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1.
Nina Jiang Yiwei Wang Danyang Li Jie Niu Shibin Wang Aizheng Chen 《Particle & Particle Systems Characterization》2019,36(9)
Various C‐doped metal oxide nanoparticles (NPs) are prepared from metal nitrates in poly‐(methyl vinyl ether‐co‐maleic anhydride) (PVM/MA) nanoreactors. The loading of metal nitrates in the nanoreactors is realized via a process of solution‐enhanced dispersion by supercritical CO2. When the temperature exceeds the thermal decomposition temperature of the nitrates, the nitrates‐loaded nanoreactors transform into C‐doped metal oxide NPs. ZnO, NiO, and Co3O4 NPs as representative of the doped oxides are successfully fabricated. A precise control over the doping concentration and doping site in the lattice is achieved by changing the mass ratio between PVM/MA and metal nitrate. The controllable carbon doping avoids undesirable aggregation of carbon species and metal oxide NPs, endows the NPs with broad and strong absorption bands in the visible light region, and creates channels for separation of photo‐generated electrons and holes. In this regard, the resultant C‐doped metal oxide NPs exhibit excellent photocatalytic, photo‐induced antibacterial, and photothermal performances. 相似文献
2.
John W. Bond 《Physica B: Condensed Matter》2011,406(8):1582-1585
By careful selection of chloride ion concentration in aqueous sodium chloride, electrochemical oxidation of α phase brass is shown to permit fabrication of either p-type copper (I) oxide/metal or n-type zinc oxide/metal Schottky barrier diodes. X-ray photoelectron and Auger electron spectroscopies provide evidence that barrier formation and rectifying qualities depend on the relative surface abundance of copper (I) oxide and zinc oxide. X-ray diffraction of the resulting diodes shows polycrystalline oxides embedded in amorphous oxidation products that have a lower relative abundance than the diode forming oxide. Conventional I/V characteristics of these diodes show good rectifying qualities. When neither of the oxides dominate, the semiconductor/metal junction displays an absence of rectification. 相似文献
3.
T. Cottineau M. Toupin T. Delahaye T. Brousse D. Bélanger 《Applied Physics A: Materials Science & Processing》2006,82(4):599-606
In this paper, we wish to present an overview of the research carried out in our laboratories with low-cost transition metal
oxides (manganese dioxide, iron oxide and vanadium oxide) as active electrode materials for aqueous electrochemical supercapacitors.
More specifically, the paper focuses on the approaches that have been used to increase the capacitance of the metal oxides
and the cell voltage of the supercapacitor. It is shown that the cell voltage of an electrochemical supercapacitor can be
increased significantly with the use of hybrid systems. The most relevant associations are Fe3O4 or activated carbon as the negative electrode and MnO2 as the positive. The cell voltage of the Fe3O4/MnO2 device is 1.8 V and this value was increased to 2.2 V by using activated carbon instead of Fe3O4. These two systems have shown superior behavior compared to a symmetric MnO2/MnO2 device which only works within a 1 V potential window in aqueous K2SO4. Furthermore, the activated carbon/MnO2 hybrid device exhibits a real power density of 605 W/kg (maximum power density =19.0 kW/kg) with an energy density of 17.3 Wh/kg.
These values compete well with those of standard electrochemical double layer capacitors working in organic electrolytes.
PACS 82.47.Uv; 82.45.Fk; 82.45.Yz 相似文献
4.
Blend films of different ratios of carboxymethyl cellulose (CMC)/polyethylene oxide (PEO) were prepared by the solution casting method. To investigate the effect of irradiation on all properties of prepared blend, it was exposed to different gamma irradiation doses (10, 20, and 30?kGy). Physical properties such as gel fraction (GF) (%) and swelling (SW) (%) were investigated. It was found that the GF (%) increases with increasing irradiation dose up to 20?kGy, while SW (%) decreases with an increase in the irradiation doses for all blend compositions. Moreover, the structural and mechanical properties of the prepared films were studied. The results of the mechanical properties obtained showed that there is an improvement in these properties with an increase in both CMC and irradiation dose up to 20?kGy. The efficiency of metal ions uptake was measured using a UV spectrophotometer. The prepared films showed good tendency to absorb and release metal ions from aqueous media. Thus, the CMC/PEO film can be used in agricultural domain. 相似文献
5.
New magnetic organic–inorganic composites based on hydrotalcite-like anionic clays for drug delivery
The structural “memory effect” of anionic clays was used to obtain layered double hydroxides (LDHs) with tailored magnetic properties, by loading iron oxides and/or spinel structures on iron partially substituted hydrotalcite-like materials. The obtained magnetic layered structures were further used as precursors for new hybrid nanostructures, such as aspirin–hydrotalcite-like anionic clays. Transmission electron microscopy (TEM) analysis shows that small iron oxide or spinel nanoparticles coexist with the fibrous drug particles on the surface of partially aggregated typical clay-like particles. The specific saturation magnetization of the loaded LDHs can be increased up to 70 emu/g by using specific post-synthesis treatments. 相似文献
6.
G.J. Exarhos C.F. Windisch Jr. K.F. Ferris R.R. Owings 《Applied Physics A: Materials Science & Processing》2007,89(1):9-18
High quality doped zinc oxide and mixed transition metal spinel oxide films have been deposited by means of sputter deposition
from metal and metal oxide targets, and by spin casting from aqueous or alcoholic precursor solutions. Deposition conditions
and post-deposition processing are found to alter cation oxidation states and their distributions in both oxide materials
resulting in marked changes to both optical transmission and electrical response. For ZnO, partial reduction of the neat or
doped material by hydrogen treatment of the heated film or by electrochemical processing renders the oxide n-type conducting.
Continued reduction was found to diminish conductivity. In contrast, oxidation of the infrared transparent p-type spinel conductors
typified by NiCo2O4 was found to increase conductivity. The disparate behavior of these two materials is caused, in part, by the sign of the
charge carrier and by the existence of two different charge transport mechanisms that are identified as free carrier conduction
and polaron hopping. While much work has been reported concerning structure/property relationships in the free carrier conducting
oxides, there is a significantly smaller body of information on transparent polaron conductors. In this paper, we identify
key parameters that promote conductivity in mixed metal spinel oxides and compare their behavior with that of the free carrier
TCO’s.
PACS 61.72.C.; 71.38.-k; 81.15.-z; 77.84.Bw; 73.61.-r 相似文献
7.
The 3D Nanoscale Evolution of Platinum–Niobium Oxide Fuel Cell Catalysts via Identical Location Electron Tomography 下载免费PDF全文
David Rossouw Lidia Chinchilla Natalia Kremliakova Gianluigi A. Botton 《Particle & Particle Systems Characterization》2017,34(7)
Current state‐of‐the‐art catalysts for polymer electrolyte membrane fuel cells, comprised of platinum nanoparticles on a high surface area carbon support, are susceptible to platinum dissolution and carbon support corrosion during operation. The use of transition metal oxides in the support material is proposed to stabilize the catalyst material by minimizing platinum dissolution and carbon corrosion. Here, the 3D structural changes are tracked for a hybrid Pt–Nb oxide on carbon catalyst before and after potential cycling utilizing identical location electron tomography. Pt dissolution is observed to varying degrees in both high and low Nb oxide content structures and appreciable carbon support corrosion in the high Nb oxide content structure but not in the low Nb oxide structure. 相似文献
8.
F. Estaline Amitha A. Leela Mohana Reddy S. Ramaprabhu 《Journal of nanoparticle research》2009,11(3):725-729
A supercapacitor using non-aqueous electrolyte and multiwalled carbon nanotube (MWNTs) nanocomposite electrodes has been designed
with polymer and metal oxide loaded carbon nanotubes as electrodes. These nanocomposites were coated on the carbon paper with
Nafion solution to obtain the flexible electrodes. Carbon paper with the nanocomposite coating was pressed on either sides
of the Nafion membrane, which acts both as a separator and as an electrolyte. The performance of asymmetric assembly of electrochemical
double layer capacitor with polymer- and metal oxide-dispersed MWNTs composite materials with non-aqueous Nafion electrolyte
is compared with symmetric assemblies, and the results are discussed. 相似文献
9.
《Current Applied Physics》2014,14(5):649-652
While sol–gel-processed metal oxides are widely used as an electron transport layer to enhance photovoltaic performances, their effect on photodetector application was not studied. We found sol–gel-processed titanium oxide deteriorated dark current characteristics in reverse biases by almost two orders of magnitude, whereas bare Al cathodes exhibited ideal dark current characteristics. Increased dark current came from space charge limited currents in microscopic p-i-p metal-semiconductor-metal configurations. The spatial variation of workfunction values was believed to form local leakage paths by partial filling of traps on the surface of sol–gel titanium oxide. 相似文献
10.
Delong He Yongning Liu Tingkai Zhao Jiewu Zhu Guang Yu 《Journal of nanoparticle research》2008,10(3):409-414
The effect of oxygen on the growth of single-walled carbon nanotubes was studied with Ni–Co alloy powder as catalyst under
helium atmosphere of 500 Torr by electric arc discharge. The oxygen included in nickel or (and) cobalt oxides was added in
catalyst. The content of oxygen in atmosphere was controlled by changing vacuum degree inside furnace before inputting buffer
gas. The examinations of TEM and Raman scattering showed that oxygen in metal oxide as catalyst promotes the nucleation of
SWCNT by taking effect on the metal catalyst particles. However, O2 in atmosphere has the role of oxidizing amorphous particles along with nanotubes. When its molar proportion is higher than
0.22 ppm (Parts per million), the carbon nanotubes produced are oxidized and their purity decreases. The diameter of single-walled
carbon nanotube obtained under different condition has a narrow distribution around 1.28 nm. 相似文献
11.
The Cu-Ni-M(III) mixed oxides (M = Al, Cr and In) were prepared by calcination of layered double hydroxide precursors with Cu2+/Ni2+/M3+ ratio of 1/2/1. The materials were characterized by means of powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric-differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS) and low temperature N2 adsorption-desorption experiments. The results indicated that calcination of precursors at 500 °C gave rise to mixed metal oxides including simple oxides and composite oxides, and the composition distributions of obtained oxides depended on the nature of trivalent cation in precursors. Under mild experimental conditions (atmospheric pressure and 25 °C), oxidation of aqueous phenol solutions by hydrogen peroxide exhibited that the Cr-containing mixed oxide achieved the highest conversion of phenol owing to the presence of more amount of composite oxide phase containing active copper centers, while the aluminum-containing one could significantly enhance deep oxidation of phenol into smaller molecules owing to the presence of more surface oxygen species. 相似文献
12.
Z. Cherkezova-Zheleva D. Paneva S. Todorova H. Kolev M. Shopska I. Yordanova I. Mitov 《Hyperfine Interactions》2014,226(1-3):529-543
Iron and iron-platinum catalysts supported on activated carbon have been successfully synthesized by wet impregnation method and low-temperature treatment in inert atmosphere. The content of the supported phases corresponds to 10 wt % Fe and 0.5 wt % Pt. Four catalytic samples were synthesized: Sample A—activated carbon impregnated with Fe nitrate; Sample B—activated carbon impregnated with Pt salt; Sample C—activated carbon impregnated consequently with Fe and Pt salts; Sample D—activated carbon impregnated simultaneously with Fe and Pt salts. The as-prepared materials were characterized by Mössbauer spectroscopy, X-ray diffraction, infrared and X-ray photoelectron spectroscopy. The spectra show that the activated carbon support and the preparation procedure give rise to the synthesis of isolated metal Pt ions and ultradispersed Fe and Pt oxide species. Probably the presence of different functional groups of activated carbon gives rise to registered very high dispersion of loaded species on support. The catalytic tests were carried out in PROX reaction. A lower activity of bimetallic Pt-Fe samples was explained with the increase in surface oxygen species as a result of predomination of iron oxide on the support leading to the increase in selectivity to the H2 oxidation. Partial agglomeration of supported iron oxide phase was registered after catalytic tests. 相似文献
13.
《Composite Interfaces》2013,20(3-4):257-262
Inorganic pigments are characterized by good dispersion and high coating ability. An interesting trend in production of permanent pigment systems may involve a precipitation process followed by roasting of the silica, co-precipitated with metal oxides. The use of zinc silicate may allow elimination of zinc oxide and, partially or even completely, carbon black from rubber mixtures. 相似文献
14.
15.
S. P. Gubin E. Yu. Buslaeva 《Russian Journal of Physical Chemistry B, Focus on Physics》2009,3(8):1172-1186
Preparative methods for the reduction of simple and complex metal oxides by supercritical isopropanol (SCI) were developed. Procedures for effective work with SCI under usual laboratory conditions were suggested. Optimum reaction conditions (temperature and pressure) and reagent ratios for reactions between SCI and metal oxides were found. Disperse oxides coated by fine-dispersity metals that could be used as catalysts were prepared. Simple methods for obtaining metal nanoparticles by the reduction in situ of metal oxide nanoparticles stabilized in polyethylene and synthetic silica (opal) matrices with SCI were developed. 相似文献
16.
通过碱沉淀法制备了Ce,Al,Ni,Cu的水合氧化物,研究了它们的Langmuir吸附等温线,并利用BET法通过吸附-脱附氮气测定了其比表面积,同时对其吸附氟离子前后的变化进行了IR谱图的表征.结果表明不同水合金属氧化物具有不同的比表面积,其孔径分布也不尽相同,吸附量与比表面积之间没有直接相关的正比关系.吸附等温线均符... 相似文献
17.
18.
J. Escard B. Pontvianne J.P. Contour 《Journal of Electron Spectroscopy and Related Phenomena》1975,6(1):17-26
Several iridium supported catalyst were studied by means of x-ray photoelectron spectroscopy. These catalysts contain 5 wt. % iridium impregnated from aqueous solution of hexachloroiridic acid on δ-alumina, silica, zinc oxide, titanium oxide and Ketjen silica alumina and are used in catalytic oxidation of olefins.Photoelectron spectra of oxides, impregnated oxides and hydrogen reduced catalysts have been recorded. Chemical shifts observed on impregnated oxides indicate that alumina and titanium oxide make possible the reduction of some of the hexachloroiridates ions into an iridium(III) chloro complex. This reaction is not detected with zinc oxide and silica.For the reduced catalysts, the iridium 4f doublet is shifted to higher binding energies with respect to that of unsupported iridium and the iridium lines have an anomalous breadth. We have postulated that an electronic interaction occurs between the support acting as an electron acceptor and the metal acting as an electron donor. The chemical shifts depend on the nature of the support, increasing ZnO < SiO2 < TiO2 < Al2O3, and may be correlated with the Fermi level in the metallic oxide. With silica-alumina and progressively de-aluminated silica-alumina, a simultaneous variation of the iridium chemical shift and catalytic activity is observed. 相似文献
19.
The determination of the surface oxide layer composition is vital to facilitate the adjustment of the sintering conditions for sufficient removal of the surface oxides for providing strong metal bonding between the metal particles during sintering. To systematically investigate the composition, morphology and thickness of the surface oxide the influence of manganese content from 0.3 to 1.8 wt.% on the surface products composition in the case of water atomized steel powder was evaluated. Analysis of the powder surfaces by X-ray photoelectron spectroscopy and high-resolution scanning electron microscopy in combination with X-ray microanalysis showed that powder particles in all cases are covered by heterogeneous oxide layer, composed of particulate features of thermodynamically stable oxides (Cr-Mn-Si) and homogeneous iron surface oxide layer in between. For increasing alloying content the fraction of stable oxide cations in the surface layer increases linearly, whereas the thickness of the iron oxide layer decreases. Moreover, from the investigation of the sintering and degassing behavior by thermal analysis coupled with mass-spectrometry (TG/DTA + MS), three different stages of carbothermal reduction process were observed and their correlation with surface oxides composition was established during sintering in argon. 相似文献
20.
The influence of ion bombardment on the composition of surfaces was investigated by means of ESCA. The bombardment of metal
oxides with inert gas ions results, not only in sputtering of the surface, but also in reduction of the oxides. The rate of
reduction is particularly high when the oxide/metal interface is within the range of the bombarding ions. Ion induced reduction
was found in oxide layers, thinner than the escape depth of the photoelectrons, on Mo, W, Nb, Ta, Ti, Zr, Si, and Bi. The
relationship between reduction phenomena, on the one hand, and the ion energy, angle of incidence, mass of the gas used for
bombardment, and ion current density, on the other hand, was investigated in the case of the Mo/Mo-oxide system.
Ion bombardment of surfaces may also result in the formation of new compounds. Two examples of this are the formation of carbides
through the bombardment of contaminated surfaces and the ion induced formation of C-F compounds from a mixture of K2SiF6 and carbon. 相似文献