CN110508296A - A kind of preparation method of semiconductor composite material based on chemical vapor deposition - Google Patents

Abstract

The invention relates to a method for preparing a semiconductor composite material based on chemical vapor deposition. In a chemical vapor deposition reaction chamber, a semiconductor synthetic raw material is used to deposit a semiconductor material on a substrate by a chemical vapor deposition method, and a coupling interface between the semiconductor material and the substrate is obtained. target product. Compared with the prior art, the present invention uses chemical vapor deposition to prepare a metal-semiconductor composite with a specific coupling interface, which not only has the excellent electrical conductivity and surface structural properties of the base metal material, but also has a special coupling interface , so that the electrocatalytic performance of the material is further improved.

Description

A kind of preparation method of semiconductor composite material based on chemical vapor deposition

technical field

The invention belongs to the technical field of metal semiconductor materials, and relates to a preparation method of a semiconductor composite material based on chemical vapor deposition.

Background technique

The basic chemical reaction process of water electrolysis plays a very important role in the fields of energy, catalyst, seawater desalination and so on. There are two main methods for industrialized hydrogen production by electrolysis: alkaline water electrolysis for hydrogen production and polymer electrolyte water electrolysis for hydrogen production. Alkaline electrolysis of water for hydrogen production is still in the development stage; the reason is that the direct use of seawater in the existing technology will lead to electrode corrosion and reduced efficiency, and a higher voltage is required to achieve hydrogen production. On the other hand, the price of high-efficiency electrode materials is relatively expensive, The requirements for the electrolyte are also higher.

Chinese patent 201910446436.6 discloses a preparation method and application of a bifunctional electrocatalyst of molybdenum disulfide composite material. Ammonium thiomolybdate and hydrazine hydrate were added to N,N-dimethylformamide together to obtain molybdenum disulfide composite material by solvothermal method, and finally stabilized by heat treatment to obtain molybdenum disulfide composite material CN/ Co ₄ S ₃ @MoS ₂ . Although the composite material for electrolysis catalysis prepared by the patent has good catalytic performance, it is prepared in liquid phase, the repetition rate is low, and the structural properties of the product are often not stable enough.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of a semiconductor composite material based on chemical vapor deposition in order to overcome the above-mentioned defects of the prior art.

The object of the present invention can be realized through the following technical solutions:

A method for preparing a semiconductor composite material based on chemical vapor deposition is characterized in that, in a chemical vapor deposition reaction chamber, a semiconductor synthetic material is used to deposit a semiconductor material on a substrate by a chemical vapor deposition method, and a coupling between the semiconductor material and the substrate is obtained. The target product of the interface.

Further, the semiconductor synthesis raw materials include chalcogen elements and transition metal oxides. During the chemical vapor deposition reaction, chalcogen elements and transition metal oxides first react to form gaseous intermediate products, and then the intermediate gaseous products and sulfur vapor further react to form molybdenum disulfide and deposit on the surface of the substrate.

Further, the semiconductor synthesis raw materials are sulfur powder and molybdenum oxide, and the corresponding semiconductor material is molybdenum disulfide.

Further, the semiconductor synthesis raw materials are selenium powder and molybdenum oxide, and the corresponding semiconductor material is molybdenum selenide.

Further, in the chemical vapor deposition process, the ratio of the added amount (mass ratio) of the chalcogen element to the transition metal oxide is about 8000-12000:1 (preferably about 10000:1).

Furthermore, in the chemical vapor deposition process, the distance between the chalcogen element and the transition metal oxide is 20-40 cm.

Further, the substrate is metal or silicon dioxide in the form of flat plate, block, foam or film. The substrate has excellent electrical conductivity and its porosity is between 0% and 100%. When a porous metal material (that is, a foamed metal material) is used as the substrate, the semiconductor can grow uniformly on the surface of the porous metal material due to vapor deposition; during the growth process, due to the rough surface of the substrate and the dense nucleation sites, the semiconductor is more inclined to Vertical growth, and finally a semiconductor array with a stable structure is formed; the porous solid material serves as a supporting substrate and provides an electrolyte supply channel to ensure the efficient process of water electrolysis. On smooth silicon oxide surfaces, the semiconductor material tends to grow horizontally. That is to say, the semiconductor material grown on the substrate has a great relationship with the roughness of the substrate surface.

Further, the grown semiconductor material is in the form of nanosheet arrays, nanoparticles or bulk. It is preferably in the form of an array of nanosheets grown vertically by the semiconductor material. This nanosheet shape enables the material to have a large specific surface area and provides more active sites for electrocatalytic reactions. The adsorption energy of hydrogen on the edge is similar to that of platinum, and it can greatly promote the hydrogen generation reaction rate in the process of electrolysis of water.

Further, the metal is one element or an alloy of several of cobalt, nickel, copper, tungsten, titanium, aluminum or iron.

Further, the deposition reaction temperature on the substrate is 300-800° C., and the deposition reaction time is 10-60 min.

Further, during the chemical vapor deposition process, the flow rate of the introduced protective gas flow is in the range of 10 to 100 sccm.

In the present invention, when the semiconductor material is grown on the substrate, a sulfide layer will be formed between the two, and the sulfide layer can effectively promote the reaction rate of oxygen generation; at the same time, a coupling interface is formed between the sulfide and the semiconductor. The interfacial pair can exist stably during the electrocatalytic reaction, and can effectively promote the hydrogen production efficiency and oxygen production efficiency during the water electrolysis reaction.

The chemical vapor deposition method used in the present invention is controllable, and composite materials of different products can be obtained by changing the reaction conditions. For example, the reaction temperature can be changed from 300 to 800 degrees Celsius, the flow rate of the introduced protective gas can be in the range of 10 to 100 sccm, the amount of raw materials can be appropriately changed, the distance between the reactants and the length of the reaction time can be adjusted to obtain different shapes. metal-semiconductor composites. First, the substrate is sulfurized, and molybdenum sulfide is deposited on the substrate. With the increase of reaction time, these specific structures become the active sites for the subsequent deposition of molybdenum sulfide. bigger and thinner. By changing the substrate material, such as smooth silicon oxide, there are few active sites, and the growth of molybdenum sulfide is not interfered with each other, so it has a triangular platelet-shaped morphology, while on rough surface materials such as iron and nickel, there are many deposition sites. , the growth of molybdenum sulfide restricts each other, squeezes, and finally forms a vertical growth sheet structure.

The metal-semiconductor composite material prepared by the invention not only has the excellent electrical conductivity of metal materials, but also has the specific properties of semiconductors, and the coupling interface formed in the middle has a catalytic effect on the hydrogen generation and oxygen generation reactions of electrolyzed water, and can be even lower. Hydrogen and oxygen are produced under overpotential. This material can not only be used in water electrolysis reactions, but also can be effectively utilized for photolysis of water, photodegradation and oxygen reduction reactions.

First, with the increase of temperature and the introduction of sulfur vapor, the substrate material begins to vulcanize, after that, sulfur vapor and _MoO3 form a gaseous intermediate product, and further this product reacts with sulfur vapor on the substrate surface, due to the existence of active sites in the substrate , molybdenum sulfide grows on these sites. At the beginning of growth, it is based on the previously formed base sulfide. First, the coupling interface is formed, that is, S and Mo bond at the surface, and the interior is the base sulfide. After further reaction, molybdenum sulfide gradually grows and forms a sheet-like structure. It can be seen that by controlling the reaction time, the molybdenum sulfide state (ie, the size, thickness, and thickness) of different growth times can be obtained.

Compared with the prior art, the present invention utilizes the semiconductor composite material grown by chemical vapor deposition to convert electrical energy into hydrogen energy, and can synthesize materials with different morphologies and different characteristics through the selection of substrate materials and semiconductor growth reaction raw materials. The material not only has a stable physical structure, but also maintains stable performance in the process of electrolysis of water. Specifically, it has the following advantages and beneficial effects:

(1) The present invention uses metal or alloy as the substrate of chemical vapor deposition technology, which can improve the stability and conductivity of the resulting composite material.

(2) The metal-semiconductor composite material synthesized by the present invention has the advantages of simple preparation, low price and stable structure.

(3) The present invention can change the morphology of the material by adjusting the chemical vapor deposition conditions.

(4) The hydrogen energy produced by the present invention is clean and pollution-free, and has the effect of energy saving and emission reduction.

(5) The semiconductor composite material synthesized in the present invention has excellent water electrolysis performance.

Description of drawings

Fig. 1 is the optical photograph of the composite material whose growth matrix is silicon oxide;

Fig. 2 is a scanning electron microscope photograph of a composite material whose matrix is an alloy;

FIG. 3 is a graph showing the relationship between the current density and the voltage of the reaction current density of the electrolyzed water and hydrogen generated by the material at different growth times.

Figure 4 is a graph showing the relationship between the current density and voltage of the hydrogen generation reaction of MoS ₂ grown on different substrates and a Tafel curve;

Figure 5 is a graph showing the relationship between the current density of the oxygen generation reaction and the voltage and the Tafel curve of MoS2 grown _on different substrates;

Fig. 6 is the electrochemical performance diagram of the oxygen generation reaction current density of the Co-MoS material prepared in Example ₃ as a function of voltage;

7 is a scanning electron microscope photograph of the Cu-MoS material prepared in Example ₅ ;

8 is a graph of the electrochemical performance of the Cu-MoS material prepared in Example ₅ as a function of the current density of the hydrogen generation reaction with voltage;

9 is a scanning electron microscope photograph of the CuNi-MoS material prepared in Example ₆ ;

Figure 10 is a graph of the electrochemical performance of the CuNi-MoS ₂ material prepared in Example 6 as a function of voltage for hydrogen generation reaction current density;

11 is a scanning electron microscope photograph of the CoNi _- MoS material prepared in Example 7;

12 is a graph showing the electrochemical performance of the hydrogen generation reaction current density of the CoNi-MoS ₂ material prepared in Example 7 as a function of voltage.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

Example 1

(1) Preparation of iron-nickel alloy-molybdenum sulfide

The iron-nickel foam alloy (as the substrate) and silicon oxide were washed with ethanol, acetone, 0.5M hydrochloric acid and deionized water in turn, the molybdenum oxide powder was placed on the silicon oxide, and put into a quartz boat, and the iron-nickel foam alloy sheet was washed. Place it above the quartz boat (that is, above the molybdenum oxide powder), and put it into the tube furnace; put the sulfur powder in another quartz boat, and also put it into the tube furnace, and the sulfur powder and molybdenum oxide are placed in the tube furnace. In different temperature control areas, the sulfur powder is located in the temperature area of the gas flow inlet, and the molybdenum oxide is located in the middle area of the tube furnace. First, nitrogen was introduced into the tube furnace to exhaust air, and then the temperature of the molybdenum oxide area was increased to 650 degrees Celsius, and then the temperature of the sulfur area was increased to 110 degrees. After 10 minutes of reaction treatment, it was cooled naturally. As shown in the optical photo in Figure 1 and the scanning electron microscope in Figure 2, through the CVD method, the sheet-like molybdenum disulfide was successfully grown vertically on different substrates. The reaction temperature can be changed from 300 to 800 degrees Celsius, the flow rate of the introduced protective gas can be in the range of 10 to 100 sccm, the amount of raw materials can be appropriately changed, the distance between the reactants and the length of the reaction time can be adjusted to obtain different morphologies of metal-semiconductor composites. As shown in Figure 3, for the grown materials with different reaction times, the current density of the electrolyzed water hydrogen generation reaction varies with the voltage. When the reaction time is 60 minutes, the material shows the best hydrogen evolution performance. From Figure 1 and Figure 2, it can be seen that on the smooth silicon oxide, there are few active sites, and the growth of molybdenum sulfide is not interfered with each other. Therefore, the molybdenum sulfide grows in a tiled shape, showing a triangular shape. On the rough material, there are many deposition sites, and the growth of molybdenum sulfide restricts each other, squeezes, and finally forms a vertically grown sheet-like structure.

(2) Iron-nickel alloy - molybdenum sulfide for electrolysis of water

A 1M potassium hydroxide solution was prepared as the electrolyte, and argon gas was passed into the electrolyte until saturation, and then a three-electrode system was used. The reference electrode was a reversible hydrogen electrode, and the carbon rod was the counter electrode. The working electrode is a clip-type iron-nickel alloy-molybdenum sulfide material, and the current density of the material under different voltages is observed. Due to the excellent electrical conductivity of the iron-nickel alloy material, the high specific surface area of molybdenum sulfide with a sheet-like structure, and the hydrogen adsorption energy similar to that of platinum, the material has a great catalytic effect on the hydrogen generation and oxygen generation reactions of electrolyzed water.

Figure 4 shows the polarization curves of _hydrogen generation and Tafel curves of MoS2 composites grown on different substrates. It can be seen from the figure that the iron-nickel alloy-molybdenum sulfide material with disulfide arrays grown vertically on the iron-nickel foam showed the best performance compared to the molybdenum disulfide grown on the FTO substrate, the untreated and the sulfided iron-nickel foam. The hydrogen evolution performance is 120mV with the lowest overpotential at a current density of 10mA cm ^-2 . It can be seen from the Tafel curve that the iron-nickel alloy-molybdenum sulfide has the lowest Tafel slope of 45.1mV/dec.

Figure 5 shows the cyclic voltammetry curves of oxygen generation and Tafel curves of composites grown on different substrates for MoS ₂ . Iron-nickel alloy-molybdenum sulfide material, in 1M KOH electrolyte, the oxygen evolution reaction has a reaction overpotential of 204mV at a current of 10mA/ ^cm2 . The Tafel curve can show the oxygen evolution reactivity of molybdenum sulfide on different substrates more deeply. Compared with other composite structural materials, the Tafel slope of iron-nickel alloy-molybdenum sulfide material is only 28.1mV/dec , with the best oxygen evolution performance. In conclusion, the iron-nickel alloy-molybdenum sulfide has excellent catalytic performance in the hydrogen generation and oxygen generation reactions of electrolyzed water.

Example 2

(1) Preparation of iron-nickel alloy-molybdenum selenide

Preparation of iron-nickel alloy-molybdenum selenide: the same as Example 1, but the sulfur powder needs to be replaced with selenium powder.

(2) Iron-nickel alloy - molybdenum selenide for water electrolysis

The hydrogen generation and oxygen generation reactions of iron-nickel alloy-molybdenum selenide: the same as Example 1, but the reaction efficiency is different.

Example 3

(1) Preparation of cobalt-molybdenum sulfide

Preparation of cobalt-molybdenum sulfide: the same as in Example 1, but the matrix material needs to be replaced with elemental cobalt sheets.

(2) Cobalt-molybdenum sulfide for electrolysis of water

Hydrogen generation and oxygen generation reaction of cobalt-molybdenum sulfide: the same as in Example 1, but the reaction efficiency is different. Referring to FIG. 6 , it can be seen that, compared with the general pure Co sheet, the cobalt-molybdenum sulfide prepared in this example has better performance of moisture-resolving oxygen.

Example 4

Preparation of silicon oxide-molybdenum sulfide: the same as Example 1, but the substrate material needs to be replaced with a silicon wafer with a thickness of 300 nm on one side. The prepared molybdenum sulfide can be observed under a light microscope, and it is a horizontal triangular piece appearance.

Example 5

(1) Preparation of copper-molybdenum sulfide

Preparation of copper-molybdenum sulfide: the same as in Example 1, but the base material needs to be replaced with elemental copper mesh.

(2) Copper-molybdenum sulfide for electrolysis of water

The hydrogen generation reaction of copper-molybdenum sulfide: the same as Example 1, but the reaction efficiency is different. Referring to FIG. 7 and FIG. 8 , it can be seen that this embodiment realizes the growth of molybdenum sulfide and the like on the copper mesh base material, and compared with the sulfided pure copper mesh, the copper-molybdenum sulfide prepared in this embodiment has Better Moisture Analysis Hydrogen Performance.

Example 6

(1) Preparation of copper-nickel alloy-molybdenum sulfide

Preparation of copper-nickel alloy-molybdenum sulfide: the same as Example 1, but the base material needs to be replaced with copper-nickel alloy foam.

(2) Copper-nickel alloy - molybdenum sulfide for water electrolysis

The hydrogen generation reaction of copper-nickel-molybdenum sulfide: the same as Example 1, but the reaction efficiency is different. Referring to FIG. 9 and FIG. 10 , it can be seen that the present embodiment realizes the growth of molybdenum sulfide and the like on the copper-nickel alloy foam. Molybdenum has better water-resolving hydrogen performance.

Example 7

(1) Preparation of cobalt-nickel alloy-molybdenum sulfide

Cobalt-nickel alloy-molybdenum sulfide preparation: the same as Example 1, but the matrix material needs to be replaced with cobalt-nickel alloy foam.

(2) Cobalt-nickel alloy - molybdenum sulfide for electrolysis of water

Hydrogen generation reaction of cobalt-nickel alloy-molybdenum sulfide: the same as Example 1, but the reaction efficiency is different. Referring to FIG. 11 and FIG. 12 , it can be seen that this embodiment realizes the growth of molybdenum sulfide and the like on the cobalt-nickel alloy foam. Compared with the cobalt-nickel alloy foam only sulfided, the cobalt-nickel alloy prepared in this embodiment- Molybdenum sulfide has better water-resolving hydrogen performance.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (10)

1. a kind of preparation method of the semiconductor composite based on chemical vapor deposition, which is characterized in that in chemical vapor deposition Product reaction chamber in, use semiconductor synthesis material with chemical vapour deposition technique the deposited semiconductor material in substrate, partly led With the purpose product of coupled interface between body material and substrate.

2. a kind of preparation method of semiconductor composite based on chemical vapor deposition according to claim 1, special Sign is that the semiconductor synthesis material includes chalcogen simple substance and transition metal oxide.

3. a kind of preparation method of semiconductor composite based on chemical vapor deposition according to claim 2, special Sign is that the semiconductor synthesis material is sulphur powder and molybdenum oxide, and corresponding semiconductor material is molybdenum disulfide.

4. a kind of preparation method of semiconductor composite based on chemical vapor deposition according to claim 2, special Sign is that the semiconductor synthesis material is selenium powder and molybdenum oxide, and corresponding semiconductor material is selenizing molybdenum.

5. a kind of preparation method of semiconductor composite based on chemical vapor deposition according to claim 2, special Sign is, in chemical vapor deposition processes, the mass ratio of chalcogen simple substance and transition metal oxide is 8000-12000:1.

6. a kind of preparation method of semiconductor composite based on chemical vapor deposition according to claim 2, special Sign is, in chemical vapor deposition processes, chalcogen simple substance is 20-40cm at a distance from transition metal oxide.

7. a kind of preparation method of semiconductor composite based on chemical vapor deposition according to claim 1, special Sign is that the substrate is the metal or silica of tabular, bulk, foam-like or film-form.

8. a kind of preparation method of semiconductor composite based on chemical vapor deposition according to claim 7, special Sign is that the metal is a kind of simple substance or several alloys in cobalt, nickel, copper, tungsten, titanium, aluminium or iron.

9. a kind of preparation method of semiconductor composite based on chemical vapor deposition according to claim 1, special Sign is that the deposition reaction temperature in substrate is 300-800 DEG C, and the deposition reaction time is 10-60min.

10. a kind of preparation method of semiconductor composite based on chemical vapor deposition according to claim 1, special Sign is, in chemical vapor deposition processes, the protection air-flow flow of introducing arrives the section 100sccm 10.