阅读说明：本技术 纳米磷化钨/碳或氮化钨/碳复合材料及其制备方法 (Nano tungsten phosphide/carbon or tungsten nitride/carbon composite material and preparation method thereof ) 是由 冯其 尧克光 邹杰鑫 廖建华 李辉 王海江 于 2019-09-30 设计创作，主要内容包括：本发明涉及催化剂材料技术领域,具体涉及一种纳米磷化钨/碳或氮化钨/碳复合材料及其制备方法。所述制备方法包括以下步骤：将钨源、碳源溶于溶剂中,得到混合溶液；调节所述混合溶液的pH值为碱性；对所述混合溶液进行加热蒸干,得到固体前驱体；在保护气氛下对所述前驱体进行煅烧处理,得到固体粉末；在保护气氛下采用磷化剂对所述固体粉末进行磷化处理,得到磷化钨/碳复合材料；或者,在保护气氛下采用氮化剂对所述固体粉末进行氮化处理,得到氮化钨/碳复合材料。本发明提供的制备方法,生产过程安全可靠,工艺条件简单易控、生产成本低,适于工业化大规模生产。(The invention relates to the technical field of catalyst materials, in particular to a nano tungsten phosphide/carbon or tungsten nitride/carbon composite material and a preparation method thereof. The preparation method comprises the following steps: dissolving a tungsten source and a carbon source in a solvent to obtain a mixed solution; adjusting the pH value of the mixed solution to be alkaline; heating and evaporating the mixed solution to dryness to obtain a solid precursor; calcining the precursor under a protective atmosphere to obtain solid powder; carrying out phosphating treatment on the solid powder by using a phosphating agent under a protective atmosphere to obtain a tungsten phosphide/carbon composite material; or nitriding the solid powder by using a nitriding agent in a protective atmosphere to obtain the tungsten nitride/carbon composite material. The preparation method provided by the invention has the advantages of safe and reliable production process, simple and easily-controlled process conditions and low production cost, and is suitable for industrial large-scale production.)

1. A preparation method of a nano tungsten phosphide/carbon or tungsten nitride/carbon composite material is characterized by comprising the following steps:

dissolving a tungsten source and a carbon source in a solvent to obtain a mixed solution; adjusting the pH value of the mixed solution to be alkaline;

heating and evaporating the mixed solution to dryness to obtain a solid precursor;

calcining the precursor under a protective atmosphere to obtain solid powder;

carrying out phosphating treatment on the solid powder by using a phosphating agent under a protective atmosphere to obtain a tungsten phosphide/carbon composite material;

or nitriding the solid powder by using a nitriding agent in a protective atmosphere to obtain the tungsten nitride/carbon composite material.

2. The method for preparing the nano tungsten phosphide/carbon or tungsten nitride/carbon composite material as claimed in claim 1, wherein the phosphating agent is ammonium dihydrogen phosphate, and the phosphating treatment is a calcination treatment of placing the solid powder and the ammonium dihydrogen phosphate in the same reaction chamber at 700-850 ℃ so that the ammonium dihydrogen phosphate is decomposed to generate PH₃And phosphating the solid powder.

3. The method for preparing nano tungsten phosphide/carbon or tungsten nitride/carbon composite material according to claim 1, wherein the nitriding agent is ammonium dihydrogen phosphate, and the nitriding treatment is to calcine the solid powder and the ammonium dihydrogen phosphate in the same reaction chamber at 900-1000 ℃ so that the ammonium dihydrogen phosphate is decomposed to generate NH₃And nitriding the solid powder.

4. The method for preparing the nano tungsten phosphide/carbon or tungsten nitride/carbon composite material as claimed in claim 1, wherein the feeding ratio of the tungsten source to the carbon source is 1: (0.25 to 3).

5. The method for preparing a nano tungsten phosphide/carbon or tungsten nitride/carbon composite material as claimed in claim 1, wherein the calcination treatment is calcination at (400 to 700) ° c.

6. The method for preparing nano tungsten phosphide/carbon or tungsten nitride/carbon composite material according to claim 1, wherein the tungsten source is at least one of ammonium metatungstate, sodium tungstate, potassium tungstate, ammonium tungstate, phosphotungstic acid, zinc tungstate and tungstic acid;

and/or the presence of a gas in the gas,

the carbon source is dopamine hydrochloride.

7. The method for preparing nano tungsten phosphide/carbon or tungsten nitride/carbon composite material according to claim 1, wherein the protective atmosphere is any one of nitrogen, argon, helium, a mixed gas of nitrogen and hydrogen, a mixed gas of argon and hydrogen, and a mixed gas of helium and hydrogen, and the volume content of hydrogen in the mixed gas is not more than 15%.

8. The method for preparing a nano tungsten phosphide/carbon or tungsten nitride/carbon composite material as claimed in claim 1, wherein the pH value of the mixed solution is adjusted to 8.5 to 9.0.

9. The method for preparing nano tungsten phosphide/carbon or tungsten nitride/carbon composite material according to claim 1, wherein the solvent is a mixed solvent of water and ethanol, and the ratio of water to ethanol is 1: (1-8).

10. A nano tungsten phosphide/carbon or tungsten nitride/carbon composite material, which is characterized in that the nano tungsten phosphide/carbon composite material is spherical particles, the nano tungsten nitride/carbon composite material is spherical particles, and the nano tungsten phosphide/carbon or tungsten nitride/carbon composite material is prepared by the preparation method of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of catalyst materials, and particularly relates to a nano tungsten phosphide/carbon or tungsten nitride/carbon composite material and a preparation method thereof.

Background

Noble metals such as platinum are widely used in catalytic processes in the fields of petrochemical industry, organic synthesis, fuel cells, automobiles, electronic industry, and the like because of their catalytic effects, but on the one hand, such noble metals are very small in reserves on the earth and are decreasing, and on the other hand, they are very expensive and have high application costs. Because of this, new catalytic materials that can replace noble metal catalysts such as platinum have been sought.

Among the numerous novel catalytic materials, tungsten phosphide (WP) or tungsten nitride (WN) exhibits platinum-like catalytic properties due to its surface properties and adsorption properties. Since the catalyst has the catalytic property, the catalyst is regarded as a potential material which can partially or completely replace noble metal platinum, and therefore, the catalyst has wide application prospect.

At present, the traditional preparation process of tungsten phosphide or tungsten nitride is to reduce WO at high temperature₃And (4) synthesizing. However, the tungsten phosphide or tungsten nitride carbon sphere composite material prepared by the method has large size, small specific surface area and low purity, and limits the catalytic activity of the tungsten phosphide or tungsten nitride. In addition, in the traditional tungsten phosphide preparation process, extremely toxic and explosive PH is often introduced₃AsThe phosphorus source brings great safety risk to operators. Therefore, it is necessary to develop a synthetic method which has a large specific surface area, high purity and a safe and environment-friendly synthetic process.

Disclosure of Invention

Aiming at the problems that the process is complicated, toxic and harmful gases are required to be used, the effective specific surface area of the obtained material is small and the like in the existing preparation of tungsten phosphide or tungsten nitride, the invention provides a nano tungsten phosphide/carbon or tungsten nitride/carbon composite material and a preparation method thereof.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method for preparing a nano tungsten phosphide/carbon or tungsten nitride/carbon composite material comprises the following steps:

dissolving a tungsten source and a carbon source in a solvent to obtain a mixed solution; adjusting the pH value of the mixed solution to be alkaline;

heating and evaporating the mixed solution to dryness to obtain a solid precursor;

calcining the precursor under a protective atmosphere to obtain solid powder;

carrying out phosphating treatment on the solid powder by using a phosphating agent under a protective atmosphere to obtain a tungsten phosphide/carbon composite material;

or nitriding the solid powder by using a nitriding agent in a protective atmosphere to obtain the tungsten nitride/carbon composite material.

Correspondingly, the nano tungsten phosphide/carbon or tungsten nitride/carbon composite material is characterized in that the nano tungsten phosphide/carbon composite material is spherical particles, the nano tungsten nitride/carbon composite material is spherical particles, and the nano tungsten phosphide/carbon or tungsten nitride/carbon composite material is prepared by the preparation method.

The invention has the technical effects that:

compared with the prior art, the preparation method provided by the invention can obtain the nano-scale spherical tungsten phosphide/carbon composite material or tungsten nitride/carbon composite material by utilizing a uniform reaction mode of an organic-inorganic hybrid precursor without flammable gas and the like, and the whole production process is safe and reliable, simple and easily controlled in process conditions, low in production cost and suitable for industrial large-scale production.

The nano tungsten phosphide/carbon or tungsten nitride/carbon composite material provided by the invention is prepared by the method, has the characteristics of small particle size, high purity, large effective specific surface area, spherical particle shape and the like, shows catalytic activity similar to platinum and can be widely applied to the field of catalysis.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is the X-ray powder diffraction pattern of the nano tungsten phosphide/carbon composite material prepared in example 1 of the present invention;

FIG. 2 is an SEM image of the nano-sized tungsten phosphide/carbon composite material prepared in example 1 of the present invention at a magnification of 10.0 kx;

FIG. 3 is an EDS diagram of a nano tungsten phosphide/carbon composite material prepared in example 1 of the present invention;

FIG. 4 is the X-ray powder diffraction diagram of the nano tungsten nitride/carbon composite material prepared in example 2 of the present invention;

FIG. 5 is an SEM image of the nano tungsten nitride/carbon composite material prepared by 2 and prepared by the method in example 1 of the invention at a magnification of 50.0 kx;

FIG. 6 is an EDS diagram of the nano tungsten nitride/carbon composite material prepared by the preparation method 2 in the embodiment 2 of the invention;

fig. 7 is a hydrogen evolution reaction polarization curve of the nano tungsten phosphide/carbon prepared in example 1 and the nano tungsten nitride/carbon composite material prepared in example 2 as a catalyst.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The noun explains:

in the invention, the nano tungsten phosphide/carbon and the nano tungsten phosphide/carbon composite material both refer to a mixture formed by nano tungsten phosphide and carbon, and the carbon is coated on the surface of tungsten phosphide particles to form nano tungsten phosphide/carbon spheres.

In the invention, the nano tungsten nitride/carbon and the nano tungsten nitride/carbon composite material both refer to a mixture formed by nano nitride and carbon, and the carbon is coated on the surface of tungsten nitride particles to form nano tungsten nitride/carbon spheres.

The invention provides a preparation method of a nano tungsten phosphide/carbon or tungsten nitride/carbon composite material, which comprises the following steps:

dissolving a tungsten source and a carbon source in a solvent to obtain a mixed solution; adjusting the pH value of the mixed solution to be alkaline;

heating and evaporating the mixed solution to dryness to obtain a solid precursor;

calcining the precursor under a protective atmosphere to obtain solid powder;

carrying out phosphating treatment on the solid powder by using a phosphating agent under a protective atmosphere to obtain a tungsten phosphide/carbon composite material;

or nitriding the solid powder by using a nitriding agent in a protective atmosphere to obtain the tungsten nitride/carbon composite material.

The above-mentioned production method is explained in detail below.

In particular, the tungsten source, the carbon source, used should be capable of dissolving in the solvent.

The tungsten source is at least one of ammonium metatungstate, sodium tungstate, potassium tungstate, ammonium tungstate, phosphotungstic acid, zinc tungstate and tungstic acid.

The carbon source is selected from dopamine hydrochloride.

The solvent is a mixture of water and ethanol, such as a mixture of deionized water and ethanol, a mixture of double distilled water and ethanol, and the like, a tungsten source and a carbon source are dissolved in the solvent, dopamine hydrochloride can be self-polymerized and crosslinked on the surface of the tungsten source in the environment of ethanol, polydopamine is finally formed on the surface of the tungsten source, and the phenomenon that the precursor particles obtained finally are too large due to the large aggregation of the tungsten source and are not favorable for forming the nano-scale tungsten phosphide/carbon composite material or the nano-scale tungsten nitride/carbon composite material is avoided.

When the tungsten source and the carbon source are dissolved in the solvent, the tungsten source and the carbon source can be dissolved in water, and then ethanol is added into the water; or mixing water and ethanol, and adding tungsten source and carbon source; or dissolving the tungsten source and the carbon source in ethanol, and adding water.

The volume ratio of water to ethanol in the solvent is 1: (1-8). And ethanol is excessive in water, so that the carbon source is fully dissolved and fully self-polymerized and crosslinked on the surface of the tungsten source. If the ethanol dosage is too small, the particle size of the obtained precursor is too large, and if the ethanol dosage is too large, the spherical shape cannot be formed.

Preferably, the feeding ratio of the tungsten source to the carbon source is 1: (0.25 to 3).

When the tungsten source and the carbon source are dissolved in the solvent, the dissolution of the carbon source can be added by mechanical stirring, such as ultrasonic oscillation, and the like, and the crosslinking polymerization is accelerated.

After the tungsten source and the carbon source are mixed, the carbon source is dopamine hydrochloride, which makes the mixed solution acidic and is not beneficial to polymerization crosslinking, therefore, in order to promote polymerization crosslinking, the pH value of the mixed solution needs to be adjusted to be alkaline, for example, alkaline substances such as sodium hydroxide, potassium hydroxide, ammonia water and the like are added. In order not to introduce impurities, aqueous ammonia is preferable.

Preferably, after the pH value is adjusted, the pH value of the mixed solution is 8.5-9.0. In this pH range, cross-linking polymerization of dopamine can be accelerated.

Before the multi-mixed solution is heated and evaporated to dryness, standing and aging treatment can be carried out on the mixed solution, wherein the standing and aging treatment time is 12-24 hours.

The solvent was then evaporated by constant temperature heating. Preferably, the constant-temperature heating temperature is 70-90 ℃, the solvent volatilization speed is high at the heating temperature, and the added ammonia water and the like can also be effectively volatilized.

Further, the constant temperature heating mode is water bath heating or oil bath heating. The two heating modes can ensure that the second mixed solution is uniformly heated and is not influenced by the change of the environmental temperature.

Before the calcining treatment is carried out on the obtained solid precursor, the washing and drying treatment can also be carried out on the obtained solid precursor. During the drying treatment, in order to avoid the oxidation reaction from affecting the final product, the drying is carried out in a vacuum environment, wherein the drying temperature is (50-80) DEG C, so as to accelerate the volatilization of the water.

In the calcining process, the adopted protective atmosphere can avoid side reaction and ensure the carbonizing process of calcining. The gas of protective atmosphere is nitrogen, argon, helium, the gas mixture of hydrogen and nitrogen, the gas mixture of hydrogen and argon, the gas mixture of hydrogen and helium, and in the gas mixture, the concentration of hydrogen volume does not exceed 15%, through adding right amount of hydrogen, can be favorable to the carbonization process, but hydrogen concentration is too high, can reduce and produce metal, and can not obtain tungsten phosphide, tungsten nitride.

Preferably, the calcination temperature of the solid precursor is (400-700) DEG C. The calcination temperature used in the calcination treatment may be 400 ℃, 410 ℃, 420 ℃, 430 ℃, 450 ℃, 480 ℃, 500 ℃, 520 ℃, 530 ℃, 535 ℃, 550 ℃, 565 ℃, 570 ℃, 600 ℃, 610 ℃, 620 ℃, 625 ℃, 640 ℃, 660 ℃, 670 ℃, 680 ℃, 690 ℃, 700 ℃ or the like, and the calcination at these temperatures gives little difference in the effect of the obtained solid powder.

The phosphating agent used in the phosphating treatment is ammonium dihydrogen phosphate (NH)₄H₂PO₄) And the nitriding agent used in the nitriding treatment is ammonium dihydrogen phosphate (NH)₄H₂PO₄) Ammonium dihydrogen phosphate generates phosphine (pH) during heating₃) And ammonia (NH)₃) At different temperatures, the solid powder obtained by calcination is phosphated or nitrided, thus obtaining the tungsten phosphide/carbon composite material or tungsten nitride/carbon composite materialAnd (5) synthesizing the materials. For example, at 700-850 deg.C, phosphorization occurs, and at 900-1000 deg.C, nitridation occurs.

Specifically, ammonium dihydrogen phosphate is placed in the windward direction of airflow in protective atmosphere, and NH is generated during heating₄H₂PO₄Decomposition by heating to form pH₃And NH₃And reducing the solid powder along with the flowing of the protective gas to obtain the tungsten phosphide or tungsten nitride. In particular, the protective atmosphere introduced is a hydrogen/argon mixture (10% by volume of hydrogen).

The preparation method of the nano tungsten phosphide/carbon or tungsten nitride/carbon composite material provided by the invention mainly utilizes a uniform reaction mode of an organic-inorganic hybrid precursor, does not need flammable gas and the like, can obtain the spherical nano tungsten phosphide/carbon composite material or tungsten nitride/carbon composite material, has the advantages of safe and reliable whole production process, simple and easily-controlled process conditions and low production cost, and is suitable for industrial large-scale production.

The nano tungsten phosphide/carbon and tungsten nitride/carbon composite material obtained by the preparation method has the characteristics of uniform particle size, low impurity content, spherical carbon sphere composite material, small particle size, uniform appearance, micropores on the surface and the like, can be used in the catalysis field of fuel cells, and can be used in the catalysis fields of other hydrogen evolution, hydrogenation, hydrogenolysis, oxygen reduction, carriers and the like.

In order to more effectively explain the technical solution of the present invention, a plurality of specific examples are described below.