CN112675924A

CN112675924A - Method for activating electrocatalyst and MoS obtained by same2Activated electrocatalyst and application

Info

Publication number: CN112675924A
Application number: CN202110002944.2A
Authority: CN
Inventors: 彭祥; 王鹏
Original assignee: Wuhan Institute of Technology
Current assignee: Wuhan Jieyuan Technology Co.,Ltd.
Priority date: 2021-01-04
Filing date: 2021-01-04
Publication date: 2021-04-20
Anticipated expiration: 2041-01-04
Also published as: CN112675924B

Abstract

The invention provides an activation method of an electrocatalyst and an obtained MoS₂An activation method of the electrocatalyst comprises the following steps: 1) putting the carbon cloth into a mixed solution consisting of sodium molybdate, thiourea and deionized water, and carrying out hydrothermal treatment to obtain a molybdenum disulfide precursor growing on the carbon cloth; 2) performing electrochemical anode treatment on the molybdenum disulfide precursor to obtain MoS₂The electrocatalyst is activated. The preparation method is simple and easy to implement, and the original structural property of the layered material is not damaged, so that the layered material is obtainedMoS of (1)₂The activated electrocatalyst has stable physical and chemical properties and good electrocatalytic performance. The layered molybdenum disulfide obtained by the treatment of the optimization method provided by the invention has excellent electrocatalysis performance under acidic conditions, and the electrocatalysis performance is not reduced after 50 times of circulation, so that the layered molybdenum disulfide has more excellent electrocatalysis performance than a precursor material.

Description

Method for activating electrocatalyst and MoS obtained by same2Activated electrocatalyst and application

Technical Field

The invention relates to the technical field of functional materials, in particular to an activation method of an electrocatalyst, the obtained activated electrocatalyst and application thereof.

Background

The hydrogen energy is widely paid attention in recent years as a green renewable energy source, and the electrochemical hydrogen evolution is a green, energy-saving and efficient hydrogen production method. The electrochemical catalyst with the highest hydrogen production efficiency is a platinum-based material at present, but the high cost and durability of the platinum-based material make the platinum-based material not widely used in practical application. Therefore, a non-noble metal hydrogen evolution reaction catalyst with low cost, high efficiency and strong durability is urgently needed to replace noble metal materials.

MoS₂The MoS has great potential in the fields of electrocatalysis, electron and energy collection due to the exposed active sites at the edges and excellent electron mobility, but the basal plane reactivity is inert due to the fact that the active sites are mostly distributed at the edge positions, and therefore a method needs to be researched to ensure that the MoS has the advantages of being capable of ensuring the MoS to be in contact with the basal plane₂More edge active sites are exposed to improve the hydrogen evolution catalytic performance. Recent studies have found MoS₂Has a unique layered structure similar to graphene, and a single or few layers of MoS due to the interconnection of adjacent planes by weak van der Waals forces₂Can be easily peeled off along these planes. Conventional MoS₂The peeling methods include a mechanical peeling method and a microwave-assisted liquid phase peeling method, however, the methods not only require multiple steps, but also have difficulty in controlling the number of layers and the thickness of the nanosheets, which greatly limits the development of the technology for peeling the two-dimensional layered material. In addition, most of the current researches focus on the materials peeled off from the substrate, and focus on the MoS after peeling₂The matrix is very rare.

Disclosure of Invention

In view of the above, the present invention is directed to a method for activating an electrocatalyst, so as to solve the problem of the existing MoS₂MoS prepared by stripping method₂The electrochemical hydrogen evolution catalytic performance is poor.

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

a method of activating an electrocatalyst, comprising the steps of:

1) putting the carbon cloth into a mixed solution consisting of sodium molybdate, thiourea and deionized water, and carrying out hydrothermal treatment to obtain a molybdenum disulfide precursor growing on the carbon cloth;

2) performing electrochemical anode treatment on the molybdenum disulfide precursorThen MoS is obtained₂The electrocatalyst is activated.

In the invention, when preparing the molybdenum disulfide precursor solution, the sequence of adding the molybdenum sulfide, the thiourea and the deionized water is not specially limited and can be any sequence; before use, the carbon cloth can be placed in deionized water and ultrasonically cleaned by an ultrasonic cleaner, wherein the cleaning power of ultrasonic cleaning is 100-150W, more preferably 150W, and the cleaning time is 10 min; after the molybdenum disulfide precursor grows on the carbon cloth, the sample can be naturally cooled to room temperature, and the sample is washed three times by deionized water and absolute ethyl alcohol to remove reaction residual substances.

In the invention, when electrochemical anode treatment is carried out on the molybdenum disulfide precursor, the molybdenum disulfide precursor (MoS) growing on the carbon cloth can be used₂CC sample) is clamped by a platinum clamp to be used as an anode electrode, a graphite rod is used as a cathode electrode, sodium sulfate with the concentration of 0.5M/L is used as electrolyte, a power supply is used for electrifying direct current to the double-electrode system, and the direct current is continued for a period of time, so that the electrochemical anode treatment of the molybdenum disulfide precursor is realized.

Optionally, the treatment temperature of the hydrothermal method in the step 1) is 180-220 ℃, the treatment time is 12-24 hours, wherein the treatment temperature is more preferably 180 ℃, the treatment time is more preferably 24 hours, the temperature rise rate of the hydrothermal method is not particularly limited, and any temperature rise rate can be adopted.

Optionally, the mass ratio of the sodium molybdate to the thiourea in the step 1) is 1: 1.2-1.4, and more preferably is 1: 1.4; the mass ratio of the sodium molybdate to the deionized water is 1: 72.

Optionally, the treatment voltage of the electrochemical treatment in the step 2) is +1 to +15V dc voltage, and the treatment time is 1 to 30min, wherein the treatment voltage is more preferably +10V, and the treatment time is more preferably 10 min.

The second purpose of the invention is to provide a MoS₂Activating an electrocatalyst, the MoS₂The activated electrocatalyst is prepared by the above method for activating an electrocatalyst.

The third purpose of the invention is to provide a MoS₂The application of an activated electrocatalyst for electrocatalytic hydrogen evolution, comprising the following steps:

the MoS is treated₂The activated electrocatalyst is loaded on the conductive substrate and made into MoS₂The cathode electrode is a functional material, and forms a loop with the anode electrode to be applied to the hydrogen production by water electrolysis; the conductive substrate is one of carbon cloth, foamed nickel and glassy carbon electrode; the anode electrode is one of carbon rod and platinum.

Compared with the prior art, the method for activating the electrocatalyst has the following advantages:

the MoS is prepared by a hydrothermal method and an electrochemical method₂The preparation method of the activated electrocatalyst is simple and easy to implement, and the original structural properties of the layered material are not destroyed, so that the obtained MoS₂The activated electrocatalyst has stable physical and chemical properties and good electrocatalytic performance. The layered molybdenum disulfide obtained by the optimization method provided by the invention has excellent electrocatalytic performance under acidic conditions, the electrocatalytic performance is not reduced after 50 times of circulation, and the layered molybdenum disulfide has more excellent electrocatalytic performance than a precursor material.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a graph of linear sweep voltammetry measurements of samples of molybdenum disulfide precursors grown on carbon cloth according to examples 1-4 of the present invention;

FIG. 2 is a sample of molybdenum disulfide precursor grown on carbon cloth according to example 1 of the present invention and the MoS of examples 1 and 5-6₂A linear sweep voltammetry test curve of the activated electrocatalyst;

FIG. 3 is a plot of linear sweep voltammetry tests for samples of molybdenum disulfide precursor grown on carbon cloth according to example 1 of the present invention and for samples of comparative example 1;

FIG. 4 shows MoS of example 1 of the present invention₂Line before and after 50 cycles of activating the electrocatalystSexual sweep voltammetry test graph.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The present invention will be described in detail below with reference to the drawings and examples.

Example 1

An activation method of an electrocatalyst specifically comprises the following steps:

1) mixing 0.25g of sodium molybdate, 0.35g of thiourea and 18ml of deionized water, and then stirring for 10min by using an electromagnetic stirrer until the mixture is uniformly mixed;

2) taking a piece of 2cm multiplied by 2cm carbon cloth, and cleaning the piece of carbon cloth for 10 minutes by using an ultrasonic cleaner, wherein the ultrasonic power of the ultrasonic cleaner is set to be 150W;

3) pouring the solution uniformly stirred in the step 1) into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and then putting the carbon cloth cleaned in the step 2) into the solution;

4) heating a high-pressure reaction kettle to 180 ℃ by using an electric heating air blast drying box, keeping the temperature for 24 hours, carrying out hydrothermal treatment on the solution which is put into the carbon cloth in the step 3), after the heating is finished, naturally cooling the reaction kettle to room temperature, then opening the reaction kettle, taking out a sample, washing the sample with deionized water and absolute ethyl alcohol for three times to obtain a molybdenum disulfide precursor growing on the carbon cloth, firstly carrying out an initial electrochemical hydrogen evolution performance test on the molybdenum disulfide precursor growing on the carbon cloth obtained in the step, namely carrying out a linear scanning voltammetry test on the sample by using an electrochemical workstation to obtain the initial performance of the sample;

5) performing electrochemical anode treatment on the molybdenum disulfide precursor growing on the carbon cloth in the step 4), namely performing electrochemical anode treatment on the molybdenum disulfide precursor (MoS) growing on the carbon cloth₂a/CC sample) is clamped by a platinum clamp to be used as an anode electrode, a graphite rod is used as a cathode electrode, and 0.5M/L sodium sulfate solution is used as electrolyte; electrifying the double-electrode system with +10V direct current by using a power supply, and continuing for 10min to obtain an optimized molybdenum disulfide sample, namely MoS, growing on the carbon cloth₂Activating the electrocatalyst, will excelAnd carrying out linear sweep voltammetry testing on the sample after the chemical reaction to obtain the optimized electrochemical hydrogen evolution performance.

Example 2

This example differs from example 1 in that: the amount of thiourea used in step 1) was 0.3 g.

Example 3

This example differs from example 1 in that: the heating temperature of the electrothermal blowing drying box in the step 4) is 200 ℃.

Example 4

This example differs from example 1 in that: and (4) heating and heat preservation time of the electrothermal blowing drying box in the step 4) is 20 h.

Example 5

This example differs from example 1 in that: the direct current voltage used in the electrochemical anode treatment in the step 5) is + 15V.

Example 6

This example differs from example 1 in that: the treatment time of the electrochemical anode treatment in the step 5) is 15 min.

Comparative example 1

This comparative example differs from example 1 in that: the direct current voltage used for the electrochemical anode treatment in the step 5) is + 25V.

The MoS of examples 1 to 6 of the present invention₂The activated electrocatalyst is used for electrocatalytic hydrogen evolution, and specifically comprises the following components: the MoS of examples 1 to 6 of the present invention₂The activated electrocatalyst is loaded on the conductive substrate and made into MoS₂The cathode electrode is made of functional materials and forms a loop with the anode electrode to be applied to hydrogen production by water electrolysis, wherein the conductive matrix is carbon cloth; the anode electrode is a carbon rod.

The molybdenum disulfide precursor samples grown on carbon cloth according to examples 1 to 4 of the present invention were subjected to linear sweep voltammetry tests, and the test results are shown in fig. 1.

As can be seen from FIG. 1, the MoS prepared by the method is comparable to that prepared by other methods₂Precursor, MoS prepared using the preparation method of the present invention₂The precursor had more excellent properties, and the MoS obtained in example 1 of the present invention was used₂Electrochemical of activated electrocatalystThe chemical hydrogen evolution performance is best.

Samples of molybdenum disulfide precursors grown on carbon cloth according to example 1 of the present invention and MoS of examples 1, 5-6₂The activated electrocatalyst was subjected to linear sweep voltammetry tests, and the test results are shown in fig. 2.

As can be seen from FIG. 2, compared with the unoptimized molybdenum disulfide, the molybdenum disulfide optimized by the present invention has significantly improved electrochemical hydrogen evolution performance, and the MoS obtained by the embodiment 1 of the present invention is adopted₂The electrochemical hydrogen evolution performance of the activated electrocatalyst is best, in this example the electrochemical anodization voltage is +10V, the treatment time is 10 minutes.

Samples of molybdenum disulfide precursor grown on carbon cloth according to example 1 of the present invention and MoS of comparative example 1₂The activated electrocatalyst was subjected to linear sweep voltammetry tests, and the test results are shown in fig. 3.

As can be seen from fig. 3, the applied voltage in comparative example 1 was too high, so that the sample performance was not improved but decreased excessively due to the treatment.

For MoS of example 1 of the invention₂The activated electrocatalyst and the sample obtained after 50 cycles were subjected to linear sweep voltammetry, and the test results are shown in fig. 4.

As can be seen from FIG. 4, the MoS of example 1 of the present invention₂The activated electrocatalyst samples showed little change in performance over 50 cycles.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method of activating an electrocatalyst, comprising the steps of:

2) subjecting the molybdenum disulfide precursor toAfter electrochemical anodization of the bodies, a small amount of MoS was observed by the naked eye₂Stripping MoS from carbon cloth by controlling optimal time and voltage of electrochemical anode treatment₂And then washing the treated sample with deionized water to obtain MoS₂The electrocatalyst is activated.

2. The method for activating an electrocatalyst according to claim 1, wherein the hydrothermal process in step 1) is performed at a temperature of 180 to 220 ℃ for 12 to 24 hours.

3. The method for activating an electrocatalyst according to claim 1, wherein the mass ratio of the sodium molybdate to the thiourea in step 1) is 1: 1.2 to 1.4, and the mass ratio of the sodium molybdate to the deionized water is 1: 72.

4. The method for activating an electrocatalyst according to claim 1, wherein the treatment voltage of the electrochemical anodization in step 2) is +1 to +15V dc voltage, and the treatment time is 1 to 30 min.

5. MoS₂An activated electrocatalyst, characterized in that said MoS₂The activated electrocatalyst prepared by the method for activating an electrocatalyst according to any one of claims 1 to 4.

6. The MoS of claim 5₂The application of the activated electrocatalyst in electrocatalytic hydrogen evolution is characterized in that the MoS is used₂The activated electrocatalyst is loaded on the conductive substrate and made into MoS₂The cathode electrode is a functional material, and forms a loop with the anode electrode to be applied to the hydrogen production by water electrolysis; the conductive substrate is one of carbon cloth, foamed nickel and glassy carbon electrode; the anode electrode is one of carbon rod and platinum.