X-ray photoelectron spectra and electronic structure of Bi2X3 (X = O, S, Se, Te)
TL;DR: In this paper, the valence band density of states and core levels have been measured for Bi 2 O 3, Bi 2 S 3, Bi 2 Se 3, and Bi 2 Te 3 by X-ray photoelectron spectroscopy.
About: This article is published in Chemical Physics.The article was published on 1977-03-01. It has received 114 citations till now. The article focuses on the topics: Electronegativity & Bismuth.
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TL;DR: Evidence is presented here showing that this model of structural distortions in post-transition metal oxides must be revised, and a high density of metal 6s states is observed at the bottom of the valence band.
Abstract: Structural distortions in post-transition metal oxides are often explained in terms of the influence of s p hybrid "lone pairs". Evidence is presented here showing that this model must be revised. The electronic structures of prototypically distorted α-PbO and α-Bi2O3 have been measured by high-resolution x-ray photoemission and soft x-ray emission spectroscopies. In contrast with the expectations of the lone pair model, a high density of metal 6s states is observed at the bottom of the valence band. The measurements are consistent with the results of density functional theory calculations.
191 citations
TL;DR: In this paper, a theoretical and experimental investigation of the electronic structure of the Bi electron lone pair was performed using a combination of gradient corrected density functional theory and x-ray photoemission.
Abstract: $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Bi}}_{2}{\mathrm{O}}_{3}$ is the thermodynamically stable phase of ${\mathrm{Bi}}_{2}{\mathrm{O}}_{3}$ at room temperature. We have performed a theoretical and experimental investigation of its electronic structure using a combination of gradient corrected density functional theory (DFT), along with x-ray photoemission and $\mathrm{O}\text{\ensuremath{-}}K$ shell x-ray absorption and emission spectroscopies. We examine the nature of bonding in $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Bi}}_{2}{\mathrm{O}}_{3}$ and in particular explore the nature of the stereochemically active Bi electron lone pair. The Bi $6s$ states are found to be concentrated at the bottom of the valence band but the states contributing to the lone pair on Bi are derived from the top of the valence band. Mixing between O $2p$ and Bi $6s$ states is found to be crucial in producing the asymmetric density on Bi. The role of the lone pair in the fast ion conductor $\ensuremath{\delta}\text{\ensuremath{-}}{\mathrm{Bi}}_{2}{\mathrm{O}}_{3}$ is also investigated, through calculation of the electronic structure with ⟨100⟩, ⟨110⟩, and ⟨111⟩ alignment of oxygen vacancies. Alignment of the vacancies along ⟨100⟩ results in the most energetically favorable configuration of the $\ensuremath{\delta}$ phase, contrary to previous force field calculations and electrostatic arguments which favor the ⟨111⟩ alignment.
177 citations
TL;DR: In this article, the process of oxidation of the Bi2Te3 surface was investigated by x-ray photoelectron spectroscopy (XPS), and the oxidized surface layer was found to have a definite thickness, with configurations where O is bonded with Bi and Te, and Bi and TE are bonded with three and four oxygens, respectively.
Abstract: The process of oxidation of the Bi2Te3 surface was investigated by x-ray photoelectron spectroscopy (XPS). The oxidized surface layer was found to have a definite thickness, with configurations where O is bonded with Bi and Te, and Bi and Te are bonded with three and four oxygens, respectively. The oxidation time dependence of the oxidized layer thickness d(t) estimated from the XPS behaved as (t-t0)1/2 when d(t) was smaller than the thickness of a single oxidized quintuple atomic layer in our oxide model and behaved as t-t1 when it was larger than that. Experimental data were compared to our oxidation process model for the layered structure with the van der Waals gap and very good agreement was found.
166 citations
TL;DR: In this article, photo-induced absorption and electrochemical techniques were employed to analyze the charge carrier dynamics that drive photoelectrochemical water oxidation on bismuth vanadate (BiVO4), both with and without cobalt phosphate (CoPi) co-catalyst.
Abstract: This paper employs photoinduced absorption and electrochemical techniques to analyze the charge carrier dynamics that drive photoelectrochemical water oxidation on bismuth vanadate (BiVO4), both with and without cobalt phosphate (CoPi) co-catalyst. These results are correlated with spectroelectrochemical measurements of Co-II oxidation to Co-III in a CoPi/FTO (fluorine doped tin oxide) electrode during dark electrocatalytic water oxidation. Electrocatalytic water oxidation exhibits a non-linear dependence on Co-III density, with a sharp onset at 1 x 10(17) Co-III cm(-2). These results are compared quantitatively with the degree of CoPi oxidation observed under conditions of photoinduced water oxidation on CoPi-BiVO4 photoanodes. For the CoPi-BiVO4 photoanodes studied herein, <= 5% of water oxidation proceeds from CoPi sites, making the BiVO4 surface the predominant water oxidation site. This study highlights two key factors that limit the ability of CoPi to improve the catalytic performance of BiVO4 : 1) the kinetics of hole transfer from the BiVO4 to the CoPi layer are too slow to effectively compete with direct water oxidation from BiVO4; 2) the slow water oxidation kinetics of CoPi result in a large accumulation of Co-III states, causing an increase in recombination. Addressing these factors will be essential for improving the performance of CoPi on photoanodes for solar-driven water oxidation.
157 citations
TL;DR: In this paper, high quality Bi2S3 and Sb2S 3 nanorods were successfully synthesized by the solvothermal treatment of a novel kind of single-source precursors (SSPs), metal di-n-octyl-dithiophosphates (M[S2P(OC8H17)2]3, M = Bi, Sb).
Abstract: High-quality Bi2S3 and Sb2S3 nanorods on a large scale were successfully synthesized by the solvothermal treatment of a novel kind of single-source precursors (SSPs), metal di-n-octyl-dithiophosphates (M[S2P(OC8H17)2]3, M = Bi, Sb). The X-ray powder diffraction (XRD) patterns show that both of these products belong to the orthorhombic M2S3 phase. The experimental results show that the Bi2S3 nanorods can be easily prepared in air at ≥140 °C for 5 h in the presence of oleylamine. Transmission electron microscopy (TEM) images show the rodlike appearance of Bi2S3 with a diameter of 7−21 nm and length of several hundred nanometers under the various reaction conditions. The effects of reaction parameters, such as reaction time, temperature, and concentration of the precursor, on the growth of nanorods were discussed in detail. The mechanism of the formation process of the nanorods was proposed. We also demonstrate that this method can be extended to the synthesis of Sb2S3 nanorods, which have an average diamete...
137 citations
References
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TL;DR: In this paper, the electronegativities of sixtynine elements have been calculated from the most recent thermochemical data, and the mean deviation of the calculated electronegativity difference, 0·208 √ †, from the difference of the average electrone-gativities is 0·046 units.
1,658 citations
TL;DR: In this article, the authors proposed that semiconductors should be chosen with high mean atomic weights and that they should be prepared with thermoelectric powers lying between 200 and 300 μVC-1.
Abstract: In the past the possibility of thermoelectric refrigeration has been considered, but all attempts to produce a practical refrigerator have failed owing to lack of suitable thermocouple materials. In this paper it is proposed that semiconductors should be used and the factors governing their selection are discussed. It is concluded that the semiconductors should be chosen with high mean atomic weights and that they should be prepared with thermoelectric powers lying between 200 and 300 μVC-1. Preliminary experiments have led to the production of a thermocouple consisting of bismuth telluride, Bi2Te3, and bismuth, capable of maintaining 26 C of cooling.
504 citations
TL;DR: In this article, a number of compounds of V−B and VI−B elements, with chemical formula M 2 v − b N 3 vi − b been synthesized as single crystals of fairly good purity.
375 citations
TL;DR: In this paper, a model for the chemical bondins in bismuth telluride is proposed, which appears to dispose of some of the difficulties involved in earlier models, and is used to explain some properties of BTE and its alloys with BTE.
304 citations
TL;DR: In this paper, X-ray photoemission studies were performed on the $4d5s5p$ elements Pd through Te using monochromatized Al ($K\ensuremath{\alpha}$) radiation.
Abstract: X-ray photoemission studies were performed on the $4d5s5p$ elements Pd through Te using monochromatized Al ($K\ensuremath{\alpha}$) radiation. With increasing atomic number the $4d$ structure evolves from $d$ bands to spin-orbit---split atomiclike core levels. Structure was observed in the $5s5p$ bands for the first time by this method. The cohesive energy was attributed to the $5p$ bands in In through Sb. Evidence for both bonding and nonbonding $5p$ bands was obtained for Te.
109 citations