Se-doped Pt-based catalyst, preparation method and application thereof

Abstract

This invention discloses a Se-doped Pt-based catalyst, its preparation method, and its application, relating to the field of catalyst technology. The preparation method of the Se-doped Pt-based catalyst includes the following steps: (1) mixing conductive carbon black and selenium dioxide powder uniformly to obtain a mixture; (2) heating the mixture to 250-350℃ under an inert atmosphere and holding for 0.5-2 h; (3) subsequently heating to 950-1100℃ and holding for 0.5-2 h to obtain powder A; (4) dissolving a platinum source in water to obtain solution B, then adding powder A to solution B and mixing uniformly, followed by rotary evaporation, grinding, and heating in a mixed atmosphere of H2 and Ar to obtain the Se-doped Pt-based catalyst. The Se-doped Pt-based catalyst prepared by the method of this invention exhibits high catalytic activity and stability in the hydrogenation reaction.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a Se-doped Pt-based catalyst, its preparation method, and its application. Background Technology

[0002] With the accelerating trend towards a green and low-carbon energy transition, hydrogen, as a clean and efficient energy carrier, is rapidly expanding its application. Whether in powering hydrogen fuel cell vehicles or in the energy storage and conversion of distributed power generation systems, hydrogen is becoming increasingly common. However, hydrogen is flammable and explosive, with an explosive limit range of 4%-75.6%. Leaks during production, storage, transportation, and use can easily lead to serious safety accidents. Against this backdrop, the need for hydrogen sensors capable of accurately and rapidly detecting hydrogen concentration is extremely urgent.

[0003] Electrochemical hydrogen sensors utilize the electrochemical reaction of hydrogen gas on sensing electrodes to collect changing electrical signals, thereby achieving accurate detection of hydrogen leaks. The primary electrochemical reaction in these sensors is the hydrogen oxidation reaction (HOR). However, in practical applications, traditional electrochemical hydrogen sensors face challenges such as insufficient catalytic activity and poor stability. There is an urgent need to develop novel catalysts to improve their overall performance and meet the stringent requirements of high sensitivity, rapid response, and long-term stable operation in real-world applications.

[0004] Currently, the catalytic performance of the hydrogen oxidation reaction in electrochemical hydrogen sensors directly affects the overall performance of the sensor. Existing catalysts suffer from insufficient catalytic activity, specifically: when low concentrations of hydrogen are present in the environment, they cannot effectively catalyze the hydrogen oxidation reaction, making it difficult to generate a captureable electrical signal. This ultimately leads to relatively low core indicators such as sensor sensitivity and response speed, significantly limiting their application in demanding scenarios such as high-precision monitoring. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a Se-doped Pt-based catalyst, its preparation method, and its application. The Se-doped Pt-based catalyst prepared using the method of this invention exhibits high catalytic activity and stability in hydrogenation reactions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing a Se-doped Pt-based catalyst, comprising the following steps: (1) Mix conductive carbon black and selenium dioxide powder evenly to obtain a mixture; (2) Heat the mixture under an inert atmosphere to 250-350℃ and keep it at that temperature for 0.5-2 h; (3) Then the temperature is raised to 950-1100℃ and held for 0.5-2 h to obtain powder A; (4) Dissolve the platinum source in water to obtain solution B, then add powder A to solution B and mix evenly. After rotary evaporation and grinding, heat the mixture in a mixed atmosphere of H2 and Ar to obtain the Se-doped Pt-based catalyst.

[0007] In this invention, Pt serves as the catalytic active site, C serves as the Pt support to uniformly disperse Pt, and Se serves as the dopant to enhance the interaction between the carbon support and Pt, suppressing sintering (agglomeration) during the heat treatment of the Pt support. The method described in this invention is simple to prepare, and the resulting catalyst exhibits high activity.

[0008] Preferably, the specific surface area of ​​the conductive carbon black in step (1) is 750-900 m². 2 / g, for example, could be 750m 2 / g、760m 2 / g、770m 2 / g、780m 2 / g、790m 2 / g、800m 2 / g、820m 2 / g、840m 2 / g、860m 2 / g、880m 2 / g、900m 2 / g or a range consisting of any two of its values.

[0009] Preferably, the average particle size of the conductive carbon black in step (1) is 25-35 nm, for example, it can be 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm or any two of these values.

[0010] Preferably, the mass ratio of conductive carbon black to selenium dioxide powder in step (1) is (0.3-2):1, for example, it can be 0.3:1, 0.5:1, 0.6:1, 0.8:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, or any range of two of these values.

[0011] Preferably, the heating rate in step (2) is 3-8℃ / min, for example, it can be 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min or any two of these values.

[0012] Preferably, the heating rate in step (3) is 5-15℃ / min, for example, it can be 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, 15℃ / min or any two of these values.

[0013] In steps (2) and (3) of this invention, if the heating temperature is too low, selenium dioxide cannot sublimate, thus preventing doping. If the heating temperature is too high, the sublimation rate will be too fast, which is not conducive to doping. If the heating rate is too slow, the heat treatment time will increase, increasing energy consumption. If the heating rate is too fast, the local reaction will be uneven, thus affecting the consistency of the sample. Therefore, by controlling the heating temperature and heating rate, this invention is beneficial to improving the activity and stability of the catalyst.

[0014] Preferably, in step (4), the volume percentage of H2 in the mixed atmosphere is 3-10%, and the volume percentage of Ar is 90-97%.

[0015] Preferably, the temperature during the heat treatment in step (4) is 50-250℃, and the holding time is 0.5-5 h.

[0016] More preferably, the temperature during the heating treatment in step (4) is 100-200℃ and the holding time is 1-3 h.

[0017] Preferably, the platinum source in step (4) includes at least one of platinum nitrate, chloroplatinic acid, and platinum acetylacetonate.

[0018] Preferably, in step (4), the ratio of platinum source to water is 0.1-0.5 g: 10-30 mL.

[0019] Secondly, the present invention also provides a Se-doped Pt-based catalyst prepared by the above method.

[0020] Thirdly, the present invention also provides an application of a Se-doped Pt-based catalyst in HOR (hydrogenation reaction).

[0021] Preferably, the Se-doped Pt-based catalyst is the Se-doped Pt-based catalyst described in the second aspect of the present invention.

[0022] Specifically, the Se-doped Pt-based catalyst is assembled into an electrochemical hydrogen sensor.

[0023] More specifically, coating the Se-doped Pt-based catalyst onto both sides of a proton exchange membrane forms an electrochemical hydrogen sensor module, which is the core component for the electrochemical reaction. When hydrogen comes into contact with the catalyst, a hydrogen oxidation reaction occurs, generating a detectable current. When combined with electrical components, it becomes an electrochemical hydrogen sensor.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes the properties of selenium dioxide (sublimation at 315℃) and controls the heat treatment temperature during sample preparation to achieve Se doping. This method can achieve efficient synthesis without liquid phase (precursor mixing is directly heat-treated in a tube furnace), achieving uniform Se doping without reaction in solution. Furthermore, the catalyst described in this invention has high catalytic activity and is suitable for HOR (hydrogenation reaction). Attached Figure Description

[0025] Figure 1 These are nitrogen adsorption-desorption isotherms of the catalysts prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0026] Figure 2 These are pore size distribution diagrams of the catalysts prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0027] Figure 3 These are the XRD patterns of the catalysts prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0028] Figure 4 These are TEM images of the catalysts prepared in Examples 1-3 and Comparative Example 1 of the present invention, and elemental distribution diagrams of Pt / SeC-0.4 (Example 2).

[0029] Figure 5 These are the XPS full spectra of the catalysts prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0030] Figure 6 These are XPS spectra of Pt4f of the catalysts prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0031] Figure 7 These are LSV curves of the catalysts prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0032] Figure 8 This is the LSV curve of the catalyst prepared in Example 2 (Pt / SeC-0.4) of the present invention. Detailed Implementation

[0033] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the scope of protection and implementation of the present invention are not limited thereto.

[0034] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0035] Example 1 This embodiment discloses a method for preparing a Se-doped Pt-based catalyst, including the following steps: (1) Weigh 0.5g of conductive carbon black (EC-300J) and 0.2g of selenium dioxide powder and grind and mix them evenly in a crucible to obtain a mixture; the mass ratio of conductive carbon black to selenium dioxide powder is 2.5:1; (2) Place the mixture in a tube furnace, pre-set the heating program in the tube furnace and introduce N2 to remove residual impurity gas in the tube. In a high-purity N2 environment, heat the mixture to 320°C at a heating rate of 5°C / min and hold it for 1 hour. (3) Then the temperature was increased to 1000℃ at a rate of 5℃ / min and held for 1h to obtain powder A; (4) Dissolve 0.22g of pure platinum nitrate powder in 15mL of deionized water and stir for 10min to obtain solution B. Then add powder A to solution B and mix overnight. After rotary evaporation and grinding, place it in a mixed atmosphere of H2 and Ar (H2 volume percentage is 5% and Ar volume percentage is 95%) for heating treatment. The heating temperature is 150℃ and kept at 2h. After cooling to room temperature, take it out to obtain Se-doped Pt-based catalyst, denoted as Pt / SeC-0.2, with a Pt loading of 20wt%.

[0036] Example 2 This embodiment discloses a method for preparing a Se-doped Pt-based catalyst, including the following steps: (1) Weigh 0.5g of conductive carbon black (EC-300J) and 0.4g of selenium dioxide powder and grind and mix them evenly in a crucible to obtain a mixture; the mass ratio of conductive carbon black to selenium dioxide powder is 1.25:1; (2) Place the mixture in a tube furnace, pre-set the heating program in the tube furnace and introduce N2 to remove residual impurity gas in the tube. In a high-purity N2 environment, heat the mixture to 320°C at a heating rate of 5°C / min and hold it for 1 hour. (3) Then the temperature was increased to 1000℃ at a rate of 5℃ / min and held for 1h to obtain powder A; (4) Dissolve 0.22g of pure platinum nitrate powder in 15mL of deionized water and stir for 10min to obtain solution B. Then add powder A to solution B and mix overnight. After rotary evaporation and grinding, place it in a mixed atmosphere of H2 and Ar (H2 volume percentage is 5% and Ar volume percentage is 95%) for heating treatment. The heating temperature is 150℃ and kept at 2h. After cooling to room temperature, take it out to obtain Se-doped Pt-based catalyst, denoted as Pt / SeC-0.4, with a Pt loading of 20wt%.

[0037] Example 3 This embodiment discloses a method for preparing a Se-doped Pt-based catalyst, including the following steps: (1) Weigh 0.5g of conductive carbon black (EC-300J) and 0.6g of selenium dioxide powder and place them in a crucible to grind and mix them evenly to obtain a mixture; the mass ratio of conductive carbon black to selenium dioxide powder is 0.83:1; (2) Place the mixture in a tube furnace, pre-set the heating program in the tube furnace and introduce N2 to remove residual impurity gas in the tube. In a high-purity N2 environment, heat the mixture to 320°C at a heating rate of 5°C / min and hold it for 1 hour. (3) Then the temperature was increased to 1000℃ at a rate of 5℃ / min and held for 1h to obtain powder A; (4) Dissolve 0.22g of pure platinum nitrate powder in 15mL of deionized water and stir for 10min to obtain solution B. Then add powder A to solution B and mix overnight. After rotary evaporation and grinding, place it in a mixed atmosphere of H2 and Ar (H2 volume percentage is 5% and Ar volume percentage is 95%) for heating treatment. The heating temperature is 150℃ and kept at 2h. After cooling to room temperature, take it out to obtain Se-doped Pt-based catalyst, denoted as Pt / SeC-0.6, with a Pt loading of 20wt%.

[0038] Comparative Example 1 A method for preparing a catalyst includes the following steps: A certain amount of platinum nitrate was dissolved in 15 mL of deionized water and stirred for 10 min to obtain solution B. Then, 0.5 g of conductive carbon black (EC-300J) was added to solution B and mixed overnight. After rotary evaporation and grinding, the mixture was placed in a mixed atmosphere of H2 and Ar (H2 volume percentage 5%, Ar volume percentage 95%) for heating treatment at 150 °C for 2 h. After cooling to room temperature, the catalyst was obtained with a Pt loading of 20 wt%, denoted as Pt / C.

[0039] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 was not doped with Se.

[0040] Comparative Example 2 A method for preparing a Se-doped Pt-based catalyst includes the following steps: (1) Weigh 0.5g of conductive carbon black (EC-300J) and 0.4g of selenium dioxide powder and grind and mix them evenly in a crucible to obtain a mixture; the mass ratio of conductive carbon black to selenium dioxide powder is 1.25:1; (2) The mixture is placed in a tube furnace. The tube furnace is pre-programmed with a heating program and N2 is introduced to remove residual impurity gases in the tube. Under high-purity N2 environment, the temperature is raised to 1000℃ at a heating rate of 5℃ / min and held for 2h to obtain powder A. (3) Dissolve 0.22g of pure platinum nitrate powder in 15mL of deionized water and stir for 10min to obtain solution B. Then add powder A to solution B and mix overnight. After rotary evaporation and grinding, place it in a mixed atmosphere of H2 and Ar (H2 volume percentage is 5% and Ar volume percentage is 95%) for heating treatment. The heating temperature is 150℃ and kept at 2h. After cooling to room temperature, take it out to obtain Se-doped Pt-based catalyst with Pt loading of 20wt%.

[0041] The difference between Comparative Example 2 and Example 1 is that in step (2) of Comparative Example 2, the temperature is directly heated to 1000°C without segmented heating, which makes the selenium dioxide sublimation rate too fast, which is not conducive to Se doping and thus leads to a decrease in the activity of the catalyst.

[0042] Comparative Example 3 A method for preparing a Se-doped Pt-based catalyst includes the following steps: (1) Weigh 0.5g of conductive carbon black (EC-300J) and 0.4g of selenium dioxide powder and grind and mix them evenly in a crucible to obtain a mixture; the mass ratio of conductive carbon black to selenium dioxide powder is 1.25:1; (2) The mixture was placed in a reaction vessel at 200°C for hydrothermal reaction for 5 hours. After the reaction, the material was taken out and then calcined in a pyrolysis furnace at 800°C for 1 hour under argon atmosphere to obtain powder A. (3) Place powder A in a tube furnace. Set the heating program in advance and introduce N2 to remove residual impurity gas in the tube. In a high-purity N2 environment, heat the powder A to 1000℃ at a heating rate of 5℃ / min and hold for 2 hours to obtain powder B. (4) Dissolve 0.22g of pure platinum nitrate powder in 15mL of deionized water and stir for 10min to obtain solution C. Then add powder B to solution C and mix overnight. After rotary evaporation and grinding, place it in a mixed atmosphere of H2 and Ar (H2 volume percentage is 5% and Ar volume percentage is 95%) for heating treatment. The heating temperature is 150℃ and kept at 2h. After cooling to room temperature, take it out to obtain Se-doped Pt-based catalyst with Pt loading of 20wt%.

[0043] The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 uses a hydrothermal method to prepare the Se-doped Pt-based catalyst, which requires the addition of organic solvents, which is not environmentally friendly. In contrast, this invention utilizes the properties of selenium dioxide (sublimation at 315℃) and controls the heat treatment temperature during sample preparation to achieve Se doping. This method can achieve a liquid-phase-free process, eliminating the need for reaction in solution to achieve uniform Se doping, making it green and environmentally friendly.

[0044] Performance testing like Figure 1-2 As shown, Figure 1 To support the nitrogen adsorption-desorption isotherm test results, this invention provides pore structure parameters for four catalyst samples: Pt / C (Comparative Example 1), Pt / SeC-0.2 (Example 1), Pt / SeC-0.4 (Example 2), and Pt / SeC-0.6 (Example 3). The nitrogen adsorption-desorption curves of all four catalyst samples exhibited hysteresis loops at high relative pressures, a characteristic of typical Type IV isotherms. Combined with TEM and pore distribution curves, it can be seen that in addition to the micropores within the carbon spheres, the accumulation between carbon spheres creates a large number of mesopores. Furthermore, the specific surface area of ​​C, SeC-0.2, SeC-0.4, and SeC-0.6 is 785.9 m². 2 / g, 872.5 m 2 / g、889.2 m 2 / g and 874.3 m 2 / g indicates that Se doping does not lead to the collapse of the porous structure or a decrease in the specific surface area of ​​the carbon support. Furthermore, the specific surface area of ​​the carbon support with different Se doping amounts is similar, and a higher specific surface area is beneficial for the uniform dispersion and support of active metals.

[0045] like Figure 3 As shown, the XRD results of the four platinum-loaded catalyst samples, in addition to the (002) and (100) diffraction peaks of carbon, show diffraction peaks at 39.8°, 46.1°, and 67.8° corresponding to the (111), (200), and (220) crystal planes of Pt, respectively, indicating that Pt particles were successfully loaded onto the carbon support. Calculations using the Scherrer equation yielded average particle sizes of 3.6 nm, 3.3 nm, 2.9 nm, and 2.9 nm for Pt / C, Pt / SeC-0.2, Pt / SeC-0.4, and Pt / SeC-0.6, respectively. This is because the interaction force between the Se-doped carbon support and Pt is enhanced, suppressing the agglomeration and sintering of Pt particles during heat treatment. Smaller particles are beneficial to the utilization rate of Pt metal.

[0046] like Figure 4 As shown, Figure 4TEM images of four catalysts are shown. Careful observation revealed that, compared to the undoped catalyst, the three Se-doped catalyst samples showed a more uniform distribution of Pt nanoparticles with slightly smaller particle sizes, consistent with the XRD results.

[0047] like Figure 5-6 As shown, Figure 5 The XPS full spectra of Pt / C, Pt / SeC-0.2, Pt / SeC-0.4, and Pt / SeC-0.6 all showed obvious Pt peaks, while Pt / SeC-0.2, Pt / SeC-0.4, and Pt / SeC-0.6 all showed obvious Se peaks, indicating the successful introduction of Pt and Se. Figure 6 The Pt 4f spectra of Pt / C, Pt / SeC-0.2, Pt / SeC-0.4, and Pt / SeC-0.6 catalysts are shown. The Pt 4f signal can be decomposed into two parts, with peaks at binding energies of 71.7 eV and 75.0 eV corresponding to the Pt 4f7 / 2 and Pt 4f5 / 2 orbitals, indicating successful Pt loading. Compared to Pt / C, the Pt 4f7 / 2 of the selenium-doped samples shows varying degrees of shift, indicating direct electron transfer between the Se-doped carbon support and Pt, enhancing the support-metal interaction. Pt / SeC-0.4 and Pt / SeC-0.6 exhibit the strongest support-metal interaction, corresponding to their smallest particle size observed in TEM tests.

[0048] like Figure 7 As shown, Figure 7 The hydroxide oxidation performance of Pt / C, Pt / SeC-0.2, Pt / SeC-0.4, Pt / SeC-0.6 and Pt / C in a standard three-electrode system was tested using a rotating disk electrode (Tianjin Aida Hengsheng Technology Development Co., Ltd., RDEGC1158).

[0049] like Figure 8 As shown, Figure 8 For comparison of the linear sweep voltammetry (LSV) curves of Pt / SeC-0.4 in 0.1 M HClO4 solution under hydrogen and nitrogen saturation conditions, the current density of Pt / SeC-0.4 remains close to zero when the potential is greater than 0.15 V in the nitrogen-saturated 0.1 M HClO4 solution, compared to the larger current density (>2 mA / cm²) under hydrogen saturation conditions. 2 This demonstrates that Pt / SeC-0.4 exhibits catalytic activity for the hydroxide reaction in a hydrogen-saturated 0.1 M HClO4 solution.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a Se-doped Pt-based catalyst, characterized in that, Includes the following steps: (1) Mix conductive carbon black and selenium dioxide powder evenly to obtain a mixture; (2) Heat the mixture under an inert atmosphere to 250-350℃ and keep it at that temperature for 0.5-2 h; (3) Then the temperature is raised to 950-1100℃ and held for 0.5-2 h to obtain powder A; (4) Dissolve the platinum source in water to obtain solution B, then add powder A to solution B and mix evenly. After rotary evaporation and grinding, heat the mixture in a mixed atmosphere of H2 and Ar to obtain the Se-doped Pt-based catalyst.

2. The method for preparing the Se-doped Pt-based catalyst as described in claim 1, characterized in that, The specific surface area of ​​the conductive carbon black in step (1) is 750-900 m². 2 / g, with an average particle size of 25-35 nm.

3. The method for preparing the Se-doped Pt-based catalyst as described in claim 1, characterized in that, In step (1), the mass ratio of conductive carbon black to selenium dioxide powder is (0.3-2):

1.

4. The method for preparing the Se-doped Pt-based catalyst as described in claim 1, characterized in that, The heating rate in step (2) is 3-8℃ / min.

5. The method for preparing the Se-doped Pt-based catalyst as described in claim 1, characterized in that, The heating rate in step (3) is 5-15℃ / min.

6. The method for preparing the Se-doped Pt-based catalyst as described in claim 1, characterized in that, In step (4), the H2 content in the mixed atmosphere is 3-10%, and the Ar content is 90-97%.

7. The method for preparing the Se-doped Pt-based catalyst as described in claim 1, characterized in that, The temperature during the heat treatment in step (4) is 50-250℃, and the holding time is 0.5-5 h.

8. The method for preparing the Se-doped Pt-based catalyst as described in claim 1, characterized in that, The platinum source in step (4) includes at least one of platinum nitrate, chloroplatinic acid, and platinum acetylacetonate.

9. A Se-doped Pt-based catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. Application of a Se-doped Pt-based catalyst in the hydrogenation reaction.

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