Amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction and preparation method

Abstract

The invention belongs to the technical field of amorphous / crystalline heterojunction catalysts, and discloses an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction and a preparation method thereof, the preparation method comprises the following steps: S1, selecting foamed nickel as a substrate, and performing pretreatment; s2, preparing a high-purity Ni target and a high-purity Zr target as magnetron sputtering target materials for later use; s3, the foamed nickel substrate pretreated in the step S1 is installed on a substrate table of magnetron sputtering equipment, then the Ni target and the Zr target in the step S2 are installed in a target seat of a magnetron sputtering coating machine, a cavity is vacuumized, and argon is introduced to enable the pressure in the magnetron sputtering coating machine to be stabilized at the working pressure; s4, sputtering a Ni target and a Zr target by using direct current to obtain an amorphous / crystalline heterojunction NiZr oxide catalyst; the amorphous / crystalline heterojunction catalyst is prepared by using a magnetron sputtering method, so that the activity of the HER catalyst is improved, and the preparation method is simple and convenient to operate.

Description

Technical Field

[0001] The invention relates to the technical field of amorphous / crystalline heterojunction catalysts, and in particular to an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction and a preparation method thereof. Background Art

[0002] Hydrogen has the advantages of high abundance, high mass energy density, and clean combustion products. At present, more than 90% of hydrogen is produced by hydrocarbon reforming, pyrolysis and gasification, in which CO2 emissions are inevitable.

[0003] Compared with these traditional methods, electrochemical water splitting is one of the simplest methods for preparing green hydrogen. Platinum group metals can be used as hydrogen evolution reaction (HER) catalysts in acidic electrolytes due to their moderate hydrogen adsorption energy. However, their high cost and scarcity limit their large-scale application. In addition, in alkaline electrolytes, the HER activity decreases by 2-3 orders of magnitude due to the slow water dissociation process. Therefore, designing low-cost and high-efficiency HER electrocatalysts, especially HER electrocatalysts used in alkaline media, is very important for the application of hydrogen energy. Now a series of alloys, metal oxides, nitrides, phosphides, sulfides, selenides, carbides, single atoms and synergistic mixtures have been developed as efficient catalysts, and various strategies such as alloying, phase engineering, interface engineering, and strain engineering have been proposed to improve the performance of HER catalysts. Among them, phase and interface engineering have been widely studied and proved to be effective methods. Amorphous materials show superior HER performance than crystals due to their unique atomic structure. However, their application is limited by poor intrinsic conductivity and stability.

[0004] Amorphous / crystalline heterojunction combines the advantages of amorphous and crystalline structures and becomes a potential HER catalyst. At present, the methods for preparing amorphous / crystalline heterojunction mainly include ultrafast heating, component adjustment method, partial crystallization of amorphous precursor, and pyrolysis method. However, the catalysts prepared by these preparation methods have low activity, low density and poor uniformity, and are difficult to operate and have low repeatability. Summary of the invention

[0005] The present invention aims to provide an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction and a preparation method thereof, wherein the amorphous / crystalline heterojunction catalyst is prepared by a magnetron sputtering method to improve the activity of the HER catalyst, and the preparation method is simple and convenient to operate.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction, using a magnetron sputtering device to prepare the amorphous / crystalline heterojunction catalyst a / c-Ni 0.9 Zr 0.1 O, comprising the following steps:

[0008] S1. Select nickel foam as substrate and pre-treat it: clean it with acetone and deionized water and dry it for later use;

[0009] S2. Prepare a circular or square high-purity Ni target and a high-purity Zr target for use as magnetron sputtering targets, and set aside for use;

[0010] S3, installing the nickel foam substrate pretreated in step S1 on the substrate table of the magnetron sputtering equipment, and then loading the high-purity Ni target and high-purity Zr target in step S2 into the target holder of the magnetron sputtering coating machine, evacuating the chamber, and introducing argon gas to stabilize the pressure in the magnetron sputtering coating machine at the working pressure;

[0011] S4, using DC sputtering high-purity Ni target and high-purity Zr target to obtain amorphous / crystalline heterojunction NiZr oxide catalyst a / c-Ni 0.9 Zr 0.1 O.

[0012] Furthermore, in S3, the chamber is evacuated to a base pressure of 5×10-4 Pa; and argon gas is introduced to stabilize the pressure in the magnetron sputtering coating machine at a working pressure of 3 Pa.

[0013] Furthermore, in S4, before using DC sputtering to sputter the high-purity Ni target and the high-purity Zr target, the high-purity Ni target and the high-purity Zr target are pre-sputtered for 5 minutes to remove surface contaminants.

[0014] Furthermore, in S4, the purity of the high-purity Ni target and Zr target by direct current sputtering is 99.95%, the sputtering power of the high-purity Ni target is 200 W, the sputtering power of the high-purity Zr target is 100 W, the rotation speed of the substrate is 20 rpm, and the sputtering time is 10 min.

[0015] Furthermore, in S4, the purity of the high-purity Ni target and Zr target by direct current sputtering is 99.95%, the sputtering power of the high-purity Ni target is 200 W, the sputtering power of the high-purity Zr target is 100 W, the rotation speed of the substrate is 20 rpm, and the sputtering time is 20 min.

[0016] Furthermore, in S4, the purity of the high-purity Ni target and Zr target by direct current sputtering is 99.95%, the sputtering power of the high-purity Ni target is 200 W, the sputtering power of the high-purity Zr target is 100 W, the rotation speed of the substrate is 20 rpm, and the sputtering time is 30 min.

[0017] The catalyst prepared by the above-mentioned method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction.

[0018] The beneficial effects of the technical solution are:

[0019] 1. The present invention adopts a magnetron sputtering method to prepare amorphous / crystalline heterojunction catalysts. As a green and environmentally friendly method, this method has the advantages of high product quality, good repeatability, simple operation, high purity, high density, good uniformity, and high adhesion strength; in addition, by adjusting the sputtering parameters, such as sputtering time, power, rotation speed, base pressure, and working gas pressure, the microstructure of the sputtered film and the HER catalyst performance can be precisely controlled;

[0020] 2. The present invention prepares crystalline and amorphous / crystalline heterojunction NiZr oxides by adjusting the magnetron co-sputtering time. In alkaline media, the HER catalyst performance and stability of the amorphous / crystalline heterostructure are better than those of the corresponding crystal structure, and the overpotential is lower, and the activity is higher than that of the commercial Pt / C catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of Ni target and Zr target sputtering in magnetron sputtering experiments in Examples 1 to 3 of the present invention and the comparative example;

[0022] Figure 2 is a curve diagram showing the variation of overpotential with time in Example 3 of the present invention and the comparative example;

[0023] Figure 3 The Tafel curve diagram is shown in Examples 1 to 3 of the present invention and the comparative example;

[0024] Figure 4 The SEM images and element distribution diagrams of Examples 1 to 3 and Comparative Examples of the present invention are shown in FIG.

[0025] In the figure, (a) is the cross-sectional morphology of NZ-30min, (b) is the morphology of nickel foam, (c) is the surface morphology of NZ-2min, (d) is the surface morphology of NZ-10min, (e) is the surface morphology of NZ-20min, (f) is the surface morphology of NZ-30min, (g), (h), (i) are the distribution of Ni, Zr and O elements on the surface of NZ-30min respectively;

[0026] Figure 5 TEM high-resolution images and electron diffraction patterns in Example 3 of the present invention and the comparative example;

[0027] In the figure, (a), (b), and (c) are the TEM bright field image, high resolution image, and electron diffraction pattern when the sputtering time is 2 minutes, respectively; (d), (e), and (f) are the TEM bright field image, high resolution image, and electron diffraction pattern when the sputtering time is 30 minutes, respectively. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0029] Example 1

[0030] A method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction, such as Figure 1 As shown, amorphous / crystalline heterojunction catalyst a / c-Ni was prepared using a magnetron sputtering device (model JGP-560, Sky Technology Development, Shenyang) 0.9 Zr 0.1 O, comprising the following steps:

[0031] S1. Select nickel foam as substrate and pre-treat it: clean it with acetone and deionized water and dry it for later use;

[0032] S2. Prepare a circular or square high-purity Ni target and a high-purity Zr target for use as magnetron sputtering targets, and set aside for use;

[0033] S3, the nickel foam substrate pretreated in step S1 is mounted on the substrate stage of the magnetron sputtering equipment, and the high-purity Ni target and high-purity Zr target in step S2 are loaded into the target holder of the magnetron sputtering coating machine, and the chamber is evacuated to 5×10 -4 Pa substrate pressure, and then pure argon gas is blown in to maintain a working pressure of 3 Pa in the magnetron sputtering equipment;

[0034] S4. Before using DC sputtering high-purity Ni target and high-purity Zr target, pre-sputter the high-purity Ni target and high-purity Zr target for 5 minutes to remove surface pollutants. Use DC sputtering high-purity Ni target and high-purity Zr target with a purity of 99.95%, the sputtering power of the high-purity Ni target is 200W, the sputtering power of the high-purity Zr target is 100W, the rotation speed of the substrate is 20rpm, and the sputtering time is 10min to obtain an amorphous / crystalline heterojunction NiZr oxide catalyst a / c-Ni 0.9 Zr 0.1 O.

[0035] Example 2

[0036] The difference between this embodiment and embodiment 1 is that:

[0037] In step S4, the sputtering time is 20 minutes.

[0038] Example 3

[0039] The difference between this embodiment and embodiment 1 is that:

[0040] In step S4, the sputtering time is 30 minutes.

[0041] Comparative Example:

[0042] The difference between this embodiment and embodiment 1 is that:

[0043] In step S4, the sputtering time is 2 minutes to obtain a crystalline NiZr oxide catalyst.

[0044] In Examples 1 to 3 and the comparative example, the samples with sputtering times of 2, 10, 20 and 30 min are denoted as NZ-2min, NZ-10min, NZ-20min and NZ-30min, respectively.

[0045] The amorphous / crystalline heterojunction NiZr oxide catalysts obtained in Examples 1 to 3 and the crystalline NiZr oxide obtained in the comparative example were tested for their electrochemical hydrogen evolution performance in 1M KOH solution. The test results are as follows: Figure 2-3 As shown, from Figure 2 It can be seen that with the increase of sputtering time, the overpotential decreases and the activity increases; the overpotential of the sample sputtered for 30 minutes is only 47mV, and the activity is higher than that of the commercial Pt / C catalyst; Figure 3 As shown, the current density is 10mA / cm 2 The stability test under the given conditions showed that the stability of the sample sputtered for 30 minutes was higher than that of the sample sputtered for 2 minutes.

[0046] The scanning electron microscope (SEM) images, element distribution maps, high-resolution images of transmission electron microscope (TEM) and electron diffraction patterns of the amorphous / crystalline heterojunction NiZr oxide catalysts obtained in Examples 1 to 3 and the crystalline NiZr oxide obtained in the comparative example are shown in FIG. Figure 4-5 As shown, the SEM cross-sectional image shows that the prepared catalyst is a nano-columnar structure, which is beneficial to the contact between the catalyst and the electrolyte and the evolution of bubbles. The surface morphology shows that with the extension of the sputtering time, the surface roughness of the catalyst increases, which is beneficial to the increase of the electrochemical active area. The energy spectrum data show that the surface Ni, Zr and O are uniformly distributed; the TEM results show that when the sputtering time is short, the obtained catalyst is a nano-crystalline NiZr oxide. With the increase of the sputtering time, the crystal structure is transformed into an amorphous / crystalline heterostructure. The improvement of the catalyst activity and stability comes from the formation of the amorphous / crystalline heterostructure.

[0047] The catalyst a / c-Ni prepared by the above-mentioned method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction 0.9 Zr0.1 O.

[0048] In summary, the present invention adopts a magnetron sputtering method to prepare amorphous / crystalline heterojunction catalysts. As a green and environmentally friendly method, this method has the advantages of high product quality, good repeatability, simple operation, high purity, high density, good uniformity, and high adhesion strength; in addition, by adjusting the sputtering parameters, such as sputtering time, power, rotation speed, base pressure and working gas pressure, the microstructure of the sputtered film and the HER catalyst performance can be precisely controlled; by adjusting the magnetron co-sputtering time and annealing, crystalline and amorphous / crystalline heterojunction NiZr oxides are prepared. In an alkaline medium, the HER catalyst performance and stability of the amorphous / crystalline heterostructure are better than those of the corresponding crystal structure, and the overpotential is lower, and the activity is higher than that of the commercial Pt / C catalyst.

[0049] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the technical solution of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction, characterized in that: The amorphous / crystalline heterojunction catalyst a / c-Ni is prepared by magnetron sputtering equipment 0.9 Zr 0.1 O, comprising the following steps: S1. Select nickel foam as substrate and pre-treat it: clean it with acetone and deionized water and dry it for later use; S2. Prepare a circular or square high-purity Ni target and a high-purity Zr target for use as magnetron sputtering targets, and set aside for use; S3, installing the nickel foam substrate pretreated in step S1 on the substrate table of the magnetron sputtering equipment, and then loading the high-purity Ni target and high-purity Zr target in step S2 into the target holder of the magnetron sputtering coating machine, evacuating the chamber, and introducing argon gas to stabilize the pressure in the magnetron sputtering coating machine at the working pressure; S4, using DC sputtering high-purity Ni target and high-purity Zr target to obtain amorphous / crystalline heterojunction NiZr oxide catalyst a / c-Ni 0.9 Zr 0.1 O.

2. The method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction according to claim 1, characterized in that: In S3, evacuate the chamber to 5 × 10 -4 Pa base pressure; and argon gas is introduced to stabilize the pressure in the magnetron sputtering coating machine at a working pressure of 3Pa.

3. The method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction according to claim 1, characterized in that: In S4, before using DC sputtering to sputter the high-purity Ni target and the high-purity Zr target, the high-purity Ni target and the high-purity Zr target were pre-sputtered for 5 minutes to remove surface contaminants.

4. The method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction according to claim 1, characterized in that: In S4, the purity of the high-purity Ni target and Zr target sputtered by DC was 99.95%, the sputtering power of the high-purity Ni target was 200 W, the sputtering power of the high-purity Zr target was 100 W, the rotation speed of the substrate was 20 rpm, and the sputtering time was 10 min.

5. The method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction according to claim 1, characterized in that: In S4, the purity of the high-purity Ni target and Zr target sputtered by DC was 99.95%, the sputtering power of the high-purity Ni target was 200 W, the sputtering power of the high-purity Zr target was 100 W, the rotation speed of the substrate was 20 rpm, and the sputtering time was 20 min.

6. The method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction according to claim 1, characterized in that: In S4, the purity of the high-purity Ni target and Zr target sputtered by DC was 99.95%, the sputtering power of the high-purity Ni target was 200 W, the sputtering power of the high-purity Zr target was 100 W, the rotation speed of the substrate was 20 rpm, and the sputtering time was 30 min.

7. A catalyst prepared by the method for preparing an amorphous / crystalline heterojunction catalyst for hydrogen evolution reaction as claimed in claim 1.

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