阅读说明：本技术 一种磷化钼纳米材料及其制备方法和用途 (Molybdenum phosphide nano material and preparation method and application thereof ) 是由 朴玲钰 于海宁 曹爽 吴志娇 伏兵 于 2018-07-04 设计创作，主要内容包括：本发明提供了一种磷化钼纳米材料及其制备方法和用途。所述磷化钼纳米材料包括由磷化钼纳米管组成的阵列。所述制备方法包括：(1)以钼原料作为阳极,在含氟化铵的电解液中与阴极进行电解,得到电解后的钼；氟化铵的电解液中溶剂中包含丙三醇；(2)将步骤(1)所述电解后的钼在惰性气体环境中加热,得到改性后的钼；(3)将步骤(2)所述改性后的钼与磷源混合,进行加热反应,得到所述磷化钼纳米材料。所述磷化钼纳米材料作为电催化领域的催化剂。本发明提供的磷化钼纳米材料形貌新颖,比表面积大,活性位点多,催化性能优良；本发明提供的制备方法操作简单,流程短,成本低廉,产业化生产前景良好。(The invention provides a molybdenum phosphide nano material and a preparation method and application thereof. The molybdenum phosphide nano material comprises an array consisting of molybdenum phosphide nanotubes. The preparation method comprises the following steps: (1) taking a molybdenum raw material as an anode, and electrolyzing the molybdenum raw material and a cathode in an electrolyte containing ammonium fluoride to obtain electrolyzed molybdenum; the solvent in the ammonium fluoride electrolyte contains glycerol; (2) heating the electrolyzed molybdenum obtained in the step (1) in an inert gas environment to obtain modified molybdenum; (3) and (3) mixing the modified molybdenum obtained in the step (2) with a phosphorus source, and carrying out heating reaction to obtain the molybdenum phosphide nano material. The molybdenum phosphide nano material is used as a catalyst in the field of electrocatalysis. The molybdenum phosphide nano material provided by the invention has the advantages of novel appearance, large specific surface area, many active sites and excellent catalytic performance; the preparation method provided by the invention is simple to operate, short in flow, low in cost and good in industrial production prospect.)

1. The molybdenum phosphide nano material is characterized by comprising an array consisting of molybdenum phosphide nanotubes.

2. The molybdenum phosphide nanomaterial of claim 1, wherein the molybdenum phosphide nanomaterial is an array consisting of molybdenum phosphide nanotubes;

preferably, in the molybdenum phosphide nano material, the outer diameter of the molybdenum phosphide nano tube is 60nm-120 nm;

preferably, in the molybdenum phosphide nano material, the inner diameter of the molybdenum phosphide nano tube is 30nm-60 nm;

preferably, in the molybdenum phosphide nano material, the thickness of the tube wall of the molybdenum phosphide nanotube is 20nm-30 nm.

3. The method for preparing molybdenum phosphide nanomaterial according to claim 1 or 2, wherein the method comprises the steps of:

(1) taking a molybdenum raw material as an anode, and electrolyzing the molybdenum raw material and a cathode in an electrolyte containing ammonium fluoride to obtain electrolyzed molybdenum;

wherein, in the electrolyte containing ammonium fluoride, a solvent used contains glycerol;

(2) heating the electrolyzed molybdenum obtained in the step (1) in an inert gas environment to obtain modified molybdenum;

(3) and (3) mixing the modified molybdenum obtained in the step (2) with a phosphorus source, and carrying out heating reaction to obtain the molybdenum phosphide nano material.

4. The method according to claim 3, wherein in the step (1), the molybdenum raw material is a molybdenum sheet;

preferably, in the step (1), the purity of molybdenum in the molybdenum raw material is more than 99%;

preferably, in the step (1), the electrolyte containing ammonium fluoride consists of ammonium fluoride and a solvent;

preferably, in the electrolyte containing ammonium fluoride in the step (1), the concentration of the ammonium fluoride is 0.1mol/L-1.0mol/L, and is preferably 0.36 mol/L;

preferably, in the electrolyte containing ammonium fluoride in the step (1), the solvent is a mixed solvent of water and glycerol;

preferably, in the mixed solvent of water and glycerol, the volume ratio of glycerol to water is 5:1-10: 1;

preferably, in step (1), the cathode is a noble metal electrode;

preferably, the noble metal electrode is a platinum electrode;

preferably, in the step (1), the voltage of the electrolysis is 10V-50V direct current voltage;

preferably, in the step (1), the electrolysis time is 0.5 to 2 hours.

5. The production method according to claim 3 or 4, characterized in that, in the step (1), the method further comprises the step (1'): before electrolysis, carrying out ultrasonic cleaning on a molybdenum raw material, then washing with water, and finally drying in a nitrogen environment to obtain a purified molybdenum raw material;

preferably, in step (1'), the ultrasonic cleaning is performed in an ultrasonic cleaner;

preferably, in the step (1'), the cleaning agent for ultrasonic cleaning is acetone and/or ethanol;

preferably, in the step (1'), the ultrasonic frequency of the ultrasonic cleaning is 50kHz-100 kHz;

preferably, in step (1'), the time for the ultrasonic cleaning is 5 minutes to 50 minutes.

6. The method according to any one of claims 3 to 5, wherein in step (2), the inert gas comprises nitrogen and/or argon;

preferably, in step (2), the temperature of heating is 50-500 ℃, preferably 350-450 ℃;

preferably, in step (2), the heating time is 60 minutes to 120 minutes, preferably 90 minutes.

7. The method according to any one of claims 3-6, wherein step (2) further comprises: soaking the molybdenum after electrolysis in the step (1) in an immersion liquid before heating, and drying in an inert gas environment;

preferably, the infusion comprises ethanol;

preferably, the soaking time is 10 minutes to 25 minutes, preferably 15 minutes;

preferably, the inert gas comprises nitrogen and/or argon.

8. The method according to any one of claims 4 to 6, wherein in step (3), the phosphorus source comprises sodium hypophosphite, preferably sodium hypophosphite monohydrate;

preferably, in the step (3), the mass ratio of the phosphorus source to the modified molybdenum in the step (2) is 5:2-5:3, preferably 5: 2.4;

preferably, the heating reaction is carried out in a tube furnace;

preferably, the temperature of the heating reaction is 200-1000 ℃, preferably 600 ℃;

preferably, the heating reaction time is 1 hour to 2 hours;

preferably, step (3) further comprises: after the heating reaction, the obtained reaction product is naturally cooled to 20-30 ℃.

9. The method for preparing according to any one of claims 3 to 8, characterized in that it comprises the steps of:

(1') performing ultrasonic cleaning on the molybdenum raw material in an ultrasonic cleaner for 15 minutes by using acetone as a cleaning agent, performing ultrasonic cleaning on the molybdenum raw material in the ultrasonic cleaner for 15 minutes by using ethanol as a cleaning agent, washing with water, and finally drying in a nitrogen environment to obtain a purified molybdenum raw material;

(1) electrolyzing the purified molybdenum raw material in the step (1') by using a 10V-50V direct current voltage in an ammonium fluoride-containing electrolyte for 0.5-2 hours by using a platinum electrode as a cathode to obtain electrolyzed molybdenum;

the electrolyte containing ammonium fluoride consists of ammonium fluoride and a solvent, wherein the concentration of the ammonium fluoride in the electrolyte containing ammonium fluoride is 0.36mol/L, the solvent is a mixed solvent of water and glycerol, and the volume ratio of the glycerol to the water is 5:1-10: 1;

(2) soaking the electrolyzed molybdenum obtained in the step (1) in ethanol for 15 minutes, drying in a nitrogen environment, and heating at the temperature of 350-450 ℃ for 90 minutes in the nitrogen environment to obtain modified molybdenum;

(3) mixing the modified molybdenum obtained in the step (2) with sodium hypophosphite monohydrate, carrying out heating reaction in a tubular furnace at the reaction temperature of 600 ℃ for 1-2 h, and naturally cooling the obtained reaction product to 20-30 ℃ after the heating reaction to obtain the molybdenum phosphide nano material;

wherein the mass ratio of the sodium hypophosphite monohydrate to the modified molybdenum in the step (2) is 5: 2.4.

10. Use of molybdenum phosphide nanomaterial according to claim 1 or 2, wherein the molybdenum phosphide nanomaterial is used as a catalyst in the field of electrocatalysis.

Technical Field

The invention relates to the field of a preparation method of a nanometer material, and particularly relates to a molybdenum phosphide nanometer material and a preparation method and application thereof.

Background

Energy is an important basis upon which humans are dependent for survival and development. However, as non-renewable energy sources are gradually exhausted, the demand of human beings for renewable clean energy sources is increasing. Hydrogen is widely concerned by people for the reasons of cleanness, no pollution and the like. Among various hydrogen production methods, hydrogen production by electrolyzing water is one of the currently important means. In which process an electrocatalyst with high catalytic activity is usually required. Metal phosphide has excellent thermal conductivity and thermal stability, and thus is widely used in the fields of lithium batteries, electronic materials, medical treatment, catalysts, and the like. In the reported literature, the preparation of molybdenum phosphide is mainly focused on powder samples, and the molybdenum phosphide is beneficial to recycling in the application process.

CN107999105A discloses a preparation method of a molybdenum phosphide hydrogen evolution catalyst with a porous rod-like morphology structure, which comprises the following steps: weighing a certain amount of soluble ammonium molybdate and ammonium dihydrogen phosphate, dissolving in deionized water, magnetically stirring to completely dissolve the solution to form a clear transparent solution, adding a certain amount of clean and dry absorbent cotton, and continuously stirring for a certain time to ensure that the absorbent cotton fully absorbs the solution as much as possible; then transferring the molybdenum phosphide precursor to an oven for drying, putting the dried product into a muffle furnace, and preserving the heat at a certain temperature for a certain time to obtain a molybdenum phosphide precursor; and finally, putting the precursor into a tubular furnace, preserving the heat for a certain time at a certain temperature in a reducing atmosphere, and cooling to room temperature to obtain the molybdenum phosphide hydrogen evolution catalyst with the rod-shaped porous morphology structure.

CN101898141A discloses a preparation method of a molybdenum phosphide catalyst and an application of the molybdenum phosphide catalyst in methane carbon dioxide reforming, and the specific scheme is as follows: (1) mixing ammonium molybdate, diammonium hydrogen phosphate, citric acid and waterAccording to the following steps: weighing at the mass ratio of 1.0: 0.87: 0-3.6: 50-70, stirring, adding into a high-pressure kettle at the temperature of 363-; (2) cooling and drying; (3)623 and 923K for 3-8 hours; (4) cooling, placing into a tube, and measuring with flow rate of 20-100 ml/min^-1H₂Reducing, heating from 473K to 923-^-1Keeping the temperature for 2 hours; at H₂Rapidly cooling to room temperature, and adding 1.0 vol% O₂Argon passivation for 8-12 hours.

However, the molybdenum phosphide catalyst obtained by the method has complicated experimental steps and is not suitable for the application of hydrogen production by water electrolysis.

Therefore, the development of the molybdenum phosphide nano material with larger specific surface area and better catalytic performance has great significance to the field.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a molybdenum phosphide nano material and a preparation method and application thereof. The molybdenum phosphide (MoP) nano material provided by the invention is novel in appearance, simple in preparation process, high in catalytic activity of the product and beneficial to recycling.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a molybdenum phosphide nanomaterial comprising an array of molybdenum phosphide nanotubes.

In the invention, the array structure formed by the molybdenum phosphide nanotubes enables the molybdenum phosphide nano-material provided by the invention to have a large specific surface area and more active sites compared with molybdenum phosphide nano-materials with other structures, such as molybdenum phosphide nano-sheets or molybdenum phosphide nano-rods, so that the catalytic performance of the molybdenum phosphide nano-material provided by the invention is more excellent.

The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.

As a preferred technical scheme of the invention, the molybdenum phosphide nano material is an array consisting of molybdenum phosphide nanotubes. Namely, when the molybdenum phosphide nano-material is a molybdenum phosphide nano-tube array, the molybdenum phosphide nano-material has more excellent specific surface area and catalytic activity.

Preferably, in the molybdenum phosphide nanomaterial, the molybdenum phosphide nanotube has an outer diameter of 60nm to 120nm, such as 60nm, 80nm, 90nm, 100nm, 110nm or 120nm, but the molybdenum phosphide nanotube is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the molybdenum phosphide nanomaterial has an inner diameter of molybdenum phosphide nanotubes of 30nm to 60nm, such as 30nm, 40nm, 45nm, 50nm, 55nm or 60nm, but the inner diameter is not limited to the recited value, and other values not recited in the range of the inner diameter are also applicable.

Preferably, in the molybdenum phosphide nanomaterial, the thickness of the tube wall of the molybdenum phosphide nanotube is 20nm to 30nm, such as 20nm, 22nm, 24nm, 26nm, 28nm or 30nm, but the thickness is not limited to the recited value, and other values not recited in the range of the value are also applicable.

In a second aspect, the present invention provides a method for preparing a molybdenum phosphide nanomaterial as described in the first aspect, wherein the method comprises the following steps:

(1) taking a molybdenum raw material as an anode, and electrolyzing the molybdenum raw material and a cathode in an electrolyte containing ammonium fluoride to obtain electrolyzed molybdenum;

wherein, in the electrolyte containing ammonium fluoride, a solvent used contains glycerol;

(2) heating the electrolyzed molybdenum obtained in the step (1) in an inert gas environment to obtain modified molybdenum;

(3) and (3) mixing the modified molybdenum obtained in the step (2) with a phosphorus source, and carrying out heating reaction to obtain the molybdenum phosphide nano material.

In the preparation method provided by the invention, the electrolysis step in the step (1) is firstly carried out, and molybdenum and ammonium fluoride (NH) in the electrolysis process are utilized₄F) Changing the shape of the molybdenum raw material into a tubular shape; and (3) improving the crystallinity and stability of the molybdenum which becomes tubular after electrolysis through the heating modification process in the step (2), so that the molybdenum can not be dissolved in use(ii) a And finally, heating and calcining the modified molybdenum and a phosphorus source to obtain a molybdenum phosphide nanotube structure, thereby forming the molybdenum phosphide nano material provided by the invention.

As a preferable technical solution of the present invention, in the step (1), the molybdenum raw material is a molybdenum sheet.

Preferably, in step (1), the purity of molybdenum in the molybdenum raw material is above 99%, such as 99.1%, 99.2%, 99.3%, 99.4%, or 99.5%.

Preferably, in the step (1), the electrolyte containing ammonium fluoride is composed of ammonium fluoride and a solvent.

Preferably, in the ammonium fluoride-containing electrolyte solution of step (1), the concentration of ammonium fluoride is 0.1mol/L to 1.0mol/L, for example, 0.1mol/L, 0.2mol/L, 0.3mol/L, 0.36mol/L, 0.4mol/L, 0.5mol/L, 0.6mol/L, 0.7mol/L, 0.8mol/L, 0.9mol/L, or 1.0mol/L, etc., but not limited to the enumerated values, and other non-enumerated values within the range of values are equally applicable, preferably 0.36 mol/L.

Preferably, in the ammonium fluoride-containing electrolyte in step (1), the solvent is a mixed solvent of water and glycerol.

Preferably, the volume ratio of glycerol to water in the mixed solvent of water and glycerol is 5:1 to 10:1, for example, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, but not limited to the recited values, and other values not recited in the above range are also applicable.

Preferably, in step (1), the cathode is a noble metal electrode.

Preferably, the noble metal electrode is a platinum electrode.

Preferably, in step (1), the voltage for electrolysis is 10V-50V dc voltage, such as 10V, 15V, 20V, 25V, 30V, 35V, 40V, 45V or 50V, but is not limited to the recited values, and other values not recited in the range of values are also applicable.

Preferably, in step (1), the electrolysis time is 0.5 hours to 2 hours, such as 0.5 hours, 1 hour, 1.5 hours, or 2 hours, but not limited to the recited values, and other values not recited within the range of values are also applicable.

As a preferred embodiment of the present invention, the step (1) further comprises the step (1'): before electrolysis, the molybdenum raw material is subjected to ultrasonic cleaning, then is washed by water, and finally is dried in a nitrogen environment to obtain the purified molybdenum raw material.

Preferably, in step (1'), the ultrasonic cleaning is performed in an ultrasonic cleaner.

Preferably, in step (1'), the cleaning agent for ultrasonic cleaning is acetone and/or ethanol. In the present invention, the acetone and/or ethanol means: the cleaning agent can be acetone, ethanol or a mixture of acetone and ethanol. The ethanol used as the cleaning agent is preferably absolute ethanol.

Preferably, in step (1'), the ultrasonic frequency of the ultrasonic cleaning is 50kHz to 100kHz, for example, 50kHz, 60kHz, 70kHz, 80kHz, 90kHz or 100kHz, etc., but is not limited to the recited values, and other values not recited within the range of the recited values are also applicable.

Preferably, in step (1'), the ultrasonic cleaning is performed for 5 minutes to 50 minutes, such as 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, or 50 minutes, but not limited to the enumerated values, and other unrecited values within the numerical range are also applicable.

In a preferred embodiment of the present invention, in the step (2), the inert gas includes nitrogen and/or argon. In the present invention, the nitrogen and/or argon means: the nitrogen gas may be used, the argon gas may be used, or a combination of the nitrogen gas and the argon gas may be used.

Preferably, in step (2), the heating temperature is 50 ℃ to 500 ℃, such as 50 ℃, 100 ℃, 150 ℃, 200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃ or 500 ℃, but not limited to the recited values, and other values not recited in the range of values are equally applicable, preferably 350 ℃ to 450 ℃.

Preferably, in step (2), the heating time is 60 minutes to 120 minutes, such as 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, or 120 minutes, but not limited to the recited values, and other values within the range are equally applicable, preferably 90 minutes.

As a preferable embodiment of the present invention, the step (2) further includes: soaking the molybdenum after electrolysis in the step (1) in an immersion liquid before heating, and drying in an inert gas environment.

Preferably, the immersion fluid comprises ethanol.

Preferably, the soaking time is 10 minutes to 25 minutes, such as 10 minutes, 15 minutes, 20 minutes, 25 minutes, etc., but not limited to the recited values, and other values not recited within the range of values are equally applicable, preferably 15 minutes.

Preferably, the inert gas comprises nitrogen and/or argon. In the present invention, the nitrogen and/or argon means: the nitrogen gas may be used, the argon gas may be used, or a combination of the nitrogen gas and the argon gas may be used.

As a preferred technical scheme of the invention, in the step (3), the phosphorus source comprises sodium hypophosphite (NaH)₂PO₂) Preferably sodium hypophosphite monohydrate (NaH)₂PO₂·H₂O)。

Preferably, in step (3), the mass ratio of the phosphorus source to the modified molybdenum of step (2) is from 5:2 to 5:3, such as 5:2, 5:2.2, 5:2.4, 5:2.6, 5:2.8 or 5:3, but not limited to the recited values, and other values not recited in this range are equally applicable, preferably 5: 2.4.

Preferably, the heating reaction is carried out in a tube furnace.

Preferably, the temperature of the heating reaction is 200 ℃ to 1000 ℃, such as 200 ℃, 300 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃ or 1000 ℃, but not limited to the recited values, and other values not recited in the range of values are equally applicable, preferably 600 ℃.

Preferably, the heating reaction is carried out for a time period of 1 hour to 2 hours, such as 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, or 2 hours, but not limited to the recited values, and other values not recited within the range of the recited values are also applicable.

Preferably, step (3) further comprises: after the heating reaction, the obtained reaction product is naturally cooled to 20-30 ℃.

As a further preferable technical scheme of the preparation method, the method comprises the following steps:

(1') performing ultrasonic cleaning on the molybdenum raw material in an ultrasonic cleaner for 15 minutes by using acetone as a cleaning agent, performing ultrasonic cleaning on the molybdenum raw material in the ultrasonic cleaner for 15 minutes by using ethanol as a cleaning agent, washing with water, and finally drying in a nitrogen environment to obtain a purified molybdenum raw material;

(1) electrolyzing the purified molybdenum raw material in the step (1') by using a 10V-50V direct current voltage in an ammonium fluoride-containing electrolyte for 0.5-2 hours by using a platinum electrode as a cathode to obtain electrolyzed molybdenum;

the electrolyte containing ammonium fluoride consists of ammonium fluoride and a solvent, wherein the concentration of the ammonium fluoride in the electrolyte containing ammonium fluoride is 0.36mol/L, the solvent is a mixed solvent of water and glycerol, and the volume ratio of the glycerol to the water is 5:1-10: 1;

(2) soaking the electrolyzed molybdenum obtained in the step (1) in ethanol for 15 minutes, drying in a nitrogen environment, and heating at the temperature of 350-450 ℃ for 90 minutes in the nitrogen environment to obtain modified molybdenum;

(3) mixing the modified molybdenum obtained in the step (2) with sodium hypophosphite monohydrate, carrying out heating reaction in a tubular furnace at the reaction temperature of 600 ℃ for 1-2 h, and naturally cooling the obtained reaction product to 20-30 ℃ after the heating reaction to obtain the molybdenum phosphide nano material;

wherein the mass ratio of the sodium hypophosphite monohydrate to the modified molybdenum in the step (2) is 5: 2.4.

In a third aspect, the present invention provides a use of the molybdenum phosphide nanomaterial as described in the first aspect, as a catalyst in the field of electrocatalysis.

Compared with the prior art, the invention has the following beneficial effects:

(1) the molybdenum phosphide nano-tube in the molybdenum phosphide nano-material provided by the invention forms a regular array, and the nano-material has the advantages of large specific surface area, more active sites, good catalytic performance, and high catalytic activity of 10mAcm^-2Exhibits a very low overpotential, which may be as low as about 270 mV.

(2) The preparation method provided by the invention is simple to operate, short in flow, low in cost and good in industrial production prospect.

Drawings

FIG. 1 is a Scanning Electron Microscope (SEM) picture of a molybdenum phosphide nanomaterial prepared in example 1 of the present invention;

FIG. 2 is an X-ray diffraction (XRD) spectrum of the molybdenum phosphide nano-material prepared in example 1 of the present invention;

FIG. 3 is a Scanning Electron Microscope (SEM) picture of a molybdenum phosphide nanomaterial prepared in example 3 of the present invention;

FIG. 4 is a Scanning Electron Microscope (SEM) picture of the molybdenum phosphide nanomaterial prepared in comparative example 1;

FIG. 5 is a Scanning Electron Microscope (SEM) picture of the molybdenum phosphide nanomaterial prepared in comparative example 2.

Detailed Description

In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

The following are typical but non-limiting examples of the invention: