CN104001521A - Carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient and preparation method thereof - Google Patents

Abstract

The invention discloses a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient and a preparation method thereof, belonging to the technical field of water electrolysis-organic electrocatalytic reduction coupling; The Pt and Cu splicing targets placed on the moving target stage are sputtered with ion beams, and the moving direction of the target stage is kept perpendicular to the seam line between Pt and Cu on the splicing target, and the sputtered Pt and Cu particles on the sputtering target are deposited on the A thin film is formed on one side of the carbon carrier cleaned by ion beams, and then a carbon-supported PtCu alloy catalyst with a controllable atomic concentration gradient is obtained through vacuum heat treatment; the Pt content of the catalyst is 0.075-0.121mg/cm ² ; the moving speed of the target stage is adjusted The atomic concentration gradient of Pt in the catalyst can be directly regulated, and the stable moving speed can make the atomic concentration of Pt change in a uniform gradient from the bottom layer of the film to the surface; the catalyst has the advantages of low Pt content, good electrochemical activity, and simple preparation.

Description

A carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient and its preparation method

technical field

The invention relates to a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient and a preparation method thereof, belonging to the technical field of water electrolysis-organic electrocatalytic reduction coupling.

Background technique

The hydrogenation reaction of organic matter is an important process in the production fields of food, chemical industry, energy, etc., and its combination with electrolysis of water may become the main method of hydrogen production in the future. The reaction conditions are mild, and there is no need to provide additional hydrogen sources. Because it is a strong acid corrosion reaction environment, the electrode can only be used as a carbonaceous material carrier and noble metals Pt and Au loaded on it. Among them, Pt has an unfilled empty d orbital and shows excellent catalytic activity and stability. The carbon-supported Pt catalyst is supported on the surface of the carbon carrier to obtain a high electrode reaction current density and is widely used.

Due to the scarcity of platinum group metal resources in my country, doping transition metals in Pt to form Pt alloys has become the development trend of carbon-supported Pt-based catalysts. The research focus of Pt-based catalysts is accordingly focused on improving catalytic activity and reducing Pt content. The transition metal Cu atom has an outer layer configuration of 3 d ¹⁰ 4 s ¹ . Since the energies of 4 s and 3 d electrons are close, they may form bonds when combined with Pt. Therefore, there is an unstable valence space for the Cu atom, making it Not only can it be used as an auxiliary agent to participate in the catalytic reaction, but it can also be used as a doping element to change the particle distribution of the active component Pt, so that the Pt crystal grains are arranged more tightly, the electron cloud density is increased, and the energy barrier required to bind oxygen atoms can be reduced.

Although the PtCu alloy catalyst can reduce the Pt content of the electrode and improve the catalytic activity, it still needs to be improved in terms of catalyst reaction selectivity and stability. Carbon-supported PtCu alloy catalysts are used in the coupling reaction process of water electrolysis-organic electrocatalytic reduction due to their unique catalytic properties. The reason is that the catalytic activity mainly depends on the concentration and preferred orientation of the catalytic main phase. First, it is near the Fermi level , the catalyst with Pt as the main phase has a smaller energy band width, and the Pt(111) crystal plane has a higher density of states than other orientations and has the best catalytic performance. The second is that the change of the Pt concentration on the catalyst surface leads to film defects. Facilitate in-situ control of catalytic activity.

According to the literature search of the existing atomic concentration gradient control technology, it is found that the US patent US4399058 mixes VIB and VIII metal salts with ammonia water, adjusts to a certain pH value by adding ammonia water, heats the metal solution, and then saturates and impregnates the metal solution On the carrier, the method of drying and roasting to obtain the carrier catalyst has the disadvantage that the active metal component is distributed more uniformly on the carrier, and the atomic concentration gradient is not obvious and difficult to control; European patent EP0204314 adopts step-by-step multiple impregnation and water washing , drying, and roasting methods to support the metal components, so that the concentration of the metal components inside the carrier catalyst is higher than that on the surface and there is an uneven distribution, which prolongs the service life of the catalyst accordingly. Due to its complicated preparation process, the cost is large Improve; Chinese patent CN99113273.4 adopts the unsaturated spray-dipping method to prepare the carrier catalyst of inhomogeneous active metal components, which reduces the manufacturing cost of the catalyst but the disadvantage is that the distribution gradient of the active metal components is poor, and it is difficult to control the active metal components in the catalyst particles. Gradient distribution in the medium; Chinese patents CN200910086745.3 and CN200910086740.0 both adopt the method of impregnating the carrier with gradually concentrated metal solution saturation or impregnating the carrier in sequence from low to high concentration of the metal impregnating solution, and then obtain activity through multiple drying and roasting treatments. The supported catalyst whose concentration of the metal component and/or the acidic additive is distributed in a gradient increase has better activity and stability, but the distribution of the concentration of the active metal component in the catalyst particles presents a multi-step form. At present, there are few reports on supported catalysts with uniform gradient changes in the concentration of active metal components and their preparation methods.

Contents of the invention

In view of the above-mentioned defects of the prior art, the present invention will solve the problem of poor uniformity of the active metal component concentration gradient, complicated preparation process, long reaction time, There are problems such as difficulty in removing intermediate reactants and large loss of precious metals.

The object of the present invention is to provide a carbon-supported PtCu alloy catalyst with a controllable atomic concentration gradient. The catalyst is to use graphite fiber cloth as a carbon carrier, and Pt and Cu particles are directly loaded on a single surface of the graphite fiber cloth to form a thin film catalyst. The thickness of the thin film catalyst is 30-50nm; the content of Pt in the catalyst is 0.075-0.121 mg/cm ² , and the content of Cu is 0.019-0.074 mg/cm ² .

In the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient according to the present invention, the atomic concentrations of the active components Pt and Cu in the catalyst show a uniform gradient change from the bottom layer of the film to the surface, wherein the atomic concentration of Pt is 26.85-90.42 % , the atomic concentration of Cu is 9.58-73.15 at. %, the atomic concentration gradient of the active components Pt and Cu is directly regulated by the moving speed of the target stage, within the moving range of the target stage, the stable moving speed of the target stage makes Pt and Cu The atomic concentration of Cu changes in a uniform gradient from the bottom layer to the surface of the film.

The carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient according to the present invention is characterized in that: the graphite fiber cloth is plain acrylonitrile graphite fiber cloth, and the surface density is 0.20-0.35 g/cm ² .

Another object of the present invention is to provide the preparation method of the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient, which specifically includes the following steps:

(1) Arrange the graphite fibers in a vacuum of 7×10 ^-3 ~ 9×10 ^-3 Pa, control the screen level voltage of the ion beam assisted cleaning source to 0.6 ~ 0.8kV, the beam current to 65 ~ 75mA, and feed High-purity Ar with a flow rate of 6.5-7.5 sccm, wherein the purity of Ar is ≥99.999%, and ion beam-assisted cleaning is performed on the surface of the graphite fiber cloth for 5-7 minutes to obtain the pretreated graphite fiber cloth;

(2) Arrange the pretreated graphite fiber obtained in step (1) in a vacuum of 7×10 ^-3 ~ 9×10 ^-3 Pa, control the screen level voltage of the ion beam sputtering source to 3.3 ~ 3.6kV, the beam current 70-90mA, and feed high-purity Ar with a flow rate of 7.5-8.5sccm, where the purity of Ar is ≥99.999%, and the extracted Ar ion beam bombards the Pt and Cu splicing targets placed on the moving target platform; then keep the target platform moving The direction is perpendicular to the seam line of Pt and Cu on the splicing target, and the moving speed of the target stage is adjusted to 5-10 mm/min, so that the atomic concentration of Pt and Cu changes in a uniform gradient from the bottom layer to the surface of the film, and the Pt and Cu splicing targets sputter out The Pt and Cu particles are deposited on the single surface of the graphite fiber cloth to form a catalyst film, the ion beam sputtering time is 5-10min, and the thickness of the catalyst film is 30-50nm;

(3) Place the carbon-supported catalyst thin film obtained in step (2) in a vacuum of 7×10 ^-3 to 9×10 ^-3 Pa, heat to 350-450°C and keep it warm for 1.0-2.0h, and cool to room temperature naturally That is, a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient is obtained.

The Pt and Cu splicing target described in the step (2) of the present invention is a sputtering target in a square shape formed by splicing a Pt target and a Cu target, and the purity of both Pt and Cu is ≥99.95%.

The carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient prepared by the present invention has important application significance in the field of water electrolysis-organic electrocatalytic reduction coupling technology; through X-ray diffraction (XRD), X-rays with etching thinning function Photoelectron spectroscopy (XPS), inductively coupled plasma emission spectrometry (ICP-AES), cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used to characterize carbon-supported PtCu with controllable atomic concentration gradient. The phase structure of the alloy catalyst, the atomic concentration of Pt from the bottom layer to the surface of the film, the content of active metal Pt, the specific surface area of electrochemical activity and the catalyst activity.

XRD was used to identify the phase structure of the catalyst. After excluding the influence of the extremely strong characteristic diffraction peaks of graphite fiber cloth, the ≤2 θ of the diffraction pattern was controlled within the range of 30° to 90°. The test results showed that the catalyst contained active metals. Thin film, the phases are Pt(111), Cu(111), PtCu(111) and PtCu ₃ (111); use the online etching function to thin the catalyst film, and combine XPS to visually characterize the Pt atoms from the bottom layer to the surface of the catalyst film The test results show that the direct control range of the atomic concentration of Pt is 26.85-90.42 at. %, the direct control range of the atomic concentration of Cu is 9.58-73.15 at. %, and the atomic concentration of Pt and Cu is from the bottom layer to the surface of the film. The uniform gradient gradually increases or decreases; ICP-AES is used to quantitatively test the content of active metals Pt and Cu in the catalyst. The test results show that the content of Pt on the graphite fiber cloth of the obtained catalyst is 0.075-0.121 mg/cm ² , and the content of Cu is 0.019 ~0.074 mg/cm ² .

The test method of CV is: use the three-electrode single-sealed electrolytic cell system to test the electrochemical activity specific surface area and catalytic activity of the catalyst, wherein, the reference electrode of the three-electrode single-sealed electrolytic cell system is a saturated calomel electrode, and the counter electrode is Platinum sheet electrode; the polytetrafluoroethylene ring gasket with inner hole diameter Ф=30mm is pressed on the surface of the prepared carbon-supported PtCu alloy catalyst with nanoporous structure, and the other side of the graphite fiber cloth without PtCu alloy catalyst is pressed on On the glassy carbon electrode with Ф=40mm, tighten the PTFE screw fastening cover with inner hole diameter Ф=40mm, and put the PTFE screw fastening cover, PTFE ring gasket, carbon-loaded PtCu The alloy catalyst and the glassy carbon electrode are tightly pressed to form the working electrode, and the reaction area of the working electrode can be accurately calculated through the diameter of the inner hole of the polytetrafluoroethylene ring gasket to be 706.5mm ² ; the electrolyte used in the CV test process has a concentration of 0.50mol/L H ₂ SO ₄ solution, the three-electrode single-sealed electrolytic cell system is equipped with an inlet pipe and an outlet pipe, and the detection instrument is CHI660D electrochemical workstation.

Before the CV test, the glassy carbon electrode and the platinum sheet electrode need to be pretreated to remove oxides, oil stains and adsorbates on the surface of the glassy carbon electrode and the platinum sheet electrode to improve the sensitivity and stability of the electrode. The pretreatment method: The glassy carbon electrode and the platinum sheet electrode are firstly polished step by step with 1#~7# metallographic sandpaper; then polished to the mirror surface on the suede with 1.0 and 0.3μm Al ₂ O ₃ slurry in turn, and moved into an ultrasonic water bath after each polishing Cleaning in medium for 3min; followed by ultrasonic cleaning with 1.0mol/L HNO ₃ solution, deionized water and analytical pure ethanol for 3min respectively; finally the glassy carbon electrode and platinum sheet electrode were cleaned in 0.5mol/L _H2 The CV method is used for activation in SO ₄ solution, the scanning range is -1.5 ~ 1.5V, and the scanning is repeated until a stable cyclic voltammogram is reached.

Before the CV test, high-purity N ₂ with a flow rate of 1.0L/min needs to be passed into the electrolyte for 15 minutes, where the purity of N ₂ is ≥99.99%, to remove dissolved oxygen in the electrolyte; the CV scanning range is -0.3～1.2V (relative to saturated calomel electrode), the potential scanning rate is 50mV/s; in the CV curve, the peak near -0.2V is the oxidation desorption peak of hydrogen, and the integral area of this peak directly reflects the surface activity reaction The number of bits, its size represents the amount of electricity involved in the oxidation reaction; according to the integrated area of the hydrogen oxidation desorption peak in the CV curve of the catalyst, the specific surface area of electrochemical activity per unit mass of Pt can be obtained, see formula (1):

(1)

In the formula: ESA is the specific surface area of electrochemical activity per unit mass of Pt, S is the integrated area of the oxidation-desorption peak of hydrogen, m is the Pt content on the ^1cm2 working electrode, ν is the scan rate, C is the unit adsorption of Pt to hydrogen Capacitance (0.21mC/cm ² ).

The test method of LSV is as follows: the test device and process are the same as the CV method, the difference is that a linear potential is applied between the working electrode and the counter electrode, that is, the relationship between the potential and time is linear, and the measured and obtained current of the working electrode varies with The curve of the electrode potential change, that is, the LSV curve, can intuitively characterize the hydrogen evolution catalytic activity of the catalyst as the cathode; the LSV scanning range takes the LSV curve of -0.40~-0.28V (relative to the saturated calomel electrode) in the non-overlapping area of the cathode area, and the potential The scan rate is 50mV/s; the exchange current density of the working electrode is calculated according to the LSV data and formula (2), that is, the reaction speed of the working electrode when the overpotential is at 0, which can quantitatively describe the ability of the working electrode to transmit the redox reaction current. The higher the current density, the higher the catalyst activity.

definition:

Transform according to the logarithmic bottom conversion formula:

(2)

In the formula: z is the charge number; F is the Faraday constant; R is the gas constant; T is the electrode reaction temperature; K is a constant; △ E is the overpotential; i ₀ is the exchange current density.

Beneficial effect and advantage of the present invention are:

(1) The present invention adopts conventional ion beam sputtering, two-way moving target stage and Pt, Cu splicing target and vacuum heat treatment method to directly prepare carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient on graphite fiber cloth;

(2) The present invention uses a two-step method, that is, first prepares a carbon-supported catalyst film, and regulates the atomic concentration of Pt from the bottom layer of the film to the surface through the moving speed of the target stage and the time of ion beam sputtering, and then heat-treats it in a vacuum. Cooling to room temperature to make a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient, and the catalyst can be directly used as an electrode for the coupling process of water electrolysis-organic electrocatalytic reduction;

(3) The present invention directly deposits active metal components on the clean and activated surface of graphite fiber cloth cleaned by ion beam sputtering, which enhances the bonding strength of catalyst active metals and graphite fiber cloth, and improves the catalytic performance of the catalyst. Stability, at the same time, the film layer structure with a uniform gradient change in the concentration of active metal atoms from the bottom layer of the film to the surface greatly improves the ESA value of the catalyst to enhance its electrocatalytic activity;

(4) The present invention has the characteristics of short preparation process, low cost, and no intermediate reactant pollution. The prepared carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient has the advantages of low Pt content and good electrochemical activity, which will promote Development of water electrolysis-organic electrocatalytic reduction coupling technology.

Description of drawings

Figure 1 is a schematic diagram of the moving direction of the target stage and the seam line of Pt and Cu on the splicing target;

Fig. 2 is the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient prepared in Example 3 and Example 5. The thickness of the procatalyst film is 1 S , and the value of S is in the range of 30 to 50 nm, which is thinned by online etching. To 0.33 (0.33 S ), 0.66 (0.66 S ) of the original film thickness and the interface between the film and graphite fiber cloth (0 S ), according to the Pt at 0 S , 0.33 S , 0.66 S and the film surface (1 S Gradient overlay diagram formed by connecting the atomic concentration values of ;

Fig. 3 is the XRD overlay pattern (30) of the carbon-supported PtCu alloy catalyst with uniform active metal atomic concentration prepared in comparative example and the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient prepared in Example 1, Example 3 and Example 5 ° ≤2θ≤90 °), wherein a, b, c and d represent the XRD patterns of Comparative Example, Example 1, Example 3 and Example 5 respectively;

Fig. 4 is the CV of the carbon-supported PtCu alloy catalyst with uniform active metal atomic concentration prepared in comparative example and the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient prepared in Example 1, Example 3, Example 4 and Example 5 Curve comparison diagram, wherein a, b, c, d and e represent the CV curve of comparative example, embodiment 1, embodiment 3, embodiment 4 and embodiment 5 respectively;

Fig. 5 is the cathode of the carbon-supported PtCu alloy catalyst with uniform active metal atomic concentration prepared in comparative example and the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient prepared in Example 1, Example 2, Example 3 and Example 5 Area LSV curve comparison diagram, wherein a, b, c, d and e represent the cathode area LSV curves of Comparative Example, Example 1, Example 3, Example 4 and Example 5, respectively.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the content described.

comparative example

The catalyst described in this comparative example is that the active metal component is supported on a single face of graphite fiber cloth to form a carbon-supported PtCu alloy catalyst with uniform active metal atomic concentration, and the preparation method of the catalyst specifically includes the following steps:

A． Arrange graphite fibers with a size of 80×80mm ² and a surface density of 0.20g/cm ² in a vacuum of 8×10 ^-3 Pa, control the screen level voltage of the ion beam-assisted cleaning source to 0.7kV, and the beam current to 705mA, And pass into the high-purity Ar of 7.0sccm flow rate, wherein the purity of Ar is more than or equal to 99.999%, carry out ion beam assisted cleaning to the graphite fiber cloth surface after 6min and obtain the pretreated graphite fiber cloth;

B． Arrange the pretreated graphite fiber obtained in step A in a vacuum of 8×10 ^-3 Pa, control the screen level voltage of the ion beam sputtering source to 3.5kV, the beam current to 80mA, and pass high-purity Ar at a flow rate of 8.0sccm , where the purity of Ar is ≥99.999%, and the extracted Ar ion beam bombards the spliced Pt and Cu targets placed on the moving target platform, where the Pt target and the Cu target are each a piece, both of which are in the shape of a plane rectangle, and form a plane square shape after splicing The sputtering target material, the purity of Pt and Cu are both ≥ 99.95%; then keep the target stage without moving, the Pt and Cu particles sputtered out of the Pt and Cu splicing target are deposited on the single surface of the graphite fiber cloth to form a catalyst film to control the ion The beam sputtering time is 10min, combined with the film thickness display value of the film thickness online detector, the catalyst film thickness value is controlled at 48nm;

C． The carbon-supported catalyst film obtained in step B was placed in a vacuum of 8×10 ^-3 Pa, heated to 400°C and kept for 1.0h, and then naturally cooled to room temperature to obtain a carbon-supported PtCu alloy catalyst with uniform concentration of active metal atoms.

The prepared carbon-supported PtCu alloy catalyst with uniform active metal atomic concentration was cut into four samples of 40×40mm ² , and XRD, CV and LSV, XPS and ICP-AES were used to investigate the phase structure and electrochemical activity respectively. The specific surface area and catalyst activity, the atomic concentration characterization of Pt on the catalyst surface, and the quantitative test of the Pt content in the catalyst.

Result: The thickness of the carbon-supported PtCu alloy film catalyst obtained in this comparative example is 48nm; there are PtCu ₃ (111) and Cu (111) phases; the ESA value is 21.7723m ² /g; the i ₀ value is 3.320mA/cm ² ; The atomic concentration of Pt on the surface of the catalyst is 57.31 at. %, and the atomic concentration of Cu is 42.69 at. %; the content of Pt is 0.138 mg/cm ² , and the content of Cu is 0.043 mg/cm ² .

Example 1

The catalyst described in this example uses graphite fiber cloth as a carbonaceous carrier, and Pt and Cu particles are directly loaded on a single surface of the graphite fiber cloth to form a thin film catalyst. The atomic concentration gradient of the active components Pt and Cu is directly regulated by the moving speed of the target stage , within the moving speed range of the target stage, the stable moving target stage speed makes the atomic concentration of Pt and Cu change in a uniform gradient from the bottom layer to the surface of the film.

The catalyst described in this embodiment is a carbon-supported PtCu alloy catalyst with a controllable atomic concentration gradient obtained by loading an active metal component on a single surface of a graphite fiber cloth. The preparation method of the catalyst specifically includes the following steps:

A． Arrange graphite fibers with a size of 80×80mm ² and a surface density of 0.20g/cm ² in a vacuum of 9×10 ^-3 Pa, control the screen level voltage of the ion beam-assisted cleaning source to 0.6kV, and the beam current to 65mA, And pass into the high-purity Ar of 6.5 sccm flow rate, wherein the purity of Ar is more than or equal to 99.999%, carry out ion beam assisted cleaning to the graphite fiber cloth surface after 5min and obtain the pretreated graphite fiber cloth;

B． Arrange the pretreated graphite fiber obtained in step A in a vacuum of 9×10 ^-3 Pa, control the screen level voltage of the ion beam sputtering source to 3.3kV, the beam current to 70mA, and pass high-purity Ar at a flow rate of 7.5sccm , wherein the purity of Ar is ≥99.999%, and the extracted Ar ion beam bombards the Pt and Cu splicing targets placed on the moving target platform, wherein the Pt target and the Cu target are each a piece, and after splicing, a planar square sputtering target is formed. The purity of Pt and Cu are both ≥99.95%; then keep the moving direction of the target stage perpendicular to the seam line of Pt and Cu on the splicing target, and the incident direction of the ion beam is perpendicular to the moving direction of the target stage and the seam of Pt and Cu on the splicing target The angle between the lines is 45°, and the moving speed of the target stage is adjusted to 10mm/min. The Pt and Cu particles sputtered out of the Pt and Cu splicing targets are deposited on the single surface of the graphite fiber cloth to form a catalyst film, and the ion beam sputtering time is controlled to 5min. , combined with the film thickness display value of the film thickness online detector, the catalyst film thickness value is controlled at 30nm, as shown in Figure 1;

C． The carbon-supported catalyst film obtained in step B was placed in a vacuum of 9×10 ^-3 Pa, heated to 350°C and kept for 2.0 hours, and cooled to room temperature naturally to obtain a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient.

The prepared carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient was cut into four samples of 40×40mm ² , and XRD, CV and LSV, XPS and ICP-AES were used to investigate the phase structure and electrochemical activity respectively. Specific surface area and catalyst activity, change characterization of Pt atomic concentration from the bottom layer to the surface of the catalyst film, and quantitative test of Pt content in the catalyst.

Results: The carbon-supported PtCu alloy thin film catalyst with controllable atomic concentration gradient obtained in this example has a thickness of 30nm; there are PtCu ₃ (111), PtCu(111) and Pt(111) phases; the ESA value is 37.6731m ² /g ; The value of i ₀ is 4.104mA/cm ² ; the atomic concentrations of Pt at 0 S , 0.33 S , 0.66 S and 1 S are 20.61 at. %, 42.23 at. %, 63.85 at. % and 85.47 at. %; Pt The content is 0.078mg/cm ² ; the atomic concentrations of Cu at 0 S , 0.33 S , 0.66 S and 1 S are 79.39 at. %, 57.77 at. %, 36.15 at. % and 14.53 at. %; the Cu content is 0.055 mg/cm ² .

Example 2

The catalyst described in this example uses graphite fiber cloth as a carbonaceous carrier, and Pt and Cu particles are directly loaded on a single surface of the graphite fiber cloth to form a thin film catalyst. The atomic concentration gradient of the active components Pt and Cu is directly regulated by the moving speed of the target stage , within the moving speed range of the target stage, the stable moving target stage speed makes the atomic concentration of Pt and Cu change in a uniform gradient from the bottom layer to the surface of the film.

The catalyst described in this embodiment is a carbon-supported PtCu alloy catalyst with a controllable atomic concentration gradient obtained by loading an active metal component on a single surface of a graphite fiber cloth. The preparation method of the catalyst specifically includes the following steps:

A． Arrange graphite fibers with a size of 80×80mm ² and a surface density of 0.35g/cm ² in a vacuum of 7×10 ^-3 Pa, control the screen level voltage of the ion beam-assisted cleaning source to 0.8kV, and the beam current to 75mA, And pass into the high-purity Ar of 7.5sccm flow rate, wherein the purity of Ar is more than or equal to 99.999%, carry out ion beam auxiliary cleaning to the graphite fiber cloth surface after 7min and obtain the pretreated graphite fiber cloth;

B． Arrange the pretreated graphite fiber obtained in step A in a vacuum of 7×10 ^-3 Pa, control the screen level voltage of the ion beam sputtering source to 3.6kV, the beam current to 90mA, and pass high-purity Ar at a flow rate of 8.5sccm , where the purity of Ar is ≥99.999%, and the extracted Ar ion beam bombards the spliced Pt and Cu targets placed on the moving target platform, where the Pt target and the Cu target are each a piece, both of which are in the shape of a plane rectangle, and form a plane square shape after splicing The sputtering target material, the purity of Pt and Cu are both ≥99.95%; then keep the moving direction of the target stage perpendicular to the seam line of Pt and Cu on the splicing target, and the incident direction of the ion beam is perpendicular to the moving direction of the target stage and aligned with the splicing target. The angle between the seam line between Pt and Cu is 45°, and the moving speed of the target stage is adjusted to 5mm/min. The sputtered Pt and Cu particles of the Pt and Cu splicing targets are deposited on the single surface of the graphite fiber cloth to form a catalyst film to control ions. The beam sputtering time is 10min, combined with the film thickness display value of the film thickness online detector, the catalyst film thickness value is controlled at 50nm;

C． The carbon-supported catalyst film obtained in step B was placed in a vacuum of 7×10 ^-3 Pa, heated to 450°C and kept for 1.0 h, and cooled to room temperature naturally to obtain a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient.

The prepared carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient was cut into four samples of 40×40mm ² , and XRD, CV and LSV, XPS and ICP-AES were used to investigate the phase structure and electrochemical activity respectively. Specific surface area and catalyst activity, change characterization of Pt atomic concentration from the bottom layer to the surface of the catalyst film, and quantitative test of Pt content in the catalyst.

Results: The carbon-supported PtCu alloy thin film catalyst with controllable atomic concentration gradient obtained in this example has a thickness of 50nm; there are PtCu ₃ (111), PtCu(111) and Pt(111) phases; the ESA value is 47.3219m ² /g ; i ₀ value is 3.498mA/cm ² ; the atomic concentrations of Pt at 0 S , 0.33 S , 0.66 S and 1 S are 46.81 at. %, 54.13 at. %, 61.45 at. % and 68.78 at. %; Pt The content is 0.121mg/cm ² ; the atomic concentrations of Cu at 0 S , 0.33 S , 0.66 S and 1 S are 53.19 at. %, 45.87 at. %, 38.55 at. % and 31.22 at. %; the Cu content is 0.074 mg/cm ² .

Example 3

The catalyst described in this example uses graphite fiber cloth as a carbonaceous carrier, and Pt and Cu particles are directly loaded on a single surface of the graphite fiber cloth to form a thin film catalyst. The atomic concentration gradient of the active components Pt and Cu is directly regulated by the moving speed of the target stage , within the moving speed range of the target stage, the stable moving target stage speed makes the atomic concentration of Pt and Cu change in a uniform gradient from the bottom layer to the surface of the film.

The catalyst described in this embodiment is a carbon-supported PtCu alloy catalyst with a controllable atomic concentration gradient obtained by loading an active metal component on a single surface of a graphite fiber cloth. The preparation method of the catalyst specifically includes the following steps:

A． Arrange graphite fibers with a size of 80×80mm ² and a surface density of 0.20g/cm ² in a vacuum of 8×10 ^-3 Pa, control the screen level voltage of the ion beam-assisted cleaning source to 0.7kV, and the beam current to 70mA, And pass into the high-purity Ar of 7.0sccm flow rate, wherein the purity of Ar is more than or equal to 99.999%, carry out ion beam assisted cleaning to the graphite fiber cloth surface after 6min and obtain the pretreated graphite fiber cloth;

B． Arrange the pretreated graphite fiber obtained in step A in a vacuum of 8×10 ^-3 Pa, control the screen level voltage of the ion beam sputtering source to 3.5kV, the beam current to 80mA, and pass high-purity Ar at a flow rate of 8.0sccm , where the purity of Ar is ≥99.999%, and the extracted Ar ion beam bombards the spliced Pt and Cu targets placed on the moving target platform, where the Pt target and the Cu target are each a piece, both of which are in the shape of a plane rectangle, and form a plane square shape after splicing The sputtering target material, the purity of Pt and Cu are both ≥99.95%; then keep the moving direction of the target stage perpendicular to the seam line of Pt and Cu on the splicing target, and the incident direction of the ion beam is perpendicular to the moving direction of the target stage and aligned with the splicing target. The angle between the seam line between Pt and Cu is 45°, and the moving speed of the target stage is adjusted to 9mm/min. The sputtered Pt and Cu particles of the Pt and Cu splicing targets are deposited on the single surface of the graphite fiber cloth to form a catalyst film to control ions. The beam sputtering time is 6 minutes, combined with the film thickness display value of the film thickness online detector, the catalyst film thickness value is controlled at 32nm;

C． The carbon-supported catalyst film obtained in step B was placed in a vacuum of 8×10 ^-3 Pa, heated to 400°C and kept for 1.0h, and cooled to room temperature naturally to obtain a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient.

The prepared carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient was cut into four samples of 40×40mm ² , and XRD, CV and LSV, XPS and ICP-AES were used to investigate the phase structure and electrochemical activity respectively. Specific surface area and catalyst activity, change characterization of Pt atomic concentration from the bottom layer to the surface of the catalyst film, and quantitative test of Pt content in the catalyst.

Results: The carbon-supported PtCu alloy thin film catalyst with controllable atomic concentration gradient obtained in this example has a thickness of 32nm; there are PtCu ₃ (111), PtCu(111) and Pt(111) phases; the ESA value is 86.0875m ² /g ; i ₀ value is 4.218 mA/cm ² ; the atomic concentrations of Pt at 0 S , 0.33 S , 0.66 S and 1 S are 26.85 at. %, 46.83 at. %, 66.86 at. % and 86.84 at. %; Pt The content is 0.075mg/cm ² ; the atomic concentrations of Cu at 0 S , 0.33 S , 0.66 S and 1 S are 73.15 at. %, 53.17 at. %, 33.14 at. % and 13.16 at. %; the Cu content is 0.019 mg/cm ² .

Example 4

The catalyst described in this example uses graphite fiber cloth as a carbonaceous carrier, and Pt and Cu particles are directly loaded on a single surface of the graphite fiber cloth to form a thin film catalyst. The atomic concentration gradient of the active components Pt and Cu is directly regulated by the moving speed of the target stage , within the moving speed range of the target stage, the stable moving target stage speed makes the atomic concentration of Pt and Cu change in a uniform gradient from the bottom layer to the surface of the film.

The catalyst described in this embodiment is a carbon-supported PtCu alloy catalyst with a controllable atomic concentration gradient obtained by loading an active metal component on a single surface of a graphite fiber cloth. The preparation method of the catalyst specifically includes the following steps:

A． Arrange graphite fibers with a size of 80×80mm ² and a surface density of 0.28g/cm ² in a vacuum of 7.5×10 ^-3 Pa, control the screen-level voltage of the ion beam-assisted cleaning source to 0.6kV, and the beam current to 75mA, And pass into the high-purity Ar of 7.5sccm flow rate, wherein the purity of Ar is more than or equal to 99.999%, carry out ion beam assisted cleaning to the graphite fiber cloth surface after 5min and obtain the pretreated graphite fiber cloth;

B． Arrange the pretreated graphite fiber obtained in step A in a vacuum of 8.5×10 ^-3 Pa, control the screen level voltage of the ion beam sputtering source to 3.3kV, the beam current to 70mA, and pass high-purity Ar at a flow rate of 7.5sccm , where the purity of Ar is ≥99.999%, and the extracted Ar ion beam bombards the spliced Pt and Cu targets placed on the moving target platform, where the Pt target and the Cu target are each a piece, both of which are in the shape of a plane rectangle, and form a plane square shape after splicing The sputtering target material, the purity of Pt and Cu are both ≥99.95%; then keep the moving direction of the target stage perpendicular to the seam line of Pt and Cu on the splicing target. The angle between the seam line and Cu is 45°, and the moving speed of the target stage is adjusted to 6mm/min. The sputtered Pt and Cu particles of the Pt and Cu splicing targets are deposited on the single surface of the graphite fiber cloth to form a catalyst film to control the ion beam. The sputtering time is 9 minutes, combined with the film thickness display value of the film thickness online detector, the thickness of the catalyst film is controlled at 44nm;

C． The carbon-supported catalyst thin film obtained in step B was placed in a vacuum of 8×10 ^-3 Pa, heated to 350°C and kept for 1.5h, and cooled to room temperature naturally to obtain a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient.

The prepared carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient was cut into four samples of 40×40mm ² , and XRD, CV and LSV, XPS and ICP-AES were used to investigate the phase structure and electrochemical activity respectively. Specific surface area and catalyst activity, change characterization of Pt atomic concentration from the bottom layer to the surface of the catalyst film, and quantitative test of Pt content in the catalyst.

Results: The carbon-supported PtCu alloy thin film catalyst with controllable atomic concentration gradient obtained in this example has a thickness of 44nm; there are PtCu ₃ (111), PtCu(111) and Pt(111) phases; the ESA value is 69.3971m ² /g ; i ₀ value is 3.635mA/cm ² ; the atomic concentrations of Pt at 0 S , 0.33 S , 0.66 S and 1 S are 41.24 at. %, 52.44 at. %, 63.64 at. % and 74.84 at. %; Pt The content is 0.119mg/cm ² ; the atomic concentrations of Cu at 0 S , 0.33 S , 0.66 S and 1 S are 58.76 at. %, 47.56 at. %, 36.36 at. % and 25.16 at. %; the Cu content is 0.031 mg/cm ² .

Example 5

The catalyst described in this example uses graphite fiber cloth as a carbonaceous carrier, and Pt and Cu particles are directly loaded on a single surface of the graphite fiber cloth to form a thin film catalyst. The atomic concentration gradient of the active components Pt and Cu is directly regulated by the moving speed of the target stage , within the moving speed range of the target stage, the stable moving target stage speed makes the atomic concentration of Pt and Cu change in a uniform gradient from the bottom layer to the surface of the film.

The catalyst described in this embodiment is a carbon-supported PtCu alloy catalyst with a controllable atomic concentration gradient obtained by loading an active metal component on a single surface of a graphite fiber cloth. The preparation method of the catalyst specifically includes the following steps:

A． Arrange graphite fibers with a size of 80×80mm ² and a surface density of 0.20g/cm ² in a vacuum of 8.5×10 ^-3 Pa, control the screen-level voltage of the ion beam-assisted cleaning source to 0.8kV, and the beam current to 65mA, And pass into the high-purity Ar of 7.0sccm flow rate, wherein the purity of Ar is more than or equal to 99.999%, carry out ion beam assisted cleaning to the graphite fiber cloth surface and obtain the pretreated graphite fiber cloth after 7min;

B． Arrange the pretreated graphite fiber obtained in step A in a vacuum of 7.5×10 ^-3 Pa, control the screen level voltage of the ion beam sputtering source to 3.6kV, the beam current to 90mA, and pass high-purity Ar at a flow rate of 8.5sccm , where the purity of Ar is ≥99.999%, and the extracted Ar ion beam bombards the spliced Pt and Cu targets placed on the moving target platform, where the Pt target and the Cu target are each a piece, both of which are in the shape of a plane rectangle, and form a plane square shape after splicing The sputtering target material, the purity of Pt and Cu are both ≥99.95%; then keep the moving direction of the target stage perpendicular to the seam line of Pt and Cu on the splicing target, and the incident direction of the ion beam is perpendicular to the moving direction of the target stage and aligned with the splicing target. The angle between the seam line between Pt and Cu is 45°, and the moving speed of the target stage is adjusted to 7mm/min. The sputtered Pt and Cu particles of the Pt and Cu splicing targets are deposited on the single surface of the graphite fiber cloth to form a catalyst film to control ions. The beam sputtering time is 8 minutes, combined with the film thickness display value of the film thickness online detector, the catalyst film thickness value is controlled at 41nm;

C． The carbon-supported catalyst film obtained in step B was placed in a vacuum of 7×10 ^-3 Pa, heated to 400°C and kept for 1.5 hours, and cooled to room temperature naturally to obtain a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient.

The prepared carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient was cut into four samples of 40×40mm ² , and XRD, CV and LSV, XPS and ICP-AES were used to investigate the phase structure and electrochemical activity respectively. Specific surface area and catalyst activity, change characterization of Pt atomic concentration from the bottom layer to the surface of the catalyst film, and quantitative test of Pt content in the catalyst.

Results: The carbon-supported PtCu alloy thin film catalyst with controllable atomic concentration gradient obtained in this example has a thickness of 41nm; there are PtCu ₃ (111), PtCu(111) and Pt(111) phases; the ESA value is 42.5129m ² /g ; i ₀ value is 3.677mA/cm ² ; the atomic concentrations of Pt at 0 S , 0.33 S , 0.66 S and 1 S are 39.43 at. %, 56.41 at. %, 73.39 at. % and 90.42 at. %; Pt The content is 0.107mg/cm ² ; the atomic concentrations of Cu at 0 S , 0.33 S , 0.66 S and 1 S are 60.57 at. %, 43.58 at. %, 26.61 at. % and 9.58 at. %; the Cu content is 0.023 mg/cm ² .

Example 6

The catalyst described in this example uses graphite fiber cloth as a carbonaceous carrier, and Pt and Cu particles are directly loaded on a single surface of the graphite fiber cloth to form a thin film catalyst. The atomic concentration gradient of the active components Pt and Cu is directly regulated by the moving speed of the target stage , within the moving speed range of the target stage, the stable moving target stage speed makes the atomic concentration of Pt and Cu change in a uniform gradient from the bottom layer to the surface of the film.

The catalyst described in this embodiment is a carbon-supported PtCu alloy catalyst with a controllable atomic concentration gradient obtained by loading an active metal component on a single surface of a graphite fiber cloth. The preparation method of the catalyst specifically includes the following steps:

A． Arrange graphite fibers with a size of 80×80mm ² and a surface density of 0.35g/cm ² in a vacuum of 8×10 ^-3 Pa, control the screen level voltage of the ion beam-assisted cleaning source to 0.6kV, and the beam current to 75mA, And pass into the high-purity Ar of 7.5sccm flow rate, wherein the purity of Ar is more than or equal to 99.999%, carry out ion beam assisted cleaning to the graphite fiber cloth surface after 5min and obtain the pretreated graphite fiber cloth;

B． Arrange the pretreated graphite fiber obtained in step A in a vacuum of 8×10 ^-3 Pa, control the screen level voltage of the ion beam sputtering source to 3.5kV, the beam current to 85mA, and pass high-purity Ar at a flow rate of 8.0sccm , where the purity of Ar is ≥99.999%, and the extracted Ar ion beam bombards the spliced Pt and Cu targets placed on the moving target platform, where the Pt target and the Cu target are each a piece, both of which are in the shape of a plane rectangle, and form a plane square shape after splicing The sputtering target material, the purity of Pt and Cu are both ≥99.95%; then keep the moving direction of the target stage perpendicular to the seam line of Pt and Cu on the splicing target, and the incident direction of the ion beam is perpendicular to the moving direction of the target stage and aligned with the splicing target. The angle between the seam line between Pt and Cu is 45°, and the moving speed of the target stage is adjusted to 8mm/min. The sputtered Pt and Cu particles of the Pt and Cu splicing targets are deposited on the single surface of the graphite fiber cloth to form a catalyst film to control ions. The beam sputtering time is 7 minutes, combined with the film thickness display value of the film thickness online detector, the catalyst film thickness value is controlled at 39nm;

C． The carbon-supported catalyst film obtained in step B was placed in a vacuum of 8×10 ^-3 Pa, heated to 450°C and kept for 1.5h, and cooled to room temperature naturally to obtain a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient.

The prepared carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient was cut into four samples of 40×40mm ² , and XRD, CV and LSV, XPS and ICP-AES were used to investigate the phase structure and electrochemical activity respectively. Specific surface area and catalyst activity, change characterization of Pt atomic concentration from the bottom layer to the surface of the catalyst film, and quantitative test of Pt content in the catalyst.

Results: The carbon-supported PtCu alloy thin film catalyst with controllable atomic concentration gradient obtained in this example has a thickness of 39nm; there are PtCu ₃ (111), PtCu(111) and Pt(111) phases; the ESA value is 47.3219m ² /g ; i ₀ value is 3.901mA/cm ² ; the atomic concentrations of Pt at 0 S , 0.33 S , 0.66 S and 1 S are 33.17 at. %, 51.45 at. %, 69.73 at. % and 88.02 at. %; Pt The content is 0.092mg/cm ² ; the atomic concentrations of Cu at 0 S , 0.33 S , 0.66 S and 1 S are 66.83 at. %, 48.55 at. %, 30.27 at. % and 11.98 at. %; the Cu content is 0.020 mg/cm ² .

The details of Figures 1 to 5 are as follows:

Figure 1 is a schematic diagram of the moving direction of the target stage and the seam line of Pt and Cu on the splicing target, wherein the moving direction of the target stage is perpendicular to the seam line of Pt and Cu on the splicing target, and the incident direction of the ion beam is perpendicular to the moving direction of the target stage and is in line with The angle between the seam line of Pt and Cu on the splicing target is 45°;

Figure 2 is the gradient superposition formed by connecting the atomic concentration values of Pt at 0 S , 0.33 S , 0.66 S and 1 S in the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient prepared in Example 3 and Example 5 Figure: The atomic concentration gradient in the catalyst prepared by the present invention is uniform and linear, and the atomic concentration gradient value can also be adjusted; (the abscissa has been added in Figure 2)

Fig. 3 is the XRD overlay pattern (30) of the carbon-supported PtCu alloy catalyst with uniform active metal atomic concentration prepared in comparative example and the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient prepared in Example 1, Example 3 and Example 5 °≤2 θ≤90 °), where a, b, c and d represent the XRD patterns of Comparative Example, Example 1, Example 3 and Example 5 respectively; After the influence of diffraction peaks, there are PtCu ₃ (111) and Cu(111) phases in a, and PtCu ₃ (111), PtCu(111) and Pt(111) phases in b, c and d, indicating that the catalyst directly Loaded on the surface of clean graphite fiber cloth, there is no pollution of intermediate reactants, and as the moving speed of the target stage changes, the characteristic diffraction peak intensity of each phase changes, that is, the content of each phase changes;

Fig. 4 is the CV of the carbon-supported PtCu alloy catalyst with uniform active metal atomic concentration prepared in comparative example and the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient prepared in Example 1, Example 3, Example 4 and Example 5 Curve comparison chart, wherein a, b, c, d and e represent the CV curves of comparative example, embodiment 1, embodiment 3, embodiment 4 and embodiment 5 respectively; it can be calculated by formula (1), and the comparative implementation Example, Example 1, Example 3, Example 4 and the ESA values of the catalysts prepared in Example 5 are 21.7723m ² /g, 37.6731m ² /g, 86.0875m ² /g, 69.3971m ² /g and 42.5129 m ² /g, the catalyst prepared by the present invention can reduce the content of Pt and significantly increase the ESA value, thereby enhancing its electrocatalytic activity;

Fig. 5 is the cathode of the carbon-supported PtCu alloy catalyst with uniform active metal atomic concentration prepared in comparative example and the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient prepared in Example 1, Example 2, Example 3 and Example 6 District LSV curve comparison diagram, wherein a, b, c, d and e represent respectively the cathode region LSV curve of comparative example, embodiment 1, embodiment 2, embodiment 3 and embodiment 6; As can be seen, five kinds of catalysts The LSV graphs in the cathode region of the cathode region are basically the same, and its value is negative; at the same potential, the absolute value of the current density value of the catalyst prepared in Example 3 is the largest, and the catalytic activity is the best. Utilize formula (2) to calculate the comparative example, implementation The i ₀ values of the catalysts prepared in Example 1, Example 2, Example 3 and Example 6 are 3.320mA/cm ² , 4.104mA/cm ² , 3.498mA/cm ² , 4.218mA/cm ² and 3.901mA/cm 2 cm ² , indicating that the atomic concentration gradient regulated structure prepared by the present invention can significantly enhance the catalytic activity of the catalyst.

Claims (5)

1. A carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient is characterized in that: the catalyst is a carbonaceous carrier with graphite fiber cloth, and Pt and Cu particles are directly loaded on the graphite fiber cloth single side to form a thin film catalyst, and the thin film The thickness of the catalyst is 30-50nm, the content of Pt in the catalyst is 0.075-0.121 mg/cm ² , and the content of Cu is 0.019-0.074 mg/cm ² . 2. the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient according to claim 1, characterized in that: the atomic concentration of active components Pt and Cu in the catalyst is a uniform gradient change from the bottom layer of the film to the surface, wherein Pt The atomic concentration of Cu is 26.85~90.42 at. %, and the atomic concentration of Cu is 9.58~73.15 at. %. 3 . The carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient according to claim 1 , characterized in that: the graphite fiber cloth is plain acrylonitrile graphite fiber cloth with an areal density of 0.20-0.35 g/cm ² . 4. the preparation method of the carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient of claim 1 is characterized in that, specifically comprises the following steps: (1) Arrange the graphite fibers in a vacuum of 7×10 ^-3 ~ 9×10 ^-3 Pa, control the screen level voltage of the ion beam assisted cleaning source to 0.6 ~ 0.8kV, the beam current to 65 ~ 75mA, and feed High-purity Ar with a flow rate of 6.5-7.5 sccm, wherein the purity of Ar is ≥99.999%, and ion beam-assisted cleaning is performed on the surface of the graphite fiber cloth for 5-7 minutes to obtain the pretreated graphite fiber cloth; (2) Arrange the pretreated graphite fiber obtained in step (1) in a vacuum of 7×10 ^-3 ~ 9×10 ^-3 Pa, control the screen level voltage of the ion beam sputtering source to 3.3 ~ 3.6kV, the beam current 70-90mA, and feed high-purity Ar with a flow rate of 7.5-8.5sccm, where the purity of Ar is ≥99.999%, and the extracted Ar ion beam bombards the Pt and Cu splicing targets placed on the moving target platform; then keep the target platform moving The direction is perpendicular to the seam line of Pt and Cu on the splicing target, and the moving speed of the target stage is adjusted to 5-10mm/min. The Pt and Cu particles sputtered by the Pt and Cu splicing targets are deposited on the single surface of the graphite fiber cloth to form a catalyst film. The ion beam sputtering time is 5 to 10 minutes, and the thickness of the catalyst film is 30 to 50 nm; (3) Place the carbon-supported catalyst thin film obtained in step (2) in a vacuum of 7×10 ^-3 to 9×10 ^-3 Pa, heat to 350-450°C and keep it warm for 1.0-2.0h, and cool to room temperature naturally That is, a carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient is obtained. 5. The preparation method of carbon-supported PtCu alloy catalyst with controllable atomic concentration gradient according to claim 4, characterized in that: the Pt and Cu splicing target described in step (2) is composed of a Pt target and a Cu After splicing the targets, a square-shaped sputtering target is formed, and the purity of Pt and Cu are both ≥99.95%.