In-situ X-ray absorption near-edge structure: a probe of the oxidation state of underpotentially adsorbed metals

Tadjeddine, A.; Lahrichi, Anissa; Tourillon, G.

doi:10.1016/0022-0728(93)87018-q

Cited by 26 publications

(25 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We believe the identity of the spots shown in this image are those of either Zn or SO 4 2- ions that may be adsorbed on top of the Zn atoms. Although Zn is known to form strong alloys with Au, even at its underpotential, we saw no morphological evidence (such as increased roughening) from our STM images of alloying. Cd is also known to alloy with Au and has recently been shown by Gewirth et al to likewise form stable upd layers on Au(111) …”

Section: Resultscontrasting

confidence: 63%

A Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy Study of Electrochemically Grown ZnS Monolayers on Au(111)

1999

View full text Add to dashboard Cite

The structure and chemical composition of electrosynthesized ZnS thin films on Au(111) substrates was studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The films were grown by alternating underpotential deposition and oxidative adsorption cycles of S and Zn from solution precursors (electrochemical atomic layer epitaxy, EC-ALE). Oxidative adsorption of the first layer of S results in a ( × )R30° adlattice on Au(111). In the initial Zn monolayer, XPS indicates the presence of SO4 2- derived from the supporting electrolyte. The coadsorbed SO4 2- can be chemically or electrochemically displaced by H2S(aq) or HS(aq) -, leading to the formation of ZnS. Atomically resolved STM images show the ZnS/Au(111) monolayer to be 6-fold symmetric with an interatomic spacing of 0.37 ± 0.01 nm. The structure of the deposit on the micrometer scale was also investigated by STM. The first complete EC-ALE cycle results in the formation of nanocrystallites of ZnS randomly distributed across Au(111) terraces. The average diameter of the crystallites is 10 ± 5 nm, and the apparent coverage of ZnS is 0.38.

show abstract

Section: Resultscontrasting

confidence: 63%

A Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy Study of Electrochemically Grown ZnS Monolayers on Au(111)

1999

View full text Add to dashboard Cite

show abstract

“…The shape of the absorption above 8985 eV is more consistent with Cu(I) than Cu(II). 45 The presence of a small amount of oxidized Cu is indicated in the EXAFS data (see below).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of silica supported AuCu nanoparticle catalysts and the effects of pretreatment conditions for the CO oxidation reaction

Bauer

Mullins

et al. 2011

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

Supported gold nanoparticles have generated an immense interest in the field of catalysis due to their extremely high reactivity and selectivity. Recently, alloy nanoparticles of gold have received a lot of attention due to their enhanced catalytic properties. Here we report the synthesis of silica supported AuCu nanoparticles through the conversion of supported Au nanoparticles in a solution of Cu(C(2)H(3)O(2))(2) at 300 °C. The AuCu alloy structure was confirmed through powder XRD (which indicated a weakly ordered alloy phase), XANES, and EXAFS. It was also shown that heating the AuCu/SiO(2) in an O(2) atmosphere segregated the catalyst into a Au-CuO(x) heterostructure between 150 °C to 240 °C. Heating the catalyst in H(2) at 300 °C reduced the CuO(x) back to Cu(0) to reform the AuCu alloy phase. It was found that the AuCu/SiO(2) catalysts were inactive for CO oxidation. However, various pretreatment conditions were required to form a highly active and stable Au-CuO(x)/SiO(2) catalyst to achieve 100% CO conversion below room-temperature. This is explained by the in situ FTIR result, which shows that CO molecules can be chemisorbed and activated only on the Au-CuO(x)/SiO(2) catalyst but not on the AuCu/SiO(2) catalyst.

show abstract

“…If it were true for the ZnS deposition, the deposition of Zn as the first UPD layer on the Au substrates would give a more ideal surface of the ZnS film. Since the strong tendency of alloying between Au and Zn has been reported, ,− however, we adopted the UPD of S on the bare Au substrates prior to the subsequent UPD of Zn.…”

Section: Resultsmentioning

confidence: 99%

Preparation of Size-Quantized ZnS Thin Films Using Electrochemical Atomic Layer Epitaxy and Their Photoelectrochemical Properties

et al. 2000

View full text Add to dashboard Cite

Size-quantized ZnS thin films were prepared by sequential underpotential deposition of S and Zn on Au{111} substrates. Observations of the high-resolution electron microscope and the energy-dispersive X-ray spectrometer revealed that ZnS films were epitaxially deposited on the Au{111} facet with a stoichiometric composition. The scanning tunneling microscope images showed that the surface of the prepared films was flat in an atomic level and no large protrusion was contained, while etch pits with the height of the monatomic step of Au{111}, which were formed in the UPD of the first S layer on the naked Au surface, were seen through ZnS films with independence of the number of ZnS layers deposited. The ZnS film-deposited Au electrodes showed anodic photocurrents in an aqueous solution containing triethanolamine as a sacrificial electron donor. The energy gap determined from the action spectra decreased with an increase of the film thickness up to ca. 15.5 ZnS layers at which the bulk band gap was obtained.

show abstract

In-situ X-ray absorption near-edge structure: a probe of the oxidation state of underpotentially adsorbed metals

Cited by 26 publications

References 27 publications

A Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy Study of Electrochemically Grown ZnS Monolayers on Au(111)

A Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy Study of Electrochemically Grown ZnS Monolayers on Au(111)

Synthesis of silica supported AuCu nanoparticle catalysts and the effects of pretreatment conditions for the CO oxidation reaction

Preparation of Size-Quantized ZnS Thin Films Using Electrochemical Atomic Layer Epitaxy and Their Photoelectrochemical Properties

Contact Info

Product

Resources

About