Method for rapidly synthesizing monatomic catalyst by plasma sputtering method and application thereof
Technical Field
The invention belongs to the field of catalysis, and particularly relates to rapid synthesis of a monatomic catalyst by combining a plasma sputtering method with a catalyst preparation technology, namely, synthesis of a monatomic catalyst material by applying a plasma sputtering technology.
Background
With the gradual depletion of fossil fuels, one potential solution is to convert solar energy, wind energy and other energy sources into electric energy for temporary storage and then discharge the electric energy when needed (peak clipping and valley filling). In view of the scale of clean energy utilization, such energy storage systems must be inexpensive and efficient, and easy to store and transport. Water is converted into hydrogen energy through electrochemical reaction, so that high-efficiency conversion and storage of electric energy generated by renewable clean energy to chemical energy can be realized, and sustainable development and utilization of clean energy such as solar energy, wind energy and the like are facilitated.
The electrochemical reaction converts water into hydrogen energy, and the use of a high-efficiency electro-catalytic Hydrogen Evolution (HER) catalyst is not available. But the scarcity of resources, high price and the like limit the industrial application of platinum. Therefore, the low load and high quality specific activity of the monatomic catalysis fully makes up the defect of insufficient resources and promotes the industrial application of the platinum. The traditional metal nano catalyst, particularly the monatomic catalyst, has the disadvantages of high synthesis difficulty, complex process flow, high energy consumption, long time consumption and difficult control of the size of the active metal.
In order to overcome the defects of the prior art, the invention mainly aims to solve the technical problems of finding a catalyst synthesis method which has the advantages of short synthesis period, simple process, low production cost, environmental friendliness and the like, improving the utilization rate of active metals, reducing the use amount of resources such as noble metals and the like, simplifying the synthesis complexity of a monatomic catalyst, synthesizing the catalyst rapidly on a large scale, and making up for the defect of difficult synthesis of common catalysts, particularly monatomic catalysts.
Disclosure of Invention
The invention aims to mainly find a catalyst synthesis method with the advantages of simple synthesis method, good process control, low production cost, environmental friendliness and the like and a high-quality catalyst with high catalytic activity by combining a plasma sputtering technology and a catalyst synthesis technology. Makes up for some of the disadvantages of the traditional catalyst synthesis process.
Synthesis of monatomic Pt1/TiOxCatalyst, Pt being dispersed in monoatomic formThe conditions are that the absolute pressure is 20pa, and the gas environment is Ar: N2The volume ratio is 9:1, the sputtering working current is 5mA, and the duration is 1 second; TiO 2xThe carrier deposition condition is 20pa absolute pressure, and the gas environment is Ar: N2The volume ratio is 9:1, the working current of sputtering deposition is 19mA, and the duration is 60 seconds;
pt and TiOxThe catalyst was obtained by alternately depositing 15 times each.
The prepared catalyst is used as a catalyst when water is converted into hydrogen energy through an electrochemical reaction.
The carrier target material used in the invention is a black titanium oxide target material with the purity of 99.99 percent, the active material target material is a platinum (Pt) target material with the purity of 99.99 percent, and the substrate is a glassy carbon sheet. Simultaneously mounting two targets on a three-target plasma sputtering instrument; the substrate is placed at a specified absolute pressure of 20pa and Ar: N2After setting the working time of the plasma sputtering apparatus on a stage in a gas atmosphere of 9:1 (volume ratio), the sputtering deposition of the carrier and the active metal is started, and the stage alternately deposits black titanium oxide in the platinum target for several times to obtain the 'sandwich-like' catalyst film. The invention finally obtains the ultralow-load Pt with high catalytic activity1/TiOxA monatomic catalyst (see figures 2-3).
The substrate with the catalyst attached to a specific area was subjected to electrochemical testing. The activity of the catalyst is tested by using a traditional three-electrode system, and specifically the test environment is 0.5M sulfuric acid, the reference electrode is a saturated calomel electrode, the counter electrode is a carbon rod, and the working electrode is a glassy carbon sheet. The electrochemistry of commercial platinum carbon (Pt/C) was tested under the same conditions and compared (see FIG. 4).
The Pt content in the obtained catalyst can be calculated after an inductively coupled plasma mass spectrometry (ICP-MS) test to obtain the Pt loading capacity of the prepared monatomic catalyst. The aggregation state of the active metal Pt can be determined by a high-resolution electron microscope (HR-TEM), a spherical aberration correction electron microscope (AC-TEM) and the like.
The invention has the advantages that:
1. according to the analysis of the current catalyst material development condition, the catalyst development inertia thinking place is limited in the complex time-consuming chemical reaction synthesis field, the invention develops the combination of the plasma sputtering technology and the catalyst synthesis technology, and widens the research field and the research direction of the catalyst material development.
2. The method has the advantages of simple process flow, low energy consumption, short time consumption, low comprehensive cost and the like, and has the capability and space of large-scale development.
3. The catalyst developed by the invention can be attached to any conductor (such as a glass carbon sheet, stainless steel, carbon paper and the like) or even a semiconductor substrate without using an adhesive, and is more energy-saving and environment-friendly in synthesis and more convenient to use.
5. The catalyst developed by the invention has the advantages that the loading capacity of the active metal can be regulated and controlled, the particle size of the active metal can also be controlled, and the use amount of the noble metal or other active metals can be effectively controlled.
6. Pt developed by the present invention1/TiOxThe catalyst has high catalytic activity, and the specific activity of the catalyst is obviously superior to that of a commercial material.
Description of the drawings:
fig. 1 is a diagram of a single-atom high-angle annular dark field (HAADF) for each layer of catalyst Pt after debugging.
FIG. 2 shows the monoatomic Pt1/TiOxHigh Resolution Transmission Electron Microscopy (HRTEM) images of the catalyst.
FIG. 3 shows the monoatomic Pt1/TiOxCatalyst High Angle Annular Dark Field (HAADF) diagram.
Figure 4 is a graph comparing catalytic performance (HER) of the as-synthesized monatomic catalyst with 20% commercial platinum carbon (20%. Pt/C).
Detailed Description
The present invention will be described in further detail with reference to the practice of experimental facts, but the embodiments of the present invention are not limited thereto, and the carrier target, the active material target, and the substrate to be used are not limited thereto.
Example 1
Polishing the glassy carbon sheet substrate by using polishing powder, cleaning and placing the polished glassy carbon sheet substrate in a vacuum drying oven for drying for later use. The two used target materials are simultaneously arranged on a three-target plasma sputtering instrument; placing the glassy carbon sheet substrate at an absolute pressure of 20pa and Ar: N29:1 (volume ratio)) On a stage in a gas atmosphere, black titanium oxide (TiO)x) The single sputtering deposition working current is 19mA and the time length is 60 seconds, the working current is 5mA and the time length is 1 second when the platinum (Pt) is deposited by single sputtering, and 15 times of deposition are alternately carried out, thus obtaining the monatomic Pt1/TiOxA catalyst film. In particular, the parameters of vacuum degree, gas environment, time, current and the like of the deposition of the carrier and the active metal are conclusion values of the test that Pt is dispersed in a titanium oxide film carrier in a monoatomic form, which is explored in advance. The dispersed state of Pt in the monolayer catalyst is clearly a monoatomic level dispersion (see fig. 1).
The substrate with the catalyst attached to a specific area was subjected to electrochemical testing. The activity of the catalyst is tested by using a traditional three-electrode system, and specifically the test environment is 0.5M sulfuric acid, the reference electrode is a saturated calomel electrode, the counter electrode is a carbon rod, and the working electrode is a catalyst/glassy carbon sheet. Electrochemical measurements were made on 20% commercial platinum carbon (20%. Pt/C) under the same conditions, and the catalytic activity was compared with each other, and the results showed that the specific activity of the catalyst according to the present invention was 11.05 times that of the 20% commercial platinum carbon (see FIG. 4).
According to calculation after inductively coupled plasma mass spectrometry (ICP-MS) test, the Pt loading capacity of the monatomic catalyst prepared by the method is 1.6%. The aggregation state of the active metal Pt is determined to be monoatomic dispersion by means of a high-resolution electron microscope (HR-TEM), a spherical aberration correction electron microscope (AC-TEM) and the like, namely, the supported monoatomic Pt is successfully synthesized by means of a plasma sputtering method in the invention1A TiOx catalyst.