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111.
Andrzej Sobczynski 《Monatshefte für Chemie / Chemical Monthly》1992,123(3):211-216
Summary Silica-supported cadmium sulfide, highly active in hydrogen photogeneration from water-methanol-KOH solution, was prepared by sulfidation of Cd2+-impregnated SiO2. The samples consisted of colloidal-size hexagonal crystallites of CdS on amorphous SiO2. A blue shift of a light absorption edge was observed for the samples with lower CdS content.
Herstellung und photokatalytische Aktivität von feinen CdS-Pulvern auf SiO2
Zusammenfassung Es wurde Cadmiumsulfid auf Kieselgel durch Sulfidierung von Cd2+-imprägniertem SiO2 hergestellt, das eine außerordentliche Aktivität bei der Wasserstoff-Photogenerierung aus Wasser-Methanol-KOH-Lösungen zeigte. Der Katalysator bestand aus hexagonalen CdS-Kristalliten von kolloidalen Ausmaßen auf amorphem SiO2. An Proben mit geringerem CdS-Gehalt wurde eine Blauverschiebung der Lichtabsorption an der Absorptionskante beobachtet.相似文献
112.
Xinbo Zhang Danzi Sun Wenya Yin Yujun Chai Minshou Zhao 《Journal of Solid State Electrochemistry》2006,10(4):236-242
This paper presents results concerning structure and electrochemical characteristics of the La0.67Mg0.33 (Ni0.8Co0.1Mn0.1)
x
(x=2.5–5.0) alloy. It can be found from the result of the Rietveld analyses that the structures of the alloys change obviously
with increasing x from 2.5 to 5.0. The main phase of the alloys with x=2.5–3.5 is LaMg2Ni9 phase with a PuNi3-type rhombohedral structure, but the main phase of the alloys with x=4.0–5.0 is LaNi5phase with a CaCu5-type hexagonal structure. Furthermore, the phase ratio, lattice parameter and cell volume of the LaMg2Ni9phase and the LaNi5 phase change with increasing x. The electrochemical studies show that the maximum discharge capacity increases from 214.7 mAh/g
(x=2.5) to 391.1 mAh/g (x=3.5) and then decreases to 238.5 mAh/g (x=5.0). As the discharge current density is 1,200 mA/g, the high rate dischargeability (HRD) increases from 51.1% (x=2.5) to 83.7% (x=3.5) and then decreases to 71.6% (x=5.0). Moreover, the exchange current density (I
0) of the alloy electrodes first increases and then decrease with increasing x from 2.5 to 5.0, which is consistent with the variation of the HRD. The cell volume reduces with increasing x in the alloys, which is detrimental to hydrogen diffusion and accordingly decreases the low-temperature dischargeability
of the alloy electrodes. 相似文献
113.
Bodnarchuk M. I. Kovalenko M. V. Stroyuk A. L. Kuchmii S. Ya. 《Theoretical and Experimental Chemistry》2004,40(5):287-292
The photochemical behavior of solutions containing a mixture of CdS and CdTe nanoparticles under pulsed irradiation conditions was investigated. It was shown that electron transfer from the CdS particles to the CdTe nanoparticles occurs during the photoexcitation of such systems. The effectiveness of the process is increased with increase in the size of the CdTe nanoparticles. Such behavior is due to decrease in the potential of the CdTe conduction band with increase in the size of the nanoparticles as a result of the appearance of quantum-dimensional effects. 相似文献
114.
Michael J. Chetcut 《Journal of Cluster Science》1996,7(3):225-245
Complexes that contain both a group 6 group 10 metal combination and a sulfur bound ligand form a growing set of species. Their chemistry is discussed and reviewed. Ligands that bind to such heterobimetallic molecules most commonly are S2– and SR– species. Metal-metal bonded complexes, and compounds where metal-metal interactions are minimal are both discussed. The structural parameters for many of the crystallographically characterized complexes are tabulated. 相似文献
115.
几种热塑性特种工程塑料的热分析研究 总被引:5,自引:0,他引:5
聚芳醚和聚芳硫醚两类聚合物都为热塑性的耐高温特种高分子材料 ,由于它们的加工性好、加工成型效率高 ,受到了世界各国的高度重视。这两类聚合物在结构上有许多相似之处 ,如它们的主链都含苯环、酮基或砜基 ,而聚芳醚类聚合物的柔性基团为醚键 ,聚芳硫醚类聚合物的柔性基团为硫醚键 ,但由于氧和硫在元素周期表中属于同一族元素 ,原子结构仍然相似 ,因而在某些方面具有一定的可比性。研究它们的性能差异对于改进聚合物性能以及进行进一步的结构设计将有一定的帮助。在这两类聚合物中 ,国内已商品化生产的品种有PEEK、PES和PPS ,有… 相似文献
116.
“Simple” energetic patterns, where simple means the use of parameters derived only from the stoichiometry of these species,
are relatively rarely discussed in the literature. In addition, entropy studies have been dominated by derivation of the absolute
quantity S° rather than the entropy of formation (TΔf
S
o). Relationships between the entropy of formation and different parameters such as negative value of the charge of the species,
the number of oxygen atoms, the natural logarithm of the molecular weight, the total number of atoms and the number of central
atoms that are gases were recently discussed by us for aqueous polynuclear oxyanions. As shown here hydrogen containing anions
do not follow this pattern. In this study, new approaches for the estimation of the entropy of formation of aqueous hydrogen
containing mono and polynuclear oxyanions are suggested, evaluated and recommended. 相似文献
117.
F. Muktepavela M. Vasylyev A. Czerwinski Z. Rogulski 《Journal of Solid State Electrochemistry》2003,7(2):83-86
The humid air induced processes of embrittlement of the Sn–Al alloy and hydrogen emission have been investigated. Using the
secondary-ion mass spectrometry, X-ray, scanning electron microscopy and energy-dispersive X-ray spectrometry techniques it
was found that the brittleness is caused by a failure of phase adhesion due to accumulation of hydrogen and formation of oxidized
layers on phase boundaries during contact of the alloy with water vapour. Specific physical and electrochemical properties
of the Sn/Al phase boundary satisfy conditions for the formation of atomic hydrogen and its reaction with Sn. Electrochemical
corrosion plays an important role at the stage of formation of atomic hydrogen. The penetration of hydrogen and its accumulation
in the bulk of the alloy is due to the high energy of the phase boundary and the low energy of formation of unstable tin hydride.
Electronic Publication 相似文献
118.
Kedong Xia Junpo Guo Cuijuan Xuan Ting Huang Zhiping Deng Lingxuan Chen Deli Wang 《中国化学快报》2019,30(1):192-196
Nitrogen doped carbon nanosheets supported molybdenum carbides nanoparticles (MoxC/NCS) have been synthesized by tuning the mass ratio of melamine and ammonia molybdate. The Mo2C/NCS-10 exhibits superior electrocatalytic performance and stability for HER, which was attributed to N-doped carbon nanosheets, small particle size, mesoporous structure, and large electrochemical active surface area. 相似文献
119.
Tianhong Zhang Morton H. Litt Charles E. Rogers 《Journal of polymer science. Part A, Polymer chemistry》1994,32(7):1323-1330
Three poly(ethylene oxide-co-ethylene sulfide)s with oxygen to sulfur ratios of 2/1, 2/2, and 1/2 were prepared by phase-transfer catalyzed polycondensations of (1) sodium sulfide and 1,2-bis (2-chloroethoxy)ethane, (2) 1,2-ethanedithiol and 1,2-bis(2-chloroethoxy)ethane, and (3) 1,2-ethanedithiol and 2-chloroethyl ether, respectively. A buffered solution with pH between the pKa of the monothiol (RSH) and the pKa2 of the dithiol (HS–R–SH), or H2S, was needed to obtain high molecular weight polymers, which suggests that nucleophiles transfer and react as monoanions rather than dianions. These poly(ethylene oxide-co-ethylene sulfide)s were oxidized completely to poly(ethylene oxide-co-ethylene sulfone)s using 3-chloroperoxybenzoic acid as oxidant. Both the final polymers and the precursors have regular sequenced structures and are semicrystalline. As expected, their glass transition temperatures and melting points increase and solubilities decrease with the decrease of ether oxygen to sulfur ratio. © 1994 John Wiley & Sons, Inc. 相似文献
120.
The structural properties of the Mg0.65Sc0.35Dx deuterides have been investigated by X-ray and neutron powder diffraction at different deuterium content (0?x?2.2 D/f.u.). The metallic phase adopts a pseudo-CsCl structure (Pm-3m space group (SG); a=3.5921(2) Å) that transforms upon hydrogenation into a face centered cubic (FCC) phase involving an elongation of the c-axis, a shrinkage of the a-axis and a re-ordering of the metallic atoms. The fully hydrided compound (2.2 D/f.u.) adopts a cubic structure (Fm-3m SG; a=4.8087(7) Å) and deuterium is located in fully occupied tetrahedral sites and partially filled (24%) octahedral sites. Upon desorption, a two-phase domain appears with coexistence of a hydrogen-rich (1.55 D/f.u.) and a hydrogen-poor (0.85 D/f.u.) phase (Fm-3m SG; a=4.7598(3) and 4.6936(3) Å, respectively). All deuterium atoms are located in the tetrahedral sites with different occupancy factors: 77% for the H-rich phase and 43% for the H-poor phase. The appearance of a plateau in the pressure-composition-isotherm curve measured at 573 K confirms this two-phase behavior. The structural properties of the Mg0.65Sc0.35Dx system are discussed and compared with other body centered cubic (BCC) alloys adopting the same structure. 相似文献