Synthesis and characterization of mesoporic materials containing highly dispersed cobalt

Jentys, Andreas; Pham, Ngan Hoang; Vinek, H.; Englisch, Martin; Lercher, Johannes A.

doi:10.1016/0927-6513(95)00079-8

Cited by 49 publications

(28 citation statements)

References 20 publications

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“…The absence of the crystalline peaks on the X-ray diagram of various salts supported on oxide surface was interpreted as monolayer or submonolayer dispersion of the salt [24]. Distribution of three-dimensional X-ray amorphous particles of CoCl 2 on a silica surface was detected for the CoCl 2 /SiO 2 composite [25,26]. Stabilization of the disordered surface phase of salt in composites CuCl 2 /Al 2 O 3 , AgCl/Al 2 O 3 , and AgCl/SiO 2 , prepared by sintering of the mechanical mix- ture of the salt and dispersed oxide, was studied in [37,38].…”

Section: Phase Compositionmentioning

confidence: 99%

“…It is known that many oxides and salts can disperse spontaneously on support surfaces to form thermodynamically stable monolayers or submonolayers [24]. Adsorption of salts on silica and alumina surfaces during the impregnation procedure trends toward dispersion of the salt as a monolayer or X-ray amorphous particles on the internal surface of silica [25][26][27].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Impact of phase composition on water adsorption on inorganic hybrids “salt/silica”

Gordeeva

Glaznev

Savchenko

et al. 2006

Journal of Colloid and Interface Science

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Section: Phase Compositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of phase composition on water adsorption on inorganic hybrids “salt/silica”

Gordeeva

Glaznev

Savchenko

et al. 2006

Journal of Colloid and Interface Science

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“…Different kinds of amphiphilic molecules have been utilised, for example, nonionic7 or neutral surfactant molecules,8 which lead not only to powders but also to thin films9 and even monolithic structures 10. The range of different morphologies enhances the options for possible applications; for example, the catalytic properties of these materials can be extended by the incorporation of guest species such as Ti,11, 12 Zr,13 V,14 Fe,15, 16 Co,17 Sn18 and Pt19 into the pore structure. Inclusion chemistry in the pore system has a wide field of possible chemical applications, such as sorption, ion exchange or polymerisation inside the channels 5.…”

Section: Introductionmentioning

confidence: 99%

Ordered Arrays of II/VI Diluted Magnetic Semiconductor Quantum Wires: Formation within Mesoporous MCM-41 Silica

Brieler¹,

Fröba²,

Chen³

et al. 2002

Chem. Eur. J.

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We present a novel way of synthesising highly ordered arrays of hollow Cd(1-x)Mn(x)S quantum wires with lateral dimensions of 3-4 nm separated by 1-2 nm SiO2 barriers by forming Cd(1-x)Mn(x)S (0 < or = x < or = 1) semiconductors inside the pore system of mesoporous MCM-41 SiO2 host structures. X-ray diffraction and transmission electron microscopy (TEM) studies reveal the hexagonal symmetry of these arrays (space group p6m) and confirm the high degree of order. Physisorption measurements show the filling of the pores of the MCM-41 SiO2. The X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), electron paramagentic resonance (EPR), and Raman studies confirm the good crystalline quality of the incorporated (Cd,Mn)S guest. The effects of reducing the lateral dimensions on the magnetic and electronic properties of the diluted magnetic semiconductor were studied by photoluminescence (PL) and PL excitation spectroscopy and by SQUID and EPR measurements in the temperature range 2-400 K. Due to the quantum confinement of the excitons in the wires, an increase of about 200 meV in the direct band gap was observed. In addition, the p-d hybridisation-related bowing of the band gap as a function of Mn concentration in the wires is much stronger than in the bulk. This effect is related to the increase in the band gap due to quantum confinement, which shifts the p-like valence band edge closer to the 3d-related states of Mn in the valence band. Thus, the p-d hybridisation and the strength of the band gap bowing are increased. Compared to bulk (II,Mn)VI compounds, antiferromagnetic coupling between the magnetic moments of the Mn2+ ions is weaker. For the samples with high Mn concentrations (x > 0.8) this leads to a suppression of the phase transition of the Mn system from paramagnetic to antiferromagnetic. This effect can be explained by the fact that the lateral dimensions of the wires are smaller than the magnetic length scale of the antiferromagnetic ordering.

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“…Surfactantassisted sol-gel method was widely used to synthesize mesoporous materials (Jentys et al 1996;Beck et al 1992;Wang et al 1999;Tanev et al 1997).With successfully synthesized MCM-like mesoporous material (Liu et al 2004;Yang et al 2015), it is believed that nanoparticles of zinc-doped titania could be possible to synthesize using similar surfactant-assisted sol-gel method.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization and photocatalytic applications of Zn-doped TiO2 nanoparticles by sol–gel method

Aware¹,

Jadhav²

2015

Appl Nanosci

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Mesoporous, nanocrystalline, Zinc-doped TiO 2 nanoparticles were synthesized by surfactant-assisted solgel method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and UV-VIS spectrometer techniques were used to characterize the synthesized products. XRD results confirm the formation of the anatase phase for the TiO 2 nanoparticles, with crystallite sizes in the range of 12.6-18.1 nm. The small crystallite size and doping with Zinc ion inhibit phase transformation and promote the growth of the TiO 2 anatase phase. The SEM and TEM micrographs revealed the spherical-like morphology with average diameter of about 12-18 nm which is in agreement with XRD results. The optical study shows that doping ions lead to an increase in the absorption edge wavelength and a decrease in the band gap energy of titania. Photocatalytic activity of the synthesized nanomaterials was successfully tested for photodegradation of methyl red as model pollutant under UV light. The photocatalytic activity results confirm that the doped nanoparticles show higher activity than undoped titania. The small grain size, high crystallinity, high specific surface area and decrease in the band gap energy of doped titania may be responsible for the high photocatalytic activity.

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Synthesis and characterization of mesoporic materials containing highly dispersed cobalt

Cited by 49 publications

References 20 publications

Impact of phase composition on water adsorption on inorganic hybrids “salt/silica”

Impact of phase composition on water adsorption on inorganic hybrids “salt/silica”

Ordered Arrays of II/VI Diluted Magnetic Semiconductor Quantum Wires: Formation within Mesoporous MCM-41 Silica

Synthesis, characterization and photocatalytic applications of Zn-doped TiO2 nanoparticles by sol–gel method

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