Interface and surface analysis of Ru/CdS
01 Jan 1996-Journal of Materials Science Letters (Kluwer Academic Publishers)-Vol. 15, Iss: 21, pp 1921-1923
About: This article is published in Journal of Materials Science Letters.The article was published on 1996-01-01. It has received 4 citations till now.
TL;DR: For a variety of metals and semiconductors, an attempt is made to generalize observations in the literature on the effect of process conditions applied during photodeposition on (i) particle size distributions, (ii) oxidation states of the metals obtained, and (iii) consequences for photocatalytic activities.
Abstract: In this review, for a variety of metals and semiconductors, an attempt is made to generalize observations in the literature on the effect of process conditions applied during photodeposition on (i) particle size distributions, (ii) oxidation states of the metals obtained, and (iii) consequences for photocatalytic activities. Process parameters include presence or absence of (organic) sacrificial agents, applied pH, presence or absence of an air/inert atmosphere, metal precursor type and concentration, and temperature. Most intensively reviewed are studies concerning (i) TiO2; (ii) ZnO, focusing on Ag deposition; (iii) WO3, with a strong emphasis on the photodeposition of Pt; and (iv) CdS, again with a focus on deposition of Pt. Furthermore, a detailed overview is given of achievements in structure-directed photodeposition, which could ultimately be employed to obtain highly effective photocatalytic materials. Finally, we provide suggestions for improvements in description of the photodeposition methods applied when included in scientific papers.
TL;DR: It is demonstrated further that a fine control of the metal Ru nanoparticle size on the TiO2 support was possible via a controlled nanocluster growth under irradiation, while the nanoparticles revealed a good resistance to thermal sintering.
Abstract: Ru/TiO₂ are promising heterogeneous catalysts in different key-reactions taking place in the catalytic conversion of biomass towards fuel additives, biofuels, or biochemicals. TiO₂ supported highly dispersed nanometric-size metallic Ru catalysts were prepared at room temperature via a solar light induced photon-assisted one-step synthesis in liquid phase, far smaller Ru nanoparticles with sharper size distribution being synthesized when compared to the catalysts that were prepared by impregnation with thermal reduction in hydrogen. The underlying strategy is based on the redox photoactivity of the TiO₂ semi-conductor support under solar light for allowing the reduction of metal ions pre-adsorbed at the host surface by photogenerated electrons from the conduction band of the semi-conductor in order to get a fine control in terms of size distribution and dispersion, with no need of chemical reductant, final thermal treatment, or external hydrogen. Whether acetylacetonate or chloride was used as precursor, 0.6 nm sub-nanometric metallic Ru particles were synthesized on TiO₂ with a sharp size distribution at a low loading of 0.5 wt.%. Using the chloride precursor was necessary for preparing Ru/TiO₂ catalysts with a 0.8 nm sub-nanometric mean particle size at 5 wt.% loading, achieved in basic conditions for benefitting from the enhanced adsorption between the positively-charged chloro-complexes and the negatively-charged TiO₂ surface. Remarkably, within the 0.5⁻5 wt.% range, the Ru content had only a slight influence on the sub-nanometric particle size distribution, thanks to the implementation of suitable photo-assisted synthesis conditions. We demonstrated further that a fine control of the metal Ru nanoparticle size on the TiO₂ support was possible via a controlled nanocluster growth under irradiation, while the nanoparticles revealed a good resistance to thermal sintering.
TL;DR: In this paper, the effect of the variation of the incident irradiance and photodeposition rate on the photocatalytic properties of ruthenium nanoparticles supported on TiO2 was evaluated by using the degradation of formic acid in water under UV-A light.
Abstract: Photoassisted synthesis is as a highly appealing green procedure for controlled decoration of semiconductor catalysts with co-catalyst nanoparticles, which can be carried out without the concourse of elevated temperatures, external chemical reducing agents or applied bias potential and in a simple slurry reactor. The aim of this study is to evaluate the control that such a photoassisted method can exert on the properties of ruthenium nanoparticles supported on TiO2 by means of the variation of the incident irradiance and hence of the photodeposition rate. For that purpose, different Ru/TiO2 systems with the same metal load have been prepared under varying irradiance and characterized by means of elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The photocatalytic activity of the so-obtained materials has been evaluated by using the degradation of formic acid in water under UV-A light. Particles with size around or below one nanometer were obtained, depending on the irradiance employed in the synthesis, with narrow size distribution and homogeneous dispersion over the titania support. The relation between neutral and positive oxidation states of ruthenium could also be controlled by the variation of the irradiance. The obtained photocatalytic activities for formic acid oxidation were in all cases higher than that of undecorated titania, with the sample obtained with the lowest irradiation giving rise to the highest oxidation rate. According to the catalysts characterization, photocatalytic activity is influenced by both Ru size and Ru0/Ruδ+ ratio.
TL;DR: In this article, the changes in RuCl 3 formation and surface roughness with various cleaning processes were investigated and it was confirmed that, during Cl 2 dry etching to remove the absorber layer, RuCl3 was formed on the Ru capping layer surface, and the surface roughs thereby deteriorated.
Abstract: Ru-capped extreme ultraviolet lithography photomasks require cleaning after patterning of the absorber layer. In this study, it was confirmed that, during Cl 2 dry etching to remove the absorber layer, RuCl 3 was formed on the Ru capping layer surface, and the surface roughness thereby deteriorated. Therefore, the changes in RuCl 3 formation and surface roughness with various cleaning processes were investigated. Among the treatments used, i . e ., sulfuric peroxide mixture, an ammonia peroxide mixture or ozonated water (DIO 3 ), DIO 3 exhibited the most effective Cl removal efficiency and surface roughness recovery. DIO 3 treatment successfully reduced the Cl-terminated Ru surface to its original state and decreased the surface roughness to the pre-Cl 2 -etched Ru value.
TL;DR: In this article, the Schottky-barrier height of metal interlayers at ultrahigh vacuum-cleaved Au-CdS, CdSe single-crystal interfaces has been used to continuously tune the effectiveSchottky barrier height over the full range reported for metals on these prototypical II-VI semiconductors, i.e., 0.e.
Abstract: Ultrathin reactive Al interlayers at ultrahigh vacuum‐cleaved Au‐CdS, CdSe single‐crystal interfaces have been used to continuously tune the effective Schottky‐barrier height over the full range reported for metals on these prototypical II‐VI semiconductors, i.e., 0–0.8 eV. Measured electrical transport properties are correlated with observed features of atomic interdiffusion chemistry and valence electronic structure.
TL;DR: In this paper, the Schottky barrier height was investigated in UHV-cleaved CdS and CdSe surfaces and metals spanning a wide range of chemical reactivity using UPS and XPS.
Abstract: Interfaces between UHV‐cleaved CdS and CdSe (1010) surfaces and metals spanning a wide range of chemical reactivity have been investigated using UPS and XPS. We have also probed the formation of Schottky barriers via J‐V and C‐V analysis, thus enabling a correlation of measured electrical transport properties with observed features of chemical reaction and interdiffusion. The experimental results reveal a systematic relationship between contact barrier heights and certain critical aspects of the reacted interface region, such as the stoichiometry of semiconductor outdiffusion and the extent of Cd cation dissociation from the reacted interface region. The use of reactive Al interlayers at noble metal contacts to control these aspects of contact formation, and hence the consequent Schottky barrier height, is demonstrated.
TL;DR: This poster presents a poster presenting a probabilistic procedure to characterize the response of the immune system to laser-spot assisted, 3D image analysis of central nervous system injury.
Abstract: Reference LPI-ARTICLE-1981-002doi:10.1002/hlca.19810640626View record in Web of Science Record created on 2006-02-21, modified on 2017-05-12
TL;DR: In this article, a large grain n-CdTe photoelectrochemical (PEC) solar cells were modified by Ru to improve the properties of PEC solar cells.
Abstract: Modification of large grain n-CdTe by Ru is shown to considerably improve the properties of n-CdTe photoelectrochemical (PEC) solar cells. The dark I-V characteristic shows a decrease in J/sub 0/ from 8.6 x 10/sup -8/ to 4.2 x 10/sup -9/ A/cm/sup 2/ and in ideality factor n from 2.12 to 1.16. Under AM1 illumination V/sub oc/ increased from 0.52 to 0.78 V vs. SCE, J/sub sc/ from 3.4 to 5.2 mA/cm/sup 2/, and fill factor from 0.42 to 0.51. The minority carrier diffusion length (L/sub p/) is shown to increase from 0.12 to 0.17 ..mu..m after Ru modification. The improvement has been interpreted as being due to removal of interface states within the bandgap as evident by subbandgap and contact potential difference (CPD) measurements.