CN1289405C - Wet chemical process of preparing low-dimensional nano nickel sulfide crystal - Google Patents

Abstract

The invention provides a wet chemical preparation method of low-dimensional nickel sulfide nanocrystals. Its main feature is to use water-in-oil microemulsion as the reaction medium, and use inorganic nickel salt, carbon disulfide, and urea as reactants to synthesize nickel sulfide one-dimensional nano-needles, tubes or two-dimensional nano-thin sheets by direct hydrothermal treatment in the reactor. crystal. Water-in-oil microemulsions are "cetyltrimethylammonium bromide (CTAB)/n-pentanol/n-hexane/water" and "Triton X-100 (Triton X-100)/isopropanol/ Cyclohexane/water" two systems. Hydrothermal treatment at 120-200°C for 5-48 hours. The thickness of the obtained nanometer sheet is 2-10nm, the diameter of the nanoneedle or tube is 5-200nm, and the length is 50-2000nm. By changing the reaction time, reactant concentration, reactant ratio and reaction medium type, or adding dodecyl mercaptan, the morphology and composition of the product can be controlled. The method has the characteristics of controllable product shape, adjustable composition, and simple process and equipment.

Description

A wet chemical preparation method of low-dimensional nickel sulfide nanocrystals

technical field

The invention relates to a wet chemical preparation method of nickel sulfide one-dimensional nano-needles, tubes or two-dimensional nano-thin layer crystals, belonging to the field of nanometer materials.

Background technique

Nanomaterials refer to materials with at least one dimension ranging from 1 to 100 nm in scale, and can be divided into zero-dimensional, one-dimensional and two-dimensional. Compared with bulk materials, nanomaterials have excellent mechanical, electrical, optical, catalytic and other properties, and have great application prospects. In recent years, they have become the most active research direction in the field of materials science and belong to the frontier of materials science. Many physical and chemical properties and scientific phenomena are closely related to the scale and dimension of materials. Therefore, the controllable synthesis of the size, dimension and shape of materials has become one of the main contents of nanomaterials research. In recent years, metal oxides, metal sulfides, and metal one-dimensional nanowires (rods, needles), two-dimensional nanosheets, and zero-dimensional quantum dots have been reported in a large number of literatures.

Metal sulfides are an important class of semiconductor materials with excellent electrical, luminescent and catalytic properties. As an important member of metal sulfides, nickel sulfide has many important properties and industrial applications. For example, nickel sulfide has an α-β phase transition accompanied by a volume change of about 4%. Metastable nickel sulfide can be used as an effective phase change toughening agent for semiconductor materials; nickel sulfide has excellent catalytic performance and can be used for hydrodesulfurization and hydrogenation. Catalysts for hydrodenitrogenation processes, especially the removal of sulfur and sulfur-containing compounds from oil and gas. In addition, nickel sulfide can also be used as a coating material for photovoltaic cells. The traditional synthesis method of nickel sulfide is to react metal nickel powder and elemental sulfur at high temperature in a sealed furnace tube. This method has obvious shortcomings: first, the melting point of sulfur is low and volatile, and the composition of the product is difficult to control; second , high temperature treatment always obtains a thermodynamically stable phase, but it is difficult to obtain a metastable phase. The low-temperature liquid-phase synthesis of nickel sulfide has attracted great interest in recent years. J.Grau et al. (J.Am.Ceram.Soc.Vol.80(1997)No.4pp.941-951) reported that nickel chloride aqueous solution reacted with thioacetamide and urea at 70-90°C to form NiS _1.03 , but the particle size of the product is on the order of microns. YUJeong et al. (Inorg.Chem.Vol.40(2001)No.1 pp.73-77) reported the reaction of nickel chloride and sodium dithionite in aqueous solution at room temperature to synthesize crystalline Ni ₃ S ₂ , Ni ₃ S ₄ and weak Crystalline non-stoichiometric product Ni _y S _x . B.Xie et al. (Chem.Lett.Vol.31(2002)pp.254-255) reported that using nickel chloride and sodium thiosulfate as raw materials, under C ₁₇ H ₃₃ COOK assisted hydrothermal environment (140 ℃) NiS nanowhiskers were synthesized. X.Jiang et al. (Adv.Mater.Vol.13(2001)No.16pp.1278-1281) reported that a nickel sulfide layer structure was prepared in a concentrated ammonia-carbon disulfide system using nickel chloride as a nickel source, but the diameter Very large (0.5-1.0 μm). S.-H.Yu et al. (Adv.Funct.Mater.Vol.12 (2002) No.4pp.277-285) reported that nickel block (or nickel nitrate) and elemental sulfur were used as raw materials in ethylenediamine, Different phases of nickel sulfide were synthesized in water, ethanol, acetone, pyridine and other solvents. RDTilley et al. (J.Phys.Chem.BVol.106 (2002) No.42pp.10895-10901) reported nickel ions attached to graphitized carbon black with H ₂ S/H ₂ mixed gas, prepared different phase of nickel sulfide nanoparticles. Y. Hu et al. (Adv. Mater. Vol. 15 (2003) No. 9 pp. 726-729) reported the synthesis of nickel sulfide microspheres. However, the products obtained by the above-mentioned preparation methods have single, uncontrollable and large sizes, some of which require strict sealing devices, and the processes and equipment are complicated. The invention uses cheap chemical reagents as raw materials and a simple reaction kettle as a reaction vessel to prepare one-dimensional nano-needles, tubes and two-dimensional nano-thin layer crystals of nickel sulfide. Products with different compositions and morphologies can be obtained by properly adjusting the reaction conditions and the ratio of reactants. The preparation method provided by the invention has the advantages of controllable product appearance, adjustable composition, and simple process and equipment.

Contents of the invention

The purpose of the present invention is to provide a wet chemical synthesis method of low-dimensional nickel sulfide nanocrystals, which is characterized by controllable product morphology, adjustable composition, and simple process and equipment.

The wet chemical preparation method of the low-dimensional nickel sulfide nanocrystal is characterized in that: the water-in-oil microemulsion is used as the reaction medium, and the inorganic nickel salt, carbon disulfide, and urea are used as the reactants, and the hydrothermal treatment is carried out in a reactor. The resulting suspension is distilled under reduced pressure, washed and dried to prepare nickel sulfide one-dimensional nano-needles, tubes or two-dimensional nano-thin lamellar crystals. This shows that the concrete steps of the wet chemical preparation method of the low-dimensional nickel sulfide nanocrystal provided by the present invention can be divided into two steps:

The first step: preparation of water-in-oil microemulsion; the second step: hydrothermal treatment. The details are as follows:

1. Preparation of water-in-oil microemulsion

First, dissolve inorganic nickel salt in distilled water to form an aqueous solution with a Ni ²⁺ concentration of 0.01-0.5 mol/L as the water phase of the microemulsion, add carbon disulfide and urea in equimolar amounts, and the molar ratio of the added amount to Ni ²⁺ is 1 ~6. In the "Cetyltrimethylammonium Bromide (CTAB)/n-pentanol/n-hexane/water" reaction medium: CTAB is a surfactant with a concentration of 0.1mol/L; n-pentanol is a cosurfactant agent, the molar ratio of co-surfactant to surfactant is 8.7; n-hexane is the oil phase; the aqueous solution of inorganic nickel salt is the water phase, and the molar ratio W of the water phase to the surfactant is 10-60. Firstly, CTAB and urea are added to the mixture of inorganic nickel salt solution, n-pentanol and n-hexane, magnetically stirred for 10-15 minutes, and then ultrasonically treated for 10-15 minutes to obtain a translucent emulsion, and then the translucent emulsion Heat it in an oven at 80-100°C for 3-5 minutes to obtain a light-transparent microemulsion, add carbon disulfide (or add dodecanethiol at the same time) and magnetically stir for 5 minutes, and then put it into the reaction kettle. In "Triton X-100 (polyethylene glycol octylphenyl ether)/isopropanol/cyclohexane/water" reaction medium: Triton X-100, isopropanol, cyclohexane, inorganic nickel salt solution Surfactant, co-surfactant, oil phase and water phase, the volume ratio is 6:7.5:30:30. Add Triton X-100 and urea to the mixed solution of inorganic nickel salt solution, isopropanol and cyclohexane, stir magnetically for 10 to 15 minutes, and then ultrasonically for 10 to 15 minutes to obtain a clear and transparent microemulsion, then add Carbon disulfide and magnetic stirring for 5 minutes can be loaded into the kettle. The inorganic nickel salt is one, two or three of nickel nitrate, nickel chloride and nickel acetate.

2. Hydrothermal treatment

Put the prepared microemulsion into a reaction kettle lined with polytetrafluoroethylene. The filling degree of the microemulsion is 70-80%. After sealing it tightly, keep it warm at a temperature of 120-200°C for 5-48 hours and then cool it naturally. to room temperature. The collected gray-black suspension is distilled under reduced pressure at a temperature below 60°C and a vacuum of less than 0.1MPa to remove volatile organic solvents, and then wash the precipitate with acetone, water, and absolute ethanol in sequence to remove the Sulfur or other organic matter, surfactant and other impurities, and then place the washed product in a desiccator to dry at room temperature.

By controlling the holding time, microemulsion system and parameters, Ni ²⁺ concentration or adding dodecyl mercaptan, nickel sulfide nanocrystals with different shapes can be prepared: nanoneedles or tubes with different diameters, nano-thin layer crystals with different thicknesses , monodisperse small platelets, nanorod crystals. By controlling the ratio of reactant Ni ²⁺ to carbon disulfide, the products with different components can be obtained: Ni ₇ S ₆ , goethite NiS, hexagonal phase NiS _1.03 , Ni ₃ S ₄ , NiS ₂ .

The reaction process is as follows:

(1)

(2)

(3)

The thickness of the obtained nanometer sheet is 2-10nm, the diameter of the nanoneedle or tube is 5-200nm, and the length is 50-2000nm.

Description of drawings

Figure 1 takes "CTAB/n-pentanol/n-hexane/water" as the reaction medium, [Ni ²⁺ ]=0.1mol/L, W=30, X-ray diffraction pattern of the product obtained by hydrothermal treatment at 130°C: (a) Ni ²⁺ :CS ₂ :CO(NH ₂ ) ₂ =1:1:1, 15 hours; (b) Ni ²⁺ :CS ₂ :CO(NH ₂ ) ₂ =1:3:3, 5 hours; ( c) Ni ²⁺ : CS ₂ : CO(NH ₂ ) ₂ =1:3:3, 15 hours; (d) Ni ²⁺ :CS 2 _: CO(NH ₂ ) ₂ =6:6:6, 15 hours . ●-NiS _1.03 ; ○-goethite NiS; ▼-Ni ₇ S ₆ ; ■-S; □-Ni ₃ S ₄ ;▲-NiS ₂

Figure 2 uses "CTAB/n-pentanol/n-hexane/water" as the reaction medium, [Ni ²⁺ ]=0.1mol/L, W=30, Ni ^{2+ :} CS ₂ :CO(NH ₂ ) ₂ =1: 3:3, transmission electron micrographs of samples obtained by hydrothermal (a) 5 hours and (b) 15 hours.

Figure 3 uses "CTAB/n-pentanol/n-hexane/water" as the reaction medium, [Ni ²⁺ ]=0.1mol/L, Ni ²⁺ :CS ₂ :CO(NH ₂ ) ₂ =1:3:3, Transmission electron micrographs of samples obtained by hydrothermal heating at 130° C. for 15 hours: (a) W=15, (b) W=45.

Figure 4 uses "CTAB/n-pentanol/n-hexane/water" as the reaction medium, [Ni ²⁺ ]=0.1mol/L, W=30, Ni ^{2+ :} CS ₂ :CO(NH ₂ ) ₂ =1: 3:3, add 1.0mL of dodecanethiol, and heat at 130°C for 15 hours to obtain the transmission electron micrograph of the sample.

Figure 5 uses "Triton X-100/isopropanol/cyclohexane/water" as the reaction medium, [Ni ²⁺ ]=0.1mol/L, Ni ^{2+ :} CS ₂ :CO(NH ₂ ) ₂ =1: 3:3, transmission electron micrographs of samples obtained by hydrothermal heating at 130°C for 15 hours.

Figure 6 uses "CTAB/n-pentanol/n-hexane/water" as the reaction medium, [Ni ²⁺ ]=0.01mol/L, W=30, Ni ²⁺ :CS ₂ :CO(NH ₂ ) ₂ =1: 3:3, transmission electron micrographs of samples obtained by hydrothermal heating at 130°C for 5 hours.

Detailed ways

Example 1:

Dissolve 2.73g CTAB and 0.07g urea in a mixed solution of 7.0mL n-pentanol and 4.0mL nickel salt solution (W=30, [Ni ²⁺ ]=0.1mol/L), then add n-hexane until the total volume is about 75mL; the mixed solution was magnetically stirred and ultrasonically treated for 15 minutes, and then heated at 100°C for 5 minutes to obtain a clear and transparent microemulsion; then add 0.07mL of carbon disulfide, namely Ni ²⁺ : CS ₂ : CO(NH ₂ ) ₂ = 1:3:3, magnetically stirred for 5 minutes and then put into a reaction kettle, kept warm at 130°C for 5 and 15 hours respectively, and then naturally cooled to room temperature. The resulting gray-black suspension was distilled under reduced pressure at 60°C to remove volatile organic solvents, washed with acetone, water, and absolute ethanol in sequence, and then placed in a desiccator to dry at room temperature to obtain the product. Figure 1(b) and Figure 1(c) are the X-ray diffraction patterns obtained by hydrothermal treatment for 5 hours and 15 hours, respectively. It can be seen from the figure that the main crystal phase of hydrothermal 5 hours is hexagonal NiS _1.03 , and the main crystal phase of the product obtained by hydrothermal heating for 15 hours is a mixture of hexagonal NiS _1.03 and rhombohedral gourite NiS. Figure 2(a) and Figure 2(b) are transmission electron micrographs obtained after 15 hours and 15 hours respectively. The product of hydrothermal treatment for 5 hours is a two-dimensional thin-layer sheet structure with a thickness less than 10 nm; the product of hydrothermal treatment for 15 hours is a needle-like structure with a diameter of 50-200 nm and a length of more than 1.0 μm.

Example 2:

Dissolve 2.73g CTAB and 0.03g (or 0.15g) urea in a mixed solution of 7.0mL n-pentanol and 4.0mL nickel salt solution (W=30, [Ni ²⁺ ]=0.1mol/L), then add n-hexane until the total volume is about 75mL; the mixed solution is magnetically stirred and ultrasonically treated for 15 minutes, and then heated at about 100°C for 5 minutes to obtain a clear and transparent microemulsion; then add 0.03mL (or 0.15mL) of carbon disulfide, namely Ni ²⁺ : CS ₂ : CO(NH ₂ ) ₂ = 1: 1: 1 (or Ni ²⁺ : CS ₂ : CO(NH ₂ ) ₂ = 1: 6: 6), magnetically stirred for 5 minutes and put into the reaction vessel , kept at 130°C for 15 hours and then cooled naturally to room temperature.

The resulting gray-black suspension was distilled under reduced pressure at 60°C to remove volatile organic solvents, washed with acetone, water, and absolute ethanol in sequence, and then placed in a desiccator to dry at room temperature to obtain the product. Figure 1(a) and Figure 1(d) are respectively Ni ²⁺ : CS ₂ :CO(NH ₂ ) ₂ =1:1:1 and Ni ²⁺ :CS ₂ :CO(NH ₂ ) ₂ =1:6 : X-ray diffraction pattern of the product obtained at 6 o'clock. It can be seen from the figure that when Ni ²⁺ : CS ₂ : CO(NH ₂ ) ₂ = 1:1:1, the product obtained is a mixture of Ni ₇ S ₆ and NiS _1.03 , while when Ni ²⁺ : CS _{2 :} CO(NH 2 ) ₂ ) The product obtained when ₂ = 6:6:6 is a mixture of Ni ₃ S ₄ and NiS ₂ .

Example 3:

Dissolve 2.73g CTAB and 0.035g (or 0.105g) urea in 7.0mL n-pentanol and 2.0mL (or 6.0mL) nickel salt solution (W=15 (or W=45), [Ni ²⁺ ]=0.1mol /L), then add n-hexane until the total volume is about 75mL; the mixed solution is magnetically stirred, ultrasonically treated for 15 minutes, and then heated at 100°C for 5 minutes to obtain a clear and transparent microemulsion; then add 0.035 mL (or 0.105 mL) of carbon disulfide, i.e. Ni ²⁺ : CS ₂ : CO(NH ₂ ) ₂ = 1:3:3, stirred by magnetic force for 5 minutes, put into the reaction kettle, kept at 130°C for 15 hours and then naturally Cool to room temperature. The resulting gray-black suspension was distilled under reduced pressure at 60°C to remove volatile organic solvents, washed with acetone, water, and absolute ethanol in sequence, and then dried in a desiccator at room temperature to obtain the product. Figure 3(a) and Figure 3(b) are transmission electron micrographs of the products obtained when W=15 and W=45, respectively. As shown in the figure, when W=15, the product obtained is needle-like morphology with a diameter of less than 10 nm and a length of about 100 nm; when W=45, the product obtained is irregular, thicker plate crystals and rod crystals with a diameter of more than 100 nm.

Example 4:

Dissolve 2.73g CTAB and 0.07g urea in a mixed solution of 7.0mL n-pentanol and 4.0mL nickel salt solution (W=30, [Ni ²⁺ ]=0.1mol/L), then add n-hexane until the total volume is about is 75mL. The mixed solution was magnetically stirred and ultrasonically treated for 15 minutes, then heated at about 100°C for 5 minutes to obtain a clear and transparent microemulsion, and then 0.07mL of carbon disulfide and 1.0mL of dodecanethiol were added, magnetically stirred for 5 minutes, and then put into the reaction Kettle, at 130 ° C for 15 hours and then naturally cooled to room temperature. The resulting gray-black suspension was distilled under reduced pressure at 60°C to remove volatile organic solvents, washed with acetone, water, and absolute ethanol in sequence, and then dried in a desiccator at room temperature to obtain the product. Figure 4 is a transmission electron micrograph of the product, from which it can be seen that the product has an irregular monodisperse sheet structure.

Example 5:

Add 7.5mL Triton X-100 and 6.0mL nickel salt solution ([Ni ²⁺ ]=0.1mol/L) to 30mL isopropanol, then add 30mL cyclohexane and 0.15g urea, then magnetically stir and sonicate A clear and transparent microemulsion can be obtained in 15 minutes, then add 0.15 mL of carbon disulfide (Ni ²⁺ :CS ₂ :CO(NH ₂ ) ₂ =1:3:3), stir magnetically for 5 minutes, and then put it into the reactor. Keep warm at 130°C for 15 hours, then naturally cool to room temperature to obtain a gray-black suspension, distill off volatile organic solvents under reduced pressure at 60°C, wash with acetone, water, and absolute ethanol in sequence, and place in a desiccator Dry at room temperature to obtain the product. Figure 5 is a transmission electron microscope photo of the product. It can be seen from the figure that the product is a flat and stretched thicker layer structure rather than a curled needle-like structure.

Embodiment 6:

Dissolve 2.73g CTAB and 0.01g urea in a mixed solution of 7.0mL n-pentanol and 4.0mL nickel salt solution (W=30, [Ni ²⁺ ]=0.01mol/L), then add n-hexane until the total volume is about is 75mL. The mixed solution was magnetically stirred and ultrasonically treated for 15 minutes, then heated at about 100°C for 5 minutes to obtain a clear and transparent microemulsion, and then 0.01mL of carbon disulfide was added, magnetically stirred for 5 minutes, then put into a reaction kettle, and heated at 130°C After 15 hours of heat preservation, it was naturally cooled to room temperature. The resulting gray-black suspension was distilled under reduced pressure at 60°C to remove volatile organic solvents, washed with acetone, water, and absolute ethanol in sequence, and then dried in a desiccator at room temperature to obtain the product. Figure 6 is a transmission electron micrograph of the product. As shown in the figure, the product is a two-dimensional thin-layer structure with a very thin thickness (less than 5 nm).

Claims (5)

1. the wet chemical preparation method of low-dimensional nanometer nickel sulfide crystalline substance, it is characterized in that: be reaction medium with the water in oil microemulsion, with inorganic nickel, dithiocarbonic anhydride, urea is reactant, in reactor, carry out hydrothermal treatment consists, gained suspension makes nickelous sulfide 1-dimention nano pin, pipe or two-dimensional nano thin layer platelet through underpressure distillation, washing, drying treatment;

Described water in oil microemulsion is cetyl trimethylammonium bromide/Pentyl alcohol/normal hexane/water or Triton X-100/Virahol/hexanaphthene/water; Wherein the preparation of cetyl trimethylammonium bromide/Pentyl alcohol/normal hexane/water is to be tensio-active agent with the cetyl trimethylammonium bromide, its concentration is 0.1mol/L, with the Pentyl alcohol is cosurfactant, the mol ratio of cosurfactant and tensio-active agent is 8.7, with the normal hexane is oil phase, the inorganic nickel aqueous solution is water, and the mol ratio of water and tensio-active agent is 10～60; The preparation of Triton X-100/Virahol/hexanaphthene/water is to be tensio-active agent with the Triton X-100, with the Virahol is cosurfactant, with the hexanaphthene is oil phase, with the inorganic nickel aqueous solution is water, and the volume ratio of Triton X-100, Virahol, hexanaphthene, the inorganic nickel aqueous solution is 6: 7.5: 30: 30;

Described inorganic nickel Ni ²⁺Concentration is 0.01-0.5mol/L; Mole such as described dithiocarbonic anhydride and urea adds add-on and Ni ²⁺Mol ratio be 1-6; Described hydrothermal treatment consists is under 120-200 ℃, is incubated 5-48 hour.

2. by the preparation method of the wet-chemical of the described low-dimensional nanometer nickel sulfide of claim 1 crystalline substance, it is characterized in that: the inorganic nickel aqueous solution be by in nickelous nitrate, nickelous chloride and the nickel acetate a kind of, two or three be dissolved in distilled water and make.

3. by the wet chemical preparation method of the described low-dimensional nanometer nickel sulfide of claim 1 crystalline substance, it is characterized in that: reactor is stainless steel and polytetrafluoroethyllining lining is arranged, the compactedness 70～80% of microemulsion.

4. by the wet chemical preparation method of the described low-dimensional nanometer nickel sulfide of claim 1 crystalline substance, it is characterized in that: the service temperature of underpressure distillation is lower than 60 ℃, and vacuum tightness is less than 0.1MPa.

5. by the wet chemical preparation method of the described low-dimensional nanometer nickel sulfide of claim 1 crystalline substance, the thickness that it is characterized in that obtained nanometer thin synusia is 2-10nm, and the diameter of nanoneedle or pipe is 5-200nm, and length is 50～2000nm.

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