Preparation and application in wave absorption of titanium sulfide nanomaterial and composite material thereof

Abstract

A titanium sulfide (TiS) nanomaterial and a composite material thereof for wave absorption are disclosed. The TiS nanomaterial is in a form of dispersed micro-particles which are bulks formed by stacking two-dimensional nano-sheets. The TiS nanomaterial is a bulk formed by stacking two-dimensional nano-sheets, thereby having a laminated structure that improves the wave absorption effect. In addition, experimental results demonstrate that the TiS nanomaterial with a dose of 40 wt % has the most excellent wave absorption performance, with a minimum reflection loss up to ?47.4 dB, an effective absorption bandwidth of 5.9 GHz and an absorption peak frequency of 6.8 GHz, which are superior to those of existing two-dimensional bulk materials. One of reasons for the excellent wave absorption performance of the TiS nanomaterial may be because the laminated micro-morphology of TiS results in the electromagnetic wave refraction loss.

Claims

1. A wave absorbing material comprising titanium sulfide (TiS) nanomaterial and paraffin, wherein the TiS nanomaterial is in a form of dispersed first micro-particles, wherein the dispersed first micro-particles are bulks of stacked first two-dimensional nano-sheets, wherein each of the first micro-particles has a size of 25-100 microns and the titanium sulfide nanomaterial has a molar ratio of Ti ions to S ions of 1:40 and wherein the titanium sulfide nanomaterial and paraffin form a wave-absorbing composite.

2. The wave absorbing material of claim 1, wherein a thickness of the first two-dimensional nano-sheets is 5-10 nm, and the bulks are irregular in shape.

3. A wave absorbing material comprising MnO.sub.2TiS composite nanomaterial and paraffin, wherein the MnO.sub.2TiS composite nanomaterial is in the form of dispersed second micro-particles, wherein the dispersed second micro-particles are bulks of stacked second two-dimensional nano-sheets, wherein each of the second micro-particles has a size of 25-100 microns and the MnO.sub.2TiS composite nanomaterial has a molar ratio of Ti ions to S ions of 1:40 and wherein the MnO.sub.2TiS composite nanomaterial and paraffin form a wave-absorbing composite.

4. The wave absorbing material of claim 3, wherein a thickness of the second two-dimensional nano-sheets is 10-20 nm, and the bulks are irregular in shape.

5. A method for preparing the wave absorbing material of claim 1, comprising the following steps: grounding uniformly crushed paraffin and TiS nanomaterial, wherein the TiS nanomaterial is prepared by the following steps: adding TiF.sub.4(COOH).sub.2.Math.2H.sub.2O and CH.sub.4N.sub.2S, wherein molar ratio of Ti ions to S ions is 1:40 and stirring the mixed solution for 5 to 20 minutes; performing a reaction by heating the mixed solution at 180-220? C. for 24-18 h; and after the reaction, cooling the mixed solution heated to room temperature, collecting, centrifuging, and washing a reaction product to obtain a black solid, and drying the black solid to obtain the TiS nanomaterial; heating and melting the grounded paraffin and the TiS nanomaterial; stirring the melted materials evenly to obtain a mixture; and pouring the mixture into a mold and pressing the poured mixture into coaxial rings to obtain the wave absorbing material formed by the paraffin and TiS nanomaterial.

6. A method of wave absorption, comprising the step of using the wave absorbing material comprising titanium sulfide (TiS) nanomaterial and paraffin of claim 1 as a wave-absorbing material.

7. A method for preparing the wave absorbing material of claim 3, comprising the following steps: grounding uniformly crushed paraffin and MnO.sub.2TiS nanomaterial, wherein the MnO.sub.2TiS nanomaterial is prepared by the following steps: adding a TiS nanomaterial to a reactor, wherein the TiS nanomaterial is in a form of dispersed micro-particles, and the dispersed micro-particles are bulks formed by stacking two-dimensional nano-sheets; adding a potassium permanganate solution to a liner of the reactor to obtain a reaction mixture, wherein a molar ratio of titanium sulfide and potassium permanganate is 1:20; tightening the reactor, and performing a reaction by heating the reactor at 120-160? C. for 12-24 h; and after the reaction, cooling the reactor to room temperature, collecting, washing, and centrifuging a reaction product at a bottom of the reactor to obtain a black solid, and drying the black solid to obtain the MnO.sub.2TiS nanomaterial; heating and melting the grounded paraffin and the MnO.sub.2TiS nanomaterial; stirring the melted materials evenly to obtain a mixture; and pouring the mixture into a mold and pressing the poured mixture into coaxial rings to obtain the wave absorbing material formed by the paraffin and MnO.sub.2TiS nanomaterial.

8. A method of wave absorption, comprising the step of using the wave absorbing material MnO.sub.2TiS composite nanomaterial and paraffin of claim 3 as a wave-absorbing material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an XRD spectrum of a two-dimensional TiS nanomaterial prepared in example 1.

(2) FIG. 2 shows XPS spectra of a two-dimensional TiS nanomaterial prepared in example 1.

(3) FIG. 3 is an SEM image of a two-dimensional TiS nanomaterial prepared in example 1.

(4) FIG. 4 is a TEM image of a two-dimensional TiS nanomaterial prepared in example 1.

(5) FIG. 5A shows the three-dimensional representation and FIG. 5B shows the contour plot of reflection losses of TiS/paraffin composite wave-absorbing material sample No. 1 in application example 1.

(6) FIG. 5C shows the three-dimensional representation and FIG. 5D shows the contour plot of reflection losses of TiS/paraffin composite wave-absorbing material sample No. 2 in application example 1.

(7) FIG. 5E shows the three-dimensional representation and FIG. 5F shows the contour plot of reflection losses of TiS/paraffin composite wave-absorbing material sample No. 3 in application example 1.

(8) FIG. 6 shows XPS spectra of a MnO.sub.2@TiS heterojunction nanomaterial prepared in example 2.

(9) FIG. 7 is an SEM image of a MnO.sub.2@TiS heterojunction nanomaterial prepared in example 2.

(10) FIG. 8A shows the three-dimensional representation and FIG. 8B shows the contour plot of reflection losses of MnO.sub.2@TiS/paraffin composite wave-absorbing material sample No. 1.

(11) FIG. 8C shows the three-dimensional representation and FIG. 8D shows the contour plot of reflection losses of MnO.sub.2@TiS/paraffin composite wave-absorbing material sample No. 2.

(12) FIG. 8E shows the three-dimensional representation and FIG. 8F shows the contour plot of reflection losses of MnO.sub.2@TiS/paraffin composite wave-absorbing material sample No. 3.

(13) FIG. 9 is a TEM image and an HAADF image of a two-dimensional TiS nanomaterial prepared in example 3.

(14) FIG. 10 shows an XRD spectrum of a two-dimensional TiS nanomaterial prepared in example 3.

(15) FIG. 11 is an SEM image of a MnO.sub.2@TiS heterojunction nanomaterial prepared in example 4.

(16) FIG. 12 shows XPS spectra of a MnO.sub.2@TiS heterojunction nanomaterial prepared in example 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(17) The present invention will be further described below through examples, but is not limited to these examples. Experimental methods without specific conditions indicated in the examples usually conform to conventional conditions and conditions described in manuals, or conditions recommended by manufacturers. Unless otherwise stated, all used general equipment, materials, reagents, etc. can be acquired from commercial sources. All required raw materials in the following examples and comparative examples are commercially available.

Example 1

(18) A method for preparing a titanium sulfide nanomaterial, and in particular preparing a TiS nanomaterial by a one-step hydrothermal method, includes the following steps:

(19) 0.5 mmol of TiF.sub.4, 6.75 mmol of (COOH).sub.2.Math.2H.sub.2O and 20 mmol of CH.sub.4N.sub.2S were added to 60 mL of deionized water in turn, and magnetically stirred for 10 min; the mixed solution was transferred to a polytetrafluoroethylene (PTFE) reactor, heated at 220? C. for 48 h, and naturally cooled to room temperature; after the reaction mixture is cooled, the supernatant was poured out, the product at the bottom of the reactor was collected, washed with absolute ethanol and centrifuged at 5,000 rpm for 10 min to obtain a black solid, and this process was repeated 3 times; the resulting sample was vacuum-dried at 60? C. for 24 h to prepare the TiS nanomaterial.

(20) The material was characterized. FIG. 1 is an XRD spectrum of a two-dimensional TiS nanomaterial prepared in example 1, reflecting the crystal structure and chemical composition of the composite material. FIG. 1 proves that a TiS intrinsic crystal material is successfully synthesized in example 1.

(21) FIG. 2 shows XPS spectra of a two-dimensional TiS nanomaterial prepared in example 1, reflecting the chemical composition and chemical valence state of the composite material. FIG. 2 proves that the nanomaterial is chemically composed of TiS, i.e., S has a valence of ?2 and Ti has a valence of +2.

(22) FIG. 3 is an SEM image of a two-dimensional TiS nanomaterial prepared in example 1. FIG. 4 is a TEM image of a two-dimensional TiS nanomaterial prepared in example 1. FIGS. 3 and 4 reflect that the composite material is a bulk formed by stacking two-dimensional nano-sheets. Two-dimensional nano-sheets are 1-5 ?m in size, 5-10 nm in thickness and 25-100 ?m in bulk size.

Application Example 1

(23) I. Preparation of a Wave-Absorbing Material Containing Titanium Sulfide of Example 1:

(24) Titanium sulfide of example 1 was used as a wave absorbent. A test sample was prepared with the ultrasonically washed and dispersed clean wave absorbent and paraffin as raw materials. A paraffin section was crushed into small particles. Certain amounts of the clean wave absorbent and crushed paraffin were weighed in proportion, ground uniformly, put in a vacuum drying oven for heating and melting, stirred evenly, and poured into a special mold for pressing into coaxial rings as TiS/paraffin composite wave-absorbing material samples with an inner diameter of 3.04 mm, an outer diameter of 7.00 mm and an overall thickness of 3.04 mm. In TiS/paraffin composite wave-absorbing material samples, doses of TiS were 20 wt %, 40 wt % and 60 wt %. TiS/paraffin composite wave-absorbing material samples No. 1, No. 2 and No. 3 were obtained. The wt % was based on the total mass of TiS/paraffin composite wave-absorbing material samples.

(25) II. Wave Absorption Performance Test of TiS/Paraffin Composite Wave-Absorbing Material by Coaxial Method:

(26) The relative complex dielectric constant and relative complex permeability of a TiS/paraffin composite absorbing material within the frequency range of 2-18 GHz were measured by a coaxial method with a vector network analyzer (PNA-L, N5234A, Agilent).

(27) The vector network analyzer was used to test the law of an influence of the dose of a TiS wave absorbent in a TiS nanomaterial on electromagnetic parameters, attenuation characteristics, impedance matching characteristics and wave absorption performance of a TiS/paraffin composite material.

(28) FIGS. 5A-5F reflect the wave absorption performance of the composite material. FIGS. 5A, 5C, SE are respectively three-dimensional representations of reflection losses of TiS/paraffin composite wave-absorbing material samples No. 1, No. 2, and No. 3 in application example 1. FIGS. 5B, 5D, 5F are respectively contour plots of reflection losses of TiS/paraffin composite wave-absorbing material samples No. 1, No. 2, and No. 3 in application example 1. Experimental results demonstrate that the TiS nanomaterial with a dose of 40 wt/o has the most excellent wave absorption performance, with a minimum reflection loss up to ?47.4 dB (superior to ?38.42 dB of the MoS.sub.2 nano-sheet), an effective absorption bandwidth of 5.9 GHz and an absorption peak frequency of 6.8 GHz, which are superior to those of existing two-dimensional bulk materials.

Example 2

(29) A TiS intrinsic material was used as a template for supporting and modifications of a material by modifying a TiS nanomaterial. Example 2 provides a method for preparing a MnO.sub.2@TiS composite nanomaterial, and in particular preparing a MnO.sub.2@TiS composite nanomaterial by a secondary hydrothermal method:

(30) 100 mg of the TiS powder material prepared in example 1 was added to a 100 mL reactor liner, a 0.05 mol/L potassium permanganate solution was prepared, 70 mL of the 0.05 mol/L potassium permanganate solution was added to a liner of the reactor, and the reactor was tightened, heated in an oven at 160? C. for 24 h, and naturally cooled to room temperature; after a reaction, the supernatant was poured out, the product at the bottom of the reactor was collected, washed with absolute ethanol and centrifuged at 5,000 rpm for 10 min to obtain a black solid, and this process was repeated 3 times; the resulting sample was vacuum-dried at 60? C. for 24 h to prepare a MnO.sub.2@TiS heterojunction nanomaterial.

(31) Experimental results demonstrate that the prepared TiS nanomaterial has a two-dimensional laminated nano-sheet stacking structure.

(32) The material was characterized.

(33) FIG. 6 shows XPS spectra of a MnO.sub.2@TiS heterojunction nanomaterial prepared in example 2, reflecting that the composite material is chemically composed of MnO.sub.2 and TiS, MnO.sub.2 is supported on TiS, Mn has valences of +2, +3 and +4, O has a valence of ?2, Ti has a valence of +2, and S has a valence of ?2.

(34) FIG. 7 is an SEM image of a MnO.sub.2@TiS heterojunction nanomaterial prepared in example 2, reflecting the morphologic structure of the composite material: the MnO.sub.2@TiS heterojunction nanomaterial is a bulk formed by stacking two-dimensional nano-sheets.

Application Example 2

(35) A wave-absorbing material containing the MnO.sub.2@TiS heterojunction nanomaterial of example 2 was prepared by the method of application example 1. In MnO.sub.2@TiS/paraffin composite wave-absorbing material samples, doses of TiS were 20 wt %, 40 wt % and 60 wt %. MnO.sub.2@TiS/paraffin composite wave-absorbing material samples No. 1, No. 2 and No. 3 were obtained. The wt % was based on the total mass of MnO.sub.2@TiS/paraffin composite wave-absorbing material samples.

(36) FIGS. 8A-8F reflect the wave absorption performance of the composite material. The wave absorption performance of TiS/paraffin composite wave-absorbing material was tested by the coaxial method. FIGS. 8A, 8C, 8E are three-dimensional representations of reflection losses of MnO.sub.2@TiS/paraffin composite wave-absorbing material samples No. 1, No. 2 and No. 3, respectively. FIGS. 8B, 8D, 8F are contour plots of reflection losses of MnO.sub.2@TiS/paraffin composite wave-absorbing material samples No. 1, No. 2 and No. 3, respectively. Wave absorption performance data in FIGS. 8A-8F shows that MnO.sub.2@TiS/paraffin composite wave-absorbing materials with doses of 20 wt %, 40 wt % and 60 wt % have minimum reflection losses up to ?65.12 dB, ?102.68 dB and ?104.54 dB, and effective absorption bandwidths up to 2.4 GHz, 5.44 GHz and 6.96 GHz, respectively.

(37) Therefore, it can be seen that the composite wave-absorbing material filled with 60 wt % of MnO.sub.2@TiS has an effective absorption bandwidth up to 6.96 GHz and a minimum reflection loss up to ?104.54 dB, thereby having the optimal comprehensive microwave absorption effect, which is also superior to the microwave absorption effect of the TiS nanomaterial in example 1.

Example 3

(38) The following adjustments were made to synthesis parameters of experimental steps in example 1 to demonstrate the generality of the method: The reaction temperature and reaction time were reduced:

(39) mmol of TiF.sub.4, 6.75 mmol of (COOH).sub.2.Math.2H.sub.2O and 20 mmol of CH.sub.4N.sub.2S were added to 60 mL of deionized water in turn, and magnetically stirred for 10 min; the mixed solution was transferred to a polytetrafluoroethylene (PTFE) reactor, heated at 180? C. for 24 h, and naturally cooled to room temperature; after a reaction, the supernatant was poured out, the product at the bottom of the reactor was collected, washed with absolute ethanol and centrifuged at 5,000 rpm for 10 min to obtain a black solid, and this process was repeated three times; the resulting sample was vacuum-dried at 60? C. for 24 h to prepare the TiS nanomaterial.

(40) FIG. 9 is a TEM image and an element distribution diagram of a TiS material. FIG. 10 is an XRD spectrum of a sample. Experimental results demonstrate that a TiS wave-absorbing nanomaterial can also be synthesized at a relatively low temperature, and this method can be used to generate the TiS nanomaterial through a reaction at 180-220? C. for 24-48 h.

Example 4

(41) The following adjustments were made to synthesis parameters of experimental steps in example 2 to demonstrate the generality of the method: The reaction temperature and reaction time were reduced:

(42) 100 mg of the TiS powder material prepared in example 1 was added to a 100 ml reactor liner, a 0.05 mol/L potassium permanganate solution was prepared, 70 mL of the 0.05 mol/L potassium permanganate solution was added to a liner of the reactor, and the reactor was tightened, heated in an oven at 120? C. for 12 h, and naturally cooled to room temperature; after a reaction, the supernatant was poured out, the product at the bottom of the reactor was collected, washed with absolute ethanol and centrifuged at 5,000 rpm for 10 min to obtain a black solid, and this process was repeated 3 times; the resulting sample was vacuum-dried at 60? C. for 24 h to prepare a MnO.sub.2@TiS heterojunction nanomaterial.

(43) FIG. 11 is an SEM image of a MnO.sub.2@TiS material. FIG. 12 shows XPS spectra of a sample. Experimental results demonstrate that a MnO.sub.2@TiS wave-absorbing nanomaterial can also be synthesized at a relatively low temperature, and this method can be used to generate the MnO.sub.2@TiS nanomaterial through a reaction at 120-160? C. for 12-24 h.