CN109821533B

CN109821533B - Transition metal boride catalyst, preparation method and application thereof

Info

Publication number: CN109821533B
Application number: CN201910135001.XA
Authority: CN
Inventors: 邹晓新; 李秋菊; 邹旭; 李国栋
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2019-02-25
Filing date: 2019-02-25
Publication date: 2021-09-21
Anticipated expiration: 2039-02-25
Also published as: CN109821533A

Abstract

A transition metal boride catalyst, a preparation method and application thereof in hydrogen production by electrocatalytic water splitting, belonging to the technical field of inorganic functional materials. The invention relates to a preparation method of a transition metal boride catalyst, which takes transition metal chloride as a metal source and MgB₂Is a boron source, and Mg powder assists in carrying out quasi-solid phase replacement reaction at the temperature of 700-1000 ℃ for 3-10 hours. Different metal sources can be selected by the method to obtain a series of pure-phase transition metal boride catalysts, such as VB, NbB, TaB, CrB, MoB, WB, FeB and RuB_1.1And the like, all of which have electrocatalytic activity. In which RuB is used_1.1Optimally, has excellent catalytic activity and stability under acidic conditions and has the current density of 10mA cm^‑2The desired overpotential is 24 mV.

Description

Transition metal boride catalyst, preparation method and application thereof

Technical Field

The invention belongs to the technical field of inorganic functional materials, and particularly relates to a transition metal boride catalyst, a preparation method and application thereof in hydrogen production by electrocatalytic water cracking.

Background

The increasing growth of the world population, the deterioration of the environment, the shortage of energy and other serious problems promote the rapid development of clean renewable green energy. The electrocatalytic water cracking hydrogen production adopts renewable resources, and accords with the sustainable development of modern society and economy. Platinum-based materials are currently the most efficient electrocatalytic materials, but their high cost and low reserves limit their application, and therefore, the development of low-cost, efficient platinum-based replacement electrocatalysts is of great interest.

Transition metal boride is a multifunctional material with high conductivity, high stability, corrosion resistance and high temperature resistance. Magnesium diboride and niobium boride are superconductors; the molybdenum diboride has excellent electron transmission capability and is a high-efficiency electrocatalytic water cracking hydrogen production material (J.Am.chem.Soc.2017,139, 12370). The transition metal boride has abundant structure and potential multifunctional characteristics, and arouses the research interest of scientists in synthesizing the metal boride. Up to now, due to the high melting point of transition metal and boron, the synthesis of transition metal boride needs to span very high energy barrier, generally requiring a high temperature and high pressure, long time solid phase sintering method. Secondly, the formation of partial transition metal boride can be approximate, the single-phase synthesis interval is narrow, multi-phase mixed boride is easy to prepare, and the single-phase preparation is very difficult. The existence of the mixed phase limits further research on potential multifunctional properties of the transition metal boride. Therefore, the method which is mild in condition, simple and easy to operate is adopted to synthesize the pure-phase transition metal boride, so that the pure-phase transition metal boride becomes a significant difficulty for the development of the boride.

Disclosure of Invention

The invention aims to prepare a pure-phase and efficient water-splitting hydrogen evolution catalyst, and provides a universal method for quasi-solid-phase displacement reaction, wherein chlorides of transition metals are used as metal sources, and MgB (magnesium gallium bromide) is used as a metal source₂Is a boron source and is assisted by Mg powder, and a series of pure-phase transition metal boride catalysts can be prepared.

The invention provides a preparation method of transition metal boride, which is characterized by comprising the following steps: grinding and mixing chloride salt of transition metal, magnesium diboride and magnesium powder according to a molar ratio of 2: 1: 1-10; calcining the obtained mixture under the vacuum degree of 1Pa or below, wherein the calcining temperature is 700-1000 ℃, the calcining time is 3-10 hours, and the heating rate is 2-5 ℃ for min^-1(ii) a 0.5mol L of the primary product obtained after calcination is used^-1Soaking the mixture in sulfuric acid solution for 2-8 hours to remove impurities, then centrifugally cleaning the mixture with water and ethanol, and drying the cleaned mixture to obtain the pure-phase transition metal boride powder.

In the method, the addition of the magnesium powder assists in promoting the reaction.

In the above method, preferably, the chloride salt of the transition metal is anhydrous vanadium trichloride, anhydrous niobium pentachloride, anhydrous tantalum pentachloride, anhydrous chromium dichloride, anhydrous molybdenum pentachloride, anhydrous tungsten hexachloride, hydrated potassium pentachlororutahenate or anhydrous ferrous chloride.

In the above method, the transition metal boride catalyst is at 0.5M H₂SO₄All have the performance of producing hydrogen by electrolyzing water under the condition that RuB is adopted_1.1The properties are optimal.

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

1. the invention can synthesize a series of pure phase transition metal borides, and is a successful universal preparation method.

2. Compared with the conventional high-temperature high-pressure method, the method has the advantages of simple synthesis process, mild reaction process, short preparation period, easy obtaining of pure phase, high repeatability and reaction temperature of 700-1000 ℃, and effectively reduces the manufacturing energy consumption and cost.

3. The synthesized samples have extremely high purity, and in the existing reports, VB, NbB, TaB, CrB, MoB and WB are synthesized under the vacuum condition for the first time.

4. The catalysts of the invention all have electrocatalytic hydrogen evolution activity, wherein RuB is used_1.1Optimally, has excellent catalytic activity and stability under acidic conditions: the current density was 10mA cm^-2The required overpotential is 24mV, stable for more than 10 hours. Compared with the traditional platinum-based catalyst, the ruthenium catalyst has richer reserves, one-fifteenth price of platinum and wide application prospect.

Drawings

FIG. 1: RuB obtained in examples 1 to 4_1.1And the X-ray diffraction (XRD) patterns of FeB-type and MoB-type transition metal borides.

FIG. 2: x-ray diffraction (XRD) patterns of the CrB-type transition metal borides obtained in examples 5-8.

FIG. 3: RuB obtained in example 1_1.1Transmission Electron Microscope (TEM) photograph of (a).

FIG. 4: transition metal boride obtained in examples 1 to 8 in an acid electrolyte (0.5M H)₂SO₄) Polarization of hydrogen evolution by cracking of waterCurve line.

FIG. 5: RuB obtained in example 1_1.1In acid electrolyte (0.5M H)₂SO₄) Stability curve of hydrogen evolution by water splitting.

Detailed Description

The present invention will be further described with reference to the following examples, but the scope of the present invention is not limited to the following examples. It will be apparent to those skilled in the art that variations or modifications of the present invention can be made without departing from the spirit and scope of the invention, and these variations or modifications are also within the scope of the invention.

Example 1

Preparation of RuB_1.1: (1) under irradiation with an infrared lamp, according to M (chloride salt representing transition metal): MgB₂: the molar ratio of Mg is 2: 1: 2 weighing the metal source, the magnesium diboride and the magnesium powder with the corresponding mass, namely 0.112g (0.3mmol) of hydrated pentachloro ruthenic acid potassium, 0.007g (0.15mmol) of magnesium diboride and 0.0072g (0.3mmol) of magnesium powder, putting the materials into a mortar, and grinding the materials to uniformly mix the materials.

(2) And (3) transferring the mixed powder obtained in the step (1) into a quartz tube, vacuumizing by using a vacuum frame, and sealing the tube in vacuum when the vacuum degree is reduced to below 1 Pa.

(3) Putting the quartz tube in which the sample is sealed in the vacuum in the step (2) into a muffle furnace, calcining for 7 hours at the temperature of 700 ℃, and raising the temperature for 2 min^-1。

(4) After cooling to room temperature, the sample was taken out, ground and then put into 0.5mol L^-1Soaking in sulfuric acid solution for 3 hr to remove impurities, centrifuging with water and ethanol for three times, oven drying at 80 deg.C, and drying to obtain RuB_1.1Catalyst fines, product mass about 0.033 g.

Performing electrocatalytic water splitting hydrogen production (HER) property test on the material prepared by the method in a standard three-electrode electrolytic cell; the product of the invention is uniformly dispersed in a perfluorinated sulfonic acid resin-isopropanol solution with the volume fraction of 10 percent, the solution is dropped on a glassy carbon electrode to be used as a working electrode in an electrolytic cell, a saturated calomel electrode is used as a reference electrode, and a carbon rod is used as a counter electrode. It should be noted that all potentials obtained by taking a saturated calomel electrode as a reference electrode in an electrocatalysis test are converted into reversible hydrogen electrode potentials in a property diagram, and an external power supply is a main battery of an electrochemical working station.

Example 2

As in example 1, M: MgB₂: the molar ratio of Mg is changed to 2: 1: 1, preparing FeB by using anhydrous ferrous chloride as a metal source and reacting at 850 ℃ for 5 hours.

Example 3

As in example 1, M: MgB₂: the molar ratio of Mg is changed to 2: 1: 4, the metal source is anhydrous molybdenum pentachloride, the reaction temperature is 850 ℃, and the reaction time is 5 hours, thus preparing the MoB.

Example 4

As in example 1, M: MgB₂: the molar ratio of Mg is changed to 2: 1: 5, the metal source is anhydrous tungsten hexachloride, the reaction temperature is 850 ℃, and the reaction time is 5 hours, so that the WB can be prepared.

Example 5

As in example 1, M: MgB₂: the molar ratio of Mg is changed to 2: 1: 1, preparing CrB by using anhydrous chromium dichloride as a metal source and controlling the reaction temperature to be 850 ℃ and the reaction time to be 5 hours.

Example 6

As in example 1, M: MgB₂: the molar ratio of Mg is changed to 2: 1: 2, the metal source is anhydrous vanadium trichloride, the reaction temperature is 950 ℃, and the reaction time is 6 hours, so that VB can be prepared.

Example 7

As in example 1, M: MgB₂: the molar ratio of Mg is changed to 2: 1: 4, the metal source is anhydrous niobium pentachloride, the reaction temperature is 900 ℃, and the reaction time is 6 hours, thus obtaining the NbB.

Example 8

As in example 1, M: MgB₂: the molar ratio of Mg is changed to 2: 1: 4, the metal source is anhydrous tantalum pentachloride, the reaction temperature is 950 ℃, and the reaction time is 6 hours, thus preparing TaB.

Some structural and performance studies were performed on the materials prepared by the above methods.

FIG. 1A shows RuB obtained in example 1_1.1The X-ray diffraction (XRD) pattern of FeB obtained in example 2, fig. 1B the X-ray diffraction (XRD) pattern of MoB obtained in example 3, fig. 1C the X-ray diffraction (XRD) pattern of WB obtained in example 4, show that the above transition metal borides prepared in this way are all in pure phase.

Fig. 2A is an X-ray diffraction (XRD) pattern of CrB obtained in example 5, fig. 2B is an X-ray diffraction (XRD) pattern of VB obtained in example 6, fig. 2C is an X-ray diffraction (XRD) pattern of NbB obtained in example 7, and fig. 2D is an X-ray diffraction (XRD) pattern of TaB obtained in example 8, which illustrate that the above-mentioned transition metal borides prepared in this way are all in pure phase.

FIG. 3A shows RuB obtained in example 1_1.1The morphology of the sample consists of particles of 100-200nm, and FIG. 3B is the RuB obtained in example 1_1.1Further proving that the synthesized sample is pure phase RuB_1.1。

FIG. 4A shows RuB obtained in example 1_1.1In acid electrolyte (0.5M H)₂SO₄) The polarization curve of hydrogen evolution by water splitting reaches the current density of 10mA cm at the overpotential of 24mV^-2. FIG. 4B shows FeB obtained in example 2 in an acid electrolyte (0.5M H)₂SO₄) The polarization curve of hydrogen evolution by water splitting reaches the current density of 10mA cm at the overpotential of 429mV^-2. FIG. 4C shows the MoB-type transition metal boride in an acid electrolyte (0.5M H) obtained in examples 3 to 4₂SO₄) The polarization curve of hydrogen evolution by water splitting is that MoB and WB respectively reach a current density of 10mA cm at overpotential of 259mV and 237mV^-2. FIG. 4D shows transition metal borides of CrB-type obtained in examples 5-8 in an acid electrolyte (0.5M H)₂SO₄) The polarization curve of hydrogen evolution by water splitting is that CrB, VB, NbB and TaB respectively reach a current density of 10mA cm at overpotentials of 592mV, 307mV, 643mV and 487mV^-2。

FIG. 5 shows RuB obtained in example 1_1.1In acid electrolyte (0.5M H)₂SO₄) The stability curve of hydrogen evolution by water cracking shows that the catalytic performance of the catalyst can be stabilized for more than 10 hours, and the catalyst has good catalytic stability.

Claims

1. A preparation method of a transition metal boride catalyst is characterized by comprising the following steps: grinding and mixing chloride salt of transition metal, magnesium diboride and magnesium powder according to a molar ratio of 2: 1: 1-10; calcining the obtained mixture under vacuum degree of 1Pa or below at 700 deg.C^oC~1000 ^oC, calcining for 3-10 hours; 0.5 mol/L of the product obtained after calcination is used^-1Soaking the mixture in sulfuric acid solution for 2-8 hours to remove impurities, then centrifugally cleaning the mixture with water and ethanol, and drying the cleaned mixture to obtain pure-phase transition metal boride catalyst powder; the chloride salt of the transition metal is anhydrous vanadium trichloride, anhydrous niobium pentachloride, anhydrous tantalum pentachloride, anhydrous chromium dichloride, anhydrous molybdenum pentachloride or anhydrous tungsten hexachloride, and the obtained transition metal boride catalyst is VB, NbB, TaB, CrB, MoB or WB.

2. A transition metal boride catalyst characterized by: is prepared by the method of claim 1.

3. Use of the transition metal boride catalyst of claim 2 in the production of hydrogen by electrocatalytic water splitting.