Core-shell zirconia-coated magnetic nanoparticles offering a strong option to prepare a novel and magnetized heteropolyacid based heterogeneous nanocatalyst for three- and four-component reactions
“…The broad bands in the range of the 450-800 cm À1 region are assigned to the stretching vibrations of Zr-O or Zr-O-Zr. 29,30 In comparison with HSiW, HSiW@ZrO 2 -300 and HSiW@ZrO 2 -400 hybrids display specic peaks at 884 cm À1 (W-O c -W) and 808 cm À1 (W-O e -W) that have conrmed the existence of HSiW with the Keggin structures. 31,32 While the bands at 884 cm À1 and 808 cm À1 are not observed in the FT-IR spectra of HSiW@ZrO 2 -500, it is implied that the Keggin structure is destroyed in the calcination process of 500 C. All the results conrm the attachment of HSiW on the hybrids when the calcination temperature is at 300 C and 400 C. The above-mentioned results suggest the successful synthesis of HSiW@ZrO 2 hybrids.…”
“…The broad bands in the range of the 450-800 cm À1 region are assigned to the stretching vibrations of Zr-O or Zr-O-Zr. 29,30 In comparison with HSiW, HSiW@ZrO 2 -300 and HSiW@ZrO 2 -400 hybrids display specic peaks at 884 cm À1 (W-O c -W) and 808 cm À1 (W-O e -W) that have conrmed the existence of HSiW with the Keggin structures. 31,32 While the bands at 884 cm À1 and 808 cm À1 are not observed in the FT-IR spectra of HSiW@ZrO 2 -500, it is implied that the Keggin structure is destroyed in the calcination process of 500 C. All the results conrm the attachment of HSiW on the hybrids when the calcination temperature is at 300 C and 400 C. The above-mentioned results suggest the successful synthesis of HSiW@ZrO 2 hybrids.…”
“…Further, another diffraction peaks appeared at 18.51°, 30.24°, 35.61° and 73.91° matched very well with the Fe 3 O 4 structure (JCPDS No. 19-0629) 34 . Figure 1 XRD patterns of ( a ) Fe 3 O 4 –FeVO 4 and ( b ) 5%, ( c ) 10%, ( d ) 15%RGO/Fe 3 O 4 –FeVO 4 nanocomposites.…”
The study used a one-step hydrothermal method to prepare Fe3O4–FeVO4 and xRGO/Fe3O4–FeVO4 nanocomposites. XRD, TEM, EDS, XPS, DRS, and PL techniques were used to examine the structurally and morphologically properties of the prepared samples. The XRD results appeared that the Fe3O4–FeVO4 has a triclinic crystal structure. Under hydrothermal treatment, (GO) was effectively reduced to (RGO) as illustrated by XRD and XPS results. UV–Vis analysis revealed that the addition of RGO enhanced the absorption in the visible region and narrowed the band gap energy. The photoactivities of the prepared samples were evaluated by degrading methylene blue (MB), phenol and brilliant green under sunlight illumination. As indicated by all the nanocomposites, photocatalytic activity was higher than the pure Fe3O4–FeVO4 photocatalyst, and the highest photodegradation efficiency of MB and phenol was shown by the 10%RGO/Fe3O4–FeVO4. In addition, the study examined the mineralization (TOC), photodegradation process, and photocatalytic reaction kinetics of MB and phenol.
“…The presence of the methoxy group can be correlated with a stretching peak at 1021 cm −1 . A strong peak at 632 cm −1 in the ZrO 2 NP sample corresponds to the Zr−O stretching vibration, 33 while in CuO nanoparticles, the stretching frequency in the region 3600−3100 cm −1 might be due to the O−H groups of the extract components. Two more peaks at 2900 and 1750 cm −1 correspond to C−H asymmetric stretching and CO stretching frequency.…”
Herein, we report
the green synthesis of copper–zirconium
bimetallic nanoparticles (Cu–Zr BNPs) from aqueous solutions
using
Azadirachta indica
leaf extract
as a reducing and stabilizing agent. The CuO, ZrO
2
NP,
and Cu–Zr BNP samples were characterized by X-ray diffraction
and Fourier transform infrared (FTIR) spectroscopy, and the morphologies
of the samples were analyzed by high-resolution transmission electron
microscopy (HR-TEM) with selected area electron diffraction analysis
(SAED). The synthesized Cu–Zr BNPs have been employed as efficient
catalysts for the selective
N
-methylation of aromatic
and aliphatic amines with dimethyl carbonate. The effect of process
conditions on the percentage conversion of benzylamine with dimethyl
carbonate as a model reaction has been investigated. The Cu–Zr
bimetallic nanoparticle catalytic system in a 1:2 molar ratio was
able to convert amines into the corresponding
N
-methylated
amines with a selectivity up to 91% at 180 °C in 4 h. The analysis
of catalytic reusability confirmed that the reported heterogeneous
catalyst can be used for five consecutive cycles without much loss
in activity. Thus, the current protocol can be considered as a simpler,
reproducible, and environmentally benign approach for
N
-methylation of amines.
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