A method for preparing an oxygen evolution and hydrogen evolution bifunctional catalyst support
By preparing Co-MOF precursors and loading them with noble/non-noble metals, the problem of scarce noble metal reserves and high cost in existing bifunctional catalysts has been solved, achieving high activity and stability of the catalyst and reducing the cost of hydrogen production from water cracking.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHAOXING INST OF NEW ENERGY & MOLECULAR ENG SHANGHAI JIAO TONG UNIV
- Filing Date
- 2024-11-26
- Publication Date
- 2026-06-30
AI Technical Summary
Existing bifunctional catalysts have scarce precious metal reserves and high operating costs, and their activity and stability cannot meet the requirements of industrial applications.
A high specific surface area doped cobalt tetroxide support was prepared using Co-MOF precursor. Through ball milling and sintering, a dual-function catalyst support for oxygen evolution and hydrogen evolution was prepared, and noble metals/non-noble metals were loaded to enhance catalytic activity and stability.
It effectively reduces the loading of precious metals, enhances the activity and stability of the catalyst, achieves synergistic catalytic effect with precious/non-precious metals, and reduces the cost of hydrogen production from water cracking.
Smart Images
Figure CN119776878B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a bifunctional catalyst support for oxygen evolution and hydrogen evolution, belonging to the field of electrocatalytic water splitting catalysts for hydrogen production. Background Technology
[0002] Currently, the main oxygen evolution catalysts used in industry are IrO2 and hydrogen evolution catalysts are Pt / C. Extensive research and development of monofunctional catalysts has been conducted in academia and industry, yielding considerable results. Research on a small number of bifunctional oxygen and hydrogen evolution catalysts mainly focuses on Ir and Pt noble metal catalysts.
[0003] However, the reserves of Ir and Pt on Earth are relatively small, and the use of pure precious metals like Ir and Pt would make water splitting for hydrogen production extremely costly, thus limiting its large-scale application. Furthermore, the activity and stability of existing bifunctional catalysts do not meet the requirements of industrial applications. Therefore, the technical problem this invention aims to solve is to explore a method that facilitates reducing the precious metal loading of bifunctional catalysts while simultaneously improving their activity and stability.
[0004] Purpose of the invention
[0005] Based on the above problems, the first objective of this invention is to propose a method for preparing a bifunctional catalyst support that can effectively reduce the loading of precious metals.
[0006] The technical solution adopted in this invention is as follows:
[0007] A method for preparing a bifunctional oxygen evolution and hydrogen evolution catalyst support includes the following steps:
[0008] (1) Preparation of Co-MOF precursors:
[0009] Cobalt nitrate, lanthanum nitrate, and nitric acid M were completely dissolved in methanol to form solution A; 2-methylimidazole was completely dissolved in methanol to form solution B; solution A was poured into solution B, and the mixture was thoroughly mixed and allowed to stand for 1-48 hours; the mixture was centrifuged and washed after standing to obtain a precipitate.
[0010] (2) Ball milling of Co-MOF precursors:
[0011] The precipitate obtained in step (1) is ball-milled at a speed of 200-600 rpm for a duration of 10-240 min.
[0012] (3) Sintering:
[0013] The powder after ball milling in step (1) is calcined in an air atmosphere or an argon atmosphere to obtain a bifunctional catalyst support for oxygen evolution and hydrogen evolution.
[0014] Further settings include:
[0015] In step (1):
[0016] The nitric acid M is selected from any one of nickel nitrate, lithium nitrate, ferric nitrate, manganese nitrate, cerium nitrate, zinc nitrate, copper nitrate, and phosphomolybdic acid.
[0017] The molar ratio of cobalt nitrate to lanthanum nitrate was maintained at 7:1-4:1; the molar ratio of cobalt nitrate to nitric acid M was maintained at 15:1-4:1; and the molar ratio of cobalt nitrate to 2-methylimidazole was maintained at 20:1-4:1.
[0018] After centrifugation, the mixture is washed with methanol or ethanol to obtain a precipitate.
[0019] In step (2):
[0020] The ball milling process was carried out at a speed of 600 rpm for a duration of 60 minutes.
[0021] In step (3):
[0022] The sintering is carried out by calcination at 400-650℃ in an argon atmosphere for 0.5-6 hours.
[0023] Alternatively, calcination can be carried out in air at 300-450℃ for 2-8 hours.
[0024] The oxygen evolution and hydrogen evolution bifunctional catalyst support prepared by this invention can be used to load noble metals or non-noble metals. Subsequent loading of noble metals / non-noble metals onto this support can effectively anchor and disperse the noble metals / non-noble metals, enhancing the overall activity and stability of the catalyst. Simultaneously, this bifunctional catalyst support can synergistically catalyze with the subsequently loaded noble metals, further improving the overall activity of the catalyst.
[0025] The beneficial effects of this invention are as follows:
[0026] This invention first prepares a Co-MOF precursor. Taking advantage of the ease of doping Co-MOF, metal atoms such as lanthanum, nickel, lithium, iron, manganese, cerium, zinc, copper, and molybdenum are successfully incorporated into the MOF. Then, the organic framework in the MOF precursor is burned off, resulting in a high specific surface area doped cobalt tetroxide support. This support has a large specific surface area, which can effectively disperse noble / non-noble metals. The presence of dopant elements allows for the modulation of the electronic states of noble metals. Furthermore, the support itself possesses bifunctional oxygen evolution and hydrogen evolution catalytic activity, enabling synergistic catalytic effects with both noble and non-noble metals. All these characteristics allow for optimizing catalyst activity and stability by reducing the noble metal loading. Therefore, this support is a highly promising bifunctional catalyst support.
[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0028] Figure 1 TEM image of the oxygen evolution and hydrogen evolution bifunctional catalyst support prepared for the example.
[0029] Figure 2 TEM images of Ce- and La-doped Co-MOF precursors prepared for the example.
[0030] Figure 3 The anodic OER activity test curve is shown in Example 1.
[0031] Figure 4 The cathode OER activity test curve is shown in Example 1. Detailed Implementation
[0032] Example 1: Preparation of a bifunctional catalyst support for oxygen and hydrogen evolution.
[0033] (1) Preparation of Co-MOF precursor: 6g of cobalt nitrate, lanthanum nitrate, and cerium nitrate were completely dissolved in 150ml of methanol to form solution A. 2-methylimidazole was completely dissolved in 400ml of methanol to form solution B. Solution A was poured into solution B while stirring, and the mixture was allowed to stand for 12h after it was fully mixed. The molar ratio of cobalt nitrate to lanthanum nitrate was maintained at 5:1, the molar ratio of cobalt nitrate to cerium nitrate was maintained at 4:1, and the molar ratio of cobalt nitrate to 2-methylimidazole was maintained at 10:1. After centrifugation, the mixture was washed with methanol to obtain the precipitate.
[0034] (2) Ball milling of Co-MOF precursor: The precipitate obtained in step (1) is ball milled at a speed of 600 rpm for a duration of 60 min.
[0035] (3) Sintering: The ball-milled powder was directly sintered in air at 330℃ for 6h to prepare an oxygen evolution and hydrogen evolution bifunctional catalyst support labeled as LN-Co3O4.
[0036] Structural confirmation:
[0037] Figure 1 This is a TEM image of the bifunctional catalyst support prepared according to an embodiment of the present invention. It can be seen that the bifunctional catalyst support has many porous structures, which are beneficial for increasing the specific surface area and also facilitate the loading of noble metals / non-noble metals.
[0038] Figure 2 The TEM image shows the Ce and La-doped Co-MOF precursor, demonstrating that the mentioned doping elements can be successfully doped.
[0039] Application Example 1
[0040] 40 mg of iridium trichloride (IrCl3), 40 mg of platinum acetylacetonate (Pt(acac)2), 3 g of terephthalaldehyde or glyoxal, and 1.5 g of citric acid were added to 70 ml of benzyl alcohol. The mixture was thoroughly sonicated and stirred to form a homogeneous solution. 100 mg of the LN-Co3O4 support prepared in the previous example was added to this solution, followed by sonication and stirring to obtain a homogeneous suspension. The suspension was heated to 200 °C while stirring and held for 6 h. After cooling, the suspension was centrifuged to obtain a precipitate, which was then washed with ethanol or acetone. The precipitate was vacuum dried or freeze-dried for 48 h. After drying, it was sintered at 380 °C in air for 4 h to obtain the bifunctional catalyst.
[0041] The oxygen evolution and hydrogen evolution bifunctional catalyst of noble metals Ir and Pt supported by the present invention was tested to examine the performance of the supported catalyst prepared by the present invention. The test method is as follows: the intrinsic electrochemical activity of the material was tested in a typical three-electrode system with a rotating disk electrode as the working electrode, a gold electrode as the counter electrode, a mercury / mercurous sulfate electrode as the reference electrode, and 0.1M HClO4 as the electrolyte; the intrinsic electrochemical stability of the system was tested in the same system at a current density of ±10mA / cm2.
[0042] Test results:
[0043] like Figure 3 The figure shows the anodic oxygen evolution reaction activity test data of the catalyst after loading noble metals Ir and Pt on the support of the present invention at 10 mA / cm2. The overpotential at 10 mA / cm2 is 285 mV, which proves that the bifunctional catalyst prepared by the present invention has good oxygen evolution reaction performance. Figure 4 The test data of the catalyst at -10 mA / cm2 for the hydrogen evolution reaction at the cathode are shown. The overpotential of the hydrogen evolution reaction at -10 mA / cm2 is 65 mV, which proves that the bifunctional catalyst of Ir and Pt supported by the present invention has good hydrogen evolution performance.
[0044] Application Example 2
[0045] 40 mg of cobalt acetate, 40 mg of platinum acetylacetonate (Pt(acac)2), and 1.5 g of citric acid were added to 20 ml of oleylamine and thoroughly sonicated and stirred to form a homogeneous mixed solution. 100 mg of the support LN-Co3O4 was added to this mixed solution, followed by sonication and stirring to obtain a homogeneous suspension. This suspension was heated to 250 °C while stirring and held at this temperature for 6 hours. After cooling, the suspension was centrifuged to obtain a precipitate, which was then washed with ethanol or acetone. The precipitate was vacuum dried or freeze-dried for 48 hours. After drying, it was sintered in air at 400 °C for 4 hours to obtain the bifunctional catalyst.
[0046] The oxygen evolution and hydrogen evolution bifunctional catalyst of Co and Pt supported by the present invention was tested to examine the performance of the supported catalyst prepared by the present invention. The test method is as follows: the intrinsic electrochemical activity of the material was tested in a typical three-electrode system with a rotating disk electrode as the working electrode, a gold electrode as the counter electrode, a mercury / mercurous sulfate electrode as the reference electrode, and 0.1M HClO4 as the electrolyte; the intrinsic electrochemical stability of the system was tested in the same system at a current density of ±10mA / cm2.
[0047] Tests showed that the oxygen evolution and hydrogen evolution bifunctional catalyst supported on Co and Pt had an oxygen evolution overpotential of 350 mV at 10 mA / cm² and a hydrogen evolution overpotential of 90 mV at -10 mA / cm², demonstrating that the support prepared in this invention still exhibits good catalytic performance in bifunctional catalysts supported on noble / non-noble metals.
Claims
1. The application of a bifunctional catalyst support for oxygen evolution and hydrogen evolution in the oxygen evolution and hydrogen evolution reaction, characterized in that: The carrier is prepared using the following steps: (1) Preparation of Co-MOF precursors: Cobalt nitrate, lanthanum nitrate, and nitric acid M were completely dissolved in methanol to form solution A; 2-methylimidazole was completely dissolved in methanol to form solution B; solution A was poured into solution B, and the mixture was thoroughly mixed and allowed to stand for 1-48 hours; the mixture was centrifuged and washed after standing to obtain a precipitate. The nitric acid M is cerium nitrate; (2) Ball milling of Co-MOF precursors: The precipitate obtained in step (1) is ball-milled at a speed of 200-600 rpm for a duration of 10-240 min. (3) Sintering: The powder after ball milling in step (2) was calcined in air to obtain LN-Co3O4, a bifunctional catalyst support for oxygen and hydrogen evolution. The prepared oxygen evolution and hydrogen evolution bifunctional catalyst support LN-Co3O4 was loaded with noble metals Ir and Pt, or with metals Co and Pt, wherein: When loading noble metals Ir and Pt: 40 mg of iridium trichloride, 40 mg of platinum acetylacetonate, 3 g of terephthalaldehyde or glyoxal and 1.5 g of citric acid were added to 70 ml of benzyl alcohol. After thorough sonication and stirring, a homogeneous mixed solution was formed. 100 mg of the prepared support LN-Co3O4 was added to the mixed solution, and after sonication and stirring, a homogeneous suspension was obtained. The suspension was heated to 200 °C while stirring and held at that temperature for 6 h. After cooling, the suspension was centrifuged to obtain a precipitate, which was washed with ethanol or acetone. The precipitate was vacuum dried or freeze-dried for 48 h. After drying, it was sintered in air at 380 °C for 4 h to obtain a bifunctional catalyst loaded with Ir and Pt. When loading Co and Pt: 40 mg cobalt acetate, 40 mg platinum acetylacetonate, and 1.5 g citric acid were added to 20 ml oleylamine and thoroughly sonicated and stirred to form a homogeneous mixed solution; 100 mg LN-Co3O4 support was added to the mixed solution and sonicated and stirred to obtain a homogeneous suspension; the suspension was heated to 250 °C while stirring and held at that temperature for 6 h; after cooling, the suspension was centrifuged to obtain a precipitate and washed with ethanol or acetone; the precipitate was vacuum dried or freeze-dried for 48 h; after drying, it was sintered in air at 400 °C for 4 h to obtain a bifunctional catalyst loaded with Co and Pt; The above-mentioned bifunctional catalysts supported on Ir and Pt, and on Co and Pt, were applied to the oxygen evolution and hydrogen evolution reactions. Specifically, the bifunctional catalyst supported on Ir and Pt had an anodic oxygen evolution reaction overpotential of 285 mV at 10 mA / cm² and a cathodic hydrogen evolution reaction overpotential of 65 mV at -10 mA / cm²; the bifunctional catalyst supported on Co and Pt had an oxygen evolution reaction overpotential of 350 mV at 10 mA / cm² and a hydrogen evolution reaction overpotential of 90 mV at -10 mA / cm².
2. The application of the oxygen evolution and hydrogen evolution bifunctional catalyst support according to claim 1 in the oxygen evolution and hydrogen evolution reaction, characterized in that: In step (1) of the carrier preparation: the molar ratio of cobalt nitrate and lanthanum nitrate is maintained at 7:1-4:
1.
3. The application of the oxygen evolution and hydrogen evolution bifunctional catalyst support according to claim 1 in the oxygen evolution and hydrogen evolution reaction, characterized in that: In step (1) of the carrier preparation: the molar ratio of cobalt nitrate to nitric acid M is maintained at 15:1-4:
1.
4. The application of the oxygen evolution and hydrogen evolution bifunctional catalyst support according to claim 1 in the oxygen evolution and hydrogen evolution reaction, characterized in that: In step (1) of the carrier preparation: the molar ratio of cobalt nitrate to 2-methylimidazole is maintained at 20:1-4:
1.
5. The application of the oxygen evolution and hydrogen evolution bifunctional catalyst support according to claim 1 in the oxygen evolution and hydrogen evolution reaction, characterized in that: In step (1) of the carrier preparation: after centrifugation, the mixed liquid after standing is washed with methanol or ethanol to obtain a precipitate.
6. The application of the oxygen evolution and hydrogen evolution bifunctional catalyst support according to claim 1 in the oxygen evolution and hydrogen evolution reaction, characterized in that: In step (2) of the carrier preparation: the ball milling speed is 600 rpm and the ball milling time is 60 min.
7. The application of the oxygen evolution and hydrogen evolution bifunctional catalyst support according to claim 1 in the oxygen evolution and hydrogen evolution reaction, characterized in that: In step (3) of the carrier preparation: the sintering is carried out by calcining in an air atmosphere at 300-450℃ for 2-8 hours.