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Chemical state

About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.


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Journal ArticleDOI
Wei-Lin Dai1, Qi Sun1, Jing-Fa Deng1, Dong Wu, Yu-Han Sun 
TL;DR: In this paper, the chemical states of Cu and Zn in an ultra-fine high performance Cu/ZnO/Al2O3 catalyst at various preparation stages for the methanol synthesis by CO2/H2 were investigated by X-ray photoelectron spectroscopy.

109 citations

Journal ArticleDOI
TL;DR: Definite assignment of the boron oxidation state will contribute to the preparation, characterization, and understanding of B-TiO2 photoactivity under visible light which has been the subject of extensive work in the past few years.
Abstract: Boron is diamagnetic in B-doped anatase TiO2 nanoparticles which exhibit photocatalytic activities in the visible light range. Using N as a paramagnetic probe for the formal oxidation state of boron in N/B-codoped TiO2, with more than 90% unpaired spin density in the N2p orbital, we infer that boron enters the oxygen vacancy substitutionally in the form of B1-. Combination of spin-Hamiltonian analysis and interpretation of light dependent EPR spectra in terms of a charge compensating mechanism supports a model of [N2-B1-]+1 for the new EPR active center which acts as a trap for electrons liberated from [N1-] centers under blue light irradiation. Definite assignment of the boron oxidation state will contribute to the preparation, characterization, and understanding of B−TiO2 photoactivity under visible light which has been the subject of extensive work in the past few years.

109 citations

Journal ArticleDOI
TL;DR: In this article, a dc reactive magnetron sputtering from a metallic Ni target in an Ar+O 2 mixed atmosphere in two sputtering modes was used for the study of the chemical composition and to detect different chemical states of bond elements.
Abstract: Nickel oxide (NiO) thin films have been prepared by dc reactive magnetron sputtering from a metallic Ni target in an Ar+O 2 mixed atmosphere in two sputtering modes. The oxygen content in the gas mixture varied from 15 to 45%. Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscope (XPS) investigations have been used for the study of the chemical composition and to detect different chemical states of bond elements. TEM observations revealed a dense fine-grained structure with the grain size in the range 4–10 nm. Atomic force microscopy (AFM) showed that the surface morphology NiO films can be modified by the process parameters as the oxygen content and the pumping speed. Scanning electron microscope (SEM) observation and energy dispersive X-ray (EDX) analyses revealed uniform morphology and homogenous dispersion of NiO, Pt and Al 2 O 3 phases. In addition, the NiO thin films were tested in order to investigate their response to CO in the range 50–200 ppm at different operating temperatures.

107 citations

Journal ArticleDOI
TL;DR: In this article, a quantitative method of determining the cerium chemical state from the Ce 3D photoelectron spectra is described in detail, based on limited diffusion of the deposited Sn atoms into the ceria layer at low temperature.

107 citations

Journal ArticleDOI
17 Sep 2013-Sensors
TL;DR: Semiconductor-based gas sensors that use n-type WO3 or p-type Co3O4 powder were fabricated and their gas sensing properties toward NO2 or NO (0.5–5 ppm in air) were investigated and no clear differences between the chemical states of the metal oxide surface exposed to NO 2 or NO could be detected from the DRIFT spectra.
Abstract: Semiconductor-based gas sensors that use n-type WO3 or p-type Co3O4 powder were fabricated and their gas sensing properties toward NO2 or NO (0.5–5 ppm in air) were investigated at 100 °C or 200 °C. The resistance of the WO3-based sensor increased on exposure to NO2 and NO. On the other hand, the resistance of the Co3O4-based sensor varied depending on the operating temperature and the gas species. The chemical states of the surface of WO3 or those of the Co3O4 powder on exposure to 1 ppm NO2 and NO were investigated by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. No clear differences between the chemical states of the metal oxide surface exposed to NO2 or NO could be detected from the DRIFT spectra.

107 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202326
202249
202184
202089
201987
201894