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Fabrication and Characterization of Monodisperse Magnetic Porous Nickel Microspheres as Novel Catalysts.

Teng C, He J, Zhu L, Ren L, Chen J, Hong M, Wang Y - Nanoscale Res Lett (2015)

Bottom Line: The strategy involves impregnation of porous polymer microspheres with nickel precursors, calcination to remove the template, followed by thermal reduction.The unique porous nanostructured Ni microspheres possess catalytic activity and excellent recyclability, as demonstrated in the catalytic reduction of 4-nitrophenol to 4-aminophenol.The micropherical Ni catalysts could be easily separated either by an external magnetic field or by simple filtration.

View Article: PubMed Central - PubMed

Affiliation: Guangdong Provincial Key Laboratory of Nano-Micro Materials Research, School of Chemical Biology & Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China.

ABSTRACT
A facile and efficient hard-templating strategy is reported for the preparation of porous nickel microspheres with excellent uniformity and strong magnetism. The strategy involves impregnation of porous polymer microspheres with nickel precursors, calcination to remove the template, followed by thermal reduction. The morphology, structure, and the property of the Ni microspheres were characterized by scanning electron microscopy, X-ray powder diffraction, N2 adsorption-desorption isotherms, thermogravimetric analysis, and magnetic hysteresis measurement. The obtained porous nickel microspheres were monodispersed with a particle size of 0.91 μm and crystallite size of 52 nm. Their saturation magnetization was much higher than that of Ni nanoparticles. The unique porous nanostructured Ni microspheres possess catalytic activity and excellent recyclability, as demonstrated in the catalytic reduction of 4-nitrophenol to 4-aminophenol. The micropherical Ni catalysts could be easily separated either by an external magnetic field or by simple filtration.

No MeSH data available.


a Magnetic hysteresis curves of the porous Ni microspheres. b Photograph of microspheres before (NiO) and after (Ni) reduction under an external magnetic field within 10 s
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Fig4: a Magnetic hysteresis curves of the porous Ni microspheres. b Photograph of microspheres before (NiO) and after (Ni) reduction under an external magnetic field within 10 s

Mentions: Porous NiO microspheres containing both mesopores and macropores were obtained with a specific surface area of 14 m2 · g−1 and a pore volume of 0.1 cm3 · g−1. The lower surface area and pore volume of porous NiO microspheres compared to the template microspheres were probably due to the shrinkage of the skeleton and the concurrent growth of NiO crystallites during calcination, as well as the higher density of NiO. Thermal reduction process further reduced the as-synthesized porous Ni microspheres. The Ni microspheres obtained by 500 °C thermal reduction possessed a specific surface area of 2.6 m2 · g−1 and a pore volume of 0.01 cm3 · g−1 with BJH mesopores of 42 nm. In contrast to porous NiO microspheres, porous Ni microspheres showed lower surface area and pore volume but larger pore size owing to phase transformation upon high-temperature reduction. To confirm the magnetic property of porous Ni microspheres, its hysteresis curve was measured at room temperature and displayed in Fig. 4. The saturation magnetization (Ms), remnant magnetization (Mr), and coercivity (Hc) were measured to be 50.26 emu · g−1, 4.58 emu · g−1, and 65 Oe, respectively, indicating the excellent magnetic property of porous Ni microspheres, as shown in Table 2 in comparison with other reported Ni nanostructures. The Ni microspheres prepared in this work exhibited much enhanced saturation magnetization than other reported Ni nanoparticles, suggesting better resistance to surface oxidation which are known to decrease the effective magnetic moment of Ni. The saturation magnetization of Ni microspheres is very close to that of bulk Ni, and the coercivity (Hc) value is much lower, probably resulting from the shape anisotropy.Fig. 4


Fabrication and Characterization of Monodisperse Magnetic Porous Nickel Microspheres as Novel Catalysts.

Teng C, He J, Zhu L, Ren L, Chen J, Hong M, Wang Y - Nanoscale Res Lett (2015)

a Magnetic hysteresis curves of the porous Ni microspheres. b Photograph of microspheres before (NiO) and after (Ni) reduction under an external magnetic field within 10 s
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593984&req=5

Fig4: a Magnetic hysteresis curves of the porous Ni microspheres. b Photograph of microspheres before (NiO) and after (Ni) reduction under an external magnetic field within 10 s
Mentions: Porous NiO microspheres containing both mesopores and macropores were obtained with a specific surface area of 14 m2 · g−1 and a pore volume of 0.1 cm3 · g−1. The lower surface area and pore volume of porous NiO microspheres compared to the template microspheres were probably due to the shrinkage of the skeleton and the concurrent growth of NiO crystallites during calcination, as well as the higher density of NiO. Thermal reduction process further reduced the as-synthesized porous Ni microspheres. The Ni microspheres obtained by 500 °C thermal reduction possessed a specific surface area of 2.6 m2 · g−1 and a pore volume of 0.01 cm3 · g−1 with BJH mesopores of 42 nm. In contrast to porous NiO microspheres, porous Ni microspheres showed lower surface area and pore volume but larger pore size owing to phase transformation upon high-temperature reduction. To confirm the magnetic property of porous Ni microspheres, its hysteresis curve was measured at room temperature and displayed in Fig. 4. The saturation magnetization (Ms), remnant magnetization (Mr), and coercivity (Hc) were measured to be 50.26 emu · g−1, 4.58 emu · g−1, and 65 Oe, respectively, indicating the excellent magnetic property of porous Ni microspheres, as shown in Table 2 in comparison with other reported Ni nanostructures. The Ni microspheres prepared in this work exhibited much enhanced saturation magnetization than other reported Ni nanoparticles, suggesting better resistance to surface oxidation which are known to decrease the effective magnetic moment of Ni. The saturation magnetization of Ni microspheres is very close to that of bulk Ni, and the coercivity (Hc) value is much lower, probably resulting from the shape anisotropy.Fig. 4

Bottom Line: The strategy involves impregnation of porous polymer microspheres with nickel precursors, calcination to remove the template, followed by thermal reduction.The unique porous nanostructured Ni microspheres possess catalytic activity and excellent recyclability, as demonstrated in the catalytic reduction of 4-nitrophenol to 4-aminophenol.The micropherical Ni catalysts could be easily separated either by an external magnetic field or by simple filtration.

View Article: PubMed Central - PubMed

Affiliation: Guangdong Provincial Key Laboratory of Nano-Micro Materials Research, School of Chemical Biology & Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China.

ABSTRACT
A facile and efficient hard-templating strategy is reported for the preparation of porous nickel microspheres with excellent uniformity and strong magnetism. The strategy involves impregnation of porous polymer microspheres with nickel precursors, calcination to remove the template, followed by thermal reduction. The morphology, structure, and the property of the Ni microspheres were characterized by scanning electron microscopy, X-ray powder diffraction, N2 adsorption-desorption isotherms, thermogravimetric analysis, and magnetic hysteresis measurement. The obtained porous nickel microspheres were monodispersed with a particle size of 0.91 μm and crystallite size of 52 nm. Their saturation magnetization was much higher than that of Ni nanoparticles. The unique porous nanostructured Ni microspheres possess catalytic activity and excellent recyclability, as demonstrated in the catalytic reduction of 4-nitrophenol to 4-aminophenol. The micropherical Ni catalysts could be easily separated either by an external magnetic field or by simple filtration.

No MeSH data available.