The Experts below are selected from a list of 1818 Experts worldwide ranked by ideXlab platform
Ekaterina A Kozlova - One of the best experts on this subject based on the ideXlab platform.
-
effect of titania regular macroporosity on the photocatalytic hydrogen evolution on cd1 xznxs tio2 catalysts under visible light
Chemcatchem, 2015Co-Authors: Ekaterina A Kozlova, Anna Yu Kurenkova, Victoria S Semeykina, E V Parkhomchuk, Svetlana V Cherepanova, Evgeny Yu Gerasimov, A A Saraev, V V Kaichev, V N ParmonAbstract:Multiphase photocatalysts Cd1−xZnxS/TiO2 were synthesized through the deposition of solid solutions of cadmium and Zinc Sulfides on the surface of titania samples with different porous structures, including a 3D-ordered meso/macroporous structure. The photocatalysts were characterized by a wide range of experimental techniques: X-ray diffraction, high-resolution transmission electron microscopy combined with energy-dispersive X-ray spectroscopy, N2 adsorption at 77 K, X-ray photoelectron spectroscopy, and UV/VIS spectroscopy. The photocatalytic activity was tested in a batch reactor for the H2 evolution reaction from aqueous solutions of Na2S/Na2SO3 under visible-light irradiation (λ=450 nm). The highest achieved photocatalytic activity was 1.8 mmol H2 per gram of photocatalyst per hour. The regular porous structure of titania was demonstrated to enhance the photocatalytic activity and stability of Cd0.4Zn0.6S/TiO2 samples.
-
new photocatalysts based on cadmium and Zinc Sulfides for hydrogen evolution from aqueous na2s na2so3 solutions under irradiation with visible light
Kinetics and Catalysis, 2012Co-Authors: T P Lyubina, Ekaterina A KozlovaAbstract:Noble metal-free, Cd1 − x Zn x S-based photocatalysts for hydrogen evolution from aqueous solutions of sodium sulfide and sodium sulfite upon irradiation with visible light (λ > 420 nm) have been synthesized and characterized by a complex of physicochemical methods. The effects of pH and catalyst and substrate concentrations on the rate of photocatalytic hydrogen evolution have been investigated. Under the optimal conditions, the quantum efficiency of the process is up to 12.9%.
Maria Luisa Foresti - One of the best experts on this subject based on the ideXlab platform.
-
ternary cadmium and Zinc Sulfides composition morphology and photoelectrochemistry
Electrochimica Acta, 2004Co-Authors: Massimo Innocenti, Sandro Cattarin, Francesca Loglio, T Cecconi, G Seravalli, Maria Luisa ForestiAbstract:Morphology, structure and electronic properties of CdS, ZnS and the mixed ternary compounds of formula Cd x Zn 1-x S deposited on Ag(111) by electrochemical atomic layer epitaxy (ECALE) have been characterized as a function of the composition. The number of the attainable x values is limited by the necessity of using well-defined ZnS/CdS deposition sequences. However, the quantitative analysis carried out with different techniques indicates that the ECALE method has a good control on composition. The morphological analysis, performed on the basis of the roughness and clusters' size evaluation, indicates both two-dimensional and three-dimensional growth. Photoelectrochemical measurements, carried out at the film electrodes in liquid junction with an alkaline (poly)sulfide electrolyte, show in all cases photospectra shapes typical of a direct transition. The bandgap of Cd x Zn 1-x S is roughly linear with composition parameter x, a behavior consistent with the formation of solid solutions in a system without miscibility gap. Despite the limits and deviations from an ideal epitaxial process, the ECALE method provides mixed ternary compounds with predictable composition and related electronic properties (e.g. the bandgap).
-
ternary cadmium and Zinc Sulfides and selenides electrodeposition by ecale and electrochemical characterization
Journal of Electroanalytical Chemistry, 2004Co-Authors: Francesca Loglio, Massimo Innocenti, Giovanni Pezzatini, Maria Luisa ForestiAbstract:Abstract Ternary compound semiconductors such as Cd x Zn 1− x S (with 0.75> x >0.31) and Cd x Zn 1− x Se (with 0.74> x >0.34) were grown on Ag (1 1 1) by the electrochemical atomic layer epitaxy (ECALE) method. The interest in ternary compounds arises from the possibility of varying the bandgap with composition. The elements forming the ternary cadmium and Zinc sulfide were, at first, deposited in the sequence: S/Cd/S/Zn…, the order being one cycle of CdS and one cycle of ZnS. However, the quantitative analysis of the compound obtained revealed a very high percentage of Cd, roughly 75%. This means that the presence of cadmium somehow hinders Zn deposition. The most effective way to increase the amount of Zn is to deposit more cycles of ZnS. As an example, the compound with 50% of Cd and 50% of Zn is obtained by performing 3 deposition cycles of ZnS per deposition cycle of CdS. Therefore, the stoichiometry of the ternary Sulfides depends on the ZnS/CdS deposition sequence. An analogous result was obtained for Cd x Zn 1− x Se. The stoichiometry of the compounds obtained with different deposition sequences was determined by classical quantitative analysis after dissolving the deposits. The composition measurements were confirmed by ex situ X-ray photoelectron spectroscopy (XPS) in ultra-high vacuum. The right 1:1 ratio between cations and anions was found for all compounds examined, whatever the stoichiometry. A systematic electrochemical investigation was carried out with ZnS/CdS deposition sequences equal to 1, 2, 5.
Massimo Innocenti - One of the best experts on this subject based on the ideXlab platform.
-
ternary cadmium and Zinc Sulfides composition morphology and photoelectrochemistry
Electrochimica Acta, 2004Co-Authors: Massimo Innocenti, Sandro Cattarin, Francesca Loglio, T Cecconi, G Seravalli, Maria Luisa ForestiAbstract:Morphology, structure and electronic properties of CdS, ZnS and the mixed ternary compounds of formula Cd x Zn 1-x S deposited on Ag(111) by electrochemical atomic layer epitaxy (ECALE) have been characterized as a function of the composition. The number of the attainable x values is limited by the necessity of using well-defined ZnS/CdS deposition sequences. However, the quantitative analysis carried out with different techniques indicates that the ECALE method has a good control on composition. The morphological analysis, performed on the basis of the roughness and clusters' size evaluation, indicates both two-dimensional and three-dimensional growth. Photoelectrochemical measurements, carried out at the film electrodes in liquid junction with an alkaline (poly)sulfide electrolyte, show in all cases photospectra shapes typical of a direct transition. The bandgap of Cd x Zn 1-x S is roughly linear with composition parameter x, a behavior consistent with the formation of solid solutions in a system without miscibility gap. Despite the limits and deviations from an ideal epitaxial process, the ECALE method provides mixed ternary compounds with predictable composition and related electronic properties (e.g. the bandgap).
-
ternary cadmium and Zinc Sulfides and selenides electrodeposition by ecale and electrochemical characterization
Journal of Electroanalytical Chemistry, 2004Co-Authors: Francesca Loglio, Massimo Innocenti, Giovanni Pezzatini, Maria Luisa ForestiAbstract:Abstract Ternary compound semiconductors such as Cd x Zn 1− x S (with 0.75> x >0.31) and Cd x Zn 1− x Se (with 0.74> x >0.34) were grown on Ag (1 1 1) by the electrochemical atomic layer epitaxy (ECALE) method. The interest in ternary compounds arises from the possibility of varying the bandgap with composition. The elements forming the ternary cadmium and Zinc sulfide were, at first, deposited in the sequence: S/Cd/S/Zn…, the order being one cycle of CdS and one cycle of ZnS. However, the quantitative analysis of the compound obtained revealed a very high percentage of Cd, roughly 75%. This means that the presence of cadmium somehow hinders Zn deposition. The most effective way to increase the amount of Zn is to deposit more cycles of ZnS. As an example, the compound with 50% of Cd and 50% of Zn is obtained by performing 3 deposition cycles of ZnS per deposition cycle of CdS. Therefore, the stoichiometry of the ternary Sulfides depends on the ZnS/CdS deposition sequence. An analogous result was obtained for Cd x Zn 1− x Se. The stoichiometry of the compounds obtained with different deposition sequences was determined by classical quantitative analysis after dissolving the deposits. The composition measurements were confirmed by ex situ X-ray photoelectron spectroscopy (XPS) in ultra-high vacuum. The right 1:1 ratio between cations and anions was found for all compounds examined, whatever the stoichiometry. A systematic electrochemical investigation was carried out with ZnS/CdS deposition sequences equal to 1, 2, 5.
Guodong Zhao - One of the best experts on this subject based on the ideXlab platform.
-
production of Zinc and lead concentrates from lean oxidized Zinc ores by alkaline leaching followed by two step precipitation using Sulfides
Hydrometallurgy, 2011Co-Authors: Youcai Zhao, Guodong ZhaoAbstract:Abstract An integrated hydrometallurgical process for the production of Zinc and lead concentrates from lean oxidized Zinc ores by alkaline leaching, followed by two-step sulfide precipitation of lead and Zinc Sulfides, is developed. The lean Zinc oxidized ore was firstly ground to a size below 0.2 mm, followed by alkaline leaching at 90 °C for 120 min in NaOH solution, in which both Zinc and lead are effectively extracted. Lead concentrates were then highly selectively and quantitatively produced from the leach solution by adding sodium sulfide as precipitant. Zinc concentrates were obtained in the same way from the Pb-free solution. Optimum conditions of lead precipitation were found to be 1.8 Na 2 S·9H 2 O/Pb weight ratio, 90 °C, 60 min and those for Zinc precipitation were 2.4 Na 2 S·9H 2 O/Zn weight ratio, 90 °C, 180 min. Finally, a scale-up experiment was carried out and found that the lead and Zinc total extraction both reached above 80% calculated from the ores and the quality of lead and Zinc concentrates can meet industrial requirements for roasting processes. Meanwhile, it was found that the loss of NaOH is negligible and the main consumption of chemicals was that of sodium sulfide.
Francesca Loglio - One of the best experts on this subject based on the ideXlab platform.
-
ternary cadmium and Zinc Sulfides composition morphology and photoelectrochemistry
Electrochimica Acta, 2004Co-Authors: Massimo Innocenti, Sandro Cattarin, Francesca Loglio, T Cecconi, G Seravalli, Maria Luisa ForestiAbstract:Morphology, structure and electronic properties of CdS, ZnS and the mixed ternary compounds of formula Cd x Zn 1-x S deposited on Ag(111) by electrochemical atomic layer epitaxy (ECALE) have been characterized as a function of the composition. The number of the attainable x values is limited by the necessity of using well-defined ZnS/CdS deposition sequences. However, the quantitative analysis carried out with different techniques indicates that the ECALE method has a good control on composition. The morphological analysis, performed on the basis of the roughness and clusters' size evaluation, indicates both two-dimensional and three-dimensional growth. Photoelectrochemical measurements, carried out at the film electrodes in liquid junction with an alkaline (poly)sulfide electrolyte, show in all cases photospectra shapes typical of a direct transition. The bandgap of Cd x Zn 1-x S is roughly linear with composition parameter x, a behavior consistent with the formation of solid solutions in a system without miscibility gap. Despite the limits and deviations from an ideal epitaxial process, the ECALE method provides mixed ternary compounds with predictable composition and related electronic properties (e.g. the bandgap).
-
ternary cadmium and Zinc Sulfides and selenides electrodeposition by ecale and electrochemical characterization
Journal of Electroanalytical Chemistry, 2004Co-Authors: Francesca Loglio, Massimo Innocenti, Giovanni Pezzatini, Maria Luisa ForestiAbstract:Abstract Ternary compound semiconductors such as Cd x Zn 1− x S (with 0.75> x >0.31) and Cd x Zn 1− x Se (with 0.74> x >0.34) were grown on Ag (1 1 1) by the electrochemical atomic layer epitaxy (ECALE) method. The interest in ternary compounds arises from the possibility of varying the bandgap with composition. The elements forming the ternary cadmium and Zinc sulfide were, at first, deposited in the sequence: S/Cd/S/Zn…, the order being one cycle of CdS and one cycle of ZnS. However, the quantitative analysis of the compound obtained revealed a very high percentage of Cd, roughly 75%. This means that the presence of cadmium somehow hinders Zn deposition. The most effective way to increase the amount of Zn is to deposit more cycles of ZnS. As an example, the compound with 50% of Cd and 50% of Zn is obtained by performing 3 deposition cycles of ZnS per deposition cycle of CdS. Therefore, the stoichiometry of the ternary Sulfides depends on the ZnS/CdS deposition sequence. An analogous result was obtained for Cd x Zn 1− x Se. The stoichiometry of the compounds obtained with different deposition sequences was determined by classical quantitative analysis after dissolving the deposits. The composition measurements were confirmed by ex situ X-ray photoelectron spectroscopy (XPS) in ultra-high vacuum. The right 1:1 ratio between cations and anions was found for all compounds examined, whatever the stoichiometry. A systematic electrochemical investigation was carried out with ZnS/CdS deposition sequences equal to 1, 2, 5.
