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41.
Dr. Weixin Zou Lixia Xu Yu Pu Haojie Cai Xiaoqian Wei Yidan Luo Dr. Lulu Li Prof. Dr. Bin Gao Prof. Dr. Haiqin Wan Prof. Dr. Lin Dong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(19):5058-5064
Bimetallic AgPd nanoparticles have been synthesized before, but the interfacial electronic effects of AgPd on the photocatalytic performance have been investigated less. In this work, the results of hydrogen evolution suggest that the bimetallic AgPd/g-C3N4 sample has superior activity to Ag/g-C3N4 and Pd/g-C3N4 photocatalysts. The UV/Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, CO adsorption diffuse reflectance FTIR spectroscopy, and FTIR results demonstrate that in the AgPd/g-C3N4, the surface electronic structures of Pd and Ag are changed, which is beneficial for faster photogenerated electron transfer and greater H2O molecule adsorption. In situ ESR spectra suggest that, under visible light irradiation, there is more H2O dissociation to radical species on the AgPd/g-C3N4 photocatalyst. Furthermore, DFT calculations confirm the interfacial electronic effects of AgPd/g-C3N4, that is, Pdδ−⋅⋅⋅Agδ+, and the activation energy of H2O molecule dissociation on AgPd/g-C3N4 is the lowest, which is the main contributor to the enhanced photocatalytic H2 evolution. 相似文献
42.
《Arabian Journal of Chemistry》2020,13(2):4246-4253
This study reports a promising method of solid-phase extraction for determining the toluene, ethylbenzene, p-xylene, m-xylene, o-xylene, 1,3,5-trimethylbenzene, and 1,2,4-trimethylbenzene in water samples by gas chromatography–mass spectrometry (GC–MS). Prior to this procedure, the magnesium–aluminum bimetallic hydroxides modified with sodium dodecylbenzenesulfonate (Mg/Al-SDBS-LDH) were prepared and served as the novel solid-phase extractant. The Mg/Al-SDBS-LDH has advantage of good hydrophobicity and larger spacing which facilitates the monoaromatic hydrocarbons (MAHCs) into the interlayer for adsorption. As a result, the seven MAHCs in 500 mL water samples were enriched greatly, and the theoretical enrichment factor reached to 125 times. Under the optimized conditions of solid-phase extraction (SPE) and GC–MS, the mass concentration of each MAHC (0.005–10, 0.01–10, or 0.05–10 ng/mL) had a fine linear relationship with peak area. The correlation coefficients were more than 0.995. The detection limits were between 0.001 and 0.01 ng/mL, and the RSD were between 3.1% and 6.6%. The method had been applied to determine the seven MAHCs in the Dongfengqu river water and laboratory wastewater of Chengdu University of Technology successfully. 相似文献
43.
《应用有机金属化学》2017,31(3)
This work consists of a study of the corrosion‐inhibiting and semiconducting properties of new binuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes with a Schiff base, H2L, obtained from the 2:1 M condensation of salicylaldehyde and o‐dianisidine, respectively. Elemental, spectral and thermal analyses were used to characterize these complexes. The magnetic susceptibilities of these complexes were also determined. Weight loss, potentiodynamic polarization and scanning optical microscopy were the techniques used to investigate the efficiency of these new compounds as corrosion inhibitors. The antibacterial activity of the compounds was measured against sulfate‐reducing bacteria. It was found that inhibition occurs via the chemisorption of metal complexes on the steel surface. This absorption obeys the Langmuir adsorption isotherm model. 相似文献
44.
Dr. Cédric Boulho Dr. Harmen S. Zijlstra Alexander Hofmann Prof. Dr. Peter H. M. Budzelaar Prof. Dr. Sjoerd Harder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17450-17459
Reaction of (TBBP)AlMe ? THF with [Cp*2Zr(Me)OH] gave [(TBBP)Al(THF)?O?Zr(Me)Cp*2] (TBBP=3,3’,5,5’‐tetra‐tBu‐2,2'‐biphenolato). Reaction of [DIPPnacnacAl(Me)?O?Zr(Me)Cp2] with [PhMe2NH]+[B(C6F5)4]? gave a cationic Al/Zr complex that could be structurally characterized as its THF adduct [(DIPPnacnac)Al(Me)?O?Zr(THF)Cp2]+[B(C6F5)4]? (DIPPnacnac=HC[(Me)C=N(2,6‐iPr2?C6H3)]2). The first complex polymerizes ethene in the presence of an alkylaluminum scavenger but in the absence of methylalumoxane (MAO). The adduct cation is inactive under these conditions. Theoretical calculations show very high energy barriers (ΔG=40–47 kcal mol?1) for ethene insertion with a bridged AlOZr catalyst. This is due to an unfavorable six‐membered‐ring transition state, in which the methyl group bridges the metal and ethene with an obtuse metal‐Me‐C angle that prevents synchronized bond‐breaking and making. A more‐likely pathway is dissociation of the Al‐O‐Zr complex into an aluminate and the active polymerization catalyst [Cp*2ZrMe]+. 相似文献
45.
Structural and optical properties of 1 at % Al-doped Zn1−xMgxO (x=0–8%) powders prepared by sol–gel method were systematically investigated by means of X-ray diffraction, scanning electron microscopy, ultraviolet–visible absorbance measurement, photoluminescence and Raman scattering spectra. All the powders retained the hexagonal wurtzite structure of ZnO. The band gap and near band emission energies determined from absorbance and photoluminescence spectra increased linearly with increasing Mg content, respectively, which implied that the Mg worked effectively on ZnO band gap engineering, irrespective of Al codoping. However, according to the PL and Raman scattering studies, for the sample of x=8%, the Al doping efficiency was decreased by higher Mg codoping. On the other hand, the effect of Mg codoping on photocatalytic degradation of methylene orange was explored experimentally. The substitution of Mg ions at Zn sites shifted the conduction band toward higher energies and then enhanced the photocatalytic activity, while the incorporation of interstitial Mg ions and decreased Al doping efficiency for higher Mg doping sample (x=8%) reduced the photocatalytic activity. 相似文献
46.
使用廉价的硅铝合金前驱体,通过简单的化学沉积方法制备了新型双金属(Sn/Ni)掺杂多孔硅微球(pSi@SnNi)。pSi@SnNi复合材料的三维多孔结构可以缓冲硅在锂化过程中的巨大体积膨胀,增加储锂活性位点。双金属(Sn/Ni)的掺杂可以提高硅的电子导电性,改进pSi的结构稳定性。由于其独特的组成和微观结构,具有适当Sn/Ni含量的pSi@SnNi复合材料显示了较大的可逆储锂容量(0.1 A·g-1下为2 651.7 mAh·g-1)、较高的电化学循环稳定性(1 A·g-1下400次循环后为1 139 mAh·g-1)和优异的倍率性能(2.5 A·g-1下为1 235.8 mAh·g-1)。 相似文献
47.
Stéphane Le Gac Luca Fusaro Vincent Dorcet Bernard Boitrel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13253-13253
48.
Dipl.‐Chem. Steffen Styra Dr. Sandra González‐Gallardo Dr. Felix Armbruster Dr. Pascual Oña‐Burgos Dipl.‐Chem. Eric Moos Dr. Matthias Vonderach Priv.‐Doz. Dr. Patrick Weis Priv.‐Doz. Dr. Oliver Hampe Dipl.‐Chem. Anneken Grün Dipl.‐Chem. Yvonne Schmitt Prof. Dr. Markus Gerhards Dipl.‐Chem. Fabian Menges Dipl.‐Chem. Maximilian Gaffga Prof. Dr. Gereon Niedner‐Schatteburg Prof. Dr. Frank Breher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(26):8436-8446
A series of bimetallic silyl halido cuprates consisting of the new tripodal silicon‐based metalloligand [κ3N‐Si(3,5‐Me2pz)3Mo(CO)3]? is presented (pz=pyrazolyl). This metalloligand is straightforwardly accessible by reacting the ambidentate ligand tris(3,5‐dimethylpyrazolyl)silanide ({Si(3,5‐Me2pz)3}?) with [Mo(CO)3(η6‐toluene)]. The compound features a fac‐coordinated tripodal chelating ligand and an outward pointing, “free” pyramidal silyl donor, which is easily accessible for a secondary coordination to other metal centers. Several bimetallic silyl halido cuprates of the general formula [CuX{μ‐κ1Si:κ3N‐Si(3,5‐Me2pz)3Mo(CO)3}]? (X=Cl, Br, I) have been synthesized. The electronic and structural properties of these complexes were probed in detail by X‐ray diffraction analysis, electrospray mass spectrometry, infrared‐induced multiphoton dissociation studies, cyclic voltammetry, spectroelectrochemistry, gas‐phase photoelectron spectroscopy, as well as UV/Vis and fluorescence spectroscopy. The heterobimetallic complexes contain linear two‐coordinate copper(I) entities with the shortest silicon–copper distances reported so far. Oxidation of the anionic complexes in methylene chloride and acetonitrile solutions at ${E{{0\hfill \atop 1/2\hfill}}}$ =?0.60 and ?0.44 V (vs. ferrocene/ferrocenium (Fc/Fc+)), respectively, shows substantial reversibility. Based on various results obtained from different characterization methods, as well as density functional theory calculations, these oxidation events were attributed to the Mo0/MoI redox couple. 相似文献
49.
Dr. Stéphane Le Gac Dr. Btissam Najjari Dr. Vincent Dorcet Dr. Thierry Roisnel Dr. Luca Fusaro Prof. Dr. Michel Luhmer Dr. Eric Furet Dr. Jean‐François Halet Dr. Bernard Boitrel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(33):11021-11038
Overhanging carboxylic acid porphyrins have revealed promising ditopic ligands offering a new entry in the field of supramolecular coordination chemistry of porphyrinoids. Notably, the adjunction of a so‐called hanging‐atop (HAT) PbII cation to regular PbII porphyrin complexes allowed a stereoselective incorporation of the N‐core bound cation, and an allosterically controlled Newton’s cradle‐like motion of the two PbII ions also emerged from such bimetallic complexes. In this contribution, we have extended this work to other ligands and metal ions, aiming at understanding the parameters that control the HAT PbII coordination. The nature of the N‐core bound metal ion (ZnII, CdII), the influence of the deprotonation state of the overhanging COOH group and the presence of a neutral ligand on the opposite side (exogenous or intramolecular), have been examined through 1H NMR spectroscopic experiments with the help of radiocrystallographic structures and DFT calculations. Single and bis‐strap ligands have been considered. They all incorporate a COOH group hung over the N‐core on one side. For the bis‐strap ligands, either an ester or an amide group has been introduced on the other side. In the presence of a base, the mononuclear ZnII or CdII complexes incorporate the carbonyl of the overhanging carboxylate as apical ligand, decreasing its availability for the binding of a HAT PbII. An allosteric effector (e.g., 4‐dimethylaminopyridine (DMAP), in the case of a single‐strap ligand) or an intramolecular ligand (e.g., an amide group), strong enough to compete with the carbonyl of the hung COO?, is required to switch the N‐core bound cation to the opposite side with concomitant release of the COO?, thereby allowing HAT PbII complexation. In the absence of a base, ZnII or CdII binds preferentially the carbonyl of the intramolecular ester or amide groups in apical position rather than that of the COOH. This better preorganization, with the overhanging COOH fully available, is responsible for a stronger binding of the HAT PbII. Thus, either allosteric or acid–base control is achieved through stereoselective metalation of ZnII or CdII. In the latter case, according to the deprotonation state of the COOH group, the best electron‐donating ligand is located on one or the other side of the porphyrin (COO?>CONHR>COOR>COOH): the lower affinity of COOH for ZnII and CdII, the higher for a HAT PbII. These insights provide new opportunities for the elaboration of innovative bimetallic molecular switches. 相似文献
50.
利用俄歇电子能谱(AES)和程序升温脱附谱(TDS)研究了NO2在Ag/Pt(110)双金属表面的吸附和分解.室温下NO2 在Ag/Pt(110)双金属表面发生解离吸附, 生成NO(ads)和O(ads)表面吸附物种. 在升温过程中NO(ads)物种发生脱附或者进一步分解. 500 K时NO2在Ag/Pt(110)双金属表面发生解离吸附生成O(ads)表面吸附物种. Pt 向Ag传递电子, 从而削弱Pt-O键的强度, 降低O(ads)从Pt 表面的并合脱附温度. 发现能够形成具有稳定组成的Ag/Pt(110)合金结构, 其表现出与Pt(110)-(1×2)相似的解离吸附NO2能力, 但与O(ads)的结合明显弱于Pt(110)-(1×2). 该AgPt(110)合金结构是可能的低温催化直接分解氮氧化物活性结构. 相似文献