阅读说明：本技术 一种用于碱性电催化析氢的空心异质材料及其制备方法 (Hollow heterogeneous material for alkaline electro-catalysis hydrogen evolution and preparation method thereof ) 是由 陈文波 刘碧桃 牟得单 付俊超 韩涛 曹仕秀 彭玲玲 强琴平 严娟 聂明航 张辉 于 2020-06-30 设计创作，主要内容包括：本发明公开了一种用于碱性电催化析氢的空心异质材料及其制备方法,该方法通过溶液法制备出Mo-MOF前驱体,然后依次采用第一步热处理碳化法、第二步热处理硫化法,最终得到氮掺杂碳的MoS<Sub>2</Sub>@Mo<Sub>2</Sub>C空心异质结构材料；所述MoS<Sub>2</Sub>@Mo<Sub>2</Sub>C空心异质结构材料整体形貌为由极薄的碳层结构包裹而成的透明管状结构、透明管状结构表面均匀分布MoS<Sub>2</Sub>@Mo<Sub>2</Sub>C复合材料组成的空心纳米颗粒。该方法原料易得、通过溶剂热法和简单的两步热处理过程即可获得异质纳米材料,制备过程简单、操作方便,容易实现大规模生产；同时,该方法得到的空心异质材料两相之间接触紧密、结构稳定,在碱性电催化析氢过程中具有优异的催化效果、导电性能好。(The invention discloses a hollow heterogeneous material for alkaline electro-catalysis hydrogen evolution and a preparation method thereofChemical conversion method to finally obtain nitrogen-doped carbon MoS 2 @Mo 2 C, hollow heterostructure material; the MoS 2 @Mo 2 The overall appearance of the C hollow heterostructure material is a transparent tubular structure formed by wrapping an extremely thin carbon layer structure, and MoS is uniformly distributed on the surface of the transparent tubular structure 2 @Mo 2 C, hollow nano particles formed by the composite material. The method has the advantages that the raw materials are easy to obtain, the heterogeneous nano material can be obtained through the solvothermal method and the simple two-step heat treatment process, the preparation process is simple, the operation is convenient, and the large-scale production is easy to realize; meanwhile, the hollow heterogeneous material obtained by the method is in close contact between two phases, has a stable structure, and has excellent catalytic effect and good conductivity in the alkaline electrocatalytic hydrogen evolution process.)

1. A hollow heterogeneous material for alkaline electrocatalytic hydrogen evolution is characterized in that: its overall appearance is formed from very thin carbon layerTransparent tubular structure that structure parcel formed, transparent tubular structure surface evenly distributed MoS₂@Mo₂C, hollow nano particles formed by the composite material.

2. The hollow heterogeneous material for alkaline electro-catalytic hydrogen evolution according to claim 1, characterized in that: the diameter of the transparent tubular structure is 200-300 nm; the thickness of the carbon layer structure is not more than 10 nm.

3. The method for preparing a hollow heterogeneous material for alkaline electro-catalytic hydrogen evolution according to claim 1 or 2, characterized in that: it is ammonium molybdate tetrahydrate ((NH)₄)₆Mo₇O_24.4H₂) Preparing a Mo-MOF precursor by using an aniline solution as a raw material through a solution method; then a first-step heat treatment carbonization method and a second-step heat treatment vulcanization method are sequentially adopted to finally prepare the nitrogen-doped carbon MoS₂@Mo₂C, hollow heterostructure material.

4. The preparation method of the hollow heterogeneous material for alkaline electro-catalytic hydrogen evolution according to claim 3, characterized in that: the mass ratio of the ammonium molybdate tetrahydrate to the aniline solution can be 2.48: 40.

5. The preparation method of the hollow heterogeneous material for alkaline electro-catalytic hydrogen evolution according to claim 3, characterized in that: the aniline solution is prepared by dissolving aniline in deionized water, wherein the volume ratio of aniline to deionized water is 3-4: 40.

6. The preparation method of the hollow heterogeneous material for alkaline electro-catalytic hydrogen evolution according to claim 3, characterized in that: the method for preparing the Mo-MOF precursor by the solution method comprises the following specific steps: firstly, dissolving ammonium molybdate tetrahydrate in an aniline solution, and introducing 99.99% nitrogen for protection after dissolving, wherein the flow rate of nitrogen gas is 40-50 ml/min; under the condition of nitrogen protection, carrying out constant-temperature magnetic stirring and heating at the temperature of 45-55 ℃; under the heating condition of constant-temperature magnetic stirring, simultaneously dropwise adding dilute hydrochloric acid to adjust the pH of the solution to 3.5-4.5, continuously preserving heat for 3-6 h after dropwise adding is finished, and obtaining an intermediate of the Mo-MOF precursor after heat preservation is finished; and finally, putting the intermediate of the Mo-MOF precursor into a centrifuge with the rotating speed of 5000-.

7. The preparation method of the hollow heterogeneous material for alkaline electro-catalytic hydrogen evolution according to claim 6, characterized in that: the concentration of the dilute hydrochloric acid is 0.8-1.2 mol/L.

8. The preparation method of the hollow heterogeneous material for alkaline electro-catalytic hydrogen evolution according to claim 3, characterized in that: the first-step heat treatment carbonization method specifically comprises the following steps: transferring the Mo-MOF precursor prepared by the solution method into an alumina ark for carbonization treatment, introducing nitrogen gas for protection, heating to 750-850 ℃ at the heating rate of 2-3 ℃/min, preserving heat for 3-5 h, and taking out to obtain Mo₂C-Mo₃C₂A heterogeneous nanowire material.

9. The method for preparing the hollow heterogeneous material for the alkaline electro-catalytic hydrogen evolution according to claim 8, characterized in that: the second-step heat treatment vulcanization method specifically comprises the following steps: mo prepared by the first heat treatment carbonization method₂C-Mo₃C₂Transferring the heterogeneous nanowire material into an alumina ark, placing a sulfur source in an upstream area for vulcanization treatment, introducing nitrogen gas for protection, heating to 600-1000 ℃ at a heating rate of 2-3 ℃/min, preserving heat for 1-4 h, and taking out to obtain the finished product of nitrogen-doped carbon MoS₂@Mo₂C, hollow heterostructure material.

10. The preparation method of the hollow heterogeneous material for alkaline electro-catalytic hydrogen evolution according to claim 9, characterized by comprising the following steps: the flow rate of nitrogen gas in the first heat treatment carbonization method and the second heat treatment vulcanization method is 40-50 ml/min, and the pressure in a nitrogen pipe for introducing nitrogen is controlled to be 0-1 Mpa.

Technical Field

The invention relates to the technical field of inorganic nano materials and energy development and storage, in particular to a hollow heterogeneous material for alkaline electro-catalysis hydrogen evolution and a preparation method thereof.

Background

In recent years, with the development of human society and the rapid increase of global population, the demand for energy has sharply increased. In addition, with the limited storage of fossil energy such as coal, oil and natural gas and the problem of environmental pollution caused by the consumption thereof, great challenges have been created to the sustainable development of our society, and the development of new energy that can be recycled and is environmentally friendly has become the focus of global research. Among many new energy sources, hydrogen is attracting attention as a novel energy source with high efficiency, cleanliness and high utility value; in the hydrogen production process, the electrocatalyst is one of important components for electrocatalytic hydrogen evolution and has great influence on the release efficiency of hydrogen. Currently, the platinum (Pt) group of metallic elements is still the most advanced Hydrogen Evolution Reaction (HER) catalyst; however, since it is expensive, scarce in quantity and impossible to produce on a large scale, there is a strong demand for the development of a catalyst for electrolyzing water having a low overpotential and abundant reserves on the earth to improve the reaction kinetics and the efficiency of water electrolysis.

Most of the HER electrocatalysts are currently more effective under acidic conditions than alkaline conditions, because the lower efficiency of the HER process of the electrocatalyst in alkaline media is related to the slow dissociation process of water on the surface of the electrocatalyst, but when the electrolysis of water is carried out in an alkaline electrolysis cell, the alkaline electrolyte has the advantages of easy availability and long-lasting performance; currently HER is still often performed under alkaline conditions. However, the problems of low catalytic activity and poor stability of the existing synthetic composite material still exist in an alkaline medium, so that designing a hydrogen evolution catalyst with excellent performance, low cost and good stability is one of the major challenges faced by the current society of rapid development.

Molybdenum disulfide (MoS)₂) Is a typical transition metal disulfide, and has a structure and performance very similar to graphene. Due to MoS₂The layers are combined through Van der Waals force, foreign atoms or molecules are introduced between the layers through intercalation, and meanwhile, the structure of the single-layer or multi-layer graphene-like nano sheet can be obtained through stripping or direct synthesis, and the performance different from that of graphene is shown. Research shows that MoS of two-dimensional layered structure₂Is a promising new energy electrode material and can be used as an electrode material for electrochemical lithium storage and magnesium storage. In recent years, nano-sized MoS₂Shows a plurality of excellent performances in the fields of electricity, light, hydrogen evolution catalysis and the like, also shows wide application prospects in the fields of novel functional nano materials, devices and the like, and has become a current related fieldResearch focus of domains. But MoS₂The catalytic action in alkaline environment is weak, on the one hand, MoS₂The slow adsorption and dissociation kinetics in alkaline electrolytes are determined by their intrinsic structural characteristics; on the other hand, MoS is under the action of Van der Waals force₂The block structure is easily formed in the preparation process, so that the conductivity is extremely low, and the exposure of active sites and the electron transmission efficiency are influenced.

Disclosure of Invention

In view of the above problems of the prior art, it is an object of the present invention to provide a hollow heterostructure material for alkaline electro-catalytic hydrogen evolution, consisting essentially of MoS₂@Mo₂The composite material has good catalytic effect on alkaline electro-catalysis hydrogen evolution, and has stable structure and good conductivity.

The invention also aims to provide a preparation method of the hollow heterogeneous material for alkaline electrocatalytic hydrogen evolution, which is simple and convenient to operate, low in cost and easy to obtain, and can be used for batch and large-scale production.

The purpose of the invention is realized by the following technical scheme:

a hollow heterogeneous material for alkaline electrocatalytic hydrogen evolution is characterized in that: the overall appearance of the carbon-coated carbon composite material is a transparent tubular structure which is formed by wrapping an extremely thin carbon layer structure, and MoS is uniformly distributed on the surface of the transparent tubular structure₂@Mo₂C, hollow nano particles formed by the composite material.

Further optimization is carried out, and the radius of the hollow nano-particles is 20-100 nm.

Further optimizing, the diameter of the transparent tubular structure is 200-300 nm; the thickness of the carbon layer structure is not more than 10 nm.

Further, the preparation method of the hollow heterogeneous material for alkaline electrocatalytic hydrogen evolution is characterized in that the hollow heterogeneous material is ammonium molybdate tetrahydrate ((NH)₄)₆Mo₇O_24.4H₂) Preparing a Mo-MOF precursor by using an aniline solution as a raw material through a solution method; then sequentially adopting a first heat treatment carbonization method and a second heat treatment carbonization methodA two-step heat treatment sulfuration method, and finally preparing the nitrogen-doped carbon MoS₂@Mo₂C, hollow heterostructure material.

Further optimization is carried out, wherein the mass ratio of the ammonium molybdate tetrahydrate to the aniline solution is 2.48: 40.

And further optimizing, dissolving aniline in deionized water to obtain the aniline solution, wherein the volume ratio of aniline to deionized water is 3-4: 40.

Further optimization, the specific steps of the solution method for preparing the Mo-MOF precursor are as follows: firstly, dissolving ammonium molybdate tetrahydrate in an aniline solution, and introducing 99.99% nitrogen for protection after dissolving, wherein the flow rate of nitrogen gas is 40-50 ml/min; under the condition of nitrogen protection, carrying out constant-temperature magnetic stirring and heating at the temperature of 45-55 ℃; under the heating condition of constant-temperature magnetic stirring, simultaneously dropwise adding dilute hydrochloric acid to adjust the pH of the solution to 3.5-4.5, continuously preserving heat for 3-6 h after dropwise adding is finished, and obtaining an intermediate of the Mo-MOF precursor after heat preservation is finished; and finally, putting the intermediate of the Mo-MOF precursor into a centrifuge with the rotating speed of 5000-.

Further optimizing, wherein the concentration of the dilute hydrochloric acid is 0.8-1.2 mol/L.

Further optimization is carried out, and the mass of the intermediate and distilled water of the Mo-MOF precursor in the centrifugal washing process is as follows: the volume is 1: 40-50.

Further optimization is carried out, the freeze drying temperature is-55 to-45 ℃, the vacuum degree is 10 to 50Pa, and the drying time is 24 to 48 hours.

Further optimization, the first heat treatment carbonization method specifically comprises the following steps: transferring the Mo-MOF precursor prepared by the solution method into an alumina ark for carbonization treatment, introducing nitrogen gas for protection, heating to 750-850 ℃ at the heating rate of 2-3 ℃/min, preserving heat for 3-5 h, and taking out to obtain Mo₂C-Mo₃C₂A heterogeneous nanowire material.

Further optimization is carried out, and the second-step heat treatment vulcanization method specifically comprises the following steps: prepared by the first heat treatment carbonization methodMo of₂C-Mo₃C₂Transferring the heterogeneous nanowire material into an alumina ark, placing a sulfur source in an upstream area for vulcanization treatment, introducing nitrogen gas for protection, heating to 600-1000 ℃ at a heating rate of 2-3 ℃/min, preserving heat for 1-4 h, and taking out to obtain the finished product of nitrogen-doped carbon MoS₂@Mo₂C, hollow heterostructure material.

The heterogeneous nanowire material has two different phases (namely Mo) of the same material through preparing a precursor and a first-step heat treatment carbonization method₂C and Mo₃C₂) The two are closely contacted; then decomposing unstable Mo by a second heat treatment vulcanization method₃C₂While Mo is added₃C₂MoS grows in situ at the phase position₂Mixing Mo₃C₂Complete conversion to MoS₂Guarantee MoS₂And Mo₂Close contact among C, high stability of the prepared hollow nano particles and hollow heterogeneous materials and MoS₂And Mo₂The heterogeneous structure formed by the mutual coordination of the two phases C can effectively enhance the electrocatalytic hydrogen evolution performance of the material in an alkaline environment.

For further optimization, the sulfur source adopts thiourea.

Further optimized, the dosage of the sulfur source is Mo₂C-Mo₃C₂10-20 times of the weight of the heterogeneous nanowire material.

Further optimizing, wherein the flow rate of nitrogen gas in the first heat treatment carbonization method and the second heat treatment vulcanization method is 40-50 ml/min, and the pressure in a nitrogen pipe for introducing nitrogen is controlled to be 0-1 Mpa.

The invention has the following technical effects:

the invention provides a hollow heterostructure material for alkaline electro-catalysis hydrogen evolution, which mainly comprises MoS₂@Mo₂C, the main body structure of the material is a transparent tubular structure consisting of a very thin carbon layer, charge transmission is facilitated, and a plurality of MoS are uniformly distributed on the surface of the transparent tubular structure₂@Mo₂Hollow nanoparticles composed of C composite materialThe particles are beneficial to the exposure of active point positions, thereby increasing the adsorption and activation in the electrolyte and having good catalytic effect on alkaline electro-catalytic hydrogen evolution.

The invention also provides a preparation method of the hollow heterogeneous material for alkaline electrocatalytic hydrogen evolution, which comprises the steps of forming two different phases of the same material by taking the nano linear structure as a precursor and matching carbonization, then decomposing unstable phases in the two phases through heat treatment and vulcanizing, and growing transition metal sulfide (MoS) in situ₂) The prepared two-phase structure is in close contact, so that the stability of the finally obtained product is ensured to be good, the stability of the catalyst is evaluated within the range of-1.1V-0V by using potential cycle with the scanning rate of 50mV/s, the scanning rate is 5000 times, compared with an initial LSV curve, the LSV curve after 5000 cycles has small change which is about 11mV, and the structure is stable, has no collapse, has good conductivity and is easy to recover through a timing current test of 12 hours; at the same time, MoS₂And Mo₂The heterogeneous structure formed by the mutual coordination of the C two phases shows excellent hydrogen evolution performance in alkaline solution, the initial voltage of electrocatalytic hydrogen evolution is 22mV vs RHE, and the current density can reach 10mA/cm when the overpotential is 129mV²。

The method has the advantages of easily obtained raw materials, simple preparation process, convenient operation, easy realization of large-scale production and wide application prospect in the aspects of energy development and storage, and can obtain heterogeneous nano materials through a solvothermal method and a simple two-step heat treatment process.

Drawings

FIG. 1 is an SEM image (low magnification) of a sample prepared in example 1 of the present invention.

FIG. 2 is an SEM image (high magnification) of a sample prepared in example 1 of the present invention.

FIG. 3 is a TEM image (low magnification) of a sample prepared in example 1 of the present invention.

FIG. 4 is a TEM image (middle magnification) of a sample prepared in example 1 of the present invention.

FIG. 5 is a TEM image (high magnification) of a sample prepared in example 1 of the present invention.

Fig. 6 is an XRD pattern of a sample prepared in example 1 of the present invention.

FIG. 7 is an XPS plot of samples prepared in example 1 of the present invention.

FIG. 8 is a graph of the alkaline electro-catalytic hydrogen production performance (voltammetric linear scan) of example 1 of the present invention.

FIG. 9 is a graph showing the stability of alkaline electrocatalytic hydrogen production (constant current) in example 1 of the present invention.

FIG. 10 is a graph showing the stability of alkaline electrocatalytic hydrogen production (chronoamperometry) in example 1 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.