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81.
MingZhuLIU ShengYiZHANG YuHuaSHEN MingLiangZHANG 《中国化学快报》2004,15(10):1249-1252
Selenium nanoparticles were prepared by a reverse microemulsion system. Sodium selenosulfate was used as selenium source. The results showed that hydrochloric acid concentration and reaction temperature had great influence on the morphology of products. The crystalline selenium nanowires and amorphous selenium nanorods were obtained in given condition. 相似文献
82.
Fonseca GS Umpierre AP Fichtner PF Teixeira SR Dupont J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(14):3263-3269
Stable transition-metal nanoparticles of the type [M(0)](n) are easily accessible through the reduction of Ir(I) or Rh(III) compounds dissolved in "dry" 1-n-butyl-3-methylimidazolium hexafluorophosphate ionic liquid by molecular hydrogen. The formation of these [M(0)](n) nanoparticles is straightforward; they are prepared in dry ionic liquid whereas the presence of the water causes the partial decomposition of ionic liquid with the formation of phosphates, HF and transition-metal fluorides. Transmission electron microscopy (TEM) observations and X-ray diffraction analysis (XRD) show the formation of [Ir(0)](n) and [Rh(0)](n) nanoparticles with 2.0-2.5 nm in diameter. The isolated [M(0)](n) nanoparticles can be redispersed in the ionic liquid, in acetone or used in solventless conditions for the liquid-liquid biphasic, homogeneous or heterogeneous hydrogenation of arenes under mild reaction conditions (75 degrees C and 4 atm). The recovered iridium nanoparticles can be reused several times without any significant loss in catalytic activity. Unprecedented total turnover numbers (TTO) of 3509 in 32 h, for arene hydrogenation by nanoparticles catalysts, have been achieved in the reduction of benzene by the [Ir(0)](n) in solventless conditions. Contrarily, the recovered Rh(0) nanoparticles show significant agglomeration into large particles with a loss of catalytic activity. The hydrogenation of arenes containing functional groups, such as anisole, by the [Ir(0)](n) nanoparticles occurs with concomitant hydrogenolysis of the C-O bond, suggesting that these nanoparticles behave as "heterogeneous catalysts" rather than "homogeneous catalysts". 相似文献
83.
Mireille Richard-Plouet Jean-Louis Guille Yves Frere Louis Danicher 《Journal of Sol-Gel Science and Technology》2002,25(3):207-213
A new process to control the distribution of metal nanoparticles is proposed. It involves the use of complexing microcapsules obtained by interfacial polycondensation. The latter are hollow spheres constituted of a polymer membrane, containing an insoluble active ingredient, such as a polyacrylic acid, which can complex Co2+ ions. These capsules are dispersed in a silica sol followed by thermal treatments and reduction under H2 which results in metallic Co nanoparticles confined in the capsules domains. The particles do not diffuse in the matrix. 相似文献
84.
Bitao Su Ke Wang Jie Bai Hongmei Mu Yongchun Tong Shixiong Min Shixiong She Ziqiang Lei 《Frontiers of Chemistry in China》2007,2(4):364-368
Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized
by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultravioletvisible spectroscopy (UV-Vis) diffuse reflectance
spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic
activity of Fe3+/TiO2 nanoparticles under visible light irradiation. The influence of doping amount of Fe3+ (ω: 0.00%–3.00%) on photocatalytic activities of TiO2 was investigated. Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorption spectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The
appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.
__________
Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(6): 55–56 [译自: 西北师范大学学报(自然科学版)] 相似文献
85.
86.
Sandrine Bouquillon Ulla Létinois-Halbes Jacques Muzart 《Journal of organometallic chemistry》2003,687(2):377-383
The reaction between palladium acetate, (−)-ephedrine and potassium acetate led to bis-chelate complex Pd[OCH(Ph)NH(Me)]2 whose the trans-structure is obtained from calculations. The use of this complex to catalyze either the 1,4-hydrogenation of (E)-2-benzyliden-1-tetralone or Heck reaction of phenyl iodide with 3-methyl-3-buten-2-ol led to a low enantiomeric excess. 相似文献
87.
G. P. Papapolymerou 《Reaction Kinetics and Catalysis Letters》1996,58(1):199-205
The unimolecular decomposition of NO has been examine on Pd and Ir and they are compared with the corresponding reactions on Pt and Rh. The runs were carried out in a differential flow reactor, at pressures from 0.01 to 5 Torr and temperatures from 500 to 1800 K. It was found that all rates of product formation could be described by Langmuir-Hinshelwood unimolecular rate expression, with an accuracy of±20% und all conditions. The decomposition of NO was virtually identical on Pt and Pd, and on Rh and Ir, but varied widely with temperature between these two groups of metals. 相似文献
88.
Electronic structure of optimized Ge5, Ge17, Ge5–O and Ge5 embedded in SiO2 nanoparticles have been studied by density functional theory to find out the effect of cluster size and Ge–O bond(s) on the optical energy gap between LUMO and HOMO. It was found that the optical energy gap depends on both cluster size and the number of Ge–O bonds nonlinearly. The optical energy gap was found to be in visible light range when the Ge5 nanoparticle has been embedded in SiO2 matrix. 相似文献
89.
一维链状冠醚配合物:[{Na(18-C-6)}2(H2O)]n[M(SCN)4]n(M=Pd、Pt)的合成与结构 总被引:1,自引:0,他引:1
The reactions of 18-crown-6 with Na2[M(SCN)4] (M= Pd,Pt) were studied and the complex 1 [{Na(18-C-6)}2(H2O)]n[Pd(SCN)4]n and complex 2 [{Na(18-C-6)}2(H2O)]n[Pt(SCN)4]n were characterized by ele-mental analysis, IR and X-ray diffraction analysis. The complexes belong to monoclinic, space group P21/n with cell dimensions, 1:a=1.05734(7),b=1.42250(10),c=1.47762(10) nm,β=107.5330(10)°,V=2.1192(2)nm3,Z=2,Dcalcd=1.460g·cm-3,F(000)=964,R1=0.0406,wR2=0.1264 and 2:a=1.05985(19),b=1.4237(3),c=1.4744(3) nm,β=107. 096(3)°, V=2.1264(7)nm3,Z=2,Dcalcd=1.690g·cm-3,F(000)=1028,R1=0.0292,wR2=0.0859. In the solid state, the complexes 1 and 2 show an one-dimensional chain of [{Na(18-C-6)}2(H2O)]2+ complex cations and [M(SCN)4]2- (M=Pd,Pt) complex anions bridged by Na-N in-teractions. 相似文献
90.
A kind of inorganic‐organic hybrid 18‐molybdodiphosphate nanoparticles ([(C4H9)4N]6P2Mo18Q62·4H2O) was firstly used as a bulk‐modifier to fabricate a three‐dimensional chemically modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior of the solid nanoparticles dispersed in the CPE in acidic aqueous solution was characterized by cyclic and square‐wave voltammetry. The hybrid 18‐molybdodiphosphate nanoparticles bulk‐modified CPE (MNP‐CPE) displayed a high electrocatalytic activity towards the reduction of nitrite, bromate and hydrogen peroxide. The remarkable advantages of the MNP‐CPE over the traditional polyoxometalates‐modified electrodes are their excellent reproducibility of surface‐renewal and high stability owing to the insolubility of the hybrid 18‐molybdodiphosphate nanoparticles. 相似文献