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61.
The adsorption of CN on Cu(1 1 1), Ni(1 1 1) and Ni(1 0 0) has been investigated using density functional theory (DFT). While experimental studies of CN on Cu(1 1 1) show the molecular axis to be essentially parallel to the surface, the normally-preferred DFT approach using the generalised gradient approximation (GGA) yields a lowest energy configuration with the C-N axis perpendicular to the surface, although calculations using the local density approximation (LDA) do indicate that the experimental geometry is energetically favoured. The same conclusions are found for CN on Ni(1 1 1); on both surfaces bonding through the N atom is always unfavourable, in contrast to some earlier published results of ab initio calculations for Ni(1 1 1)/CN and Ni(1 0 0)/CN. The different predictions of the GGA and LDA approaches may lie in subtly different relative energies of the CN 5σ and 1π orbitals, a situation somewhat similar to that for CO adsorbed on Pt(1 1 1) which has proved challenging for DFT calculations. On Ni(1 0 0) GGA calculations favour a lying-down species in a hollow site in a geometry rather similar to that found experimentally and in GGA calculations for CN on Ni(1 1 0). 相似文献
62.
Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu2−xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells. 相似文献
63.
A simple “chimney” method was used to eliminate the voids in an arrangement of quantum dots sized 2 nm on a solid substrate, which resulted in a large well ordered superlattice of area in the order more than 1 μm2. Based on the principle of speeding up the interparticle interaction of nanoparticles to overcome the particle-substrate one, a lateral centripetal force originated from a glass tube acting as a chimney in a simple evaporation device is imposed. This method allows the packing process to be controlled in a mechanical force field, that is, with the same nanogold dispersion different patterns on a substrate—from separate dots to an ordered compact monolayer or even a multilayer structure—could be easily obtained. 相似文献
64.
Metal foils for Raman scattering were prepared by HNO_3 etching method. These foils werefound to exhibit a strong SERS effect and excellent thermal stability. SERS spectra of cystaminehave been taken to illustrate the usefulness of this sample preparation method in the studies ofchemisorption. The ring opening reactions of an epoxy compound have been observed on the topof chemisorbed cystamine on silver foils. 相似文献
65.
Yong-liang Zhu Bin Wang Jian Yu Zhao-xia Guo 《高分子科学》2007,(3):291-296
PEG (Polyethylene Glycol)-grafted nano-titania has been obtained in a one-step procedure using hexamethylene diisocyanate as the coupling agent and dibutyltin dilaurate as the catalyst in toluene at 80℃ and characterized qualitatively by FTIR and quantitatively by elemental analysis and thermogravimetric analysis. A comparison of nano-titania with two other commonly used inorganic nanoparticles, nano-silica and nano-alumina, is made, revealing that reactivity order is nano- silica 〉 nano-alumina 〉 nano-titania in view of PEG grafting. Possible mechanism of PEG grafting is also discussed. 相似文献
66.
AB5型球形合金粉的表面处理研究 总被引:2,自引:0,他引:2
由雾化(Gas-atomization)技术制备的AB5型球形合金粉,作为镍氢电池负极材料具有很多优点:粉粒呈球状便于在多孔基片内装填;耐压耐磨性好;抗碱能力强且不易解胶.但它的电化学初活性差,难于活化.有碍电池中的应用.采用适宜的氧化剂(铜盐水溶液)处理,使球粒表面形成一个富铜、富镍亚层,显著地改善了合金粉的电化学活性.经处理的MlNi3.8CO0.5Mn0.3Al0.4球形合金粉,仅3次充放电循环其放电量便可达到240mA·h·g-1;而未经处理的同一合金粉即便经6次充放电循环其放电量也只有103mA·h·g-1. 相似文献
67.
68.
A.G. Dobrikova M.I. Dimitrov S.G. Taneva I.B. Petkanchin 《Colloids and surfaces. B, Biointerfaces》2007,56(1-2):114-Optics
Using microelectrophoresis and electric light scattering techniques, we investigated the adsorption characteristics, surface coverage and surface electric parameters of superstructures from two isoforms of plastocyanin, PCa and PCb, in an oxidized state adsorbed on β-ferric hydrous oxide particles. The surface electric charge and electric dipole moments of the composite particles and the thickness of the protein adsorption layer are determined in a wide pH range, at different ionic strengths and concentration ratios of PC to β-FeOOH. The adsorption of the two proteins was found to shift the particles’ isoelectric point and to alter the total electric charge and the electric dipole moments of the oxide particles to different extent. A “reversal” in the direction of the permanent dipole moment is observed at lower pH for PCb- than for PCa-coated oxide particles. Strict correlation is found between the changes in the electrokinetic charge of the composite particles and the variation in their “permanent” dipole moments. Data suggest that the adsorption of the proteins is driven by electrostatic and/or hydrophobic interactions with the oxide surfaces dependent on pH. The adsorption behaviour is consistent with the involvement of the “eastern” and “northern” patches of the plastocyanin molecules in their adsorption on the oxide surfaces that are differently charged depending on pH. 相似文献
69.
S. M. A. Shibli V. S. Dilimon V. S. Saji 《Journal of Solid State Electrochemistry》2007,11(2):201-208
It has been recently proved that RuO2 can act as an effective surface activator of aluminum alloy sacrificial anodes. TiO2 has the property of stabilizing RuO2 coating and resisting biofouling on metal surfaces. Hence, a mixed oxide catalytic coating of TiO2 and RuO2 can enhance the galvanic performance of aluminum alloy sacrificial anodes and resists biofouling on the anode surface. In the present work RuO2–TiO2 mixed oxide was coated on aluminum alloy sacrificial anodes. The large and uniform porous nature of the coating was found to facilitate efficient ion diffusion. The coating was found to persist on the anode even after 3 months of galvanic exposure. The anode having an optimum combination of the mixed oxide had 70% TiO2 as the major component in the coating. The catalytic coating significantly improved the performance of the anodes to a large extent. 相似文献