CN113481528A

CN113481528A - Composite catalyst and preparation method and application thereof

Info

Publication number: CN113481528A
Application number: CN202110757651.5A
Authority: CN
Inventors: 张嘉恒; 易明杰; 李娜; 朱振业; 马佳钰
Original assignee: Shenzhen Graduate School Harbin Institute of Technology
Current assignee: Shenzhen Graduate School Harbin Institute of Technology
Priority date: 2021-07-05
Filing date: 2021-07-05
Publication date: 2021-10-08
Anticipated expiration: 2041-07-05
Also published as: CN113481528B

Abstract

The invention discloses a composite catalyst and a preparation method and application thereof, wherein the composite catalyst comprises an MXene substrate, a rhenium disulfide nanosheet loaded on the surface of the MXene substrate and doped with a non-metal atom, and a platinum monatomic loaded on the rhenium disulfide nanosheet doped with the non-metal atom. The load platinum monoatomic can realize high atom utilization efficiency, greatly reduce the consumption of platinum and save the cost. The rhenium disulfide nanosheet has a large surface area and can contain more platinum atoms, and the non-metal atom doping of the rhenium disulfide nanosheet can increase the number of active sites, improve the conductivity and capture the proton capacity of the rhenium disulfide nanosheet. MXene material is introduced to improve the number of active sites and the electric conductivity of the rhenium disulfide nanosheets. The MXene substrate and the rhenium disulfide nanosheet loaded on the surface of the MXene substrate and doped with the non-metal atoms are integrally used as a carrier of a platinum single atom to realize the loading of the platinum single atom, so that the composite catalyst has excellent electrocatalytic performance.

Description

Composite catalyst and preparation method and application thereof

Technical Field

The invention relates to the field of catalysis, in particular to a composite catalyst and a preparation method and application thereof.

Background

Energy and environment are the most major problems involved in the sustainable development of human society, and 80% of the global energy demand is derived from fossil fuels, which ultimately leads to exhaustion of the fossil fuels, and the use thereof also leads to serious environmental pollution. The gradual shift from the use of fossil fuels to the use of sustainable and pollution-free non-fossil energy sources is a natural trend of development. Hydrogen is one of ideal clean energy sources, is also an important chemical raw material, and is widely regarded by all countries in the world. Compared with other hydrogen production modes, the electrocatalytic hydrogen evolution is favored because of simple preparation method, high efficiency and pure product.

Commercial Pt/C as the best hydrogen evolution catalyst has lower overpotential, smaller Tafel slope and higher current density, but its high price and scarce reserves severely restrict its large-scale commercial application. Therefore, it is urgently required to develop a catalyst having excellent electrocatalytic properties to reduce the amount of Pt used even in place of commercial Pt/C.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a composite catalyst, a preparation method and applications thereof, and aims to solve the problem that the existing commercial Pt/C catalyst is expensive and cannot be applied in large-scale commercial applications.

The technical scheme of the invention is as follows:

in a first aspect of the present invention, a composite catalyst is provided, wherein the composite catalyst includes an MXene substrate, a rhenium disulfide nanosheet doped with a non-metal atom and supported on the surface of the MXene substrate, and a platinum monoatomic layer supported on the rhenium disulfide nanosheet doped with a non-metal atom.

Optionally, the mass ratio of the MXene substrate, the rhenium disulfide nanosheet doped with the non-metal atom, and the platinum monoatomic group is (10-20): (2-6): (0.26-4).

Optionally, the non-metal atoms are selected from one or more of N atoms, B atoms, and F atoms.

Optionally, the MXene substrate is selected from Mo₂CT_xSubstrate, Ti₃C₂T_xSubstrate, Ti₂CT_xSubstrate, Cr₂CT_xSubstrate and V₂CT_xOne or more of a substrate.

In a second aspect of the present invention, there is provided a method for preparing the composite catalyst of the present invention, comprising the steps of:

adding MXene, perrhenate, a sulfur-containing compound and ionic liquid into water to obtain a mixed solution;

reacting the mixed solution at the temperature of 100-300 ℃ for 5-7 h;

reacting the product obtained after the reaction with H₂PtCl₆·6H₂Adding O into an organic solvent, stirring, centrifuging and drying to obtain a composite catalyst precursor;

and placing the composite catalyst precursor in a reducing gas atmosphere for reduction reaction to obtain the composite catalyst.

Optionally, the perrhenate is selected from one or two of ammonium perrhenate and sodium perrhenate.

Optionally, the sulfur-containing compound is selected from one or two of thiourea and thioacetamide.

Optionally, the ionic liquid is selected from one or more of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-methyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate.

Optionally, the temperature of the reduction reaction is 250-350 ℃, and the time of the reduction reaction is 1-2 h.

In a third aspect of the present invention, an application of the composite catalyst of the present invention in an electrocatalytic hydrogen evolution reaction or an application of the composite catalyst prepared by the preparation method of the present invention in an electrocatalytic hydrogen evolution reaction is provided.

Has the advantages that: the invention provides a composite catalyst and a preparation method and application thereof, wherein the composite catalyst comprises an MXene substrate, a rhenium disulfide nanosheet loaded on the surface of the MXene substrate and doped with a non-metal atom, and a platinum monatomic loaded on the rhenium disulfide nanosheet doped with the non-metal atom. The uniform load of the platinum monoatomic can enable all platinum atoms to have catalytic activity, so that high atom utilization efficiency is realized, compared with commercial Pt/C, the amount of platinum can be greatly reduced, the catalytic activity of the platinum is fully utilized, and the cost is saved while the catalytic activity is higher. The edge sites of the rhenium disulfide nanosheets have high electrocatalytic activity and quick electrochemical response, have a 1T' phase crystal structure with thermodynamic stability, have metallicity which is more favorable for charge transmission, have a large surface area, can contain more platinum atoms, and can increase the number of active sites, improve electronegativity and improve conductivity by doping the rhenium disulfide nanosheets with non-metal atoms, so that the proton capturing capacity is further enhanced. As the MXene material has excellent metal conductivity, the conductivity of the whole rhenium disulfide nanosheet can be further improved by introducing the MXene material, and the transmission of electrons is accelerated. In addition, MXene has a two-dimensional layered structure, the agglomeration phenomenon of rhenium disulfide nanosheets can be relieved to a great extent, the specific surface area is increased, and the number of active binding sites is further increased. The MXene substrate and the rhenium disulfide nanosheet doped with the non-metal atoms and loaded on the surface of the MXene substrate have the advantages of large surface area, more active sites, excellent electric conductivity and proton capturing capability, and the MXene substrate and the rhenium disulfide nanosheet doped with the non-metal atoms and loaded on the surface of the MXene substrate are used as a carrier of a platinum monatomic to realize the loading of the platinum monatomic, so that the composite catalyst has excellent electrocatalytic performance.

Drawings

FIG. 1 (a) shows Mo in example 1 of the present invention₂CT_xFIG. 1 (b) is an SEM photograph of NBF-ReS in example 1 of the present invention₂/Mo₂CT_xFIG. 1 (c) is an SEM photograph of the present invention in example 1Pt/NBF-ReS₂/Mo₂CT_xSEM image of (d).

FIG. 2 shows Pt/NBF-ReS in example 1 of the present invention₂/Mo₂CT_xMapping graphs of corresponding elements, wherein (a) in fig. 2 is a Mapping graph of an F element, (B) in fig. 2 is a Mapping graph of a C element, (C) in fig. 2 is a Mapping graph of an O element, (d) in fig. 2 is a Mapping graph of an Re element, (e) in fig. 2 is a Mapping graph of an N element, (F) in fig. 2 is a Mapping graph of an S element, (g) in fig. 2 is a Mapping graph of an Mo element, (h) in fig. 2 is a Mapping graph of a B element, and (i) in fig. 2 is a Mapping graph of a Pt element.

FIG. 3 shows Pt/NBF-ReS in example 1 of the present invention₂/Mo₂CT_xSpherical aberration electron micrographs of (A).

FIG. 4 shows Mo in example 1 of the present invention₂CT_x、NBF-ReS₂/Mo₂CT_xAnd Pt/NBF-ReS₂/Mo₂CT_xComparative example 1 ReS₂XRD pattern of (a).

FIG. 5 shows NBF-ReS in example 1 of the present invention₂/Mo₂CT_x、Pt/NBF-ReS₂/Mo₂CT_xReS in comparative example 2₂/Mo₂CT_x、Pt/ReS₂/Mo₂CT_xAnd polarization plots of commercial Pt/C.

FIG. 6 shows NBF-ReS in example 1 of the present invention₂/Mo₂CT_x、Pt/NBF-ReS₂/Mo₂CT_xReS in comparative example 2₂/Mo₂CT_x、Pt/ReS₂/Mo₂CT_xAnd Tafel plot of commercial Pt/C.

FIG. 7 shows NBF-ReS in example 1 of the present invention₂/Mo₂CT_x、Pt/NBF-ReS₂/Mo₂CT_xReS in comparative example 2₂/Mo₂CT_x、Pt/ReS₂/Mo₂CT_xAnd Tafel slope and overpotential map of commercial Pt/C.

Detailed Description

The invention provides a composite catalyst, a preparation method and application thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The monatomic catalysts (SACs) refer to catalysts having excellent catalytic performance in which metals are uniformly dispersed in a monatomic form on a carrier. Compared with the traditional carrier type catalyst, the SACs have the advantages of high activity, good selectivity, high utilization rate of noble metal and the like, and are widely applied to the fields of oxidation reaction, hydrogenation reaction, water gas shift, photocatalytic hydrogen production, electrochemical catalysis and the like. The electrocatalyst currently in commercial use is Pt/C, but because platinum is a precious metal, it is expensive to manufacture. The preparation of the platinum into the monatomic catalyst can greatly reduce the platinum amount required by the reaction and fully utilize the catalytic activity of the platinum. Based on this, the embodiment of the present invention provides a composite catalyst, where the composite catalyst includes an MXene substrate, a rhenium disulfide nanosheet doped with a non-metal atom and supported on the surface of the MXene substrate, and a platinum monoatomic atom supported on the rhenium disulfide nanosheet doped with a non-metal atom.

In this embodiment, the composite catalyst is a monatomic catalyst, and a single platinum atom supported by the composite catalyst can make all platinum atoms have catalytic activity, so that high atom utilization efficiency is achieved. The inventors have found that the high activity and selectivity of the monatomic catalyst can be attributed to the interaction between the active metal atoms and the support and the resulting change in electronic structure, and therefore the support is one of the important factors affecting the performance of the monatomic catalyst. The rhenium disulfide nanosheet interlayer van der Waals acting force is weaker, the edge sites have higher electrocatalytic activity and faster electrochemical response, the rhenium disulfide nanosheet interlayer van der Waals acting force has a thermodynamically stable 1T' phase crystal structure, is favorable for metal property of charge transmission, has larger surface area and more active sites, can contain more platinum atoms, and becomes an excellent carrier of a monatomic catalyst due to the unique structure and electronic characteristics of the platinum atoms. Although the rhenium disulfide is nanoThe edge sites of the sheet have higher electrocatalytic activity and faster electrochemical response, but the electronic conductivity of the sheet has anisotropic behavior, namely slow electron transfer on the basal plane of the nano-sheet and insufficient reactivity on the active sites, and the sheet shows higher overpotential and Tafel slope, and limits the HER (electrocatalytic hydrogen evolution) performance of the rhenium disulfide. Therefore, in order to improve the problems of rhenium disulfide, on one hand, a defect engineering is utilized to dope a rhenium disulfide nanosheet with a non-metal atom, so that the number of active sites is increased, the electronegativity of the rhenium disulfide nanosheet is improved, the conductivity of the rhenium disulfide nanosheet is improved, and the proton capturing capability of the rhenium disulfide nanosheet is further enhanced; on the other hand, as the MXene material is a two-dimensional inorganic compound material and is composed of transition metal carbide, nitride or carbonitride with the thickness of several atomic layers, the MXene material has excellent metal conductivity, chemical stability and hydrophilicity, and the conductivity of the rhenium disulfide nanosheet is further improved by introducing the MXene material, so that the electron transmission is accelerated. In addition, MXene has a two-dimensional layered structure, the agglomeration phenomenon of the rhenium disulfide nanosheets can be relieved to a great extent, the surface area of the rhenium disulfide nanosheets is increased, and the number of active binding sites of the rhenium disulfide nanosheets is further increased. Finally, MXene substrate and ReS doped with non-metal atoms and loaded on the surface of the MXene substrate₂The nano-sheet is used as a carrier of platinum single atoms.

In this embodiment, the MXene substrate and the rhenium disulfide nanosheet doped with a non-metal atom and loaded on the surface of the MXene substrate have a relatively large surface area, relatively many active sites, excellent electrical conductivity and proton capturing capability, and when the rhenium disulfide nanosheet is used as a carrier of a platinum monatomic to load the platinum monatomic, the composite catalyst can have excellent electrocatalytic performance.

In one embodiment, the rhenium disulfide nanosheet doped with the non-metal atom is supported on the surface of the MXene substrate, the surface of the MXene substrate is completely wrapped by the rhenium disulfide nanosheet doped with the non-metal atom, and the platinum monatomic is supported on the rhenium disulfide nanosheet doped with the non-metal atom. The nonmetal atom-doped rhenium disulfide nanosheet and the MXene nanosheet have a certain angle, that is, the nonmetal atom-doped rhenium disulfide nanosheet and the MXene nanosheet are not in parallel position relation, for example, the nonmetal atom-doped rhenium disulfide nanosheet can be vertically loaded on the surface of the MXene nanosheet.

In one embodiment, the mass ratio of the MXene substrate, the rhenium disulfide nanosheets doped with a non-metallic atom, and the platinum monoatomic group is (10-20): (2-6): (0.26-4).

In one embodiment, the mass ratio of the MXene substrate, the rhenium disulfide nanosheets doped with a non-metallic atom, and the platinum monoatomic group is (10-20): (2-6): (1-4). The ratio can enable rhenium disulfide nanosheets to uniformly coat (support) the MXene substrate, and the platinum monatomic content of the ratio can achieve the best HER performance.

In one embodiment, the non-metal atoms are selected from one or more of N atoms, B atoms, and F atoms, but are not limited thereto.

In one embodiment, the non-metal atom is selected from the group consisting of a N atom, a B atom, and a F atom. In the embodiment, N atoms, B atoms and F atoms are simultaneously doped in the rhenium disulfide nanosheets, and the doping of the N atoms, the B atoms and the F atoms increases the number of the total active sites of the rhenium disulfide nanosheets, improves the electronegativity of the rhenium disulfide nanosheets, and enhances the proton capturing capability of the rhenium disulfide nanosheets, so that the number of the total active sites of the composite catalyst is increased, the electronegativity of the composite catalyst is improved, and the proton capturing capability of the composite catalyst is enhanced. Since F is the element with the strongest electronegativity, the F atom is doped into the rhenium disulfide nanosheet, so that the electronegativity of the rhenium disulfide nanosheet can be improved, and the proton capturing capability of the rhenium disulfide nanosheet is further enhanced.

In one embodiment, the MXene substrate is selected from Mo₂CT_xSubstrate, Ti₃C₂T_xSubstrate, Ti₂CT_xSubstrate, Cr₂CT_xSubstrate and V₂CT_xOne or more of the substrates, but not limited thereto, wherein T represents a functional group and x represents the number of functional groups. Since the MXene material is a layered material formed by extracting the A layer from the MAX material through a chemical stripping method, functional groups are introduced in the preparation process. The functional group can be hydroxyl, oxygen ion,Acid radical ions, and the like. For example, when etching MAX materials with HF acid, the functional groups therein present fluoride ions.

The embodiment of the invention also provides a preparation method of the composite catalyst, which comprises the following steps:

s11, adding MXene, perrhenate, a sulfur-containing compound and ionic liquid into water to obtain a mixed solution;

s12, reacting the mixed solution at the temperature of 100-300 ℃ for 5-7 h;

s13, mixing the product obtained after the reaction with H₂PtCl₆·6H₂Adding O into an organic solvent, stirring, centrifuging and drying to obtain a composite catalyst precursor;

s14, placing the composite catalyst precursor in a reducing gas atmosphere for reduction reaction to obtain the composite catalyst.

In the embodiment, MXene is used as a substrate, an ionic liquid, perrhenate and a sulfur-containing compound are used as reactants, a non-metal atom-doped rhenium disulfide nanosheet is synthesized on the MXene substrate through a coprecipitation method, and a platinum monoatomic group is loaded on the non-metal atom-doped rhenium disulfide nanosheet through adsorption and reduction, so that the composite catalyst comprising the MXene substrate, the non-metal atom-doped rhenium disulfide nanosheet and the platinum monoatomic group is finally obtained. Wherein the ionic liquid provides non-metal atoms, perrhenate as a rhenium source, and a sulfur-containing compound as a sulfur source. The preparation method in the embodiment is simple and low in cost.

In step S11, in one embodiment, the MXene is selected from Mo₂CT_x、Ti₃C₂T_x、Ti₂CT_x、Cr₂CT_xAnd V₂CT_xBut is not limited thereto. Below with MoC₂T_xFor example, the preparation of Mo₂CT_xThe nanosheets are derived from bulk Mo by HF₂Ga₂C, selectively etching the Ga layer. When in specific implementation, Mo is added₂Ga₂Adding the C powder into HF solution, stirring for a period of time to fully react, and centrifugingThen obtaining Mo product₂CT_x。

In one embodiment, the perrhenate is selected from one or two of ammonium perrhenate and sodium perrhenate, but is not limited thereto, and the perrhenate serves as a rhenium source for synthesizing rhenium disulfide nanosheets, and the rhenium source may be selected from ammonium perrhenate, sodium perrhenate and the like.

In one embodiment, the sulfur-containing compound is selected from one or two of thiourea and thioacetamide, but is not limited thereto. The sulfur-containing compound is used as a sulfur source for synthesizing the rhenium disulfide nanosheet, and the sulfur source can be thiourea, thioacetamide and the like.

In one embodiment, the ionic liquid is selected from one or more of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-methyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate. The ionic liquid provides non-metal atoms, and the non-metal atoms of the rhenium disulfide nanosheets are doped. When the ionic liquid is selected from one or more of 1-butyl-3-methylimidazole tetrafluoroborate, 1-methyl-3-methylimidazole tetrafluoroborate and 1-ethyl-3-methylimidazole tetrafluoroborate, N, B, F atom codoping of rhenium disulfide nanosheets can be realized.

In step S12, a coprecipitation reaction is performed between the ionic liquid, the sulfur-containing compound, and the perrhenate to generate a rhenium disulfide nanosheet doped with a non-metal atom and uniformly grow on the surface of the MXene substrate, that is, in the reaction process, the rhenium disulfide doped with a non-metal atom grows on the surface of the MXene substrate while being generated to form a nanosheet, and finally the nanosheet is completely wrapped on the surface of the MXene substrate, so that the loading of the rhenium disulfide nanosheet doped with a non-metal atom is realized on the surface of the MXene substrate.

In step S13, the MXene substrate loaded with the non-metal atom-doped rhenium disulfide nanosheet on the surface obtained in step S12 is adsorbed with [ PtCl₆]^2-Combined, i.e. doped with non-metallic atoms, with rhenium disulfide nanosheets [ PtCl ]₆]^2-Adsorbed on the surface thereof, in other words, the obtained composite catalyst precursor comprises an MXene substrate, and rhenium disulfide nano-particles doped with non-metal atoms and loaded on the MXene substrateRice flakes [ PtCl ] adsorbed on rhenium disulfide nanosheets doped with non-metallic atoms₆]^2-。

In one embodiment, the organic solvent is selected from one or more of ethanol, methanol, propanol, and the like, but is not limited thereto.

In step S14, the composite catalyst precursor obtained in step S13 is reduced in a reducing gas atmosphere to effect [ PtCl ]₆]^2-Reducing to Pt monoatomic atoms and forming Pt-S bonds with sulfur in rhenium disulfide.

In one embodiment, the reducing gas is H₂。

In one embodiment, the temperature of the reduction reaction is 250-350 ℃, and the time of the reduction reaction is 1-2 h. The temperature and time can be controlled to [ PtCl ]₆]^2-Sufficiently reduced.

The embodiment of the invention also provides an application of the composite catalyst in the embodiment of the invention in electrocatalytic hydrogen evolution reaction. The embodiment of the invention also provides application of the composite catalyst prepared by the preparation method in the embodiment of the invention in electrocatalytic hydrogen evolution reaction. The composite catalyst provided by the embodiment of the invention can be applied to electrochemical hydrogen evolution reaction and Zn-air batteries (ZABs), but is not limited to the application.

The invention is further illustrated by the following specific examples.

The commercial Pt/C used in the following tests was purchased from sigma, with a Pt loading of 5.3%.

Example 1

2g of Mo₂Ga₂Powder C was ground for 30min, then slowly added to 20mL of HF solution and placed on a magnetic stirring heating sleeve at 55 ℃ and stirred for 7 days. Then, centrifuging at 10000rpm for 10min to obtain Mo₂CT_xWashing Mo with deionized water₂CT_xSeveral times until the pH value of the solution reaches about 6. Finally, the Mo obtained is₂CT_xThe powder was dried in a freeze dryer. Mo₂CT_xAs shown in FIG. 1 (a), from whichIt is shown that Mo₂CT_xIs a two-dimensional sheet structure. The XRD pattern is shown in FIG. 4.

50mg of Mo₂CT_xThe powder was added to 30mL deionized water, sonicated for 2h, and 322mg ammonium perrhenate (NH) was added₄ReO₄) 50mg of 1-butyl-3-methylimidazolium tetrafluoroborate, 410mg of thiourea (CH)₄N₂S), stirring for 30min, transferring to a 50mL stainless steel high-pressure reaction kettle, and keeping at the temperature of 200 ℃ for 6 h. After the reaction is finished and cooled, sequentially carrying out centrifugation, washing and drying to obtain an intermediate product which is recorded as NBF-ReS₂/Mo₂CT_xThe SEM image is shown in FIG. 1 (b), from which NBF-ReS can be seen₂The nano sheet is loaded on Mo₂CT_xThe XRD pattern of the surface is shown in figure 4.

30mg of H₂PtCl₆·6H₂O、50mg NBF-ReS₂/Mo₂CT_xAdding into 30mL ethanol, stirring for 1 hr, centrifuging, drying the obtained insoluble product at 70 deg.C for 6 hr, collecting dried powder 50mg, placing into a tube furnace, and placing in Ar/H at flow rate of 10mL/min₂(95%/5%) atmosphere at 2 ℃ for min^-1After the temperature rise rate is increased to 300 ℃, the temperature is kept for 1h, and after the reaction, a composite catalyst is obtained and is recorded as Pt/NBF-ReS₂/Mo₂CT_xWherein the loading of Pt is 5.4%. The XRD pattern is shown in FIG. 4, from which FIG. 4 it can be seen that Pt/NBF-ReS₂/Mo₂CT_xPresence of ReS₂And Mo₂CT_xCharacteristic peak of (a); the SEM is shown in FIG. 1 (C), the Mapping of the corresponding elements is shown in FIG. 2, (a) in FIG. 2 is the Mapping of the F element, (B) in FIG. 2 is the Mapping of the C element, (C) in FIG. 2 is the Mapping of the O element, (d) in FIG. 2 is the Mapping of the Re element, (e) in FIG. 2 is the Mapping of the N element, (F) in FIG. 2 is the Mapping of the S element, (g) in FIG. 2 is the Mapping of the Mo element, (h) in FIG. 2 is the Mapping of the B element, and (i) in FIG. 2 is the Mapping of the Pt element, thereby proving that Pt/NBF-ReS is obtained by using the method of the present invention₂/Mo₂CT_xThe material contains F, C, O, Re, N, S, Mo, B and Pt elements, and proves the successful doping of F, N, B; the spherical aberration electron microscope image is shown in FIG. 3It is clearly seen that Pt is present as a single atom, demonstrating successful loading of Pt single atoms.

Comparative example 1

322mg of ammonium perrhenate (NH)₄ReO₄) 410mg of thiourea (CH)₄N₂S) is added into 30mL of ethanol, stirred for 30min and then transferred to a 50mL stainless steel autoclave and kept at a temperature of 200 ℃ for 6 h. After the reaction is finished and cooled, the reaction solution is sequentially centrifuged, washed and dried to obtain a composite catalyst precursor which is recorded as ReS₂The XRD pattern is shown in figure 4.

Comparative example 2

2g of Mo₂Ga₂Powder C was ground for 30min, then slowly added to 20mL of HF solution and placed on a magnetic stirring heating sleeve at 55 ℃ and stirred for 7 days. Then, centrifuging at 10000rpm for 10min to obtain Mo₂CT_xWashing Mo with deionized water₂CT_xSeveral times until the pH value of the solution reaches about 6. Finally, the Mo obtained is₂CT_xThe powder was dried in a freeze dryer.

50mg of Mo₂CT_xThe powder was added to 30mL of deionized water, sonicated for 2h, and then 322mg of ammonium perrhenate (NH) was added₄ReO₄) 410mg of thiourea (CH)₄N₂S), stirring for 30min, transferring to a 50mL stainless steel high-pressure reaction kettle, and keeping at the temperature of 200 ℃ for 6 h. After the reaction is finished and cooled, sequentially carrying out centrifugation, washing and drying to obtain an intermediate product which is recorded as ReS₂/Mo₂CT_x。

30mg of H₂PtCl₆·6H₂O、50mg ReS₂/Mo₂CT_xAdding into 30mL ethanol, stirring for 1 hr, centrifuging, drying the obtained insoluble product at 70 deg.C for 6 hr, collecting dried powder 50mg, placing into a tube furnace, and placing in Ar/H at flow rate of 10mL/min₂(95%/5%) atmosphere at 2 ℃ for min^-1After the temperature rise rate is increased to 300 ℃, the temperature is kept for 1h, and after the reaction, a composite catalyst is obtained and is recorded as Pt/ReS₂/Mo₂CT_x。

Examples of the inventionNBF-ReS in 1₂/Mo₂CT_x、Pt/NBF-ReS₂/Mo₂CT_xReS in comparative example 2₂/Mo₂CT_x、Pt/ReS₂/Mo₂CT_xAnd working electrode made of commercial Pt/C at 0.5M H₂SO₄HER test was performed in the electrolyte, and the polarization curve is shown in FIG. 5, from which FIG. 5 shows Pt/NBF-ReS₂/Mo₂CT_xHas the lowest overpotential and the maximum current density, and the hydrogen evolution activity is higher than that of the Pt/C which is commercially used at present. Pt/NBF-ReS₂/Mo₂CT_xAnd Pt/ReS₂/Mo₂CT_xBy contrast, the doping of the N, B, F atoms can improve the hydrogen evolution activity of the catalyst. The corresponding Tafel curve is shown in FIG. 6. The Tafel slope and overpotential plots are shown in FIG. 7, and it can be seen from FIGS. 6 and 7 that Pt/NBF-ReS₂/Mo₂CT_xHas the lowest Tafel slope of 24mV/dec, and the Tafel slope of commercial Pt/C of 62mV/dec, Pt/ReS₂/Mo₂CT_xThe Tafel slope of (b) is 86mV/dec, NBF-ReS₂/Mo₂CT_xThe Tafel slope of (1) is 126mV/dec, ReS₂/Mo₂CT_xThe Tafel slope of (d) is 140 mV/dec. As can be seen from FIG. 7, Pt/NBF-ReS₂/Mo₂CT_xHas the lowest overpotential of 29mV, the overpotential of commercial Pt/C of 47mV, Pt/ReS₂/Mo₂CT_xThe overpotential of (a) is 58mV, NBF-ReS₂/Mo₂CT_xHas an overpotential of 118mV, ReS₂/Mo₂CT_xThe overpotential of (2) is 147 mV. Thus, Pt/NBF-ReS₂/Mo₂CT_xThe catalyst has the advantages of lowest overpotential, maximum current density, minimum Tafel slope, best hydrogen evolution activity, superior comprehensive performance to commercial Pt/C and great potential for replacing the commercial Pt/C.

In summary, the invention provides a composite catalyst, a preparation method and an application thereof. The composite catalyst comprises an MXene substrate, a rhenium disulfide nanosheet loaded on the surface of the MXene substrate and doped with a non-metal atom, and a platinum single supported on the rhenium disulfide nanosheet doped with a non-metal atomAn atom. The uniform load of platinum monoatomic can make all platinum atoms have catalytic activity, thus realize high atom utilization efficiency, compare commercial Pt/C, can greatly reduce the consumption of platinum, make full use of its catalytic activity, have higher catalytic activity while saving cost. Rhenium disulfide (ReS)₂) The edge sites have higher electro-catalytic activity and faster electrochemical response, have a 1T' phase crystal structure with stable thermodynamics, have metallicity more favorable for charge transmission, have larger surface area, can contain more platinum atoms, and can increase the number of active sites, improve the electronegativity and the conductivity of the active sites by doping the non-metal atoms of the rhenium disulfide nanosheets, thereby further enhancing the proton capturing capacity of the active sites. As the MXene material has excellent metal conductivity, the introduction of the MXene material can further improve the ReS₂The conductivity of the whole nanosheet accelerates the transmission of electrons. In addition, MXene has a two-dimensional layered structure, the agglomeration phenomenon of rhenium disulfide can be relieved to a great extent, the specific surface area is increased, and the number of active binding sites is further increased. The MXene substrate and the rhenium disulfide nanosheet loaded on the surface of the MXene substrate and doped with the non-metal atoms have the advantages of large surface area, more active sites, excellent electric conductivity and proton capturing capability, and when the MXene substrate and the rhenium disulfide nanosheet loaded on the surface of the MXene substrate and doped with the non-metal atoms are used as a carrier of a platinum single atom, the composite catalyst can have excellent electrocatalytic performance.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims

1. The composite catalyst is characterized by comprising an MXene substrate, rhenium disulfide nanosheets doped with non-metal atoms and supported on the surface of the MXene substrate, and platinum monatomic supported on the rhenium disulfide nanosheets doped with non-metal atoms.

2. The composite catalyst according to claim 1, wherein the mass ratio of MXene substrate, rhenium disulfide nanosheet doped with a non-metallic atom, and platinum monatomic is (10-20): (2-6): (0.26-4).

3. The composite catalyst according to claim 1, wherein the non-metal atom is selected from one or more of N atom, B atom, F atom.

4. The composite catalyst according to claim 1, wherein the MXene substrate is selected from Mo₂CT_xSubstrate, Ti₃C₂T_xSubstrate, Ti₂CT_xSubstrate, Cr₂CT_xSubstrate and V₂CT_xOne or more of a substrate.

5. A method for preparing the composite catalyst according to any one of claims 1 to 4, comprising the steps of:

reacting the mixed solution at the temperature of 100-300 ℃ for 5-7 h;

6. The preparation method of claim 5, wherein the perrhenate is selected from one or two of ammonium perrhenate and sodium perrhenate.

7. The method according to claim 5, wherein the sulfur-containing compound is one or two selected from thiourea and thioacetamide.

8. The method of claim 5, wherein the ionic liquid is selected from the group consisting of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1-methyl-3-methylimidazolium tetrafluoroborate.

9. The method as claimed in claim 5, wherein the temperature of the reduction reaction is 250-350 ℃, and the time of the reduction reaction is 1-2 h.

10. Use of a composite catalyst according to any one of claims 1 to 4 in an electrocatalytic hydrogen evolution reaction;

alternatively, the use of a composite catalyst prepared by the preparation method according to any one of claims 5 to 9 in an electrocatalytic hydrogen evolution reaction.