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A general strategy for nanohybrids synthesis via coupled competitive reactions controlled in a hybrid process.

Wang R, Yang W, Song Y, Shen X, Wang J, Zhong X, Li S, Song Y - Sci Rep (2015)

Bottom Line: A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process.The core alloying and shell gradient-doping strategy can efficiently eliminate the crystal lattice mismatch in different components.Consequently, varieties of gradient core-shell nanohybrids can be synthesized using CoM, FeM, AuM, AgM (M = Zn or Al) alloys as cores and transition metal gradient-doping ZnO or Al2O3 as shells, endowing these nanohybrids with unique magnetic and optical properties (e.g., high temperature ferromagnetic property and enhanced blue emission).

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, School of Mathematics and Physics, University of Science &Technology Beijing, Beijing 100083, China.

ABSTRACT
A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process. The latent time of nucleation and the growth of nanohybrids can be well controlled due to the formation of controllable intermediates in the coupled competitive reactions. Thus, spatiotemporal-resolved synthesis can be realized by the hybrid process, which enables us to investigate nanohybrid formation at each stage through their solution color changes and TEM images. By adjusting the bi-channel solvents and kinetic parameters of each stage, the primary components of alloyed cores and the second components of transition metal doping ZnO or Al2O3 as surface coatings can be successively formed. The core alloying and shell gradient-doping strategy can efficiently eliminate the crystal lattice mismatch in different components. Consequently, varieties of gradient core-shell nanohybrids can be synthesized using CoM, FeM, AuM, AgM (M = Zn or Al) alloys as cores and transition metal gradient-doping ZnO or Al2O3 as shells, endowing these nanohybrids with unique magnetic and optical properties (e.g., high temperature ferromagnetic property and enhanced blue emission).

No MeSH data available.


Wide-viewed TEM image (a), HR-TEM image of one single particle (a: inset), STEM-HAADF image of one single particle (b), point-by-point EDX scanning of one single particle (c), high energy resolution XPS for Al (d), high energy resolution XPS for Fe (e) and XRD (f) of FeAl@Al(1-x)FexOy nanohybrids synthesized using all NMP-phased reaction systems at a resident time of 0.73 ~ 0.88 s in microfluidic channel and 20 min in the cooling receiver.Right-bottom inset in Fig. 2a is the NPs solution. JCPDS No for XRD analysis: bcc Fe, 6-0696; α-Al2O3, 46-1212; γ-Al2O3, 10-0425. In XRD (f), : the corresponding metallic phases; *: the corresponding metal oxides.
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f2: Wide-viewed TEM image (a), HR-TEM image of one single particle (a: inset), STEM-HAADF image of one single particle (b), point-by-point EDX scanning of one single particle (c), high energy resolution XPS for Al (d), high energy resolution XPS for Fe (e) and XRD (f) of FeAl@Al(1-x)FexOy nanohybrids synthesized using all NMP-phased reaction systems at a resident time of 0.73 ~ 0.88 s in microfluidic channel and 20 min in the cooling receiver.Right-bottom inset in Fig. 2a is the NPs solution. JCPDS No for XRD analysis: bcc Fe, 6-0696; α-Al2O3, 46-1212; γ-Al2O3, 10-0425. In XRD (f), : the corresponding metallic phases; *: the corresponding metal oxides.

Mentions: After the systematical investigation of the reaction kinetics, nanohybrids with uniform morphology and good crystallinity can be obtained as the growth time in the microchannel is controlled in 0.30–0.45 second (Ltotal = 25–30 cm) and then the solution is collected in the cooling receiver (the resident time: ~20 min), where the light-brown solution becomes brown (Fig. 2a: right-bottom inset). The detailed reaction conditions are described in Part I of SI, together with those for other typical nanohybrids. As shown in Fig. 2a, uniform NPs with a mean diameter of 4.8 ± 0.3 nm (Fig. s3a-i) can be obtained. Even though the core shell structure is not so distinct, contrast differences between the inner parts and the surface layers can be observed from one typical HRTEM image (Fig. 2a: right-top inset; Fig. s4a) in spite of eccentric in shape. The STEM-HAADF (Z-contrast) images equipped with Gatan GIF 2000 energy filter system and energy dispersive X-ray spectrometries (EDX) for some typical particles were performed. Figure 2b is the STEM-HAADF image for one typical single particle, showing clear contrast difference between the center and the surface layer. The atom ratios between Fe and Al recorded by point-by-point EDX scanning (point step: ~1.6 nm) show a significant change from the surface layer to the center part of this particle (Fig. 2c). The Al/Fe ratio gradually increases from 10/90 at the center of the core (~2.5 nm in diameter) to 35/65 at the interface between the core and the surface coating (~1.0 nm thick), and to 50/50 ~ 70/30 at the out layer of the surface coating, forming an interface with gradually-decreasing Fe content.


A general strategy for nanohybrids synthesis via coupled competitive reactions controlled in a hybrid process.

Wang R, Yang W, Song Y, Shen X, Wang J, Zhong X, Li S, Song Y - Sci Rep (2015)

Wide-viewed TEM image (a), HR-TEM image of one single particle (a: inset), STEM-HAADF image of one single particle (b), point-by-point EDX scanning of one single particle (c), high energy resolution XPS for Al (d), high energy resolution XPS for Fe (e) and XRD (f) of FeAl@Al(1-x)FexOy nanohybrids synthesized using all NMP-phased reaction systems at a resident time of 0.73 ~ 0.88 s in microfluidic channel and 20 min in the cooling receiver.Right-bottom inset in Fig. 2a is the NPs solution. JCPDS No for XRD analysis: bcc Fe, 6-0696; α-Al2O3, 46-1212; γ-Al2O3, 10-0425. In XRD (f), : the corresponding metallic phases; *: the corresponding metal oxides.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4377631&req=5

f2: Wide-viewed TEM image (a), HR-TEM image of one single particle (a: inset), STEM-HAADF image of one single particle (b), point-by-point EDX scanning of one single particle (c), high energy resolution XPS for Al (d), high energy resolution XPS for Fe (e) and XRD (f) of FeAl@Al(1-x)FexOy nanohybrids synthesized using all NMP-phased reaction systems at a resident time of 0.73 ~ 0.88 s in microfluidic channel and 20 min in the cooling receiver.Right-bottom inset in Fig. 2a is the NPs solution. JCPDS No for XRD analysis: bcc Fe, 6-0696; α-Al2O3, 46-1212; γ-Al2O3, 10-0425. In XRD (f), : the corresponding metallic phases; *: the corresponding metal oxides.
Mentions: After the systematical investigation of the reaction kinetics, nanohybrids with uniform morphology and good crystallinity can be obtained as the growth time in the microchannel is controlled in 0.30–0.45 second (Ltotal = 25–30 cm) and then the solution is collected in the cooling receiver (the resident time: ~20 min), where the light-brown solution becomes brown (Fig. 2a: right-bottom inset). The detailed reaction conditions are described in Part I of SI, together with those for other typical nanohybrids. As shown in Fig. 2a, uniform NPs with a mean diameter of 4.8 ± 0.3 nm (Fig. s3a-i) can be obtained. Even though the core shell structure is not so distinct, contrast differences between the inner parts and the surface layers can be observed from one typical HRTEM image (Fig. 2a: right-top inset; Fig. s4a) in spite of eccentric in shape. The STEM-HAADF (Z-contrast) images equipped with Gatan GIF 2000 energy filter system and energy dispersive X-ray spectrometries (EDX) for some typical particles were performed. Figure 2b is the STEM-HAADF image for one typical single particle, showing clear contrast difference between the center and the surface layer. The atom ratios between Fe and Al recorded by point-by-point EDX scanning (point step: ~1.6 nm) show a significant change from the surface layer to the center part of this particle (Fig. 2c). The Al/Fe ratio gradually increases from 10/90 at the center of the core (~2.5 nm in diameter) to 35/65 at the interface between the core and the surface coating (~1.0 nm thick), and to 50/50 ~ 70/30 at the out layer of the surface coating, forming an interface with gradually-decreasing Fe content.

Bottom Line: A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process.The core alloying and shell gradient-doping strategy can efficiently eliminate the crystal lattice mismatch in different components.Consequently, varieties of gradient core-shell nanohybrids can be synthesized using CoM, FeM, AuM, AgM (M = Zn or Al) alloys as cores and transition metal gradient-doping ZnO or Al2O3 as shells, endowing these nanohybrids with unique magnetic and optical properties (e.g., high temperature ferromagnetic property and enhanced blue emission).

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, School of Mathematics and Physics, University of Science &Technology Beijing, Beijing 100083, China.

ABSTRACT
A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process. The latent time of nucleation and the growth of nanohybrids can be well controlled due to the formation of controllable intermediates in the coupled competitive reactions. Thus, spatiotemporal-resolved synthesis can be realized by the hybrid process, which enables us to investigate nanohybrid formation at each stage through their solution color changes and TEM images. By adjusting the bi-channel solvents and kinetic parameters of each stage, the primary components of alloyed cores and the second components of transition metal doping ZnO or Al2O3 as surface coatings can be successively formed. The core alloying and shell gradient-doping strategy can efficiently eliminate the crystal lattice mismatch in different components. Consequently, varieties of gradient core-shell nanohybrids can be synthesized using CoM, FeM, AuM, AgM (M = Zn or Al) alloys as cores and transition metal gradient-doping ZnO or Al2O3 as shells, endowing these nanohybrids with unique magnetic and optical properties (e.g., high temperature ferromagnetic property and enhanced blue emission).

No MeSH data available.