Nitrogen-containing molecule modified MXene loaded Pt monatomic catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalyst preparation, and provides a nitrogen-containing molecule modified MXene loaded Pt monatomic catalyst, a preparation method and application, the preparation method comprises the following steps: S1, preparing an NH2 / CC electrode; s2, dipping the NH2 / CC electrode in a mixed solution of an MXene suspension and chloroplatinic acid hexahydrate at room temperature for reaction, and then irradiating and drying with a mercury lamp to obtain an NH2-MX / Pt-CC electrode; and S3, carrying out secondary amino modification to obtain the catalyst containing nitrogen molecule modified MXene to load Pt single atoms. According to the preparation method of the catalyst with the nitrogen-containing molecule modified MXene loaded with the Pt single atoms, the atom utilization rate of the material is effectively increased, reaction active sites are increased, meanwhile, the interaction between the two-dimensional material and the Pt atoms is enhanced, and the stability of the catalyst under the industrial and current density is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst, a preparation method and an application thereof. Background Art

[0002] Hydrogen energy is widely regarded as one of the most promising clean energy sources in the 21st century and plays an important role in achieving the global carbon neutrality goal. As an efficient and pollution-free energy carrier, hydrogen can not only be used as a fuel to power industry, transportation and power generation, but also play a key role in energy storage and distributed energy systems. However, most of the current industrial hydrogen production technologies rely on fossil fuels, such as natural gas reforming and coal gasification. Although these methods are mature and have certain economic advantages, they are still accompanied by large amounts of carbon dioxide emissions, which limits their application in sustainable development goals.

[0003] In contrast, water electrolysis has attracted much attention due to its simple process, pure products and zero carbon emissions. Water electrolysis is the process of using electricity to decompose water into hydrogen and oxygen. Its main reactions are: 2H 2 O(l)→2H 2 (g)+O 2 (g) The realization of this reaction requires key components such as electrolytic cells, anodes, cathodes and electrolytes, and the decomposition reaction is completed by driving electron transfer through an external electric field. Depending on the electrolyte, water electrolysis hydrogen production technology can be divided into three main types: alkaline electrolysis (AWE), proton exchange membrane electrolysis (PEM) and solid oxide electrolysis (SOE), each with different application scopes and technical characteristics. For example, alkaline electrolysis is widely used due to its low cost and mature technology, while proton exchange membrane electrolysis has shown significant advantages in renewable energy systems because it can operate at high current density and fast response.

[0004] With the rapid development of renewable energy, using renewable resources such as wind energy and solar energy to provide electricity for water electrolysis to produce hydrogen has become an ideal green energy solution for the preparation of nitrogen-containing molecules modified MXene to load Pt single-atom catalysts. This can not only significantly reduce the carbon footprint of the electrolysis process, but also achieve the storage and efficient utilization of renewable energy through "electricity-hydrogen conversion". However, at this stage, water electrolysis to produce hydrogen still faces many challenges, such as high electricity costs, durability of catalysts, and efficiency issues of the electrolysis system. Therefore, how to improve the energy conversion efficiency of water electrolysis, develop high-performance and low-cost catalytic materials, and optimize system design have become the focus of research.

[0005] In summary, water electrolysis is an environmentally friendly and sustainable way of hydrogen production, which not only has broad application prospects in energy transformation, but also promotes the progress of basic scientific research and engineering technology. Platinum (Pt) is considered to be one of the most effective catalysts for hydrogen evolution reaction (HER) in water electrolysis due to its excellent electrochemical properties. At the same time, the research on Pt-based catalysts in water electrolysis has made significant progress, showing a diversified development trend from material design, performance optimization to system integration. However, achieving a balance between cost, performance and stability remains a key direction for future research. Through the combination of nanotechnology, theoretical calculations and advanced manufacturing processes, Pt-based catalysts are expected to play a key role in the commercialization of water electrolysis and provide strong support for the widespread popularization of clean energy. Studies have shown that through the nano-scaling and surface engineering of Pt-based catalysts, the catalytic efficiency of Pt per unit mass can be significantly improved due to its high specific surface area and abundant surface active sites. Single-atom Pt catalysts maximize atomic utilization and have excellent HER activity and stability. Or through the development of composite materials, the electronic structure of Pt can be effectively adjusted to optimize catalytic activity, causing the d-band center of Pt to shift, thereby reducing the adsorption energy of intermediates (such as H*) in the hydrogen evolution reaction and increasing the reaction rate. In addition, the introduction of carbon materials can provide additional conductive paths and support, which helps to improve the stability and conductivity of the catalyst.

[0006] Kim et al. (Haiyan Jin, Miran Ha, Min Gyu Kim, et al. ADVANCED ENERGYMATERIALS, 2023, 13, 2204213) synthesized a nitrogen-containing molecule-modified MXene to load Pt single-atom catalysts by regulating vanadium-nitrogen co-doped carbon (VNC). The atomically dispersed catalyst composed of Pt SAs, Pt-Pt / V diatoms and small clusters on the surface of VNC prepared a Pt single-atom catalyst with ultra-high mass activity, and its catalytic efficiency far exceeded that of commercial platinum carbon (Pt / C). However, the catalyst only showed excellent hydrogen evolution activity at a lower current density.

[0007] Liu et al. (Haifeng Yuan, Jiawei Li, , Xiaoyan Liu, eat al. Enhanced interfacial stability of Pt / TiO 2 / Ti via Pt-O bonding for efficient acidicelectrolyzer, 2024, 492, 152339) using TiO 2Anchoring ultra-low loading Pt nanopolyhedrons (Pt / TiO 2 The Pt-O bond between Pt and titanium dioxide enhances the interface, optimizes the electronic structure of platinum anchored on titanium dioxide, improves the hydrogen adsorption energy, and enhances the intrinsic activity of HER. Only 23 mV is required to achieve 10 mA cm in acidic electrolytes. -2 The current density is 180 mA cm -2 The stability of the reaction was shown by stably running for 25 h at a current density of 1.5 %; however, the activity and stability of the hydrogen evolution reaction at an industrial current density were still not tested.

[0008] In summary, the existing technology has the problem of Pt single atom catalyst dissolving and falling off and structural degradation under high current density.

[0009] In view of this, the present invention is proposed. Summary of the invention

[0010] The purpose of the present invention is to propose a preparation method for nitrogen-containing molecule-modified MXene to load Pt single-atom catalyst, so as to solve the problem that Pt single-atom catalyst in the prior art has poor activity and stability under high current density, and is prone to dissolution, shedding and structural degradation.

[0011] To achieve the above object, the technical solution of the present invention is achieved as follows: A method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst comprises the following steps: Step S1, preparation of NH 2 / CC electrode; Step S2: NH 2 The / CC electrode was immersed in a mixed solution of MXene suspension and hexahydrate chloroplatinic acid at room temperature for reaction, and then dried under mercury lamp to obtain NH 2 -MX / Pt-CC electrode; Step S3: Perform secondary amino modification to modify NH 2 The -MX / Pt-CC electrode is immersed in a nitrogen-containing organic molecule solution for ultrasonic treatment, and then dried by irradiation with a mercury lamp. The obtained electrode is then immersed in a mixed solution of the MXene suspension and hexahydrate chloroplatinic acid at room temperature for reaction, and then dried by irradiation with a mercury lamp to obtain a nitrogen-containing molecule-modified MXene to load a Pt single atom catalyst.

[0012] Further, step S1 is specifically: immersing the hydrophilic carbon cloth in a nitrogen-containing organic molecule solution for ultrasonic treatment, and then drying it with a mercury lamp to obtain NH 2 / CC electrode; or Will Na 2 SO4 and aniline were added to deionized water to form a precursor solution, hydrophilic carbon cloth was used as the working electrode, Pt sheet and Ag / AgCl were used as the counter electrode and reference electrode respectively, and NH 2 / CC electrode; or The mixed solution of dopamine solution and phosphate buffer was used as the electrolyte solution, the hydrophilic carbon cloth was used as the working electrode, the Pt sheet and Ag / AgCl were used as the counter electrode and the reference electrode respectively, and NH 2 / CC electrode.

[0013] Furthermore, the concentration of the nitrogen-containing organic molecule solution is 1-10 mg / mL; and the ultrasonic treatment time of the nitrogen-containing organic molecule solution is 10-50 min.

[0014] Furthermore, the nitrogen-containing organic molecule is at least one of ethylenediamine, dopamine hydrochloride, 3-aminopropyltriethoxysilane, nucleotide and amide.

[0015] Furthermore, the concentration of the chloroplatinic acid hexahydrate solution is 5-20 mg / mL.

[0016] Furthermore, the reaction time in the mixed solution of the MXene suspension and chloroplatinic acid hexahydrate is 10 to 60 minutes.

[0017] Furthermore, the wattage of the mercury lamp is 100-500W, and the irradiation drying time of the mercury lamp is 10-50 min.

[0018] Furthermore, the distance between the hydrophilic carbon cloth and the mercury lamp for drying is 5 to 30 cm.

[0019] In a second aspect of the present invention, a catalyst is provided which is prepared by using any one of the above-mentioned methods for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst.

[0020] The third aspect of the present invention provides an application of a catalyst prepared by any one of the above-mentioned methods for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst in the field of hydrogen evolution by electrolysis of water.

[0021] Compared with the prior art, the nitrogen-containing molecule-modified MXene to load Pt single-atom catalyst, preparation method and application described in the present invention have the following beneficial effects: The present invention discloses a nitrogen-containing molecule-modified MXene for loading a Pt single-atom catalyst, a preparation method and an application. Steps S1 to S3 are interrelated, inseparable and work together. In step S1, a hydrophilic carbon cloth is used as a support, and the surface of the two-dimensional material MXene is modified by nitrogen-containing molecules to improve the loading capacity of the Pt species. Then, in steps S2 and S3, a low-temperature method is used to combine the chelation and adhesion of the nitrogen-containing molecules to load the Pt species in the chloroplatinic acid aqueous solution on the surface of the two-dimensional material, and then the nitrogen-containing molecules and a mercury lamp are further used to regulate the electronic structure and morphology of the Pt on the surface to prepare a Pt single-atom catalyst that grows self-on the surface of the two-dimensional material. The electrode utilizes the chelation, strong adhesion and reducibility of the nitrogen-containing molecules and the mercury lamp to prepare NH 2 -MX / Pt SAC composite catalyst, in which the structure of metal single atoms not only increases the active sites of the catalyst, but also reduces the loading amount of precious metals. At the same time, the synergistic effect between Pt single atoms and two-dimensional materials also improves the catalytic performance and stability of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a HAADF-STEM image of a catalyst prepared by the method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst as described in Example 1 of the present invention; Figure 2 This is a SEM spectrum of a catalyst prepared by the method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst as described in Example 1 of the present invention; Figure 3 This is a Raman graph of a catalyst prepared by the method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst as described in Example 1 of the present invention; Figure 4 The electrochemical performance diagram (LSV) of the hydrogen evolution reaction of the catalyst prepared by the preparation method of a nitrogen-containing molecule-modified MXene to load Pt single-atom catalyst described in the examples and comparative examples of the present invention; Figure 5 This is a stability test diagram of the hydrogen evolution reaction of a catalyst prepared by the preparation method of a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst described in Example 1 of the present invention; Figure 6 This is a stability test diagram of the hydrogen evolution reaction of a catalyst prepared by the preparation method of a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst described in Comparative Example 2 of the present invention; Figure 7This is a test chart of the hydrogen evolution reaction stability of the catalyst prepared by the preparation method of a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst described in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The descriptions of "first", "second", etc. mentioned in the embodiments of the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0024] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0025] MXene is a new type of transition metal carbon / nitride two-dimensional nano-layered material. Its unique physical and chemical properties have attracted widespread attention from the academic community in recent years in many fields such as energy storage and conversion, sensors, and multifunctional polymer composites. It is worth mentioning that MXene contains a carbon layer with properties similar to graphene, and a transition metal layer that can exhibit properties similar to transition metal oxides. The former gives it good conductivity, while the latter gives it good energy storage performance. This allows MXene to be used directly as a double-layer capacitor electrode material, or as a conductive matrix to be composited with other pseudocapacitive materials to prepare hybrid capacitor electrode materials. Its larger interlayer spacing can be intercalated with other materials, thereby further increasing the density of the material and having a higher volumetric specific capacity. The high conductivity of MXene and the high specific capacity of pseudocapacitive materials can be used to optimize electrochemical performance.

[0026] In the prior art, Pt single-atom catalysts have poor activity and stability at high current density, and are prone to dissolution, shedding and structural degradation.

[0027] In order to solve the above technical problems, Figures 1 to 7 As shown, the applicant proposes a method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst, comprising the following steps: Step S1, preparation of NH 2 / CC electrode; Step S2: NH 2The / CC electrode was immersed in a mixed solution of MXene suspension and hexahydrate chloroplatinic acid at room temperature for reaction, and then dried under mercury lamp to obtain NH 2 -MX / Pt-CC electrode; Step S3: Perform secondary amino modification to modify NH 2 The -MX / Pt-CC electrode is immersed in a nitrogen-containing organic molecule solution for ultrasonic treatment, and then dried by irradiation with a mercury lamp. The obtained electrode is then immersed in a mixed solution of the MXene suspension and hexahydrate chloroplatinic acid at room temperature for reaction, and then dried by irradiation with a mercury lamp to obtain a nitrogen-containing molecule-modified MXene to load a Pt single atom catalyst.

[0028] Specifically, step S1 is as follows: immersing the hydrophilic carbon cloth in a nitrogen-containing organic molecule solution for ultrasonic treatment, and then drying it with a mercury lamp to obtain NH 2 / CC electrode; or Will Na 2 SO 4 and aniline were added to deionized water to form a precursor solution, hydrophilic carbon cloth was used as the working electrode, Pt sheet and Ag / AgCl were used as the counter electrode and reference electrode respectively, and NH 2 / CC electrode; or The mixed solution of dopamine solution and phosphate buffer was used as the electrolyte solution, the hydrophilic carbon cloth was used as the working electrode, the Pt sheet and Ag / AgCl were used as the counter electrode and the reference electrode respectively, and NH 2 / CC electrode.

[0029] Specifically, the concentration of the nitrogen-containing organic molecule solution is 1-10 mg / mL to obtain more uniform amino coverage; the ultrasonic treatment time of the nitrogen-containing organic molecule solution is 10-50 min to fully dissolve and penetrate the nitrogen-containing molecules.

[0030] Specifically, the nitrogen-containing organic molecule is at least one of ethylenediamine, dopamine hydrochloride, 3-aminopropyltriethoxysilane, nucleotide and amide.

[0031] Preferably, the nitrogen-containing organic molecule is dopamine hydrochloride. Dopamine hydrochloride has the chemical properties of high adhesion and polymerization. By modifying MXene, the chemical structure of MXene can be further regulated. At the same time, its chemical properties can be used to tightly combine the MXene material with the carbon cloth surface during the self-growth process, thereby enhancing the stability of the electrode surface under high current density. At the same time, after modification, the N source can further adjust the charge of the subsequent Pt metal and optimize the electronic structure of Pt. At the same time, through the bonding effect with Pt metal, Pt metal can be evenly loaded on the MXene surface to avoid the agglomeration of Pt particles (this agglomeration is not conducive to the occurrence of HER reaction). At the same time, the successful preparation of single atoms improves the atomic utilization rate, reduces the use of precious metals, and optimizes the preparation method and cost control.

[0032] Specifically, the concentration of the chloroplatinic acid hexahydrate solution is 5-20 mg / mL. When the concentration of the chloroplatinic acid hexahydrate solution is within this range, the catalyst can exhibit good activity and stability.

[0033] Specifically, the reaction time in the mixed solution of the MXene suspension and chloroplatinic acid hexahydrate is 10 to 60 min to ensure full combination of Pt single atoms and MXene.

[0034] Specifically, the wattage of the mercury lamp is 100-500W, and the mercury lamp irradiation drying time is 10-50 min to fully dry and fix the catalyst structure; the distance between the hydrophilic carbon cloth and the mercury lamp irradiation drying is 5-30 cm to ensure a uniform and effective drying effect.

[0035] Specifically, in the mixed solution of the MXene suspension and chloroplatinic acid hexahydrate, the ratio of the solute mass in the MXene suspension to the solute mass in the chloroplatinic acid hexahydrate is 8:1, so as to obtain the optimal Pt loading amount and MXene modification effect.

[0036] In a second aspect of the present invention, a catalyst is provided which is prepared by using any one of the above-mentioned methods for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst.

[0037] The third aspect of the present invention provides an application of a catalyst prepared by any one of the above-mentioned methods for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst in the field of hydrogen evolution by electrolysis of water. Example 1

[0038] In this embodiment, a method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst is proposed, comprising the following steps: Step S1, preparation of NH2 / CC electrode; Step S2: NH 2 The / CC electrode is immersed in a mixed solution of MXene suspension and hexahydrate chloroplatinic acid at room temperature for reaction, and the reaction time in the mixed solution of MXene suspension and hexahydrate chloroplatinic acid is 30 minutes; then it is dried by mercury lamp to obtain NH 2 -MX / Pt-CC electrode; Step S3: Perform secondary amino modification to modify NH 2 The MX / Pt-CC electrode is immersed in a nitrogen-containing organic molecule solution for ultrasonic treatment, and then dried by irradiation with a mercury lamp. The obtained electrode is then immersed in a mixed solution of the MXene suspension and hexahydrate chloroplatinic acid at room temperature for reaction, and then dried by irradiation with a mercury lamp to obtain a nitrogen-containing molecule-modified MXene to load a Pt single atom catalyst NH 2 -MX / Pt SAC.

[0039] Specifically, in this embodiment, step S1 is specifically: immersing the hydrophilic carbon cloth (CC) in a nitrogen-containing organic molecule solution for ultrasonic treatment, and then drying it with a mercury lamp to obtain NH 2 / CC electrode.

[0040] More specifically, in this embodiment, step S1 is specifically as follows: first pre-treat the hydrophilic carbon cloth, then pour 30 mg of nitrogen-containing organic molecules into 10 mL of deionized water to prepare a nitrogen-containing organic molecule solution, then immerse the pre-treated hydrophilic carbon cloth in the nitrogen-containing organic molecule solution for ultrasonic treatment for 20 min, and dry it with a mercury lamp, the wattage of the mercury lamp is 250 W, the mercury lamp irradiation drying time is 20 min, the distance between the hydrophilic carbon cloth and the mercury lamp is 25 cm, and NH 2 / CC electrode.

[0041] More specifically, in this embodiment, the area of ​​the hydrophilic carbon cloth is 1*2cm 2 .

[0042] Specifically, in this embodiment, the nitrogen-containing organic molecule is dopamine hydrochloride.

[0043] Specifically, in this embodiment, the concentration of the nitrogen-containing organic molecule solution is 3 mg / mL.

[0044] Specifically, in this embodiment, the pretreatment of the hydrophilic carbon cloth includes the following steps: immersing the hydrophilic carbon cloth in a nitric acid solution (3 mol / L) to remove impurities, then ultrasonically cleaning the hydrophilic carbon cloth with acetone, ethanol and deionized water in sequence, and drying at 40-90°C after cleaning to obtain the pretreated hydrophilic carbon cloth.

[0045] Specifically, in this embodiment, the preparation of the MXene suspension includes the following steps: using concentrated hydrochloric acid and lithium fluoride in an oil bath at 30-60°C to slowly etch the MXene precursor (Ti 3 AlC 2 ), and then filtered, washed, ultrasonicated and centrifuged to obtain a few layers of MXene (Ti 3 C 2 ) suspension.

[0046] Specifically, in this embodiment, in the mixed solution of the MXene suspension and chloroplatinic acid hexahydrate, the ratio of the solute mass in the MXene suspension to the solute mass in the chloroplatinic acid hexahydrate is 8:1.

[0047] Therefore, when preparing the mixed solution of the MXene suspension and chloroplatinic acid hexahydrate, 3 mL of the MXene suspension was first taken, and then the solute mass required for the required chloroplatinic acid hexahydrate aqueous solution was calculated based on the ratio of the solute mass in the MXene suspension to the solute mass in the chloroplatinic acid hexahydrate being 8:1, and then the mixture was heated to 40 ℃ and then heated to 30 ℃. 6 PtCl 6 6H 2 The required H O solution concentration can be inferred 6 PtCl 6 6H 2 O aqueous solution volume.

[0048] In this embodiment, the concentration of the chloroplatinic acid hexahydrate solution is selected to be 10 mg / mL.

[0049] In this embodiment, the unique chemical properties of dopamine hydrochloride are used to modify MXene, effectively improving the catalytic activity and stability of the catalyst. The modification of dopamine hydrochloride not only optimizes the electronic structure of the MXene surface and increases its surface active sites, but also avoids the agglomeration of Pt particles through good combination with Pt metal ions, thereby improving the atomic utilization of Pt.

[0050] Among them, dopamine hydrochloride has the chemical properties of high adhesion and polymerization. Through the modification of MXene, the chemical structure of MXene can be further regulated. At the same time, its chemical properties can be used to closely combine the MXene material with the carbon cloth surface during the self-growth process, thereby enhancing the stability of the electrode surface under high current density. At the same time, after the modification, the N source can further adjust the charge of the subsequent Pt metal and optimize the electronic structure of Pt. At the same time, through the bonding effect with Pt metal, Pt metal can be evenly loaded on the MXene surface to avoid the agglomeration of Pt particles (this agglomeration is not conducive to the occurrence of HER reaction). At the same time, the successful preparation of single atoms improves the atomic utilization rate, reduces the use of precious metals, and optimizes the preparation method and cost control. Example 2

[0051] In this embodiment, different from Embodiment 1, the concentration of the nitrogen-containing organic molecule solution is 1 mg / mL; and the ultrasonic treatment time of the nitrogen-containing organic molecule solution is 50 min.

[0052] The reaction time in the mixed solution of the MXene suspension and chloroplatinic acid hexahydrate is 60 minutes.

[0053] In this embodiment, the concentration of the chloroplatinic acid hexahydrate solution is selected to be 20 mg / mL.

[0054] The wattage of the mercury lamp is 500W, the irradiation drying time of the mercury lamp is 10 minutes, and the distance between the hydrophilic carbon cloth and the mercury lamp is 30 cm. Example 3

[0055] In this embodiment, different from Embodiment 1, the concentration of the nitrogen-containing organic molecule solution is 10 mg / mL; and the ultrasonic treatment time of the nitrogen-containing organic molecule solution is 10 min.

[0056] In this embodiment, the concentration of the chloroplatinic acid hexahydrate solution is 5 mg / mL.

[0057] The reaction time in the mixed solution of the MXene suspension and chloroplatinic acid hexahydrate is 10 minutes.

[0058] The wattage of the mercury lamp is 100 W, the irradiation drying time of the mercury lamp is 50 min, and the distance between the hydrophilic carbon cloth and the mercury lamp is 5 cm.

[0059] Comparative Example 1 In this comparative example, step S1 is the same as that in Example 1, and steps S2 and S3 are different from those in Example 1, which are specifically as follows: Step S2: NH 2The / CC electrode was immersed in 3 mL of MXene suspension at room temperature for 30 min and then dried under mercury lamp for 20 min to obtain NH 2 -MX-CC-1 electrode; Step S3: Perform secondary amino modification to modify NH 2 The -MX-CC-1 electrode was immersed in a nitrogen-containing organic molecule solution for ultrasonic treatment, and then dried with a mercury lamp for 20 minutes. The obtained electrode was then immersed in 3 mL of the MXene suspension at room temperature for a static reaction for 30 minutes, and then dried with a mercury lamp for 20 minutes to obtain a Pt-free catalyst.

[0060] Comparative Example 2 In this comparative example, unlike Example 1, no secondary amino modification is performed and step S3 is not included.

[0061] Comparative Example 3 In this comparative example, different from Example 1, step S1 prepares NH 2 The method for forming the / CC electrode is different, and in this comparative example, no secondary amino modification is performed and step S3 is not included.

[0062] The specific preparation process of step S1 is as follows: a mixed solution of dopamine solution and phosphate buffer is used as an electrolyte solution, a hydrophilic carbon cloth is used as a working electrode, a Pt sheet and Ag / AgCl are used as a counter electrode and a reference electrode respectively, and NH 2 / CC electrode. Performance Testing

[0063] 1. The catalyst prepared by the method for preparing a nitrogen-containing molecule-modified MXene to load Pt single-atom catalyst described in Example 1 of the present invention was subjected to spherical aberration-corrected transmission electron microscopy (AC-TEM) analysis. The results are shown in Figure 1 .

[0064] like Figure 1 It can be seen that the NH 2 The surface of the -MX / Pt SAC catalyst has evenly distributed Pt single-atom bright spots. The evenly distributed single-atom Pt increases the catalytic active sites while reducing the loading amount of the precious metal Pt.

[0065] 2. Scanning electron microscope (SEM) analysis was performed on the catalyst prepared by the method for preparing a nitrogen-containing molecule-modified MXene to load Pt single-atom catalyst described in Example 1 of the present invention. The results are shown in Figure 2 .

[0066] from Figure 2 It can be clearly seen that the fibers on the surface of the hydrophilic carbon cloth have been completely covered, and the surface is coated with a dense layer. This is due to the high adhesion of nitrogen-containing molecules, which allows the active substances to grow on the surface of the hydrophilic carbon cloth, which is beneficial to the stability of the catalyst under industrial and current density conditions.

[0067] 3. Raman spectroscopy (Raman) analysis was performed on the catalyst prepared by the preparation method of a nitrogen-containing molecule-modified MXene to load Pt single-atom catalyst described in Example 1 of the present invention. The results are shown in Figure 3 .

[0068] Depend on Figure 3 It can be clearly observed that at 100 cm -1 , 400 cm -1 , 600 cm -1 TiO 2 This confirms the successful growth of MXene in the composite catalyst. -1 Vibrations belonging to the Pt-H bonds appeared on the left and right, which were caused by the bonding of Pt single atoms with some MXene surface groups.

[0069] 4. The catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were prepared by using a traditional three-electrode system at 0.5 mol L -1 H 2 SO 4 The materials were subjected to hydrogen evolution reaction test in the solution, and the NH 2 -MX / Pt SAC electrode was used as the working electrode, Pt sheet as the counter electrode, and Ag / AgCl electrode as the reference electrode. The electrochemical properties of the material were determined by linear sweep polarization curve (LSV). The results are shown in Figure 4 ; and the stability of the material was tested by chronoamperometry. The results are shown in Figures 5 to 7 and Table 1.

[0070] like Figure 4 As shown in Table 1, at 500 mA cm -2 and 1000 mA cm -2 At a current density of , the overpotential required for the catalyst prepared in Example 1 is only 124 mV and 177 mV respectively; the overpotential required for the catalyst prepared in Example 2 is 200 mV and 384 mV respectively, and the overpotential required for the catalyst prepared in Example 3 is 235 mV and 385 mV respectively; as shown in Table 1, the overpotential required for the catalyst prepared in Example 4 is 241 mV and 392 mV respectively.

[0071] The catalyst prepared in Comparative Example 1 has a drastic decrease in catalytic activity due to the absence of Pt metal active material. The performance of the catalyst prepared in Comparative Example 1 is extremely poor, and no readings are available at 500 and 1000 mA cm -2 The required HER overpotential of the material at the current density.

[0072] Depend on Figure 4 As shown in Table 1, the required overpotential of the catalyst prepared in Comparative Example 2 is 145mV and 219mV; after introducing metal Pt by the modified self-growth method, the electrocatalytic hydrogen evolution performance of Comparative Example 2 is significantly better than that of Comparative Example 1, which shows that the introduction of Pt species plays a very important role in the preparation of highly active and highly stable electrocatalytic materials for hydrogen evolution reaction. In particular, the secondary modification of dopamine provides more active sites for hydrogen evolution reaction, and at the same time, the high adhesion of dopamine itself is used to enhance the connection between Pt single atoms and two-dimensional materials, achieving a synergistic catalytic effect, which greatly improves the electrocatalytic hydrogen evolution performance of Example 1.

[0073] Table 1 Catalysts of Examples 1-3 and Comparative Examples 2-3 500 mA cm -2 and 1000 mA cm -2 Required HER overpotential at current density

[0074] like Figure 5 As shown, at 0.5 mol L -1 H 2 SO 4 In the solution, under constant potential conditions, the catalyst prepared by the method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst described in Example 1 of the present invention can drive 1000 mA cm -2 The current density was kept stable for 1094 hours, and good hydrogen evolution stability was maintained. In Comparative Example 1, due to the introduction of the inactive substance Pt, the activity was sharply reduced and the stability was very poor, so the stability test was not carried out.

[0075] like Figure 6 , Figure 7 As shown, the catalysts prepared in Comparative Examples 2 and 3 had a high conductivity at 1000 mA cm -2 The stable operation of current density does not exceed 30 hours. The catalysts prepared in Comparative Examples 2 and 3 show poor stability compared with Example 1.

[0076] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst, characterized in that: The following steps are involved: Step S1, preparing NH2 / CC electrode; Step S2, immersing the NH2 / CC electrode in a mixed solution of a MXene suspension and hexahydrate chloroplatinic acid at room temperature for reaction, and then drying with a mercury lamp to obtain an NH2-MX / Pt-CC electrode; Step S3, perform secondary amino modification, immerse the NH2-MX / Pt-CC electrode in a nitrogen-containing organic molecule solution for ultrasonic treatment, then dry it with a mercury lamp, and then immerse the obtained electrode in a mixed solution of the MXene suspension and hexahydrate chloroplatinic acid at room temperature for reaction, and then dry it with a mercury lamp to obtain a nitrogen-containing molecule-modified MXene to load Pt single atom catalysis.

2. The method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst according to claim 1, characterized in that: Step S1 specifically comprises: immersing the hydrophilic carbon cloth in a nitrogen-containing organic molecule solution for ultrasonic treatment, and then drying it with a mercury lamp to obtain an NH2 / CC electrode; or Na2SO4 and aniline were added to deionized water to form a precursor solution, a hydrophilic carbon cloth was used as a working electrode, a Pt sheet and Ag / AgCl were used as a counter electrode and a reference electrode, respectively, and an NH2 / CC electrode was obtained by electrodeposition in the precursor solution; or A mixed solution of dopamine solution and phosphate buffer was used as an electrolyte solution, a hydrophilic carbon cloth was used as a working electrode, a Pt sheet and Ag / AgCl were used as a counter electrode and a reference electrode, respectively, and deposited in the electrolyte solution to obtain an NH2 / CC electrode.

3. The method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst according to claim 2, characterized in that: The concentration of the nitrogen-containing organic molecule solution is 1-10 mg / mL; and the ultrasonic treatment time of the nitrogen-containing organic molecule solution is 10-50 min.

4. The method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst according to claim 3, characterized in that: The nitrogen-containing organic molecule is at least one of ethylenediamine, dopamine hydrochloride, 3-aminopropyltriethoxysilane, nucleotide and amide.

5. The method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst according to claim 1, characterized in that: The concentration of the chloroplatinic acid hexahydrate solution is 5-20 mg / mL.

6. The method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst according to claim 1, characterized in that: The reaction time in the mixed solution of the MXene suspension and chloroplatinic acid hexahydrate is 10 to 60 minutes.

7. The method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst according to claim 1, characterized in that: The wattage of the mercury lamp is 100-500W, and the irradiation drying time of the mercury lamp is 10-50 minutes.

8. The method for preparing a nitrogen-containing molecule-modified MXene to load a Pt single-atom catalyst according to claim 2, characterized in that: The distance between the hydrophilic carbon cloth and the mercury lamp for irradiation and drying is 5 to 30 cm.

9. A catalyst prepared by the method for preparing a Pt single-atom catalyst supported by a nitrogen-containing molecule-modified MXene as described in any one of claims 1 to 8.

10. Use of a catalyst prepared by the method for preparing a nitrogen-containing molecule-modified MXene loaded with a Pt single-atom catalyst as claimed in any one of claims 1 to 8 in the field of hydrogen evolution by electrolysis of water.

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