An X-Ray Photoelectron Spectroscopic Study of Copper Chromite Catalysts

1979 ◽  
Vol 33 (4) ◽  
pp. 380-384 ◽  
Author(s):  
J. A. Schreifels ◽  
A. Rodero ◽  
W. E. Swartz
Keyword(s):  
Spectroscopic Study ◽  
Calcination Temperature ◽  
Photoelectron Spectroscopy ◽  
Copper Chromite ◽  
Oxidation States ◽  
Surface Species ◽  
Catalytic Surface ◽  
X Ray

A series of copper chromite catalysts have been studied by x-ray photoelectron spectroscopy. The data indicate that in the as-received form the copper is present as a mixture of Cu(OH)2 and CuO. After calcination at 500 °C only CuO is present. The chromium is present as Cr+3 and Cr+4 when no promoter is added. When a BaO promoter is added, the Cr+6 is stabilized. Calcination at 500°C for varying periods of time alter the relative amounts of Cr+3 and Cr+6 on the catalytic surface. In addition, the relative amounts of the various oxidation states are a function of calcination temperature. At a calcination temperature of 240°C a Cr+5 surface species is reproducibly observed in one of the catalysts.

scholarly journals Studies of Effects of Calcination Temperature on the Crystallinity and Optical Properties of Ag-Doped ZnO Nanocomposites

2019 ◽  
Vol 3 (1) ◽  
pp. 18 ◽  
Author(s):  
Md. Molla ◽  
Mai Furukawa ◽  
Ikki Tateishi ◽  
Hideyuki Katsumata ◽  
Satoshi Kaneco
Keyword(s):  
Optical Properties ◽  
Calcination Temperature ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Band Edge ◽  
High Yield ◽  
Band Edge Emission ◽  
X Ray ◽  
Calcination Temperatures ◽  
Doped Zno

Ag-doped ZnO nanocomposites are successfully synthesized at different calcination temperatures and times through a simple, effective, high-yield and low-cost mechanochemical combustion technique. Effects of calcination temperature on the crystallinity and optical properties of Ag/ZnO nanocomposites have been studied by X-ray diffraction (XRD), UV−visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL) and X-ray photoelectron spectroscopy (XPS). The XRD patterns of the synthesized Ag/ZnO exhibit a well-crystalline wurtzite ZnO crystal structure. The grain size of Ag/ZnO nanocomposites is found to be 19 and 46 nm at calcination temperatures of 400 °C and 700 °C, respectively. The maximum absorption in the UV region is obtained for Ag/ZnO nanocomposites synthesized at a calcination temperature of 500 °C for 3 h. The peak position of blue emissions is almost the same for the nanocomposites obtained at 300–700 °C calcination temperatures. The usual band edge emission in the UV is not obtained at 330 nm excitation. Band edge and blue band emissions are observed for the use of low excitation energy at 335–345 nm.

scholarly journals Photocatalytic CO2 Reduction and Electrocatalytic H2 Evolution over Pt(0,II,IV)-Loaded Oxidized Ti Sheets

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1909
Author(s):  
Ju Hyun Yang ◽  
So Jeong Park ◽  
Choong Kyun Rhee ◽  
Youngku Sohn
Keyword(s):  
Hydrogen Evolution ◽  
Photoelectron Spectroscopy ◽  
Co2 Reduction ◽  
Oxidation States ◽  
X Ray ◽  
Catalytic Activities ◽  
Before And After ◽  
Reduction Methods ◽  
Chemical States ◽  
Sputter Deposited

Energy recycling and production using abundant atmospheric CO2 and H2O have increasingly attracted attention for solving energy and environmental problems. Herein, Pt-loaded Ti sheets were prepared by sputter-deposition and Pt4+-reduction methods, and their catalytic activities on both photocatalytic CO2 reduction and electrochemical hydrogen evolution were fully demonstrated. The surface chemical states were completely examined by X-ray photoelectron spectroscopy before and after CO2 reduction. Gas chromatography confirmed that CO, CH4, and CH3OH were commonly produced as CO2 reduction products with total yields up to 87.3, 26.9, and 88.0 μmol/mol, respectively for 700 °C-annealed Ti under UVC irradiation for 13 h. Pt-loading commonly negated the CO2 reduction yields, but CH4 selectivity was increased. Electrochemical hydrogen evolution reaction (HER) activity showed the highest activity for sputter-deposited Pt on 400 °C-annealed Ti with a HER current density of 10.5 mA/cm2 at −0.5 V (vs. Ag/AgCl). The activities of CO2 reduction and HER were found to be significantly dependent on both the nature of Ti support and the oxidation states (0,II,IV) of overlayer Pt. The present result could provide valuable information for designing efficient Pt/Ti-based CO2 recycle photocatalysts and electrochemical hydrogen production catalysts.

Single-layer MoS2formation by sulfidation of molybdenum oxides in different oxidation states on Au(111)

2017 ◽  
Vol 19 (21) ◽  
pp. 14020-14029 ◽  
Author(s):  
Norberto Salazar ◽  
Igor Beinik ◽  
Jeppe V. Lauritsen
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Photoelectron Spectroscopy ◽  
Single Layer ◽  
Oxidation States ◽  
Scanning Tunneling ◽  
Molybdenum Oxides ◽  
Tunneling Microscopy ◽  
X Ray

The sulfidation pathway from MoO3to MoS2on Au(111) revealed by a combination of Scanning Tunneling Microscopy and X-Ray Photoelectron Spectroscopy.

Characterization of europium implanted LiNbO3

1993 ◽  
Vol 8 (10) ◽  
pp. 2679-2685 ◽  
Author(s):  
P. Moretti ◽  
B. Canut ◽  
S.M.M. Ramos ◽  
R. Brenier ◽  
P. Thévenard ◽  
...  
Keyword(s):  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Rutherford Backscattering ◽  
Oxidation States ◽  
Xps Spectra ◽  
X Ray ◽  
Partial Recrystallization ◽  
Lower Charge

LiNbO3 single crystals were implanted at room temperature with Eu+ ions at 70 keV with fluence ranging from 0.5 to 5 × 1016 ions · cm−2. The damage in the implanted layer has been investigated by Channeling Rutherford Backscattering (RBS-C), and the oxidation states of the cations have been determined by x-ray photoelectron spectroscopy (XPS). Following implantation, a fully amorphized layer of 60 nm is generated, even for the lowest fluence employed. Subsequent annealing in air, in the range 800–1250 K, was applied to restore tentatively the crystallinity and promote the substitutional incorporation of Eu in the crystal. Only a partial recrystallization of the damaged layer was observed. For as-implanted samples, XPS spectra clearly reveal europium in Eu2+ and Eu3+ states, and the Nb5+ ions are driven to lower charge states.

Pd/SiO2 Organic-Inorganic Hybrid Materials by Sol-Gel Method: Preparation and Thermal Stability under H2 Atmosphere

2015 ◽  
Vol 1118 ◽  
pp. 20-27
Author(s):  
Jing Yang ◽  
Bao Song Li ◽  
Xiang Huo ◽  
Hao Xu ◽  
Hai Yun Hou
Keyword(s):  
Thermal Stability ◽  
Calcination Temperature ◽  
Hybrid Materials ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Inorganic Hybrid ◽  
X Ray ◽  
Good Thermal Stability ◽  
Pd Doping

Pd/SiO2 organic-inorganic hybrid materials were prepared by adding PdCl2 into methyl-modified silica sol. The Pd/SiO2 hybrid materials were characterized by X-ray diffraction (XRD), fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of calcination temperature and Pd-doping on the phase transition of Pd element and the thermal stability of CH3 group in the Pd/SiO2 organic-inorganic hybrid materials were investigated. The results showed that the reduced metallic Pd0 exhibits good thermal stability under H2 atmosphere in the calcination process. Pd element in noncalcined Pd/SiO2 materials exists in PdCl2 form, calcination at 200 °C in a H2 atmosphere produces some metallic Pd0 and calcinations at 350 °C results in the complete transformation of Pd2+ to metallic Pd0. With the increase of calcination temperature, the Pd0 particle sizes increase and the hydrophobic Si−CH3 bands decrease in intensity. As the calcination temperature is greater than or equal to 350 °C, the loading of metallic Pd0 nearly has no influence on the chemical structure but, with the increase of Pd content, the formed Pd0 particle size increases. To keep the hydrophobicity of Pd/SiO2 membrane materials, the optimal calcination temperature is about 350 °C under H2 atmosphere.

OXIDATION STATES OF IRON IN BAHAMIAN POTTERY BY X-RAY PHOTOELECTRON SPECTROSCOPY

Archaeometry ◽  
1990 ◽  
Vol 32 (1) ◽  
pp. 47-54 ◽  
Author(s):  
J. B. LAMBERT ◽  
L. XUE ◽  
J. M. WEYDERT ◽  
J. H. WINTER
Keyword(s):  
Photoelectron Spectroscopy ◽  
Oxidation States ◽  
X Ray
Sign in / Sign up

Export Citation Format

Share Document