Preparation method of platinum-based supported catalyst
Through radio frequency capacitive coupled plasma technology, electron energy is adjusted, transition metal ions are reduced at room temperature, and small-size, high loading, clean surface platinum-transition metal nanoclusters are prepared, solving the catalyst activity and selection in the prior art The problem of low performance significantly improves the catalytic performance.
Patent Information
- Application Number
- CN202411438170.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-15
- Publication Date
- 2024-12-31
AI Technical Summary
The prior art is difficult to prepare small size, high loading, clean surface platinum-transition metal alloy nanoparticles at room temperature, and conventional radio frequency inductively coupled plasma cannot reduce transition metal ions, resulting in reduced catalyst activity and selectivity.
Through radio frequency capacitively coupled plasma technology, the bias voltage on the substrate stage in the discharge cavity is adjusted, and the electron energy is controlled to reduce transition metal ions at room temperature to form platinum-transition metal nanoclusters, avoiding high-temperature and high-pressure processes and nanoparticles Reunion.
The platinum-transition metal alloy cluster with adjustable proportions is achieved at room temperature, which significantly improves the activity and selectivity of the catalyst, reduces the overpotential of the electrocatalytic decomposition of water, and improves the catalytic performance.
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Figure CN119215932A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of inorganic nano material preparation, and specifically relates to a method for preparing a platinum-based supported catalyst. Background Art
[0002] Supported platinum-based catalysts have broad application prospects in the fields of fuel cells, reforming and isomerization of crude oil, removal of nitrogen / carbon oxides, synthesis of natural products and drug intermediates. Heterogeneous atom-doped onion carbon materials have excellent properties such as high conductivity, thermal stability, and chemical stability, and are widely used as catalyst carriers. The catalytic performance of supported platinum-based catalysts is closely related to the size and composition of precious metals. Small particle size, especially single-atom platinum-based catalysts, show higher catalytic performance. The preparation methods of supported platinum-based catalysts include liquid phase synthesis method or high-temperature reduction method. Among them, the liquid phase synthesis method requires the addition of a large amount of surfactant to prevent the agglomeration of platinum-based catalysts during the synthesis process, but the surfactant remaining on the surface of the catalyst reduces its catalytic activity. The high-temperature reduction method will cause the agglomeration and Oswald ripening of nanoparticles at higher temperatures, resulting in larger size and wider distribution of synthesized precious metals, which reduces the activity and selectivity of the catalyst. Therefore, the preparation of small-sized, high-loaded, and clean-surface catalysts is still a difficult problem in the industry. Radio frequency capacitively coupled plasma is widely used in the synthesis of platinum-based supported catalysts due to its high electron temperature and low ion temperature. However, due to the high chemical potential of iron, cobalt and nickel transition metal ions, conventional radio frequency inductively coupled plasma cannot reduce transition metals due to low electron energy, and therefore cannot prepare platinum-based transition metal alloy nanoparticles at room temperature. Summary of the invention
[0003] In order to solve the technical problems raised in the background technology, the present invention is based on radio frequency capacitively coupled plasma technology, and regulates the energy of electrons reaching the catalyst surface by adjusting the bias voltage on the substrate stage in the discharge chamber, thereby reducing transition metal ions at room temperature to form platinum-based transition metal nanoclusters. The preparation method does not require a high temperature and high pressure process, and avoids the agglomeration of nanoparticles and surface contamination.
[0004] A method for preparing a platinum-based supported catalyst is as follows: Step 1, metal ion loaded heteroatom doped onion carbon: uniformly disperse the precursor containing platinum ions and transition metal ions (iron, cobalt, nickel) and heteroatom doped onion carbon in water, adjust the pH value of the solution, ultrasonically disperse and freeze-dry to obtain metal ion loaded heteroatom doped onion carbon.
[0005] Step 2, plasma reduction of the precursor: the precursor is placed on the substrate stage of the radio frequency capacitive coupled discharge quartz chamber, the discharge gas is introduced and a pulsed positive bias voltage of 100-1000 V is applied to perform plasma treatment, and finally an amorphous platinum-based-transition metal alloy cluster is loaded on heterogeneous atom-doped onion carbon, i.e., a platinum-based loaded catalyst is obtained.
[0006] In the above technical solution, in step 1, the platinum ion is one or more of chloroplatinic acid, potassium chloroplatinate, and platinum acetate, and the transition metal ion is one or more of chlorides of iron, cobalt, and nickel or acetic acid compounds.
[0007] In the above technical solution, in step 1, the pH value is 8-10, and the reagent for adjusting the pH value is ammonia water or sodium hydroxide.
[0008] In the above technical solution, in step 2, the discharge gas is one or more of argon, hydrogen, nitrogen or ammonia.
[0009] In the above technical solution, in step 2, the RF frequency of the power supply is 13.56 MHZ, the discharge power is 80~500 W, the discharge time is 5 min~180 min, the gas flow rate is 1~100 sccm, the gas pressure is 1~100 Pa, and the voltage of the applied pulse positive bias is 100~1000V.
[0010] In the above technical solution, in step 2, the platinum-based alloy cluster is a platinum-based-transition metal alloy cluster, whose chemical composition is a binary or ternary alloy cluster of platinum, nickel, cobalt, and iron alloy, and whose average particle size is 0.5 to 2 nm.
[0011] Beneficial effects: The invention discloses a method for preparing a platinum-based supported catalyst. The invention uses an external power supply to apply a forward pulse voltage to a substrate stage in a plasma cavity to accelerate ionized electrons. Under the same gas pressure, the pulse voltages applied to the substrate stage are different, and the energy of the electrons in the plasma cavity is different. When the bias voltage is 300 V, the electron energy distribution is 10-20 eV; when the bias voltage is 1000 V, the electron energy is 20-50 eV. The method can reduce transition metal ions at room temperature to prepare platinum-based-transition metal alloy clusters with adjustable proportions. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 : A schematic flow chart of a method for preparing a platinum-based supported catalyst.
[0013] Figure 2 : PtNi / C high-angle annular dark field image-scanning transmission electron microscope image.
[0014] Figure 3 : Size distribution of PtNi / C.
[0015] Figure 4 : Element distribution map of PtNi / C by high-angle annular dark field image-scanning transmission electron microscope.
[0016] Figure 5 : HER performance of PtNi / C. DETAILED DESCRIPTION
[0017] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.
[0018] Example 1 like Figure 1 As shown, oxygen-doped onion carbon with a diameter of 50 nm and deionized water are mixed evenly, and then a mixed solution of 0.2 ml of 20 g / L chloroplatinic acid and 0.4 ml of 15 g / L nickel chloride is added dropwise, and then freeze-dried after ultrasonic treatment for 30 min to obtain a precursor of oxygen-doped onion carbon loaded with chloroplatinic acid and nickel chloride; the precursor is placed on a substrate stage of a capacitively coupled plasma discharge quartz chamber for discharge treatment, and the discharge parameters are: the flow rates of hydrogen and ammonia are 20 sccm and 10 sccm respectively, the discharge power is 120 W, the discharge time is 30 min, the gas pressure of the discharge chamber is 15 Pa, and the external positive bias is 500 V, and finally platinum-nickel alloy nanoparticles loaded with oxygen-doped onion carbon are obtained.
[0019] Example 2 Oxygen-doped onion carbon with a diameter of 50 nm was evenly mixed with deionized water, and then a mixed solution of 0.15 ml of 25 g / L chloroplatinic acid and 0.3 ml of 16 g / L nickel chloride was added dropwise. After ultrasonic treatment for 20 min, freeze-drying was performed to obtain a precursor of oxygen-doped onion carbon loaded with chloroplatinic acid and nickel chloride; the precursor was placed on the substrate stage of a capacitively coupled plasma discharge quartz chamber for discharge treatment. The discharge parameters were: the flow rates of hydrogen and ammonia were 1 sccm and 1 sccm respectively, the discharge power was 80 W, the discharge time was 5 min, the gas pressure was 1 Pa, and the external positive bias was 100 V. Finally, platinum-nickel alloy nanoparticles loaded with oxygen-doped onion carbon were obtained.
[0020] Example 3 Oxygen-doped onion carbon with a diameter of 50 nm was evenly mixed with deionized water, and then a mixed solution of 0.25 ml of 30 g / L chloroplatinic acid and 0.8 ml of 20 g / L nickel chloride was added dropwise. After ultrasonic treatment for 40 min, freeze-drying was performed to obtain a precursor of oxygen-doped onion carbon loaded with chloroplatinic acid and nickel chloride. The precursor was placed on the substrate stage of a capacitively coupled plasma discharge quartz chamber for discharge treatment. The discharge parameters were: the flow rates of nitrogen and ammonia were 100 sccm and 100 sccm respectively, the discharge power was 500 W, the discharge time was 180 min, the gas pressure was 100 Pa, and the external positive bias was 1000 V. Finally, platinum-nickel alloy nanoparticles loaded with oxygen-doped onion carbon were obtained.
[0021] Experimental Results Figure 2 This is a high-angle annular dark field image-scanning transmission electron microscope image of the oxygen-doped onion carbon supported PtNi (PtNi / C) prepared in Example 1. It can be observed that there are many uniformly dispersed PtNi on the onion carbon support.
[0022] Figure 3 is the size distribution of PtNi / C prepared in Example 1, and its average size is 1.51 nm.
[0023] Figure 4 This is the element distribution diagram of the oxygen-doped onion carbon loaded with PtNi prepared in Example 1. It can be observed that PtNi is uniformly dispersed on the surface of the carbon carrier.
[0024] Figure 5 The HER performance of PtNi / C prepared in Example 1 is shown in Figure 1. The overpotential of the catalyst for hydrogen production from water electrolysis (current density of 10 mA cm -2 ) can reach 22 mV, which is nearly 50 mV lower than that of commercial Pt / C, significantly reducing the overpotential of electrocatalytic water decomposition and improving the energy efficiency.
[0025] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for preparing a platinum-based supported catalyst, characterized in that: Step 1, metal ion loaded heteroatom doped onion carbon: uniformly disperse the precursor containing platinum ions and transition metal ions and heteroatom doped onion carbon in water, adjust the pH value of the solution, perform ultrasonic dispersion and freeze drying, and obtain metal ion loaded heteroatom doped onion carbon; Step 2, plasma reduction of the precursor: the precursor is placed on a substrate stage of a radio frequency capacitively coupled discharge quartz chamber, a discharge gas is introduced and a pulsed positive bias voltage of 100-1000 V is applied to perform plasma treatment, and finally an amorphous platinum-based-transition metal alloy cluster is loaded on heterogeneous atom-doped onion carbon, i.e., a platinum-based loaded catalyst is obtained.
2. The method for preparing a platinum-based supported catalyst according to claim 1, wherein: In step 1, the platinum ion is one or more of chloroplatinic acid, potassium chloroplatinate, and platinum acetate, and the transition metal ion is one or more of chlorides of iron, cobalt, and nickel or acetic acid compounds.
3. The method for preparing a platinum-based supported catalyst according to claim 1, characterized in that: In step 1, the pH value is 8-10, and the pH value is adjusted by using ammonia water or sodium hydroxide.
4. The method for preparing a platinum-based supported catalyst according to claim 1, characterized in that: In step 2, the discharge gas is one or more of argon, hydrogen, nitrogen or ammonia.
5. The method for preparing a platinum-based supported catalyst according to claim 1, characterized in that: In step 2, the RF frequency of the power supply is 13.56 MHZ, the discharge power is 80-500 W, the discharge time is 5 min-180 min, the gas flow rate is 1-100 sccm, the gas pressure is 1-100 Pa, and the voltage of the applied pulse positive bias is 100-1000 V.
6. The method for preparing a platinum-based supported catalyst according to claim 1, characterized in that: In step 2, the platinum-based alloy cluster is a platinum-based-transition metal alloy cluster, whose chemical composition is a binary or ternary alloy cluster of platinum, nickel, cobalt, and iron alloy, and whose average particle size is 0.5 to 2 nm.