Catalyst based on carbon nanosheet loaded Cu monatomic Pt sub-nanocluster as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and relates to a catalyst based on a carbon nanosheet loaded Cu monatomic Pt sub-nanocluster as well as a preparation method and application thereof. The preparation method comprises the following steps: adding a nitrogen-containing precursor and benzenetricarboxylic acid into water, and uniformly stirring to obtain a suspension; adding a copper-containing compound and a platinum-containing compound into the suspension, uniformly stirring, and drying to obtain precursor powder; and carrying out heat treatment on the precursor powder under protective gas to obtain the catalyst. According to the invention, Cu monatomic and Pt atomic clusters are anchored on the ultrathin carbon nanosheets, so that the prepared catalyst can be used as a hydrogen evolution catalyst to be applied to hydrogen production, and has excellent electrochemical performance under an alkaline condition.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts and relates to a Cu single-atom Pt sub-nano cluster catalyst based on carbon nanosheets and a preparation method and application thereof. Background Art

[0002] The hydrogen evolution reaction (HER) is one of the half-reactions in the water electrolysis process, which involves splitting water molecules into hydrogen and oxygen, and is crucial to achieving an efficient hydrogen economy. Solving the inherent kinetic barriers in the hydrogen evolution reaction has always been an important obstacle to advancing sustainable energy conversion technologies. Electrochemical water splitting powered by renewable energy provides a green and sustainable way to efficiently produce hydrogen.

[0003] Compared with water electrolysis in acidic media, alkaline water electrolysis technology is more popular and feasible in practical industrial hydrogen production due to its advantages of rugged equipment and cheap electrolyzer structure. To date, platinum-based catalysts have been widely used as alkaline HER electrocatalysts due to their suitable hydrogen adsorption energy. However, the weak water dissociation ability of Pt leads to insufficient supply of H* protons in the Volmer step, especially when operating at industrial current density in anion exchange membrane water electrolysis. In this context, the design and development of high energy density, low price, sustainable green electrochemical catalysts has become a current research hotspot.

[0004] In order to solve the above problems and further promote the development of sustainable energy, researchers are committed to designing and developing electrochemical catalysts with high performance and environmental friendliness. Atomically dispersed platinum catalysts are indeed an ideal catalyst with high atom utilization, but they still need to be improved. On the one hand, atomically dispersed platinum catalysts tend to aggregate into clusters or dissolve in long-term tests. In addition, due to the strong and non-free regulation of metal-support interactions, the activity is still easily limited by the charge transfer from the metal to the surrounding support atoms. In order to overcome these dilemmas, it is crucial to design a catalyst whose valence can be flexibly adjusted and whose electronic structure of the supported metal is also easily adjusted. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst and a preparation method and application thereof. The prepared catalyst can be used as a hydrogen evolution catalyst for hydrogen production and has excellent electrochemical performance under alkaline conditions.

[0006] One object of the present invention is achieved by the following technical solutions:

[0007] A carbon nanosheet-supported Cu single atom Pt sub-nano cluster catalyst, wherein the catalyst uses the carbon nanosheet as a carrier, and the Cu single atom and the Pt sub-nano cluster are independently and dispersedly anchored on the carrier.

[0008] Cu atoms are anchored on the carrier in a monodispersed form, and Pt is anchored on the carrier in a subnano cluster form. Subnano clusters refer to tiny clusters composed of several atoms with a size of subnanometer level, with a size between 0.2 and 10 nm.

[0009] The second object of the present invention is achieved by the following technical solutions:

[0010] A method for preparing a Cu single-atom Pt sub-nano cluster catalyst based on carbon nanosheets, comprising the following steps:

[0011] (1) adding a nitrogen-containing precursor and benzenetricarboxylic acid into water and stirring to obtain a suspension;

[0012] (2) adding a copper-containing compound and a platinum-containing compound to the above suspension, stirring and drying to obtain a precursor powder;

[0013] (3) The precursor powder is heat-treated under a protective gas to obtain the carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst.

[0014] Preferably, in step (1), the mass ratio of the nitrogen-containing precursor to trimesic acid is 2 to 50:1, more preferably 5 to 20:1.

[0015] Preferably, in step (1), the ratio of the mass of the nitrogen-containing precursor to the volume of water is 1 g: 1-100 ml, more preferably 1 g: 2-20 ml.

[0016] Preferably, in step (1), the stirring time is 0.5 to 3 hours, and the stirring speed is 100 to 800 rpm.

[0017] Preferably, in step (1), the nitrogen-containing precursor includes one or more of melamine, urea, cyanamide, and dicyandiamide.

[0018] Preferably, in step (2), the mass ratio of the copper-containing compound to the platinum-containing compound is 1:(1-20), more preferably 1:(2-8).

[0019] Preferably, in step (2), the mass ratio of the copper-containing compound to the nitrogen-containing precursor is 0.5 to 100:1, more preferably 1 to 50:1.

[0020] Preferably, the copper-containing compound is one or more of copper acetylacetonate, copper chloride and copper nitrate.

[0021] Preferably, the platinum-containing compound is one or more of chloroplatinic acid hexahydrate, platinum chloride, and platinum nitrate.

[0022] Preferably, in step (2), the stirring time is 1 to 30 minutes, and the stirring speed is 100 to 800 rpm.

[0023] Preferably, in step (2), drying comprises: placing the suspension in a water bath for heating and stirring until it is dried into powder, the heating time is 0.5 to 5 hours, and the heating temperature is 60 to 100°C.

[0024] Preferably, in step (3), the protective gas is nitrogen and / or argon, and the flow rate of the protective gas is 100 to 600 sccm.

[0025] Preferably, in step (3), the heat treatment comprises: heating to 800-1000° C. at a rate of 2-8° C. / min and keeping the temperature for 1-3 h.

[0026] The third object of the present invention is achieved by the following technical solutions:

[0027] The invention discloses an application of a Cu single atom Pt sub-nano cluster catalyst supported on a carbon nanosheet as a hydrogen evolution catalyst in the production of hydrogen by electrolysis of water, especially in the production of hydrogen by electrolysis of water under alkaline conditions.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention provides a Cu single atom Pt sub-nano cluster catalyst based on carbon nanosheets, wherein the catalyst uses carbon nanosheets as carriers, and Cu single atoms and Pt sub-nano clusters are independently dispersedly anchored on the carbon nanosheets. Cu is monodispersed on the carbon nanosheets in the form of atoms, and Pt is deposited and dispersed on the nanosheets in the form of sub-nano clusters rather than large particles. The Cu single atom Pt sub-nano cluster catalyst supported on the carbon nanosheets can be used as a hydrogen evolution catalyst for hydrogen production.

[0030] 2. The present invention precisely synthesizes a bimetallic catalyst of Cu single atom Pt sub-nanoclusters by in-situ adsorption and high-temperature pyrolysis. A large number of defect sites are formed on the surface of the prepared ultrathin carbon nanosheets, which can be used to anchor active metal single atoms and increase the loading amount. Under this preparation method, the growth of Pt is regulated by adding Cu to generate atomic sub-nanoclusters instead of large particles. At the same time, Cu has a strong ability to promote the water dissociation step, thereby improving the catalytic activity of the catalyst in the alkaline HER reaction. The electrocatalytically active material anchoring Pt atomic clusters and Cu single atoms on ultrathin carbon nanosheets can be used as a hydrogen evolution catalyst for hydrogen production, and has excellent electrochemical properties under alkaline conditions.

[0031] 3. The method of the present invention for preparing carbon nanosheet-loaded Cu single-atom Pt sub-nano cluster catalyst is simple and feasible with low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a projection electron microscope image of the Cu single atom Pt sub-nano cluster catalyst based on ultra-thin carbon nanosheets supported by Example 1 of the present invention;

[0033] Figure 2 This is a spherical aberration corrected high-resolution transmission electron microscopy image of the ultrathin carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst prepared in Example 1 of the present invention;

[0034] Figure 3 This is a projection electron microscope image of the ultra-thin carbon nanosheet-supported Pt cluster catalyst prepared in Comparative Example 2 of the present invention;

[0035] Figure 4 This is an EDS element mapping electron microscope image of the ultra-thin carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst prepared in Example 1 of the present invention;

[0036] Figure 5 The linear sweep voltammetry curves of hydrogen evolution of the catalysts prepared in Example 1 and Comparative Examples 1-2 of the present invention in 1M KOH electrolyte;

[0037] Figure 6 This is a chronopotentiometric stability test curve of the ultra-thin carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The technical scheme of the present invention is further described below by specific examples and accompanying drawings. It should be understood that the specific examples described herein are only used to help understand the present invention and are not intended for specific limitations of the present invention. The accompanying drawings used herein are only for better illustrating the disclosure of the present invention and do not have a limiting effect on the scope of protection. If not otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0039] Example 1

[0040] This embodiment is a preparation method based on ultra-thin carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst, and the preparation method comprises the following steps:

[0041] (a) adding 1 mg of dicyandiamide powder and 0.1 mg of benzenetricarboxylic acid powder to 5 ml of deionized water and stirring at 500 rpm for 0.5 h until white, to obtain a white suspension;

[0042] (b) adding 5 mg of copper acetylacetonate and 20 mg of chloroplatinic acid hexahydrate to the above suspension and stirring at 500 rpm for 10 min, heating the obtained mixture to 80° C. in a water bath and stirring vigorously for 0.5 h until dry, to obtain a precursor powder;

[0043] (c) The precursor powder is heated to 900° C. at a rate of 5° C. / min and kept at this temperature for 2 h under the protection of 300 sccm argon gas to obtain the Cu single atom Pt sub-nano cluster catalyst based on ultra-thin carbon nanosheets.

[0044] The above-prepared Cu single atom Pt sub-nano cluster catalyst based on carbon nanosheets was scanned by transmission electron microscopy. Figure 1 As shown: It can be seen that the ultrathin carbon nanosheets still maintain the morphology of nanosheets, there are no visible metal nanoparticles during the pyrolysis process, and SAED shows an amorphous structure.

[0045] The above-prepared Cu single-atom Pt sub-nano cluster catalyst based on ultra-thin carbon nanosheets was observed by high-resolution transmission electron microscopy with spherical aberration correction. The results are as follows: Figure 2 As shown: It can be seen that many diffusely distributed atomic images can be observed on the surface of the carbon nanosheets, and some atoms gather together to form sub-nanometer clusters.

[0046] Depend on Figure 4 It can be seen that the EDS element mapping image further confirms that Pt is mainly atomic clusters, and Cu appears randomly on the carbon nanosheets in the form of single atoms.

[0047] Example 2

[0048] This embodiment is a preparation method based on ultra-thin carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst, and the preparation method comprises the following steps:

[0049] (a) adding 0.6 mg of dicyandiamide powder and 0.05 mg of benzenetricarboxylic acid powder to 3 ml of deionized water and stirring at 400 rpm for 1 h until white, to obtain a white suspension;

[0050] (b) adding 4 mg of copper acetylacetonate and 30 mg of chloroplatinic acid hexahydrate to the above suspension and stirring at 400 rpm for 8 min, heating the obtained mixture to 70° C. in a water bath and stirring vigorously for 0.5 h until dry, to obtain a precursor powder;

[0051] (c) The precursor powder is heated to 850° C. at a rate of 4° C. / min and kept at this temperature for 3 h under the protection of 200 sccm argon gas to obtain the Cu single atom Pt sub-nano cluster catalyst based on ultra-thin carbon nanosheets.

[0052] Example 3

[0053] This embodiment is a preparation method of a Cu single atom Pt sub-nano cluster catalyst based on carbon nanosheets, and the preparation method comprises the following steps:

[0054] (a) adding 1.5 mg of dicyandiamide powder and 0.2 mg of benzenetricarboxylic acid powder to 8 ml of deionized water and stirring at 600 rpm for 1 h until white to obtain a white suspension;

[0055] (b) adding 8 mg of copper nitrate and 40 mg of chloroplatinic acid hexahydrate to the above suspension and stirring at 600 rpm for 5 min, heating the obtained mixture to 90° C. in a water bath and stirring vigorously for 1 h until dry, to obtain a precursor powder;

[0056] (c) The precursor powder is heated to 950° C. at 6° C. / min and kept at this temperature for 1.5 h under the protection of 400 sccm argon gas to obtain the Cu single atom Pt sub-nano cluster catalyst based on ultra-thin carbon nanosheets.

[0057] Comparative Example 1

[0058] Comparative Example 1 is a preparation method based on ultra-thin carbon nanosheets loaded with Cu single atom catalyst, and the preparation method comprises the following steps:

[0059] (a) adding 1 mg of dicyandiamide powder and 0.1 mg of benzenetricarboxylic acid powder to 5 ml of deionized water and stirring at 500 rpm for 0.5 h until white, to obtain a white suspension;

[0060] (b) adding 5 mg of copper acetylacetonate to the above suspension and stirring at 500 rpm for 10 min, heating the obtained mixture to 80° C. in a water bath and stirring vigorously for 0.5 h until dry, to obtain a precursor powder;

[0061] (c) The precursor powder is heated to 900° C. at a rate of 5° C. / min and kept at this temperature for 2 h under the protection of 300 sccm argon gas to obtain the ultrathin carbon nanosheet-supported Cu single atom catalyst.

[0062] Comparative Example 2

[0063] Comparative Example 2 is a preparation method based on ultra-thin carbon nanosheet-supported Pt cluster catalyst, and the preparation method comprises the following steps:

[0064] (a) adding 1 mg of dicyandiamide powder and 0.1 mg of benzenetricarboxylic acid powder to 5 ml of deionized water and stirring at 500 rpm for 0.5 h until white, to obtain a white suspension;

[0065] (b) adding 20 mg of chloroplatinic acid hexahydrate to the above suspension and stirring at 500 rpm for 10 min, heating the obtained mixture to 80° C. in a water bath and vigorously stirring for 0.5 h until dry, to obtain a precursor powder;

[0066] (c) The precursor powder is heated to 900° C. at a rate of 5° C. / min and kept at this temperature for 2 h under the protection of 300 sccm argon gas to obtain the ultrathin carbon nanosheet-supported Pt particle catalyst.

[0067] In the catalyst preparation process of Comparative Example 2, copper acetylacetonate was not added, and the lack of Cu to regulate the growth of Pt resulted in the formation of large clusters and large particles (about 20 nm in size) instead of sub-nano clusters. Figure 3 shown.

[0068] Comparative Example 3

[0069] Comparative Example 3 is a preparation method based on ultra-thin carbon nanosheet-supported Pt cluster catalyst, and the preparation method comprises the following steps:

[0070] (a) adding 1 mg of dicyandiamide powder and 0.1 mg of benzenetricarboxylic acid powder to 5 ml of deionized water and stirring at 500 rpm for 0.5 h until white, to obtain a white suspension;

[0071] (b) adding 25 mg of chloroplatinic acid hexahydrate to the above suspension and stirring at 500 rpm for 10 min, heating the obtained mixture to 80° C. in a water bath and vigorously stirring for 0.5 h until dry, to obtain a precursor powder;

[0072] (c) The precursor powder is heated to 900° C. at a rate of 5° C. / min and kept at this temperature for 2 h under the protection of 300 sccm argon gas to obtain the ultrathin carbon nanosheet-supported Pt particle catalyst.

[0073] The catalysts prepared in Example 1 and Comparative Examples 1-3 were subjected to hydrogen evolution test in 1M KOH electrolyte. Figure 5 It can be seen that in 1M KOH electrolyte, when the catalyst of the water electrolysis test system is the ultra-thin carbon nanosheet-supported Cu single atom Pt sub-nano cluster catalyst prepared in Example 1 of the present invention, only a low overpotential of 177.2 mV is required to make the current density of the reaction system reach 500 mA / cm -2 , which is significantly better than Cu single atom catalyst (350.9mV), Pt particle catalyst (251.2mV) and commercial platinum carbon catalyst (221.1mV). At the same time, with the increase of current density, the advantages of Cu single atom Pt sub-nano cluster catalyst become more and more obvious.

[0074] In Comparative Example 3, the amount of chloroplatinic acid hexahydrate added was increased, and the final Pt loading amount increased. However, in the absence of Cu, the more Pt was loaded, the larger the particles would be deposited on the carbon nanosheets. The Pt clusters reduced the catalytic performance, and a low overpotential of 330 mV was required to make the current density of the reaction system reach 500 mA / cm -2 .

[0075] The stability of the ultrathin carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst prepared in Example 1 was tested by chronopotentiometry. The test results are as follows: Figure 6 As shown: It can be seen that at 500mA / cm -2 Under high current density, the Cu single atom Pt sub-nano cluster catalyst based on ultra-thin carbon nanosheets can ensure almost no attenuation of catalytic activity within 1400 h, and the potential degradation rate is only 7.35 μV h -1 . This indicates that the catalyst has excellent practical potential for industrial application.

[0076] The various aspects, embodiments, and features of the present invention should be considered to be illustrative in all aspects and not limiting of the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0077] In the preparation method of the present invention, the order of each step is not limited to the order listed. For those skilled in the art, without creative work, the order of each step is also within the protection scope of the present invention. In addition, two or more steps or actions can be performed simultaneously.

[0078] Finally, it should be noted that the specific embodiments described herein are merely examples of the present invention, and are not intended to limit the implementation methods of the present invention. A person skilled in the art of the present invention may make various modifications or supplements to the specific embodiments described, or replace them in a similar manner. It is not necessary and impossible to provide all examples of all implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still fall within the scope of protection of the present invention, and interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A Cu single atom Pt sub-nano cluster catalyst based on carbon nanosheets, characterized in that: The catalyst uses carbon nanosheets as carriers, and Cu single atoms and Pt sub-nanoclusters are independently and dispersedly anchored on the carriers.

2. A method for preparing a Cu single-atom Pt sub-nano cluster catalyst based on carbon nanosheets, characterized in that: The preparation method comprises the following steps: (1) adding a nitrogen-containing precursor and benzenetricarboxylic acid into water and stirring to obtain a suspension; (2) adding a copper-containing compound and a platinum-containing compound to the above suspension, stirring and drying to obtain a precursor powder; (3) The precursor powder is heat-treated under a protective gas to obtain the carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst.

3. The preparation method according to claim 2, characterized in that: In step (1), the mass ratio of the nitrogen-containing precursor to trimesic acid is 2 to 50:

1.

4. The preparation method according to claim 2, characterized in that: In step (1), the ratio of the mass of the nitrogen-containing precursor to the volume of water is 1 g: 1 to 100 ml.

5. The preparation method according to claim 2, characterized in that: The nitrogen-containing precursor includes one or more of melamine, urea, cyanamide, and dicyandiamide; The copper-containing compound is one or more of copper acetylacetonate, copper chloride, and copper nitrate; The platinum-containing compound is one or more of chloroplatinic acid hexahydrate, platinum chloride, and platinum nitrate.

6. The preparation method according to claim 2, characterized in that: In step (2), the mass ratio of the copper-containing compound to the platinum-containing compound is 1:(1-20).

7. The preparation method according to claim 2, characterized in that: In step (2), drying comprises: placing the suspension in a water bath, heating and stirring until it is dried into powder, the heating time is 0.5 to 5 hours, and the heating temperature is 60 to 100°C.

8. The preparation method according to claim 2, characterized in that: In step (3), the protective gas is nitrogen and / or argon, and the flow rate of the protective gas is 100 to 600 sccm.

9. The preparation method according to claim 2, characterized in that: In step (3), the heat treatment includes: heating to 800-1000° C. at a rate of 2-8° C. / min and keeping the temperature for 1-3 hours.

10. Use of a carbon nanosheet-supported Cu single-atom Pt sub-nano cluster catalyst as a hydrogen evolution catalyst in hydrogen production by electrolysis of water, as described in claim 1 or prepared by the preparation method described in claim 2.

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