Influence Factors of Preparing Carbon-encapsulated Iron Nanoparticles by Gaseous Detonation Method

doi:10.15541/jim20150544

Abstract

Abstract:

Effects of molar ratio of hydrogen to oxygen and ferrocene mass on synthesis of carbon-encapsulated iron nanoparticles (Fe@C) were studied. Fe@C were prepared by using ferrocene as material resource, which decomposed by high temperature and high speed caused by hydrogen and oxygen detonation in homemade detonation tube. The samples were characterized by X-ray diffraction, transmission electron microscope and high resolution transmission electron microscope and it can be found that the molar ratio of hydrogen to oxygen, and ferrocene mass interact each other in the preparation of Fe@C. The molar ratio of hydrogen to oxygen mainly influences the morphology, particle size and dispersion of Fe@C, while ferrocene mass has a great affect on the synthesis of Fe@C. Part of iron element will be oxidized at small dosage of ferrocene, on the contrary, ferrocene couldn’t be decomposed completely. When the molar ratio of hydrogen to oxygen is 2:1, ferrocene mass ranges in 2.5-3.5 g, spherical or ellipsoidal like Fe@C is prepared with a clear core-shell structure, and thickness of carbon shell at about 10 nm. In consideration of particle size uniformity, morphology structure and dispersion, the best condition for preparing Fe@C is, the molar ratio of hydrogen to oxygen at 2:1, ferrocene mass at 3.5 g.

Key words: gaseous detonation method, carbon-encapsulated iron, hydrogen and oxygen ratio, ferrocene

CLC Number:

O389

YAN Hong-Hao, ZHAO Tie-Jun, SUN Gui-Lei, LI Xiao-Jie, HUN Chang-Hong. Influence Factors of Preparing Carbon-encapsulated Iron Nanoparticles by Gaseous Detonation Method[J]. Journal of Inorganic Materials, 2016, 31(5): 542-546.

Figures/Tables 12

Fig. 1 Schematic of gaseous detonation tube

Table 1 Conditions of initial experimental with different ratio of hydrogen to oxygen

Sample	Temperature/℃	Initial pressure/MPa	Ferrocene mass/g	n(H₂):n(O₂)
1#	140	0.1	3.5	1:1
2#	140	0.1	3.5	2:1

Table 2 Conditions of initial experimental with different ferrocene mass

Sample	Temperature/℃	Initial pressure/MPa	Ferrocene mass/g	n(H₂):n(O₂)
1#	120	0.1	1.5	2:1
2#	120	0.1	2.5	2:1
3#	120	0.1	3.0	2:1
4#	120	0.1	3.5	2:1
5#	120	0.1	4.0	2:1

Table 3 Moles of each element in the reactants and the corresponding oxygen balance

Sample	Mole of each element				n(H):n(O)	Oxygen balance
Sample	H	O	C	Fe	n(H):n(O)	Oxygen balance
1#	0.536	0.348	0.188	0.0188	1.5:1.0	<0
2#	0.652	0.232	0.188	0.0188	2.8:1.0	<0

Fig. 2 XRD patterns of samples prepared with different ratio of hydrogen to oxygen

Table 4 Average particle size of the detonation products

Sample	Phases	2θ/(°)	FWHM	Mean grain size, D/nm
1#	Fe	44.5	0.274	31
1#	Fe₃C	43.2	0.401	21
2#	Fe	44.5	0.374	23
2#	Fe₃C	43.3	0.553	16

Fig. 3 TEM images of samples prepared with different ratio of hydrogen to oxygen Ratios of hydrogen to oxygen of A to B are 1:1, 2:1, respectively

Table 5 Moles of each element in the reactants and the corresponding oxygen balance

Sample	Mole of each element				n(H):n(O)	Oxygen balance
Sample	H	O	C	Fe	n(H):n(O)	Oxygen balance
1#	0.545	0.232	0.081	0.0081	2.3:1	<0
2#	0.598	0.232	0.134	0.0134	2.6:1	<0
3#	0.625	0.232	0.161	0.0161	2.7:1	<0
4#	0.652	0.232	0.188	0.0188	2.8:1	<0
5#	0.679	0.232	0.215	0.0215	2.9:1	<0

Fig. 4 XRD patterns of detonation products with different ferrocene mass Ferrocene mass of 1#, 2#, 3#, 4# and 5# are 1.5, 2.5, 3.0, 3.5 and 4.0 g, respectively

Table 6 Average particle size of iron in detonation products

Sample	Phases	2θ/(°)	FWHM	Mean grain size, D/nm
1#	Fe	44.5	0.169	50
2#	Fe	44.6	0.275	30
3#	Fe	44.6	0.221	38
4#	Fe	44.5	0.374	23
5#	Fe	44.6	0.264	32

Fig. 5 TEM images of detonation products with different ferrocene masses Ferrocene mass: A) 1.5 g; B) 2.5 g; C) 3.5 g

Fig. 6 HR-TEM images of detonation products prepared with different ferrocene masses Ferrocene mass: (a) 1.5 g; (b) 2.5 g; (c) 3.5 g

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