experiments on GaN powder at 1230, 800, and 630 cm -1 and may not be readily distinguishable from the oxide peaks. To confirm this assignment, IR spectra of the particles were taken after several weeks of exposure to air.…”

Section: Resultsmentioning

confidence: 99%

Passivation of GaAs Nanocrystals by Chemical Functionalization

et al. 2008

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The effective use of nanocrystalline semiconductors requires control of the chemical and electrical properties of their surfaces. We describe herein a chemical functionalization procedure to passivate surface states on GaAs nanocrystals. Cl-terminated GaAs nanocrystals have been produced by anisotropic etching of oxide-covered GaAs nanocrystals with 6 M HCl(aq). The Cl-terminated GaAs nanocrystals were then functionalized by reaction with hydrazine or sodium hydrosulfide. X-ray photoelectron spectroscopic measurements revealed that the surfaces of the Cl-, hydrazine-, and sulfide-treated nanocrystals were As-rich, due to significant amounts of As0. However, no As0 was observed in the photoelectron spectra after the hydrazine-terminated nanocrystals were annealed at 350 degrees C under vacuum. After the anneal, the N 1s peak of hydrazine-exposed GaAs nanocrystals shifted to 3.2 eV lower binding energy. This shift was accompanied by the appearance of a Ga 3d peak shifted 1.4 eV from the bulk value, consistent with the hypothesis that a gallium oxynitride capping layer had been formed on the nanocrystals during the annealing process. The band gap photoluminescence (PL) was weak from the Cl- and hydrazine- or sulfide-terminated nanocrystals, but the annealed nanocrystals displayed strongly enhanced band-edge PL, indicating that the surface states of GaAs nanocrystals were effectively passivated by this two-step, wet chemical treatment.

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Section: Resultsmentioning

confidence: 99%

Passivation of GaAs Nanocrystals by Chemical Functionalization

et al. 2008

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“…Cyano, that is ÈC3N groups, also absorb in this region, and they indeed could have been formed on TMAmodiÐed alumina, since methane and ammonia are known to react to HC3N on alumina and aluminium nitride catalysts at about 1300 K.37 However, ÈC3N species would not be produced on bare alumina since no carbon was present. Centeno et al 38 have suggested that a combination of peaks at other frequencies may also result in these types of absorption bands. In the end, then, the origin of the peak at about 2100 cm~1 remains unknown.…”

Section: Reaction Of Ammonia On Tma-modiðed Aluminamentioning

confidence: 99%

Successive reactions of gaseous trimethylaluminium and ammonia on porous alumina

Puurunen¹,

Lindblad

Root

et al. 2001

Phys. Chem. Chem. Phys.

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Successive reactions of gaseous trimethylaluminium (TMA) and ammonia on porous alumina were studied with the goal of Ðnding suitable process conditions for preparing aluminium nitride (AlN) by atomic layer deposition (ALD), a technique based on separate saturating gasÈsolid reactions. The reaction of TMA was studied at 353È623 K on alumina dehydroxylated at 473È1073 K, and the following reaction of ammonia at 423È823 K. Reference samples were prepared by reacting ammonia at 623 and 823 K with alumina dehydroxylated at 833 K. The samples were characterised by elemental analysis of carbon and nitrogen and by IR and 1H NMR. TMA reacted with alumina in a saturating manner at 353È573 K. Reaction took place through ligand exchange with surface OH groups, with release of methane, and through dissociation of TMA on pairs of coordinatively unsaturated Al and O ions. Aluminium-bonded methyl groups remained on the surface. Decomposition of TMA occurred at 600 K and above. Ammonia had reacted with most of the methyl groups by 573 K, but 723 K was required to remove them all. Primary, secondary and tertiary amino groups were formed in the reaction, and ammonia molecules were adsorbed on the surface. The average H/N ratio in the amino groups decreased with increasing reaction temperature. Good temperatures for AlN deposition by ALD seem to be any temperature up to 573 K for the TMA reaction and 723 K or above for the ammonia reaction.

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“…Moreover, commercially available cells, enabling the control of the environmental conditions (temperature, pressure, and atmosphere) have made it an indispensable tool to study catalysts in situ . This technique has already been successfully used to characterize oxynitrides systems. − …”

Section: Introductionmentioning

confidence: 99%

“…17 This technique has already been successfully used to characterize oxynitrides systems. [18][19][20][21][22][23][24][25] On the other hand, XPS or ESCA, which stands for "electron spectroscopy for chemical analysis", has a special place among surface analytical techniques. This technique is useful to probe both the elemental composition of the surface of catalysts and the oxidation state and electronic environment of each component.…”

Section: Introductionmentioning

confidence: 99%

Nitrided Zeolites: A Spectroscopic Approach for the Identification and Quantification of Incorporated Nitrogen Species

Srasra¹,

Delsarte²,

Gaigneaux³

2010

J. Phys. Chem. C

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The combination of X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) allowed a clear identification and quantification of nitrogenous species incorporated upon nitridation in three different zeolites one Y zeolite (Si/Al ratio of 2.6) and two ultrastable Y zeolites (Si/Al ratios of 13 and 37). Both the amount and the chemical nature of incorporated nitrogen species were controlled by the nitridation temperature. Namely, an increase of the temperature induces an increase of the nitrogen content and the appearance of nitrogenous species in the following order of increasing temperature: NH4 +, adsorbed NH3, −NH2, >NH, and >N−. Based on these spectroscopic results, a mechanism of nitridation in function of temperature was proposed, this mechanism being independent of the properties of the parent zeolite. We evidenced here that the replacement of hydroxyls groups located in the microposity of the zeolite by nitrogen species was effective which can be very motivating result for the application of these materials as shape selective catalysts.

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DRIFTS Study of the Surface Structure and Nitridation Process of Mixed Galloaluminophosphate Oxynitride (AlGaPON) Catalysts

Cited by 16 publications

References 54 publications

Passivation of GaAs Nanocrystals by Chemical Functionalization

Passivation of GaAs Nanocrystals by Chemical Functionalization

Successive reactions of gaseous trimethylaluminium and ammonia on porous alumina

Nitrided Zeolites: A Spectroscopic Approach for the Identification and Quantification of Incorporated Nitrogen Species

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