Novel fuel cell catalyst based on novel silicon carbide material
By uniformly dispersing Pt nanoparticles on the new silicon carbide material SixC-Ni, a catalyst with a multi-stage pore structure was formed, and the problems of high platinum consumption, slow reaction kinetics and poor stability of direct methanol fuel cell were solved, and efficient and stable methanol oxidation reaction was achieved.
Patent Information
- Application Number
- CN202311695820.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-11
- Publication Date
- 2025-06-13
AI Technical Summary
The existing direct methanol fuel cell has high anode platinum, slow reaction kinetics and poor stability, which limits the development of fuel cells.
SixC-Ni based on new silicon carbide material is used as a support, and 2-10nm Pt nanoparticles are uniformly dispersed, and prepared by vapor deposition method to form a catalyst with a multi-stage pore structure to improve methanol oxidation activity and stability.
When the anode platinum loading is significantly reduced to 0.1 mgPt cm-2, the power can reach 66.7 mW cm-2, and the stability of the catalyst is improved, which performs better than commercial platinum carbon catalysts.
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Figure CN120149436A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of electrocatalysis, and particularly to a novel fuel cell catalyst based on a new silicon carbide material. Background Art
[0002] Proton exchange membrane fuel cells have the advantages of high efficiency, low pollution, and being not restricted by the Carnot cycle, and are an important part of the future energy structure. Among them, direct methanol fuel cells have the characteristics of richer sources, safe transportation and storage, and are suitable for heavy vehicles and even portable power supply devices.
[0003] Although the electrode potential of methanol electrooxidation is similar to that of hydrogen oxidation, the oxidation of methanol in acidic conditions can only be activated on the platinum surface, and the reaction kinetics is slow and it is easily poisoned by intermediates. At present, the platinum loading on the anode of methanol fuel cells is 1 - 4 mg Pt cm -2 , which is much higher than the anode loading of hydrogen-oxygen fuel cells. Considering the high price of platinum, the above factors increase the use cost, which seriously restricts the development of direct methanol fuel cells. It is particularly necessary to develop a novel and efficient direct methanol fuel cell catalyst.
[0004] Developing platinum-based alloys is an effective means to improve the reaction activity of methanol electrooxidation, thereby reducing the platinum consumption of fuel cells. Among them, platinum-ruthenium alloys have better methanol electrooxidation effects. The article titled "Shape-Control of Pt-Ru Nanocrystals: Tuning Surface Structure for Enhanced Electrocatalytic Methanol Oxidation" reported the methanol oxidation activities of platinum-ruthenium alloys with different morphologies. However, ruthenium also belongs to precious metals and is easily oxidized and dissolved in high-temperature, high-humidity, and proton-rich environments, which also limits the development of methanol electrooxidation catalysts. The metal ions leached from the catalyst will block the proton channels of the fuel cell, increase the internal resistance of the proton exchange membrane, and thus reduce the output current of the fuel cell. In addition, the oxidative corrosion of conductive carbon black at oxidation potentials is also a problem worthy of concern.
[0005] In summary, it is difficult to solve the comprehensive problems in the application of direct methanol fuel cells by alloying or developing topological structures with a single active center. Summary of the Invention
[0006] The purpose of the present invention is to solve the technical problems of high platinum consumption, slow reaction kinetics, and poor stability at the anode of existing direct methanol fuel cells, and aims to provide a novel fuel cell catalyst based on a new silicon carbide material.
[0007] The electrocatalyst structure of the present invention is Si xThe surface of the C-Ni silicon carbide new material is uniformly dispersed with 2-10 nm Pt nanoparticles. The silicon carbide with a hierarchical pore structure accelerates the mass transfer of methanol. The electronic interaction between the metal and the support improves the methanol oxidation activity and stability. The onset potential and mass activity of methanol electrooxidation are significantly improved compared with commercial platinum carbon. The anode platinum loading in the direct methanol fuel cell is only 0.1 mg Pt cm -2 When the power can reach 66.7 mW cm -2 ;
[0008] Among them, the range of x in the SixC-Ni silicon carbide new material is 0.5-1, and the mass ratio of Ni to SixC is (0.5-1):100; the material is prepared by chemical vapor deposition. First, the nickel precursor is alloyed with silane gas to form a nickel-silicon alloy, and then the nickel in the nickel-silicon alloy catalyzes the chemical vapor deposition of light alkanes on the support to obtain the SixC-Ni material, and its synthesis temperature is 700-900 °C.
[0009] Taking Si x C-Ni silicon carbide new material as the carrier, the preparation method of the platinum-based electrocatalyst includes the following steps:
[0010] Step 1: By the impregnation method, bind the nickel precursor on the surface of the support, then carry out calcination treatment, and then carry out reduction treatment to obtain silicon carbide precursor 1;
[0011] Step 2: Alloy the silicon carbide precursor 1 in a silane atmosphere, then evacuate the silane gas in the reaction system, and then carry out heat treatment in a light alkane atmosphere to obtain silicon carbide precursor 2;
[0012] Step 3: Carry out acid-base etching treatment on the silicon carbide precursor 2, and then wash and dry to obtain a high-surface-area silicon carbide SixC-Ni nano-new material;
[0013] Step 4: By the impregnation method, bind the platinum precursor on the surface of the Si x C-Ni silicon carbide new material support;
[0014] Step 5: Use a reducing agent to reduce the product obtained in step one to obtain a Pt / Si x C-Ni supported catalyst new material.
[0015] Among them, the calcination treatment in step 1 is calcination in an air or nitrogen atmosphere at 400-800 °C for 1-5 hours; preferably, the calcination treatment is calcination in an air or nitrogen atmosphere at 450-500 °C for 2-4 hours;
[0016] The reduction treatment in step 1 is at 500-800 °C in H 2 and N 2Reduce for 1 to 5 hours under the atmosphere of; preferably, the reduction treatment is carried out at 600 - 700 °C in H 2 and N 2 Reduce for 2 to 4 hours under the atmosphere of.
[0017] The alloying treatment in the silane atmosphere described in step 2 is carried out by heating in the silane atmosphere at 300 - 800 °C for 1 - 5 h;
[0018] The heat treatment in the lower - carbon alkane atmosphere described in step 2 is carried out by reacting in the methane atmosphere at 600 - 900 °C for 1 - 5 h; the lower - carbon alkane is one of methane, ethane, propane, and butane.
[0019] The acid - base etching treatment described in step 3 is carried out by first performing hydrothermal treatment with an alkaline aqueous solution and then performing hydrothermal treatment with an acidic aqueous solution;
[0020] Preferably, in step 1, the addition amounts of the nickel precursor and the carrier are added according to the mass of nickel: the mass of the carrier is (1 - 10):20;
[0021] Preferably, in step 1, the nickel precursor includes inorganic nickel salts and organic nickel salts. The inorganic precursors include nickel chloride, nickel sulfate, and nickel nitrate, and the organic nickel salts include one or a mixture of two or more of nickel acetate, nickel acetylacetonate, and nickel dichloride - 1,10 - phenanthroline.
[0022] Preferably, in step 1, the impregnation method includes equal - volume impregnation, over - volume impregnation, multiple impregnation, and impregnation precipitation.
[0023] Preferably, in step 1, the carrier is one or a mixture of two or more of silica, magnesia, zinc oxide, and alumina.
[0024] Preferably, in step 3, the acid includes one or a mixture of two or more of hydrochloric acid, sulfuric acid, nitric acid, and perchloric acid.
[0025] Preferably, in step 3, the base includes one or a mixture of two or more of sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, and tetra - tert - butylammonium hydroxide.
[0026] Preferably, in step 4, the platinum precursor includes inorganic platinum salts and organic platinum salts.
[0027] Preferably, in the platinum precursor in step 4, the inorganic platinum salts include one or a mixture of two or more of chloroplatinic acid, platinum nitrate, and dichlorotetraammineplatinum.
[0028] Preferably, in the platinum precursor in step 4, the organic platinum salts include one or a mixture of two or more of platinum acetylacetonate, platinum acetate, and dichloro(1,10 - phenanthroline)platinum.
[0029] Preferably, the impregnation methods in Step 1 and Step 4 include equal-volume impregnation, over-volume impregnation, impregnation precipitation, and multiple impregnations.
[0030] Preferably, the mass of the platinum element in Step 4 relative to the mass of the Si x C-Ni silicon carbide material support is (0.1-60):100.
[0031] Preferably, the reducing agent in Step 5 includes one or a mixture of two or more of hydrogen, sodium borohydride, ethylene glycol, oleylamine, ascorbic acid, dimethylformamide, and sodium citrate.
[0032] Beneficial effects
[0033] (1) The platinum in the prepared catalyst is uniformly dispersed on the surface of the Si x C-Ni support new material.
[0034] (2) The electron transfer between the metal and the support regulates the electronic structure of platinum and increases the reaction activity.
[0035] (3) The support that is more corrosion-resistant than traditional carbon black and the stronger anchoring effect improve the stability of anodic oxygen evolution.
[0036] (4) The catalyst with a hierarchical pore structure accelerates the mass transfer of methanol and weakens the concentration polarization. Description of the drawings
[0037] Figure 1 The transmission electron microscope photograph (TEM) of Pt / Si x C-Ni prepared in Example 1 of the present invention.
[0038] Figure 2 The comparison diagram of the methanol oxidation performance of Pt / Si x C-Ni and commercial Pt / C catalysts prepared in Example 1 of the present invention.
[0039] Figure 3 The comparison diagram of the polarization curve and power curve of Pt / Si x C-Ni and commercial Pt / C catalysts as the anode catalyst of a direct methanol fuel cell prepared in Example 1 of the present invention.
[0040] Figure 4 The comparison diagram of the stability test of Pt / Si x C-Ni and commercial Pt / C catalysts as the anode catalyst of a direct methanol fuel cell prepared in Example 1 of the present invention.
[0041] Figure 5 The structural schematic diagram of Pt / Si x C-Ni prepared in Example 1 of the present invention. Detailed implementation manners
[0042] The present invention will be described in detail below with reference to the accompanying drawings to facilitate the understanding of those skilled in the art.
[0043] The transmission electron microscope photographs were measured on a Talos F200S. The X-ray photoelectron spectroscopy was measured on a Thermo Fischer ESCALAB Xi+. The platinum metal content was measured by inductively coupled plasma emission spectroscopy on an Optima 5300DV. The electrochemical tests were carried out on a Chenhua CHI 760e electrochemical workstation. The test system was a three-electrode system, where the working electrode was a glassy carbon electrode, the auxiliary electrode was a graphite rod electrode, and the reference electrode was Hg / HgCl 2 electrode. The platinum loading of the cathode catalyst for fuel cell testing was 0.8 mg Pt cm -2 , the platinum content of the catalyst was 40 wt%, the methanol concentration of the anode feed was 1 M, and the cathode feed was high-purity oxygen with a humidity of 100%.
[0044] Example 1
[0045] Take 100 mg of Si x C-Ni silicon carbide new material as a carrier and 20 mg of chloroplatinic acid hexahydrate were mixed and dispersed in 100 ml of water. After stirring for 12 hours, ammonia water was added for precipitation. After suction filtration, washing, and drying, it was reduced in a 5% H 2 / N 2 atmosphere at 300 °C for 3 hours. After natural cooling, the Pt / Si x C-Ni catalyst was obtained.
[0046] Example 2
[0047] Take 200 mg of Si x C-Ni silicon carbide new material as a carrier and 40 mg of dichlorotetraammineplatinum were mixed and dispersed in 100 ml of water. The reaction system was cooled to below 2 °C, and 100 mg of sodium borohydride was added for reduction for 2 hours. After suction filtration, washing, and drying, the Pt / Si x C-Ni catalyst was obtained.
[0048] Example 3
[0049] Take 100 mg of Si x C-Ni silicon carbide new material as a carrier and 40 mg of platinum acetylacetonate were mixed and dispersed in 100 ml of acetone. After ultrasonic treatment for 1 hour, acetone was removed by rotary evaporation under reduced pressure at room temperature. It was reduced in a 10% H 2 / N 2 atmosphere at 400 °C for 1 hour. After natural cooling, the Pt / Si x C-Ni catalyst was obtained.
[0050] Test example
[0051] The catalyst prepared in Example 1 was tested by inductively coupled plasma emission spectroscopy, and the platinum content of the catalyst was measured to be 6.5 wt%.
[0052] The catalyst prepared in Example 1 was ultrasonically dispersed in a mixed solution of isopropanol and perfluorosulfonic acid oligomer to prepare a catalyst slurry, which was dropped onto a 3 mm platinum-carbon electrode with a platinum loading of 0.014 mg Pt cm -2 , and after drying, in 0.1 M HClO saturated with nitrogen 4 and 0.5 M MeOH, a cyclic voltammetry scan curve was obtained at a scan rate of 50 mV s -1 . The test results are as Figure 2 shown.
[0053] The slurry of the catalyst prepared in Example 1 was sprayed on the surface of the carbon paper to maintain a platinum content of 0.1 mg Pt cm -2 , hot-pressed with a proton membrane and a cathode catalyst layer and assembled with a flow field. After introducing methanol, the polarization curve and power curve were tested at 80 °C. The test results are as Figure 3 shown.
[0054] The Pt / SixC-Ni catalyst slurry obtained in the above steps was sprayed on the surface of the carbon paper to maintain a platinum content of 0.1 mg Pt cm-2, hot-pressed with a proton membrane and a cathode catalyst layer and assembled with a flow field. After introducing methanol, the polarization curve and power curve were tested at 80 °C. Under the condition of maintaining the voltage at both ends of the battery at 0.3 V at 80 °C and continuously introducing methanol, the stability data of the fuel cell were measured, and the time interval between each measurement was 1 h. The test results are as Figure 4 shown.
[0055] Figure 1 This is the transmission electron microscope photograph (TEM) of Pt / Si x C-Ni prepared in Example 1 of the present invention. The particle size distribution of platinum nanoparticles is 3.7 ± 1.2 nm, and the lattice fringes of the loaded nanoparticles belong to the 111 crystal plane of platinum.
[0056] Figure 2 This is a comparison chart of the methanol oxidation performance of Pt / SixC-Ni and commercial Pt / C catalysts prepared in Example 1 of the present invention. The onset potential of Pt / SixC-Ni is increased by 60 mV compared with that of the commercial Pt / C catalyst. The mass activity calculated by dividing the peak current density by the mass of platinum on the surface of the electrode per unit area is 0.78 A mgpt-1, which is twice that of commercial Pt / C (0.39 A mgpt-1).
[0057] Figure 3Pt / Si prepared in Example 1 of the present invention x Comparison diagrams of polarization curves and power curves of C-Ni and commercial Pt / C catalysts as anodic catalysts for direct methanol fuel cells, Pt / Si x The maximum output power of C-Ni as an anodic catalyst for direct methanol fuel cells reaches 66.7 mW, while that of commercial Pt / C with the same platinum loading is only 22.6 mW cm -2 .
[0058] Figure 4 Pt / Si prepared in Example 1 of the present invention x Comparison diagram of stability tests of C-Ni and commercial Pt / C catalysts as anodic catalysts for direct methanol fuel cells, Pt / Si x After 25 hours of testing, C-Ni as an anodic catalyst for direct methanol fuel cells still maintains 84% of its output power, while that of commercial platinum carbon is only 47%.
[0059] Combined Figure 3 and Figure 4 It can be seen that Pt / Si x C-Ni catalyst exhibits higher intrinsic activity, anti-intermediate poisoning ability and working temperature cycle stability during methanol electrooxidation.
Claims
1. A fuel cell catalyst, characterized in that, The catalyst is Pt / Si x C-Ni, where Pt is the loading, and the mass ratio of Pt to the Pt / Si x C-Ni catalyst is (1-8):20; Si x C-Ni is the loading material, where the range of x is 0.5-1, and the mass ratio of Ni to Si x C-Ni is (0.5-1):100; The Si is prepared by depositing low-carbon alkanes on a nickel precursor through chemical vapor deposition x C-Ni material, and then a platinum precursor is loaded onto the surface of the Si x C-Ni material by impregnation to obtain a Pt / Si x C-Ni catalyst.
2. The catalyst according to claim 1, characterized in that, The Pt nanoparticles of the Pt / SixC-Ni catalyst have a particle size of 2 to 10 nm, and / or the Si x C-Ni material has a specific surface area of 300 to 500 m 2 g -1 and / or the Si x C-Ni material has a hierarchical pore structure, including micropores, mesopores and macropores, where the micropores have a pore diameter of less than 20 nm, the mesopores have a pore diameter of 20 to 50 nm, the macropores have a pore diameter of 50 to 100 nm, and / or the crystal form is 3C-SiC.
3. The catalyst according to claim 1, characterized in that, The Si x C-Ni material is prepared by a vapor deposition method. A nickel precursor is alloyed with silane gas to form a nickel-silicon alloy, and then low-carbon alkane vapor deposition is catalyzed by nickel in the nickel-silicon alloy on a carrier.
4. The catalyst according to claim 1, characterized in that, The catalyst Pt / Si x C-Ni is prepared by binding a platinum precursor to the surface of Si x C-Ni silicon carbide material by impregnation and then reducing it with a reducing agent.
5. The catalyst according to claim 3 or 4, characterized in that, the nickel precursor is one or a mixture of two or more of nickel chloride, nickel sulfate, nickel nitrate, nickel acetate, nickel acetylacetonate, nickel dichloride 1,10-phenanthroline; the lower alkane is methane, ethane, propane or butane; the silane gas is one or a combination of two of monosilane gas, disilane gas or trisilane gas; the carrier is one or a mixture of two or more of silica, magnesia, zinc oxide, alumina; the platinum precursor is one or a mixture of two or more of chloroplatinic acid, platinum nitrate, dichlorotetraammineplatinum, platinum acetylacetonate, platinum acetate, dichloro(1,10-phenanthroline)platinum; the impregnation method is isovolumetric impregnation method, over-volume impregnation method, multiple impregnation method or impregnation precipitation method; the reducing agent is hydrogen, sodium borohydride, ethylene glycol, oleylamine, ascorbic acid, dimethylformamide or sodium citrate.
6. The catalyst according to claim 1, characterized in that, the platinum precursor uses chloroplatinic acid hexahydrate and the reducing agent uses hydrogen; or the platinum precursor uses dichlorotetraammineplatinum and the reducing agent uses sodium borohydride; or the platinum precursor uses platinum acetylacetonate and the reducing agent uses hydrogen.
7. A preparation method of a fuel cell catalyst, characterized in that, comprises the following preparation steps: Step 1: By the impregnation method, bind the nickel precursor on the surface of the carrier, then carry out calcination treatment, and then carry out reduction treatment to obtain silicon carbide precursor 1; Step 2: Carry out alloying treatment on silicon carbide precursor 1 in a silane atmosphere, then evacuate the silane gas in the reaction system, and then carry out heat treatment in a lower alkane atmosphere to obtain silicon carbide precursor 2; Step 3: Carry out acid-base etching treatment on silicon carbide precursor 2, and then obtain a high-surface silicon carbide SixC-Ni nanonew material after washing and drying; Step 4: Bind the platinum precursor to the surface of Si x C-Ni silicon carbide new material by the impregnation method; Step 5: Use a reducing agent to reduce the product obtained in Step 1 to obtain Pt / Si x New material of C-Ni supported catalyst 8. The preparation method according to claim 7, characterized in that, the nickel precursor in Step 1 is one or a mixture of two or more of nickel chloride, nickel sulfate, nickel nitrate, nickel acetate, nickel acetylacetonate, nickel dichloride 1,10-phenanthroline; the carrier used in Step 1 is one or a mixture of two or more of silica, magnesia, zinc oxide, alumina; the silane in Step 2 is one or a combination of two of monosilane, disilane or trisilane; the lower alkane in Step 2 is methane, ethane, propane or butane; the platinum precursor in Step 4 is one or a mixture of two or more of chloroplatinic acid, platinum nitrate, dichlorotetraammineplatinum, platinum acetylacetonate, platinum acetate, dichloro(1,10-phenanthroline)platinum; the reducing agent in Step 5 is hydrogen, sodium borohydride, ethylene glycol, oleylamine, ascorbic acid, dimethylformamide or sodium citrate.
9. The preparation method according to claim 7, characterized in that, The impregnation methods described in Step 1 and Step 4 are equal-volume impregnation method, over-volume impregnation method, multiple impregnation method or impregnation precipitation method; The calcination treatment described in Step 1 is calcination in air or nitrogen atmosphere at 400-800 °C for 1-5 hours; The reduction treatment described in Step 1 is carried out under an atmosphere of H 2 and N 2 at 500 - 800 °C for 1 - 5 hours; The alloying treatment in silane atmosphere described in Step 2 is heating in silane atmosphere at 300-800 °C for 1-5 h; The heat treatment in lower alkane atmosphere described in Step 2 is reacting in methane atmosphere at 600-900 °C for 1-5 h; The acid-base etching treatment described in Step 3 is hydrothermal treatment with alkaline aqueous solution first and then hydrothermal treatment with acidic aqueous solution.
10. An application of the catalyst as described in Claims 1-6 or the catalyst prepared by the preparation method as described in Claims 7-9, characterized in that, the catalyst is applied to a direct methanol fuel cell.