共查询到20条相似文献,搜索用时 49 毫秒
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Ya.M. Kolotyrkin G.M. Florianovich V.A. Goryachkin F.M. Mikheyeva 《Journal of Electroanalytical Chemistry》1976,69(3):407-414
It was established that addition of hydrogen peroxide to a solution of sulphuric acid leads to acceleration of the active dissolution of chromium and to the shift of its passivation potential in negative direction. Similar data were obtained for Fe-28% Cr alloy in H2SO4 solution containing H2O2 and for iron in sulphuric acid with K2Cr2O7 additions. The conclusion was made that depending on the potential the molecules of oxygen-containing oxidizers can undergo different transmissions on the surface of the metal, including transformations connected with the direct participation of the oxidizer in the anodic dissolution of the metal or in the building of inhibiting or passivating layers on the metallic surface. 相似文献
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Zhang XQ Trinh TT van Santen RA Jansen AP 《Journal of the American Chemical Society》2011,133(17):6613-6625
The mechanism of the initial stage of silicate oligomerization from solution is still not well understood. Here we use an off-lattice kinetic Monte Carlo (kMC) approach called continuum kMC to model silicate oligomerization in water solution. The parameters required for kMC are obtained from density functional theory (DFT) calculations. The evolution of silicate oligomers and their role in the oligomerization process are investigated. Results reveal that near-neutral pH favors linear growth, while a higher pH facilitates ring closure. The silicate oligomerization rate is the fastest at pH 8. The temperature is found to increase the growth rate and alter the pathway of oligomerization. The proposed pH and temperature-dependent mechanism should lead to strategies for the synthesis of silicate-based materials. 相似文献
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V. I. Alekseev M. M. Perkas V. S. Yusupov G. Yu. Lazarenko 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(8):1380-1385
The main regularities of variations in the thermodynamic properties of components of cubic vanadium carbide, depending on the composition in the region of homogeneity, are investigated experimentally. It is believed that these regularities are inherent only to metal oxides. This serves as the basis for the concept that passivation during the corrosion of metals occurs due to the formation of surface metal oxide whose composition corresponds to the maximum concentration of oxygen in the region of homogeneity. The thermodynamic stimulus of corrosion is in this case reduced to almost zero. 相似文献
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Il Kim Hong Ki Choi Jae Ha Kim Seong Ihl Woo 《Journal of polymer science. Part A, Polymer chemistry》1994,32(5):971-977
The kinetics of propylene polymerization catalyzed over a superactive and stereospecific catalyst for the initial build-up period was investigated in slurry-phase. The catalyst was prepared from Mg(OEt)2/benzoyl chloride/TiCl4 co-activated with AlEt3 in the absence or presence of external donor. Despite a very fast activation of the prepared catalyst the acceleration stage of polymerization could be identified by the precise estimation of polymerization kinetics for a very short period of time after the commencement of polymerization (ca. 2 min). The initial polymerization rate, (dRp/dt)0 extrapolated to the beginning of the polymerization was second order with respect to monomer concentration. The dependence of initial polymerization rate on the concentration of AlEt3 could be represented by Langmuir adsorption mechanism. The initial rate was maximum at about Al/Ti ratio of 20. The activation energy for the initiation reaction was estimated to be 14.3 kcal/mol for a short-time polymerization. The addition of a small amount of p-ethoxy ethyl benzoate (PEEB) as an external donor increased the percentage of isotactic polymer, which was obtained after 120 s of polymerization, to 98% and the initial polymerization rate decreased sharply as [PEEB]/[AlEt3] increased. © 1994 John Wiley & Sons, Inc. 相似文献
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V. Yu. Frolov A. I. Oflidi S. N. Bolotin A. I. Shestavin V. T. Panyushkin 《Russian Journal of Applied Chemistry》2008,81(4):639-642
Effect of anode amalgamation on the degree of passivation of the electrodes and on the current efficiency in electrosynthesis of coordination compounds of copper(II), nickel(II), zinc(II), and cadmium(II) with galactaric acid was studied. An improvement of anodic synthesis characteristics was observed when amalgamated zinc, copper, and cadmium were used. Complex compounds of 1 : 1 composition were obtained and the structure of the coordination environment of the metal ion was determined by IR spectroscopy. 相似文献
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Zhenghui Fan Yuan Yin Bing Cai Qingshan Ma Qianlong Liu Xinhang Liu Yinhua Lv Wen-Hua Zhang 《Chemical science》2022,13(35):10512
Defect passivation along with promoted charge transport is potentially an effective but seldom exploited strategy for high-performance perovskite solar cells (PSCs). Herein, the in situ defect passivation and carrier transport improvement are simultaneously realized by introducing a conductive polymer (i.e., emerald salt, ES) into the precursor solution of methylammonium (MA)-free perovskites. The interaction between ES and uncoordinated Pb2+ reduces defect density to suppress the non-radiative recombination. Moreover, ES can act as a “carrier driver” to promote the carrier transport due to its conductive feature, resulting in efficient PSC devices with a decent power conversion efficiency (PCE) of 23.0%, which is among the most efficient MA-free PSCs. The ES-based unencapsulated devices show superior stability, retaining 89.1% and 83.8% of their initial PCEs when subjected to 35 ± 5% relative humidity (RH) storage and 85 °C thermal aging for 1000 h, respectively. To further assess the large-area compatibility of our strategy, 5 × 5 cm2 mini modules were also fabricated, delivering an impressive efficiency of 19.3%. This work sheds light on the importance of conductive additives in boosting cell performance by playing multiple roles in passivating defects, retarding the moisture invasion, and enhancing and balancing charge transport.A conductive polymer, emerald salt (ES), is introduced into methylammonium (MA)-free perovskite solar cells, enhancing the device performance and stability by passivating defects, promoting charge transportation, and retarding the moisture invasion. 相似文献
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Traces of Fe, Co, Ni, Cu, Zn, Cd and Pb in salt solutions (e.g. KCl, Ca(NO3)2, A12(SO4)3, Cr2(SO4)3, (NH4)2SO4) are determined by flame AAS after preconcentration with thiuram disulphide (TDS) as collector precipitate. The preconcentration recovery is mainly influenced by pH, TDS amount and its aging in the sample solution. Conditions of an optimal preconcentration procedure were elaborated. Detection limits vary from 0.5 ng/ml (for Cd) to 8.3 ng/ml (for Pb) and the relative standard deviation is 2 to 6 %. The accuracy of the results was checked by differential pulse anodic stripping voltammetry and by electrothermal AAS. 相似文献
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G.A. Razuvaev A.V. Shabanov A.N. Egorochkin V.A. Kuznetzov S.F. Zhiltsov 《Journal of organometallic chemistry》1980,202(4):363-378
Complexing of molecular oxygen with arylmercury compounds and phenyl derivatives of Group IV and V elements has been studied by electronic spectroscopy. The type of complexing appeared to depend on the nature of the central heteroatom in the organometallic compounds.The chemical model for the reaction of R2Hg (R = Et, n-Pr, n-Bu, Ph) with CCl4 indicates that the complex R2Hg · L (L = molecular oxygen, aromatic compound) is formed in the initial stage of the interaction. By studying the influence of π-donors on this process the correlation between the yield of alkylmercuric chloride and the donor properties of the ligand has been determined. 相似文献
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The formation of narrow pores during leaching of Vycor glass by sulphuric acid was investigated using the positron lifetime technique. During the leaching process the pore diameter remained roughly constant (except for the case of cold leaching). The time of processing changed the total length of capillaries, but not their number; at the temperature 50°C during 20 min of leaching the average leaching depth was 24 μm. 相似文献