Platinum-based self-supporting membrane catalyst, preparation method and application of platinum-based self-supporting membrane catalyst in electro-catalytic hydrogen evolution

Abstract

The invention belongs to the technical field of membrane catalysts, and discloses a platinum-based self-supporting membrane catalyst, a preparation method and application of the platinum-based self-supporting membrane catalyst in electro-catalytic hydrogen evolution. A polypyrrole layer is deposited on the surface of carbon cloth, a terephthalic acid (BDC) ligand is covalently grafted to a polypyrrole nitrogen site through brominated hydrocarbon bridging molecules, a grafted composite substrate is immersed in a metal source and organic ligand solution, and a series of MOFs crystal films with uniform sizes are prepared through a hydrothermal method. Platinum nanoparticles are deposited on the surface of a CC (at) MOF crystal film by adopting a wet reduction method, the CC (at) MOF / Pt platinum-based self-supporting film catalyst is formed through high-temperature heat treatment, and the catalyst has the characteristics of rich active sites, high specific surface area, high stability and the like, shows excellent hydrogen evolution reaction performance in an acid medium, and provides a basis for industrial application of the self-supporting film catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane catalysts, and in particular relates to a platinum-based self-supporting membrane catalyst, a preparation method and application thereof in electrocatalytic hydrogen evolution. Background Art

[0002] Hydrogen is an ideal renewable energy carrier. The electrocatalytic hydrogen evolution reaction can produce hydrogen cleanly and efficiently, and is an important way to produce green hydrogen in the future. It is attractive to use the abundant seawater resources on the earth's surface to produce hydrogen. However, the low performance and poor stability of electrocatalysts in the process of seawater electrolysis have seriously hindered the large-scale production of hydrogen energy. Rational design and preparation of suitable carriers are the key to developing efficient and stable catalysts and realizing large-scale application of electrocatalytic hydrogen evolution.

[0003] Metal-organic frameworks (MOFs) are compounds composed of organic ligands and metal ions, forming organic-inorganic materials. The inorganic components in MOFs, such as layers, clusters, and chains, are connected to organic linkers through strong bonds promoted by coordination groups such as phosphonates, carboxylates, and free compounds, forming 3D hybrid frameworks with good electrocatalytic properties. The presence of well-defined functional groups and highly organized crystal structures in MOFs make them very suitable for electrocatalytic applications.

[0004] The use of pure MOFs in electrochemical applications is still limited due to their insufficient conductivity. This is because the relatively small size of MOF crystals causes them to aggregate together and form a structure without pores when carbonized at high temperatures, which hinders the exposure of active sites, limits the ability of mass transfer and electrolyte penetration, and leads to poor electrochemical performance.

[0005] Therefore, there is an urgent need to develop catalysts with abundant active sites, large specific surface area and high stability for electrocatalytic hydrogen evolution. Summary of the invention

[0006] In view of this, the present invention proposes a platinum-based self-supporting film catalyst, a preparation method and application thereof in electrocatalytic hydrogen evolution. The platinum-based self-supporting film catalyst obtained by the preparation method has the advantages of abundant active sites, large specific surface area, high stability, etc., exhibits excellent hydrogen evolution reaction performance, and can be applied to electrocatalytic hydrogen evolution.

[0007] The first aspect of the present invention provides a method for preparing a platinum-based self-supporting film catalyst, comprising the following steps:

[0008] S1. Using the pretreated carbon cloth as a substrate for pyrrole deposition to obtain a carbon cloth with polypyrrole deposited on the surface, namely CC@PPy;

[0009] S2. The CC@PPy, KOH and 1,4-dibromobutane are dispersed in N,N-dimethylformamide (DMF), heated and stirred for reaction, and after the reaction is completed, the product is washed and dried to obtain CC@PPy-(CH2)4Br;

[0010] S3. K2CO3, dimethyl 2-aminoterephthalate, and the CC@PPy-(CH2)4Br are dispersed in DMF, heated and stirred for reaction, and after the reaction is completed, the product is washed and dried to obtain a film;

[0011] S4. The membrane is heated and stirred in an aqueous H2SO4 solution for reaction. After the reaction is completed, the product is washed and dried to obtain CC@PPy-(CH2)4-BDC. In this step, dimethyl 2-aminoterephthalate is hydrolyzed under acidic conditions to generate terephthalic acid (BDC).

[0012] S5. adding the CC@PPy-(CH2)4-BDC to a DMF solution containing a metal source and terephthalic acid, and performing a hydrothermal reaction to form a dense MOF layer on the surface of the substrate. After the reaction is completed, the MOF layer is cooled to room temperature, and the product is washed and vacuum dried to obtain a CC@MOF crystal film.

[0013] S6. Add the CC@MOF crystal film to H2PtCl6 solution under stirring, and add NaBH4 aqueous solution dropwise. After the reaction is completed, the product is washed and dried, and calcined at high temperature to obtain a CC@MOF / Pt thin film, that is, the platinum-based self-supporting film catalyst.

[0014] Furthermore, in step S1, the pyrrole deposition is specifically as follows: pyrrole is dispersed in water to obtain a pyrrole aqueous solution, the pretreated carbon cloth is immersed in the pyrrole aqueous solution, an ammonium persulfate solution is added dropwise, and after the polymerization reaction is completed, the carbon cloth is taken out and vacuum dried.

[0015] Furthermore, in step S1, the molar ratio of pyrrole to ammonium persulfate in the ammonium persulfate solution is 1:(2-3).

[0016] Furthermore, in step S1, during the pyrrole deposition process, the usage ratio of pyrrole, water and ammonium persulfate solution is 100 μL:100 mL:25 mL, and the concentration of the ammonium persulfate solution is 0.023 mol / L.

[0017] Furthermore, in step S2, the dosage ratio of CC@PPy, KOH, 1,4-dibromobutane and DMF is 200 mg:80 mg:80 mg:30 mL, and the heating and stirring reaction temperature is 60-80° C. and the time is 16-24 h.

[0018] Furthermore, in step S3, the usage ratio of CC@PPy-(CH2)4Br, K2CO3, dimethyl 2-aminoterephthalate and DMF is 200 mg:80 mg:80 mg:30 mL, and the heating and stirring reaction temperature is 60-80°C and the time is 16-24 h.

[0019] Furthermore, in step S4, the ratio of the membrane to the H2SO4 aqueous solution is 30 mg:30 mL, and the concentration of the H2SO4 aqueous solution is 0.08 mol / L.

[0020] Furthermore, in step S5, the metal source is selected from salts with one of Zr, Mn, Cu, Fe, Al, V and Cr as the metal center.

[0021] Further, in step S5, the concentration of the metal source in the solution containing the metal source and terephthalic acid is 24 mmol L -1 The molar ratio of terephthalic acid to the metal source is 4:1, the temperature of the hydrothermal reaction is 120 to 200° C., and the time is 10 to 24 hours.

[0022] Furthermore, in step S5, the metal source is ZrCl4, and the DMF solution containing the metal source and BDC also contains acetic acid.

[0023] Further, in step S6, the ratio of the amount of CC@MOF crystal film, H2PtCl6 solution and NaBH4 aqueous solution is 0.2 g: 10 mL: 10 mL; wherein the concentration of H2PtCl6 solution is 50 mmol L -1 The concentration of NaBH4 aqueous solution is 10 mmol L -1 .

[0024] The second aspect of the present invention provides a platinum-based self-supporting film catalyst prepared according to the above-mentioned preparation method.

[0025] The third aspect of the present invention provides a use of the above-mentioned platinum-based self-supporting film catalyst in an electrocatalytic hydrogen evolution reaction.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention introduces a bromohydrocarbon bridging molecule, and firmly grafts the terephthalic acid molecule onto the substrate surface in the form of a covalent bond through a nucleophilic substitution reaction, and constructs a three-dimensional interconnected CC@MOF crystal membrane structure through an in situ growth method. This structure combines the advantages of CC and MOF materials such as high specific surface area and chemical stability.

[0028] (2) The self-supporting structural material prepared by the in-situ method does not require a complicated coating process, which can significantly enhance its structural strength. Combined with its high specific surface area and the interconnected pore structure inside the MOF, it creates abundant active sites. The prepared self-supporting membrane exhibits excellent hydrogen evolution reaction performance in acidic media, providing a basis for the industrial application of self-supporting catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of a method for preparing a platinum-based self-supporting film catalyst according to an embodiment of the present invention;

[0030] Figure 2 This is an electron microscope image of CC@UIO-66 prepared in Example 1 of the present invention;

[0031] Figure 3 This is an electron microscope image of CC@UIO-66 / Pt prepared in Example 1 of the present invention;

[0032] Figure 4 This is an electron microscope image of CC@UIO-66 / Pt prepared in Example 1 of the present invention after heat treatment;

[0033] Figure 5 This is an electron microscope image of CC@UIO-66 / Pt prepared in Comparative Example 1 of the present invention;

[0034] Figure 6 This is an electron microscopy image of CC@UIO-66 / Pt prepared in Comparative Example 2 of the present invention;

[0035] Figure 7 The electrode polarization curves of the catalysts prepared in Example 1 of the present invention and Comparative Examples 1-2 and commercially available Pt / C are shown. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. However, the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the invention thorough and complete, and fully convey the scope of the present invention to those skilled in the art.

[0037] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0038] According to an exemplary embodiment of the present invention, the present invention provides a method for preparing a platinum-based self-supporting film catalyst, referring to Figure 1 As shown, it includes: steps S01 to S06.

[0039] In step S01, the pretreated carbon cloth is used as a substrate for pyrrole deposition to obtain a carbon cloth with polypyrrole deposited on the surface, which is denoted as CC@PPy. The purpose of this is to provide nitrogen active sites for subsequent covalent grafting.

[0040] It should be noted that the purpose of pre-treating the carbon cloth is: (1) removing oxides and other impurities on the surface of the carbon cloth; and (2) increasing the hydrophilicity of the surface of the carbon cloth to facilitate the subsequent deposition of polypyrrole.

[0041] According to an embodiment of the present invention, the method of pyrrole deposition is: dispersing pyrrole in water to obtain a pyrrole aqueous solution, immersing the pretreated carbon cloth in the pyrrole aqueous solution, dropping an ammonium persulfate solution, and after the polymerization reaction is completed, taking out and vacuum drying.

[0042] It should be noted that the amount of pyrrole used is determined by the area of ​​the carbon cloth. Too much or too little pyrrole will cause uneven distribution of polypyrrole on the surface of the carbon cloth, thereby affecting the distribution of MOF on the surface of the carbon cloth. In order to make the morphology of polypyrrole regular, according to an embodiment of the present invention, the molar ratio of pyrrole to ammonium persulfate is 1:2-1:3. Too high or too low a ratio will cause irregular morphology of polypyrrole, which will affect the subsequent hydrogen evolution performance of the membrane catalyst.

[0043] According to an embodiment of the present invention, when pyrrole is deposited, the usage ratio of pyrrole, water and ammonium persulfate solution is 100 μL:100 mL:25 mL, and the concentration of the ammonium persulfate solution is 0.023 mol / L.

[0044] In step S02, CC@PPy, KOH powder and 1,4-dibromobutane are dispersed in DMF, heated and stirred for reaction, and after the reaction is completed, filtered, washed and dried to obtain CC@PPy-(CH2)4Br.

[0045] It should be noted that step S02 is a nucleophilic substitution reaction. The bromine atom of the bromine atom of the bromine (bridging molecule) replaces the H atom in the PPy molecule. The reaction yield is very low when no auxiliary reagent is added. In a strong alkaline medium at 60-80°C, the nitrogen site in the PPy molecule can be activated to increase the activity of bromine replacing hydrogen, thereby increasing the reaction yield and shortening the reaction time.

[0046] According to an embodiment of the present invention, the usage ratio of CC@PPy, KOH powder, 1,4-dibromobutane and N,N-dimethylformamide is 200 mg:80 mg:80 mg:30 mL, the heating and stirring reaction temperature is 60-80° C., and the time is 16-24 h.

[0047] In step S03, K2CO3, dimethyl 2-aminoterephthalate, and the CC@PPy-(CH2)4Br are dispersed in DMF, heated and stirred for reaction, and after the reaction is completed, the product is washed and dried to obtain a membrane.

[0048] It should be noted that step S03 is also a nucleophilic substitution reaction, and the two ends of the bridging molecule are respectively connected to the ligand molecule and the substrate by covalent bonds to ensure that the ligand molecule and the substrate are strongly coupled. The difference is that in this step, the bromine atom replaces the hydrogen atom in the amino group of the ligand molecule 2-aminoterephthalate, so potassium carbonate is used for activation, thereby increasing the reaction yield and shortening the reaction time.

[0049] According to an embodiment of the present invention, the usage ratio of CC@PPy-(CH2)4Br, K2CO3, dimethyl 2-aminoterephthalate and DMF is 200 mg:80 mg:80 mg:30 mL, the heating and stirring reaction temperature is 60-80°C, and the time is 16-24 h.

[0050] In step S04, the film is heated and stirred in a H2SO4 aqueous solution for reaction. After the reaction is completed, the product is washed and dried to obtain CC@PPy-(CH2)4-BDC.

[0051] It should be noted that, because the final ligand required is terephthalic acid, which has a certain acidity, in the first two steps of covalent grafting reaction, in order to protect the stability of the ligand molecule in an alkaline medium, 2-aminoterephthalic acid dimethyl ester is selected to protect the carboxylic acid group in the ligand. After covalent grafting, the dimethyl ester group is hydrolyzed into a dicarboxylic acid group by hydrolysis in an acidic aqueous solution, thereby ensuring the activity and stability of the ligand molecule. According to an embodiment of the present invention, the ratio of the membrane to the H2SO4 aqueous solution is 30 mg: 30 mL.

[0052] It should be noted that the concentration of the H2SO4 aqueous solution is used to control the pH of the reaction system, which is generally controlled at about 1 to 2. According to an embodiment of the present invention, the concentration of the H2SO4 aqueous solution is 0.08 mol / L.

[0053] In step S05, the CC@PPy-(CH2)4-BDC is added to an N,N-dimethylformamide solution containing a metal source and terephthalic acid for a hydrothermal reaction to form a dense MOF layer on the surface of the substrate. After the reaction is completed, the solution is cooled to room temperature, and the product is washed and vacuum dried to obtain a CC@MOF crystal film.

[0054] It should be noted that, because the high-valent metal salt has a low reactivity with the terephthalic acid molecule, in order to shorten the reaction time and obtain MOF crystals with higher crystallinity, the synthesis reaction needs to be carried out at a certain temperature and pressure. According to the embodiment of the present invention, a reactor is selected, the reaction time is 10 to 24 hours, and the reaction temperature is 120-200°C. This reaction finally obtains MOF crystals with regular shape and high crystallinity.

[0055] According to an embodiment of the present invention, the metal source is selected from salts with one of Zr, Mn, Cu, Fe, Al, V and Cr as the metal center. For example, the metal source can be a transition metal such as Cr / V / F / Mn / Al. Its metal valence is similar to that of the Zr metal selected in this experiment, and can chelate with the terephthalic acid ligand to generate the corresponding MOF crystal.

[0056] It should be noted that, compared with CC@PPy-(CH2)4-BDC, it is necessary to maintain an excess of N,N-dimethylformamide solution containing metal source and phthalic acid to ensure that the reactants are sufficient on the substrate surface to form a dense MOF layer. According to an embodiment of the present invention, the concentration of the metal source is 24 mmol L -1 .

[0057] It should be noted that the molar ratio of the ligand to the metal source will affect the metal loading, dispersion and coordination environment of the prepared catalyst surface, and thus affect the hydrogen evolution catalytic activity of the catalyst. According to the embodiment of the present invention, it is necessary to keep a slight excess of terephthalic acid, and the molar ratio of the ligand terephthalic acid to the metal source is 4:1, so as to ensure that the dispersion and loading of the metal particles of the prepared catalyst are high and there is no obvious agglomeration.

[0058] In step S06, the CC@MOF crystal film is added to H2PtCl6 solution under stirring, and NaBH4 aqueous solution is added dropwise. After the reaction is completed, the product is washed and dried, and calcined at high temperature to obtain a CC@MOF / Pt thin film, that is, the platinum-based self-supporting film catalyst.

[0059] According to an embodiment of the present invention, the usage ratio of CC@MOF crystal film, H2PtCl6 solution and NaBH4 aqueous solution is 0.2g:10mL:10mL; wherein the concentration of H2PtCl6 solution is 50mmol L -1 The concentration of NaBH4 aqueous solution is 10 mmol L -1 .

[0060] According to an embodiment of the present invention, high temperature calcination is specifically as follows: placing the CC@MOF / Pt film in an alumina crucible, calcining it to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere, keeping it at that temperature for 2 hours, and cooling it naturally.

[0061] According to the preparation method of the platinum-based self-supporting film catalyst provided by the above embodiment of the present invention, the catalyst precursor after the ligand and metal salt mixed hydrothermal treatment is heat-treated by room temperature reduction and controlled pyrolysis to prepare a self-supporting metal catalyst. The self-supporting metal catalyst retains the excellent structural strength of the carbon cloth and the porous carbon cage derived from MOF, so that the prepared catalyst has a high and uniformly dispersed metal loading. Thanks to the stable dispersion and spatial confinement of the porous carbon cage, the platinum-based metal catalyst is dispersed in the pore structure to form sub-nano particles with higher free energy, which significantly enhances its catalytic activity and cycle stability.

[0062] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the carbon-based metal nickel catalyst provided by the present invention and its preparation method and application are described in detail with specific embodiments below.

[0063] Example 1

[0064] The present invention is a method for preparing CC@UIO-66 / Pt thin film catalyst

[0065] S1. The cut carbon cloth was heated to reflux at 70° C. in nitric acid for 10 hours, ultrasonically cleaned with deionized water until neutral, and then vacuum dried at 60° C.

[0066] S2. Transfer 100 μL of pyrrole into a beaker containing 100 mL of deionized water, add carbon cloth under stirring, and after 10 minutes, add 145 mg / 25 mL of APS solution and polymerize for 4 hours. After the reaction is completed, take out the carbon cloth and dry it in vacuum at 60°C for 3 hours. Record it as CC@PPy.

[0067] S3. Take 0.2 g of CC@PPy, 0.080 g of KOH powder and 0.080 g of 1,4-dibromobutane and disperse them in 30 mL of DMF, then stir vigorously at 60 ° C for 24 h. Wash the product with deionized water and ethanol, and finally dry it in a vacuum oven at 60 ° C overnight and record it as CC@PPy-(CH2)4Br.

[0068] S4. A mixture of 0.2 g CC@PPy-(CH2)4Br, 0.080 g K2CO3 powder and 0.080 g dimethyl 2-aminoterephthalate was dispersed in 15.0 mL DMF, then vigorously stirred at 80 °C for 24 h, the product was washed with deionized water and ethanol, and dried in a vacuum oven at 60 °C overnight.

[0069] S5. The mixture of the composite carbon cloth substrate in step S4 and 0.3 g H2SO4 was stirred vigorously at 80°C for 24 h in 30.0 mL H2O. The product was washed with deionized water several times, dried in a vacuum oven at 60°C overnight, and recorded as CC@PPy-(CH2)4-BDC.

[0070] S6, add a mixture of 58.2mg ZrCl4, 200mg CC@PPy-(CH2)4-BDC and 2.5mL acetic acid (acetic acid is used for morphology control of zirconium-based metal organic framework) into 30mL DMF, ultrasonicate for 10min, then add BDC (39.87mg, 0.24mmol) into the above mixed solution, transfer to the reactor and react in an oven at 120℃ for 24h. After cooling to room temperature, dry the sample in air at 80℃, and the product is recorded as CC@UIO-66. The electron microscope image is as follows Figure 2 shown.

[0071] S7. H2PtCl6 (100 μL, 50 mmol / L) was dispersed in 10 mL of deionized water, and 0.2 g of CC@UIO-66 crystal film was added under stirring. Then NaBH4 (10 mL, 0.026 mol / L) solution was added dropwise to the above system for reaction. The product was washed and dried to obtain CC@UIO-66 / Pt film. The electron microscope image is shown in the figure below. Figure 3 shown.

[0072] S8. Place the CC@UIO-66 / Pt film in an alumina crucible, heat it to 800°C at a rate of 5°C / min in a nitrogen atmosphere, and keep it at that temperature for 2 hours, then cool it down naturally to obtain the CC@UIO-66 / Pt film catalyst. Figure 4 shown.

[0073] Example 2

[0074] The present invention is a method for preparing CC@MIL-101 / Pt thin film catalyst

[0075] Steps S1 to S5 are the same as those in Example 1 above. The corresponding CC@PPy-(CH2)4-BDC composite substrate can be prepared by referring to the above method.

[0076] S6. Add 0.24mmol Cr(NO3)3·9H2O, 200.00mg CC@PPy-(CH2)4-BDC and BDC (39.87mg, 0.24mmol) into 30mL DMF and mix evenly. Transfer to a reactor and react in an oven at 200℃ for 10h. After cooling to room temperature, wash with methanol and H2O, and dry the sample in air at 80℃, which is recorded as CC@MIL-101.

[0077] Steps S7 to S8 are the same as those in the above-mentioned embodiment 1, and the corresponding CC@MIL-101 / Pt thin film catalyst can be prepared by referring to the above-mentioned method.

[0078] Example 3

[0079] The present invention is a method for preparing CC@MIL-53 / Pt thin film catalyst

[0080] Steps S1 to S5 are the same as those in Example 1 above. The corresponding CC@PPy-(CH2)4-BDC composite substrate can be prepared by referring to the above method.

[0081] S6, 0.24mmol Al(NO3)3·9H2O, 200.00mg CC@PPy-(CH2)4-BDC in step S5, BDC (39.87mg, 0.24mmol) were added to DMF (30mL) and mixed evenly, transferred to a reactor and reacted in an oven at 200℃ for 10h. After cooling to room temperature, it was washed with methanol and H2O, and the sample was dried in air at 80℃ and recorded as CC@MIL-53.

[0082] Steps S7 to S8 are the same as those in the above-mentioned embodiment 1, and the corresponding CC@MIL-53 / Pt thin film catalyst can be prepared by referring to the above-mentioned method.

[0083] Example 4

[0084] The present invention is a method for preparing CC@MIL-100 / Pt thin film catalyst

[0085] Steps S1 to S5 are the same as those in Example 1 above. The corresponding CC@PPy-(CH2)4-BDC composite substrate can be prepared by referring to the above method.

[0086] S6, take 0.24mmol FeCl3·6H2O, 200.00mg CC@PPy-(CH2)4-BDC

[0087] BDC (39.87 mg, 0.24 mmol) was added to DMF (30 mL) and mixed evenly, then transferred to a reactor and reacted in an oven at 200°C for 10 h. After cooling to room temperature, it was washed with methanol and H2O, and the sample was dried in air at 80°C and recorded as CC@MIL-100.

[0088] Steps S7 to S8 are the same as those in the above-mentioned embodiment 1, and the corresponding CC@MIL-100 / Pt thin film catalyst can be prepared by referring to the above-mentioned method.

[0089] Example 5

[0090] The present invention is a method for preparing CC@Mn-BDC / Pt thin film catalyst

[0091] Steps S1 to S5 are the same as those in the above-mentioned embodiment 1, and the corresponding CC@PPy-(CH2)4-BDC composite substrate can be prepared by referring to the above-mentioned method.

[0092] S6, 0.24mmol of MnCl2, 200.00mg of CC@PPy-(CH2)4-BDC in step S5, and BDC (39.87mg, 0.24mmol) were added to DMF (30mL) and mixed evenly, and then transferred to a reactor and reacted in an oven at 200℃ for 10h. After cooling to room temperature, the sample was washed with methanol and H2O, and dried in air at 80℃, which was recorded as CC@Mn-BDC.

[0093] Steps S7 to S8 are the same as those in the above-mentioned embodiment 1, and the corresponding CC@Mn-BDC / Pt thin film catalyst can be prepared by referring to the above-mentioned method.

[0094] Example 6

[0095] The present invention is a method for preparing CC@V-BDC / Pt thin film catalyst

[0096] Steps S1 to S5 are the same as those in the above-mentioned embodiment 1, and the corresponding CC@PPy-(CH2)4-BDC composite substrate can be prepared by referring to the above-mentioned method.

[0097] S6, 0.24mmol of VOSO4, 200.00mg of CC@PPy-(CH2)4-BDC in step S5, and BDC (39.87mg, 0.24mmol) were added to DMF (30mL) and mixed evenly, and then transferred to a reactor and reacted in an oven at 200℃ for 10h. After cooling to room temperature, the sample was washed with methanol and H2O, and dried in air at 80℃, which was recorded as CC@V-BDC.

[0098] Steps S7 to S8 are the same as those in the above-mentioned embodiment 1, and the corresponding CC@Mn-BDC / Pt thin film catalyst can be prepared by referring to the above-mentioned method.

[0099] Example 7

[0100] The present invention is a method for preparing CC@HKUST-1 / Pt thin film catalyst

[0101] Steps S1 to S5 are the same as those in the above-mentioned embodiment 1, and the corresponding CC@PPy-(CH2)4-BDC composite substrate can be prepared by referring to the above-mentioned method.

[0102] S6, 0.24mmol Cu(NO3)3·3H2O, 15.00mg CC@PPy-(CH2)4-BDC in step S5, BDC (39.87mg, 0.24mmol) were added to DMF (30mL) and mixed evenly, transferred to a reactor and reacted in an oven at 200℃ for 10h. After cooling to room temperature, it was washed with methanol and H2O, and the sample was dried in air at 80℃ and recorded as CC@HKUST-1.

[0103] Steps S7 to S8 are the same as those in the above-mentioned embodiment 1, and the corresponding CC@Mn-BDC / Pt thin film catalyst can be prepared by referring to the above-mentioned method.

[0104] Comparative Example 1

[0105] Based on the preparation method of Example 1, the amount of pyrrole was reduced in step S2. Specifically, the amount of pyrrole was 75 μL. The prepared CC@UIO-66 / Pt catalyst was named CC@UIO-66 / Pt-L. The electron microscope image is shown in FIG. Figure 5 shown.

[0106] Comparative Example 2

[0107] On the basis of the preparation method in Example 1, the amount of pyrrole was increased in step S2. Specifically, the amount of pyrrole was 125 μL. At this time, the amount of pyrrole monomer was greater than ammonium persulfate. The prepared CC@UIO-66 / Pt catalyst was named CC@UIO-66 / Pt-H. The electron microscope image is as follows: Figure 6 shown.

[0108] The hydrogen evolution activity of the catalysts prepared in Example 1 and Comparative Examples 1-2 and commercially available Pt / C was tested using a three-electrode system. The electrode polarization curves are shown in Figure 7 shown.

[0109] The specific test method is as follows: the CC@UIO-66 / Pt sheet is clamped on the working electrode, the glassy carbon electrode is used as the working electrode, the saturated calomel (SCE) electrode is used as the reference electrode, and the electrolyte is 0.5M H2SO4 solution. The bias voltage applied during the electrochemical impedance spectroscopy (EIS) test is 100mV, and the scan rate during the polarization curve test is set to 5mV·S-1. The measured potential value is converted to the reversible hydrogen electrode (RHE) potential using the Nernst equation, and the conversion formula is: (Vvs.RHE=Vvs.SCE+0.244+0.0591×PH).

[0110] according to Figure 7 The electrode polarization curves in Figure 2 show that the CC@UIO-66 / Pt catalyst prepared in the present invention exhibits the best catalytic activity in acidic medium. -2It has the lowest overpotential in the judgment criteria under current density, which is far better than commercial platinum carbon.

[0111] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a platinum-based self-supporting film catalyst, characterized in that: The following steps are involved: S1. Using the pretreated carbon cloth as a substrate for pyrrole deposition to obtain a carbon cloth with polypyrrole deposited on the surface, namely CC@PPy; S2. The CC@PPy, KOH and 1,4-dibromobutane are dispersed in DMF, heated and stirred for reaction, and after the reaction is completed, the product is washed and dried to obtain CC@PPy-(CH2)4Br; S3. K2CO3, dimethyl 2-aminoterephthalate, and the CC@PPy-(CH2)4Br are dispersed in N,N-dimethylformamide, heated and stirred for reaction, and after the reaction is completed, the product is washed and dried to obtain a film; S4. The film is heated and stirred in an aqueous H2SO4 solution. After the reaction is completed, the product is washed and dried to obtain CC@PPy-(CH2)4-BDC; S5. adding the CC@PPy-(CH2)4-BDC to an N,N-dimethylformamide solution containing a metal source and terephthalic acid, and performing a hydrothermal reaction to form a dense MOF layer on the surface of the substrate. After the reaction is completed, the MOF layer is cooled to room temperature, and the product is washed and vacuum dried to obtain a CC@MOF crystal film. S6. Add the CC@MOF crystal film to H2PtCl6 solution under stirring, and add NaBH4 aqueous solution dropwise. After the reaction is completed, the product is washed and dried, and calcined at high temperature to obtain a CC@MOF / Pt thin film, that is, the platinum-based self-supporting film catalyst.

2. The preparation method according to claim 1, characterized in that: In step S1, the pyrrole deposition is specifically as follows: pyrrole is dispersed in water to obtain a pyrrole aqueous solution, the pretreated carbon cloth is immersed in the pyrrole aqueous solution, an ammonium persulfate solution is added dropwise, and after the polymerization reaction is completed, the carbon cloth is taken out and vacuum dried; the molar ratio of pyrrole to the ammonium persulfate in the ammonium persulfate solution is 1:(2-3).

3. The preparation method according to claim 1, characterized in that: In step S2, the usage ratio of CC@PPy, KOH, 1,4-dibromobutane and N,N-dimethylformamide is 200 mg:80 mg:80 mg:30 mL, and the heating and stirring reaction temperature is 60-80° C. and the time is 16-24 h.

4. The preparation method according to claim 1, characterized in that: In step S3, the usage ratio of CC@PPy-(CH2)4Br, K2CO3, dimethyl 2-aminoterephthalate and DMF is 200 mg:80 mg:80 mg:30 mL, the temperature of heating and stirring the reaction is 60-80°C, and the time is 16-24 h.

5. The preparation method according to claim 1, characterized in that: In step S4, the concentration of the H2SO4 aqueous solution is 0.08 mol / L, and the ratio of the membrane to the H2SO4 aqueous solution is 30 mg: (30-50) mL.

6. The preparation method according to claim 1, characterized in that: In step S5, in the solution containing a metal source and terephthalic acid, the metal source is selected from salts with one of Zr, Mn, Cu, Fe, Al, V and Cr as the metal center.

7. The preparation method according to claim 6, characterized in that: In step S5, the solution containing the metal source and terephthalic acid has a concentration of the metal source of 24 mmol L -1 The molar ratio of terephthalic acid to the metal source is 4:1, the temperature of the hydrothermal reaction is 120 to 200° C., and the time is 10 to 24 hours.

8. The preparation method according to claim 1, characterized in that: In step S6, the CC@MOF crystal film, H2PtCl6 solution and NaBH4 aqueous solution are used in a ratio of 0.2 g: 10 mL: 10 mL; wherein the concentration of H2PtCl6 solution is 50 mmol / L -1 The concentration of NaBH4 aqueous solution is 10 mmol L -1 .

9. A platinum-based self-supporting film catalyst prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the platinum-based self-supporting film catalyst according to claim 9 in an electrocatalytic hydrogen evolution reaction.

Images