A catalyst, its preparation method and application
By loading PtO nanoclusters onto a Mo2C support, the problems of low loading utilization and poor stability of Pt-based catalysts were solved, achieving high-efficiency electrocatalytic hydrogen evolution performance, reducing costs and expanding the application prospects of hydrogen production through water electrolysis.
Patent Information
- Application Number
- CN202411954238.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-10-17
- Estimated Expiration
- 2044-12-27
AI Technical Summary
Existing precious metal Pt-based composite catalysts suffer from problems such as low loading utilization, poor dispersion, poor stability, and difficult synthesis, especially with insufficient activity and high cost under alkaline conditions.
PtO nanoclusters were supported on a Mo2C nanostructure. The intermediate transition state of PtO was precisely synthesized by controlling the flow rate of the atmosphere introduced during the reaction. The nanostructure of Mo2C provided anchoring sites, improving the stability and dispersibility of PtO. The simplified preparation method solved technical problems in catalyst application. Surface electronic interactions enhanced interfacial activation ability and improved hydrogen evolution reaction kinetics.
This method achieves efficient loading and dispersion of PtO, improves the stability and activity of the catalyst, reduces the amount of precious metals used, lowers the cost, and demonstrates good electrocatalytic performance in the field of water electrolysis for hydrogen production.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of electrocatalysis, and particularly relates to a catalyst and a preparation method and application thereof. BACKGROUND
[0002] With the consumption of fossil energy, hydrogen energy has attracted widespread attention due to its high energy density, abundant reserves and clean pollution-free advantages, and water electrolysis is considered to be very promising. Current studies show that platinum (Pt) based catalysts have the best hydrogen evolution performance under acidic conditions, but the alkaline hydrogen evolution activity of metal Pt catalysts is obviously insufficient and the electrochemical stability is poor, and the price of Pt material is expensive. Therefore, it is of great significance to research and develop low-load, high-activity Pt-based catalysts under full pH conditions. Dispersing Pt on the carrier can effectively reduce the Pt loading and size, and effectively improve the electrochemical activity of Pt. Carbon is the most widely used carrier material in industry, and the Pt loading of commercial platinum-carbon (Pt / C) catalyst is mostly 20wt% and 40wt%. However, its cost is high, the number of exposed active sites is small, and there are problems such as unstable catalyst interface and short service life. At the same time, some oxidation products of the carbon carrier, such as carbon monoxide, will strongly adsorb on the Pt surface, further reducing the catalytic activity of Pt. Therefore, it is of great significance to further explore different carrier materials and optimize the preparation process of noble metal Pt-based materials. SUMMARY
[0003] The main purpose of the present application is to solve the problems and deficiencies existing in the prior art, and to provide a catalyst and a preparation method and application thereof, which can solve the problems of low loading utilization, poor dispersion, poor stability and difficult synthesis of existing noble metal Pt-based composite catalysts.
[0004] To solve the above technical problems, the technical scheme of the present application is as follows:
[0005] A catalyst, comprising a nanostructured Mo2C carrier and PtO nanoclusters loaded on the Mo2C carrier.
[0006] In the above scheme, the size of the PtO nanoclusters is 2-5nm.
[0007] In the above scheme, the loading of Pt is 0.1-10wt%.
[0008] In the above scheme, the nanostructure morphology of Mo2C is flaky, flower-shaped, strip-shaped, tubular or linear.
[0009] The preparation method of the catalyst comprises the following steps:
[0010] Mixing the nanostructured Mo2C carrier with a platinum metal compound solution to obtain a mixed solution;
[0011] The mixed solution is stirred and reacted at 50-95 DEG C for 0.5-5h, and the reaction atmosphere is continuously introduced;
[0012] After the reaction, the catalyst is obtained after filtration, washing and drying.
[0013] In the above scheme, the platinum-containing metal compound includes one or more of a combination of ammonium hexachloroplatinate, chloroplatinic acid hexahydrate or platinum dichloride.
[0014] In the above scheme, the concentration of the platinum-containing metal compound solution is 0.2-0.4 mM / L.
[0015] In the above scheme, the mass ratio of the Pt element content in the mixed solution to Mo2C is 1-10:100.
[0016] In the above scheme, the reaction atmosphere is oxygen or an oxygen-containing atmosphere.
[0017] In the above scheme, the flow rate of the reaction atmosphere is 140-200 sccm.
[0018] In the above scheme, the platinum-containing metal compound solution is an aqueous solution or an alcohol solution.
[0019] The application of the catalyst in electrocatalytic hydrogen production.
[0020] Compared with the prior art, the application has the following beneficial effects:
[0021] 1) The method of controlling the flow rate of the introduced atmosphere during the reaction process is adopted to accurately control the synthesis of the intermediate transition state PtO of the Pt metal oxide. The catalytic performance of PtO is better than that of the metal Pt, because the long Pt-O bond is beneficial to proton-electron coupling and accelerates the release of H2. However, PtO belongs to the transition state of the oxidation of the metal Pt, has poor stability, and is easily oxidized into high-oxidation-state PtO2 during the synthesis process. Therefore, the application can accurately control the synthesis of PtO, simultaneously utilize the carrier effect to improve the stability of PtO, and improve the activity of the PtO catalyst under alkaline conditions.
[0022] 2) The nano-Mo2C is used as the carrier of PtO, the controllable adjustment of the Pt loading in the Mo2C-PtO material can be realized through different feeding ratios of the platinum-containing metal compound and Mo2C, the large specific surface area and the rich overhanging bonds on the surface of the nano-Mo2C structure provide sufficient anchoring sites for the PtO nanoclusters, greatly improve the uniformity, dispersity and stability of the PtO nanoclusters loaded on the surface of the Mo2C material, greatly improve the effective loading rate of Pt and reduce the amount of Pt, and reduce the cost of the catalyst.
[0023] 3) The extremely small PtO nanoclusters prepared by the method are decorated on the surface of the high-conductivity Mo2C matrix, which greatly promotes the electron interaction between the interfaces, enhances the activation ability of the interface water, greatly improves the hydrogen evolution reaction kinetics, and the Mo2C matrix itself also serves as a hydrogen evolution active phase to improve the active site density, thereby showing good electrocatalytic hydrogen evolution performance, which is superior to most platinum-based electrocatalysts, and has a very broad application prospect in the field of water electrolysis hydrogen production;
[0024] 4) The preparation method disclosed by the application is simple, no raw materials other than the platinum source are used, no by-products are generated, the product has high purity, and is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS
[0025] Figure 1 The figure is a schematic diagram of the preparation process of the Mo2C-PtO material described in the application;
[0026] Figure 2 The figure is an XRD spectrum of the Mo2C-PtO material prepared in Examples 1-3 of the application;
[0027] Figure 3 The figure is an XPS spectrum of the Mo2C-PtO material prepared in Examples 4 and 5 of the application;
[0028] Figure 4 The figure is a scanning electron microscope image of the Mo2C-PtO material prepared in Example 1 of the application;
[0029] Figure 5 The figure is a transmission electron microscope image of the Mo2C-PtO material prepared in Example 1 of the application;
[0030] Figure 6 The figure is an element distribution map of the Mo2C-PtO material prepared in Example 1 of the application, wherein Figure 6 a is a transmission electron microscope dark field image, Figure 6 b, c, e, f are distribution maps of Pt, C, Mo, and O elements, respectively, Figure 6 d is an all-element distribution summary map;
[0031] Figure 7 The figure is a scanning electron microscope image of the Mo2C-PtO material prepared in Example 2 of the application;
[0032] Figure 8 The figure is a transmission electron microscope image of the Mo2C-PtO material prepared in Example 2 of the application;
[0033] Figure 9 The figure is a transmission electron microscope image of the Mo2C-PtO material prepared in Example 3 of the application;
[0034] Figure 10Polarization curve of electrocatalytic hydrogen evolution reaction of the nano-carbide molybdenum material prepared in Example 1, 2 and 3 of the present application in 1M KOH solution;
[0035] Figure 11 Tafel slope graph of the nano-carbide molybdenum material prepared in Example 1, 2 and 3 of the present application in 1M KOH solution;
[0036] Figure 12 Scanning electron microscope graph of the material prepared in Comparative Example 1 of the present application;
[0037] Figure 13 Transmission electron microscope graph of the material prepared in Comparative Example 2 of the present application;
[0038] Figure 14 XPS graph of the material prepared in Comparative Example 3 and Example 1 of the present application;
[0039] Figure 15 Polarization curve of electrocatalytic hydrogen evolution reaction of the nano-carbide molybdenum material prepared in Example 1 and Comparative Example 3, 5 of the present application in 1M KOH solution;
[0040] Figure 16 Tafel slope graph of the nano-carbide molybdenum material prepared in Example 1 and Comparative Example 3, 5 of the present application in 1M KOH solution;
[0041] Figure 17 XPS graph of the material prepared in Comparative Example 4 and Example 1 of the present application;
[0042] Figure 18 XPS graph of the material prepared in Comparative Example 5 and Example 1 of the present application;
[0043] Figure 19 Transmission electron microscope graph of the material prepared in Comparative Example 6 of the present application;
[0044] Figure 20 Transmission electron microscope graph of the material prepared in Comparative Example 7 of the present application. DETAILED DESCRIPTION
[0045] The principles and features of the present application are described below in connection with examples, which are only used to explain the present application and not to limit the scope of the present application. In addition, it is worth mentioning that the raw materials involved in the present application are ordinary commercially available products unless otherwise specified.
[0046] In the following examples, the nano-Mo2C used is Mo2C nanosheet, and the specific preparation method comprises the following steps: 0.5 g of molybdenum disulfide, 1.6 g of sodium carbonate and 5 g of urea are ground and uniformly mixed, and then the mixture is heated to 850°C at a heating rate of 5°C / min in a tube furnace, and then kept at 850°C for 4 h, and then cooled, washed with water and dried to obtain Mo2C nanosheet;
[0047] Example 1
[0048] A Mo2C-PtO catalyst, and a schematic diagram of the preparation process thereof is shown in Figure 1 , and the specific steps comprise the following steps:
[0049] 1) 500 mg of Mo2C is added to an aqueous solution of chloroplatinic acid with a volume of 64 mL and a concentration of 0.2 mM / L, i.e. the mass ratio of Pt element to Mo2C is 1:100, and then ultrasonic mixing is performed for 1 h to uniformly disperse.
[0050] 2) The mixed solution is placed in a magnetic stirring water bath and heated and stirred, and oxygen is continuously introduced at a flow rate of 160 sccm, and then kept at 90°C for 1 h, and then cooled to room temperature.
[0051] 3) The Mo2C-PtO composite catalyst is obtained by washing with deionized water, suction filtration and drying.
[0052] The XRD pattern of the product obtained in this example is shown in Figure 2 . The characteristic peak height of the obtained product is consistent with the standard card Mo2C JCPDS #72-1683, but no PtO characteristic peak is observed. Since the loading of Pt is less than 5wt%, the characteristic peak is masked by background noise.
[0053] Figure 4 The scanning electron microscope image of the product obtained in this example is shown in the results, which shows that the morphology of the obtained sheet-shaped Mo2C is maintained well. Figure 5 The transmission electron microscope image of the product obtained in this example is shown in Figure 5 a, which shows the crystal (101) crystal face of PtO, and the interplanar spacing thereof is 0.227 nm. Figure 5 a, the particle size of the PtO nanocluster on the Mo2C nanosheet carrier is about 2 nm, Figure 6 The element distribution map of the obtained product shows that the fine PtO nanoclusters are uniformly dotted on the surface of the Mo2C nanosheet carrier.
[0054] 5 mg of the product obtained in this example is dispersed in 1 mL of isopropanol, and 20 μL of Nafion solution is added dropwise, and then ultrasonic mixing is performed for 30 min, and then the mixture is dropped onto foamed copper and dried to prepare a hydrogen evolution electrode, which is placed in 1M KOH for testing. The measured electrocatalytic hydrogen evolution reaction polarization curve and Tafel slope graph are respectively shown in Figure 10 and Figure 11as shown. The results show that when the current density is 10 mA cm -2 , the hydrogen evolution reaction overpotential is only 10 mV, and the Tafel slope is only 24 mV dec -1 , and under the condition of a large current of 1000 mA cm -2 , the overpotential is as low as 336 mV, showing excellent electrocatalytic hydrogen evolution performance.
[0055] Example 2
[0056] A Mo2C-PtO catalyst was prepared by the method substantially the same as in Example 1, except that the volume of the chloroplatinic acid solution put in Example 1 was changed to 320 mL, and the concentration was 0.4 mM / L, and the mass ratio of Pt element to Mo2C was 10:100.
[0057] Figure 2 The XRD spectrum in the present embodiment shows that the product obtained in the present embodiment is Mo2C, Figure 7 The scanning electron microscope image in the present embodiment can see that the product maintains the original Mo2C flaky morphology. Figure 8 The TEM image in the present embodiment can observe the obvious PtO particle distribution on the surface of the Mo2C carrier, and the particle size of the nanocluster is about 5 nm. It shows that with the increase of the PtO loading, the PtO nanocluster particle size grows up.
[0058] The water electrolysis hydrogen evolution reaction polarization curve and the Tafel slope graph of the product obtained in the present embodiment were measured by the method described in Reference Example 1, as shown in Figure 10 and Figure 11 respectively. The results show that when the current density is 10 mA cm -2 , the hydrogen evolution reaction overpotential is only 41 mV, and the Tafel slope is only 38 mV dec -1 , and under the condition of a large current of 1000 mA cm -2 , the overpotential is as low as 475 mV.
[0059] Example 3
[0060] A Mo2C-PtO catalyst was prepared by the method substantially the same as in Example 1, except that the water bath temperature in Example 1 was changed to 50℃, and the holding time was 5h.
[0061] Figure 2 The XRD spectrum in the present embodiment shows that the product obtained in the present embodiment is Mo2C, Figure 9 The transmission electron microscope image in the present embodiment can also clearly observe the uniform dispersion of PtO nanocluster particles on the Mo2C nanosheet substrate.
[0062] The water electrolysis hydrogen evolution reaction polarization curve and the Tafel slope graph of the product obtained in the present embodiment were measured by the method described in Reference Example 1, as shown inFigure 10 and Figure 11 The results show that when the current density is 10 mA cm -2 , the hydrogen evolution reaction overpotential is only 63 mV, and the Tafel slope is only 52 mV dec -1 , and under the condition of a large current of 1000 mA cm -2 , the overpotential is as low as 521 mV.
[0063] Example 4
[0064] A Mo2C-PtO catalyst was prepared by the method substantially the same as in Example 1, except that the gas flow rate in Example 1 was changed to 140 sccm.
[0065] Figure 3 The XPS spectrum in Example 4 shows that the Pt element in the product obtained in this example exists in the form of PtO, and the obtained PtO is relatively pure.
[0066] Example 5
[0067] A Mo2C-PtO catalyst was prepared by the method substantially the same as in Example 1, except that the gas flow rate in Example 1 was changed to 200 sccm.
[0068] Figure 3 The XPS spectrum in Example 5 shows that the Pt element in the product obtained in this example exists in the form of PtO, and the obtained PtO is relatively pure.
[0069] Comparative Example 1
[0070] A Mo2C-PtO material was prepared by the method substantially the same as in Example 1, except that the temperature of water bath stirring was controlled at 100°C, and the time was 2h.
[0071] The SEM image of the product obtained in Comparative Example 1 is shown in Figure 12 The results show that too high water bath stirring temperature can cause a certain degree of damage to the morphology of the Mo2C carrier.
[0072] Comparative Example 2
[0073] A Mo2C-PtO material was prepared by the method substantially the same as in Example 1, except that the temperature of water bath stirring was controlled at 30°C.
[0074] The TEM image of the product obtained in Comparative Example 2 is shown in Figure 13 The Mo2C substrate surface is not loaded with PtO nanoclusters, and the results show that too low water bath stirring temperature cannot promote the decomposition of chloroplatinic acid and deposition on Mo2C.
[0075] Comparative Example 3
[0076] A Mo2C-PtO material was prepared in the same way as in Example 1, except that the oxygen flow rate during the reaction was controlled at 300 seem.
[0077] The XPS spectrum of the product obtained in this comparative example is shown in Figure 14 , and the Pt element in the product obtained exists in the form of PtO2 with a higher valence of nearly 50%, and the electrochemical activity diagram of the product obtained is shown in Figure 15 , Figure 16 The results show that the excessive oxygen flow rate during the continuous atmosphere flow can cause excessive oxidation of the Pt element, resulting in the formation of PtO2, and the electrochemical activity is also reduced accordingly.
[0078] Comparative Example 4
[0079] A Mo2C-PtO material was prepared in the same way as in Example 1, except that the oxygen flow rate during the reaction was controlled at 220 seem.
[0080] The XPS spectrum of the product obtained in this comparative example is shown in Figure 17 , and the Pt element in the product obtained exists in the form of PtO2 with a higher valence and PtO with an intermediate valence. The results show that when the oxygen flow rate exceeds 200 seem, the amount of PtO2 formed will increase with the increase of the oxygen flow rate.
[0081] Comparative Example 5
[0082] A Mo2C-PtO material was prepared in the same way as in Example 1, except that the oxygen flow rate during the reaction was controlled at 100 seem.
[0083] The XPS spectrum of the product obtained in this comparative example is shown in Figure 18 , and the Pt element in the product obtained exists in the form of Pt with a lower valence and PtO with an intermediate valence, and the electrochemical activity diagram of the product obtained is shown in Figure 15 , Figure 16 The results show that the presence of Pt with a lower valence can reduce the electrochemical activity.
[0084] Comparative Example 6
[0085] A Mo2C-PtO material was prepared in the same way as in Example 1, except that Mo2C was replaced by MoS2.
[0086] The TEM diagram of the product obtained in this comparative example is shown in Figure 19 , and in the product obtained, the Pt element forms relatively dense nanoparticles resulting in agglomeration, and the results show that the bulk MoS2 cannot provide sufficient attachment sites for Pt.
[0087] Comparative Example 7
[0088] A Mo2C-PtO material was prepared in substantially the same manner as Example 1, except that Mo2C was replaced with carbon support.
[0089] The TEM image of the product obtained in the present comparative example is shown in Figure 20 In the product obtained, Pt elements agglomerated into relatively dense nanoparticles. The results show that it is difficult to highly disperse Pt on carbon material using this synthesis method.
[0090] It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.
Claims
1. A catalyst, characterized in that The catalyst includes a nanostructured Mo2C carrier and PtO nanoclusters supported on the Mo2C carrier. The preparation method of the catalyst includes the following steps: mixing the nanostructured Mo2C carrier with a platinum metal compound solution to obtain a mixed solution; stirring the mixed solution at 50°C-95°C for 0.5 h-5 h while continuously introducing a reaction atmosphere; after the reaction is completed, filtering, washing, and drying to obtain the catalyst; the reaction atmosphere is oxygen or an oxygen-containing atmosphere, and the flow rate of the reaction atmosphere is 140-200 sccm.
2. The catalyst according to claim 1, characterized in that The size of the PtO nanoclusters is 2-5 nm.
3. The catalyst according to claim 1, wherein The Pt loading is 0.1-10 wt %.
4. The catalyst according to claim 1, characterized in that The nanostructure morphology of the Mo2C is flake-shaped, flower-shaped, ribbon-shaped, tubular or linear.
5. The method for preparing the catalyst according to claim 1, wherein The steps include: mixing the nanostructured Mo2C support with a platinum-containing metal compound solution to obtain a mixed solution; The mixed solution is stirred and reacted at 50° C.-95° C. for 0.5 h-5 h, and a reaction atmosphere is continuously introduced, wherein the reaction atmosphere is oxygen or an oxygen-containing atmosphere, and the flow rate of the reaction atmosphere is 140-200 sccm; After the reaction is completed, the catalyst is obtained after filtering, washing and drying.
6. The preparation method according to claim 5, wherein The concentration of the platinum metal compound solution is 0.2~0.4 mM / L.
7. The preparation method according to claim 5, wherein The mass ratio of the Pt element content to Mo2C in the mixed solution is 1-10:
100.
8. Use of the catalyst according to claim 1 in electrocatalytic hydrogen production.