Method for preparing metal complex hydride nanorods

Abstract

A method for preparing metal complex hydride nanorods, comprising the steps of: (1) preparing one-dimensional coordination polymers by mixing metal complex hydrides with organic solvents and subsequent drying; (2) preparing coordination polymer nanostructures by mechanical milling the one-dimensional coordination polymers that obtained from step (1), in which the one-dimensional coordination polymers are vaporized and then deposited onto the substrate; (3) preparing metal complex hydride nanorods by removing the organic ligands from the coordination polymer nanostructures that obtained from step (2). This method is simple and feasible, and exhibits excellent generality. Moreover, the purity of the metal complex hydrides nanostructures is high.

Claims

1. A method for preparing metal complex hydride nanorods, comprising the steps of: (1) preparing one-dimensional coordination polymers by mixing metal complex hydrides with organic solvents and subsequent drying; (2) preparing coordination polymer nanorods by mechanical milling the one-dimensional coordination polymers that obtained from step (1), in which the one-dimensional coordination polymers is vaporized and then deposited onto a substrate; (3) obtaining the metal complex hydride nanorods by removing organic ligands from the coordination polymer nanorods that obtained from step (2).

2. The method of claim 1, wherein said metal complex hydrides are metal alanates and metal borohydrides.

3. The method of claim 1, wherein said organic solvents are ethyl methyl ether, methyl propyl ether, diethyl ether (Et.sub.2O), ethyl propyl ether, methyl tertiary butyl ether (MTBE), tetrahydrofuran (THF) and ethylene oxide.

4. The method of claim 1, wherein said mechanical milling are planetary ball milling and horizontal ball milling.

5. The method of claim 4, wherein the ball-to-powder ratio is 20-100:1, the speed is 300-600 r/min, and the time is 1-10 hours.

6. The method of claim 1, wherein the step (3), the organic ligands are removed by heat treatment and/or vacuum treatment of the coordination polymer nanorods that obtained in step (2) to prepare metal complex hydride nanorods.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows XRD (X-ray diffraction) patterns of the products in different preparation periods in Example 1 of the present invention;

(2) FIG. 2 shows FTIR (Fourier Transform Infrared Spectroscopy) spectra of the products in different preparation periods in Example 1 of the present invention;

(3) FIGS. 3(a), 3(b), 3(c) and 3(d) show respectively SEM (scanning electron microscope) images of the products in different preparation periods in Example 1 of the present invention.

(4) FIG. 4 shows a schematic diagram of the mechanical-force driven physical vapor deposition (MFPVD) process;

(5) FIG. 5 shows a TEM (Transmission electron microscope) image of the resultant product in Example 2 of the present invention;

(6) FIG. 6 shows an EDS (energy dispersive spectrometer) spectrum of the resultant product in Example 2 of the present invention;

(7) FIG. 7 shows TPD (temperature programmed desorption) curves of the raw material and resultant product in Example 3 of the present invention;

(8) FIG. 8 shows volumetric hydrogen release curves of the raw material and resultant product in Example 3 of the present invention;

(9) FIG. 9(a) shows a SEM image of the resultant product in Example 3 of the present invention at room temperature;

(10) FIG. 9(b) shows a SEM image of the resultant product in Example 3 of the present invention at 200 C.;

(11) FIG. 9(c) shows a SEM image of the resultant product in Example 3 of the present invention at 400 C.;

(12) FIG. 10 shows a TEM image of the resultant product in Example 4 of the present invention.

IMPLEMENTATION EXAMPLES OF THE PRESENT INVENTION

(13) The structure analysis of the samples were carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectrometer (EDS). The XRD patterns were obtained by a X'Pert PRO X-ray diffractometer (PANalytical, The Netherland) operated at 40 kV and 40 mA and a measuring step of 0.05. Fourier transform infrared spectrum was recorded using a Bruker Tensor 27 unit (Germany) in transmission mode. The pellet testing sample was prepared by cold-pressing a mixture of powder and potassium bromide (KBr) at a weight ratio of 1:100. The energy dispersive spectrum was measured by FEI Tecnai G2 F20 S-TWIN electron microscope at 200 kV.

(14) The hydrogen desorption properties of the samples were investigated by temperature-programmed desorption (TPD) curve and volumetric release curve. The TPD was performed by using an online mass spectrometer. Temperature-programmed desorption curve were measured by a mass spectrometer and a temperature-control heating device at a heating rate of 2 C./min under continuously flowing pure Ar at a flowing rate of 20 mL/min. The hydrogen volumetric release curve was assessed by using a hydrogen volumetric release with an initial state of vacuum at a heating rate of 2 C./min.

(15) The morphological observations of the samples of the examples were carried out by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The SEM observations were performed with a Hitachi-S4800 microscope (Japan) at 5 kV. The TEM observations were performed on a FEI Tecnai G2 F20 S-TWIN electron microscope (USA) at 200 kV.

(16) FIG. 4 shows the schematic diagram of the milling jar of the implementation examples of the present invention. The ring-like arrow indicates the rotating directions. The milling balls 2 and the raw materials are milling in the space 1. The vaporized raw materials 4 float through the tunnel of the filter 3, then contacts with the substrate 6 of the top of the milling jar, and then deposit onto the substrate 6 to form deposition 5.

Example 1

(17) In a glovebox filled with Ar atmosphere, 1 g of Mg(AlH.sub.4).sub.2 and 100 mL of Et.sub.2O were loaded in a flask and stirred for 60 min. Then the mixture was heated and dried at 40 C., and 1.8 g of white powder (i.e. one-dimensional coordination polymers) was obtained. Then the white powder was loaded in a milling jar equipped with a filter and a substrate, and milled at room temperature in a plenary ball mill at ball-to-powder of 60:1 and speed of 500 r/min for 1.5 hours. After the mechanical-force driven physical vapor deposition (MFPVD), the deposition (i.e. coordination polymer nanorods) was obtained on the substrate. Finally, the resultant product (i.e. metal complex hydride nanorods) was obtained by heat-treating the deposition on the substrate at 90 C. for 15 min.

(18) XRD patterns, FTIR spectra and SEM images were obtained for the samples in different preparing stages.

(19) FIG. 1 shows the XRD patterns. The diffraction peaks of raw materials (i.e. Mg(AlH.sub.4).sub.2) fit well with the typical diffraction peaks of Mg(AlH.sub.4).sub.2. The white powder after drying exhibits the typical diffraction peaks of Mg(AlH.sub.4).sub.2.Et.sub.2O. There is no peaks in the XRD pattern of the deposition after MFPVD, and after heat treatment at 90 C., the typical diffraction peaks of Mg(AlH.sub.4).sub.2 appears again for the resultant product.

(20) FIG. 2 shows the FTIR spectra. Only AlH bonds can be detected for the raw material, and AlH, CH and CO bonds are detected for the white powder (dried product) after drying. The spectrum of the deposition after MFPVD is almost the same as the white powder. After heat treatment at 90 C., only AlH bonds of Mg(AlH.sub.4).sub.2 are detected while CH and CO bonds disappeared.

(21) FIG. 3 shows the SEM images. In FIG. 3(a), it can be seen that raw material is particles with different sizes and shapes. In FIG. 3(b), it can be seen that the white powder after drying is uniform microrods with length of more than 10 m and diameter of 1 m. In FIG. 3(c), it can be seen that the deposition after MFPVD is nanorods with a length of more than 1 m and a diameter of 20-40 nm. In FIG. 3(d), it can be seen that the resultant product remains the nanorod-like morphology.

(22) The above results reveal that Mg(AlH.sub.4).sub.2 can reacts with Et.sub.2O to form Mg(AlH.sub.4).sub.2.Et2O microrods, and after the following MFPVD, Mg(AlH.sub.4).sub.2.Et.sub.2O nanorods (i.e. the deposition) were obtained. Finally, Mg(AlH.sub.4).sub.2 nanorods were obtained after removing the Et.sub.2O molecules by heat treatment.

(23) As shown in FIG. 4, Mg(AlH.sub.4).sub.2.Et.sub.2O microrods were milled with the milling balls 2 in the space 1 of milling jar and then vaporized. The vaporized Mg(AlH.sub.4).sub.2.Et.sub.2O floats through the channel of the filter 3 and deposits onto the substrate 6 to form Mg(AlH.sub.4).sub.2.Et.sub.2O nanorods.

Example 2

(24) In a glovebox filled with Ar atmosphere, 0.5 g of Mg(AlH.sub.4).sub.2 and 60 mL of MTBE were loaded in a flask and stirred for 40 min. Then the mixture was heated to 45 C. to dry, and 0.9 g of white powder was obtained. Then the white powder was loaded in the milling jar as shown in FIG. 4, and milled within an ice-water bath in a horizontal ball mill at a ball-to-powder ratio of 80:1 and a speed of 450 r/min for 1 hour. After mechanical-force driven physical vapor deposition, the deposition on the substrate was obtained. Finally, the resultant product was obtained by heat-treating the deposition at 95 C. for 10 min.

(25) FIG. 5 shows the SEM images of the resultant product. It can be seen that the resultant product is nanorods with a diameter of 20 nm and a length of more than 200 nm.

(26) FIG. 6 shows the EDS spectrum of the resultant product. It can be seen that Mg and Al are dominant in the resultant product, and the purity is 95%.

Example 3

(27) In a vacuum glovebox, 2 g of Mg(AlH.sub.4).sub.2 and 150 mL of Et.sub.2O were loaded in a flask and stirred for 60 min. Then the mixture was heated to 40 C. to dry, and 3.6 gram of white powder was obtained. Then the white powder was loaded in a milling jar equipped with a filter and a substrate, and milled within an ice-water bath in a plenary ball mill at a ball-to-powder of 50:1 and a speed of 550 r/min for 2 hours. After mechanical-force driven physical vapor deposition, the deposition on the substrate was obtained. Finally, the resultant product was obtained by vacuum treatment of the deposition for 6 hours.

(28) FIG. 7 shows the TPD curves of the raw material (i.e. Mg(AlH.sub.4).sub.2) and the resultant product. It can be seen in FIG. 7 that the dehydrogenation temperature of the resultant product is lowered by 25 C. in comparison to that of the raw material.

(29) FIG. 8 shows the volumetric hydrogen release curves of the raw material and resultant product. It can be seen in FIG. 8 that the resultant hydrogen product releases 8.7 wt % of hydrogen at 450 C., and the purity is 94%.

(30) FIG. 9(a) shows the SEM images of the resultant product at room temperature. FIG. 9(b) shows the SEM images of the resultant product at 200 C. FIG. 9(c) shows the SEM images of the resultant product at 400 C. It can be seen that the morphology of the resultant product remains almost unchanged during dehydrogenation.

Example 4

(31) In a glovebox filled with Ar atmosphere, 1 gram of LiBH.sub.4 and 100 mL of MTBE were loaded in a flask and stirred for 60 min. Then the mixture was dried at 10 C. under a pressure less than 10 Pa, and 4.3 g of a white powder was obtained. Then the white powder was loaded in a milling jar equipped with a filter and a substrate, and milled within a dry-ice bath in a plenary ball mill at a ball-to-powder of 50:1 and a speed of 550 r/min for 0.5 hours. After mechanical-force driven physical vapor deposition, the deposition was obtained. The deposition is the resultant product.

(32) FIG. 10 shows the TEM images of the resultant product. It can be seen that the resultant product is nanobelts with diameter of 20 nm.

Example 5

(33) In a vacuum glovebox, 1 gram of Eu(BH.sub.4).sub.2 and 100 mL of THF were loaded in a flask and stirred for 60 min. Then the mixture was dried at 30 C. under a pressure less than 5 Pa, and a solid powder was obtained. Then the solid powder was loaded in a milling jar equipped with a filter and a substrate, and milled at room temperature in a horizontal ball mill at a ball-to-powder of 70:1 and a speed of 550 r/min for 2 hours. After the mechanical-force driven physical vapor deposition, the deposition on the substrate was obtained. Finally, the resultant product was obtained by heat treating the deposition at 80 C. for 15 min, which is nanorods with a diameter of 30 nm.

Example 6

(34) In a vacuum glovebox, 1 gram of Yb(BH.sub.4).sub.2 and 100 mL of THF were loaded in a flask and stirred for 60 min. Then the mixture was dried at 30 C. under a pressure less than 5 Pa, and a solid powder was obtained. Then the solid powder was loaded in a milling jar equipped with a filter and a substrate, and milled within ice-water bath in a horizontal ball mill at a ball-to-powder of 70:1 and a speed of 550 r/min for 2 hours. After the mechanical-force driven physical vapor deposition, the deposition was obtained. Finally, the resultant product was obtained by heat treating the deposition at 80 C. for 15 min, which is nanorods with diameter of 25 nm.