CN115863679A - Microporous carbon-coated platinum nanoparticle electrocatalyst and preparation method thereof - Google Patents
Microporous carbon-coated platinum nanoparticle electrocatalyst and preparation method thereof Download PDFInfo
- Publication number
- CN115863679A CN115863679A CN202211641253.8A CN202211641253A CN115863679A CN 115863679 A CN115863679 A CN 115863679A CN 202211641253 A CN202211641253 A CN 202211641253A CN 115863679 A CN115863679 A CN 115863679A
- Authority
- CN
- China
- Prior art keywords
- carbon
- coated
- solution
- catalyst
- noble metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Abstract
The invention relates to a microporous carbon-coated platinum nanoparticle electrocatalyst and a preparation method thereof. The method comprises the following steps: adding a noble metal ion solution and a volatile metal ion solution into the carbon substrate solution, and uniformly dispersing; adding soluble carbon nitrogen compound solution, mixing uniformly and freeze-drying; carbonizing the product in an inert atmosphere to obtain microporous carbon-coated nano particles; and (4) pickling the product, and carbonizing again to obtain the microporous carbon-coated platinum nanoparticle electrocatalyst. Compared with the prior art, the method can load the noble metal Pt catalyst coated with porous carbon on the carbon substrate in situ, can inhibit the fusion of adjacent platinum particles in a long-cycle process on the premise of not sacrificing the stability of the catalyst, and overcomes the problem that the activity and the stability of the conventional Pt/C catalyst are difficult to obtain at the same time. In addition, the method also provides reference for preparing other high-activity and high-stability porous carbon-coated noble metal catalysts.
Description
Technical Field
The invention relates to the field of electrocatalysts, in particular to a microporous carbon-coated platinum nanoparticle electrocatalyst and a preparation method thereof.
Background
The hydrogen fuel cell cathode reaction, oxygen Reduction Reaction (ORR), involves multi-step electron transfer, has slow kinetic process, and is highly dependent on the precious metal platinum (Pt) catalyst with scarce resources and high price. This has become a major factor limiting the large-scale industrialization of hydrogen fuel cell power technologies. Therefore, reducing the loading of Pt in the ORR catalyst while maintaining the catalytic performance is an urgent problem to be solved to reduce the cost of fuel cells and promote the commercialization of fuel cell power technologies.
The main technical means for reducing the Pt loading capacity at the present stage is to reduce the size of the catalyst, namely, prepare ultrafine Pt nano particles (less than or equal to 5 nm) and promote Pt unit mass to provide more active sites so as to improve the electrochemical effective active area (ECSA) of the catalyst. However, ultrafine Pt nanoparticles have poor thermodynamic stability and are prone to agglomerate into large particles during start-up and cyclic loading by physical coalescence and/or Ostwald ripening processes, resulting in a gradual decrease in ECSA and durability. On the other hand, maintaining the same power density or current density under lower Pt loading conditions also results in O 2 And H 2 The O conveying speed is increased, so that the Pt atom dissolution and the Ostwald ripening are accelerated, and the degradation of the catalyst in the running process of the PEMFC is further accelerated.
The invention of Chinese patent CN 114225935A onion-shaped supported carbon-coated platinum catalyst and the application thereof, and the carbon coating method of CN 114142044A platinum carbon catalyst, etc. starting from Pt/C catalyst, the carbon-coated Pt/C catalyst is obtained by blending the Pt/C catalyst with carbon source compound or organic molecule and then carbonizing, which effectively improves the stability of the Pt/C catalyst. However, most of the carbon-coated Pt/C catalysts reported at present are coated with closed carbon layers, and the activity is lower than that of uncoated Pt/C. The reason for this is that the surface carbon layer prevents the Pt particles from directly contacting with the reactant, the outer d-orbital of the Pt atom must be hybridized with the p-orbital of the outermost carbon atom to enhance the electron cloud density and fermi level of the carbon layer electrons to accelerate the reaction process, but the interaction is weaker with the increase of the carbon layer thickness, which results in the decrease of the activity of the Pt/C catalyst.
Disclosure of Invention
It is an object of the present invention to overcome at least one of the above-mentioned drawbacks of the prior art and to provide a microporous carbon-coated platinum nanoparticle electrocatalyst with a porous carbon coating that can allow the passage of reactants while providing protection for Pt particles, and a method for preparing the same.
The purpose of the invention can be realized by the following technical scheme:
the inventors have appreciated that in the prior art, due to the lack of high temperature pore formers, the carbon-coated Pt/C catalysts obtained by these methods are often coated with a relatively thick closed carbon layer on the surface, and are all less active than uncoated Pt/C. The invention starts from a Pt/C catalyst, a carbon layer is coated on the surface of the Pt/C catalyst to form a closed structure, and the migration and agglomeration processes of Pt nano particles are limited, wherein the specific scheme is as follows:
a method for preparing a microporous carbon-coated platinum nanoparticle electrocatalyst, comprising the steps of:
adding a noble metal ion solution and a volatile metal ion solution into the carbon substrate solution, and uniformly dispersing;
adding a soluble carbon nitrogen compound solution, uniformly mixing, and freeze-drying;
carbonizing the product in an inert atmosphere to obtain microporous carbon-coated nano particles;
and (4) pickling the product, and carbonizing again to obtain the microporous carbon-coated platinum nanoparticle electrocatalyst.
Zn and Pt ions are reduced into metal or alloy in the carbonization process, a carbon nitride compound is carbonized to form a carbon layer to be coated on the surface of the metal, and partial Zn is volatilized on the coated carbon layer to form micropores. And corroding Zn in the alloy after acid pickling to only leave metal Pt, and carbonizing again to obtain the microporous carbon-coated platinum nanoparticle electrocatalyst.
According to the invention, the pore-forming agent zinc is introduced into the Pt nano-particles skillfully before the carbon layer coats Pt, and then the Pt nano-particles are carbonized at high temperature. The characteristic that metal Zn is volatile at high temperature is utilized, micropores are introduced into a carbon layer coated on the metal surface, then hot nitric acid is utilized to wash away residual metal Zn and unstable Pt atoms, and carbonization is carried out again to obtain the microporous carbon-coated Pt nano-particles.
After acid washing, zn in the Pt-Zn particles is removed, and a large number of unsaturated coordinated Pt atoms, such as atoms at the edges, corners and the like of irregular Pt particles, pt-O bonds and the like, are left on the surface of the Pt particles. Meanwhile, the carbon substrate is also partially oxidized to form C-O and N-O bonds on the surface. The re-carbonization provides sufficient energy to cause the irregular Pt particles to rearrange, remove the oxidized species on the carbon substrate, and thus improve the activity and stability of the catalyst. The catalyst activity and stability will be reduced to some extent without secondary carbonization.
Further, the volatile metal is metal which is volatile at 700-900 ℃, and comprises zinc. The pore-forming agent metal is volatile after the carbon cladding layer is formed at 700-900 ℃, the residual pore-forming agent is easy to remove by acid cleaning, and the metal zinc is a preferred pore-forming agent.
Further, the pore-forming agent precursor is a zinc salt solution, and comprises zinc chloride, zinc sulfate, zinc nitrate or zinc acetate aqueous solution.
Further, the carbon substrate comprises carbon aerogel or ketjen black; the noble metal ion solution comprises a platinum tetrachloride, chloroplatinic acid or potassium chloroplatinate aqueous solution; the soluble carbon nitrogen compound solution is dicyandiamide or a melamine aqueous solution.
Furthermore, the content of the noble metal in the catalyst is 20-50wt%; the mass ratio of the volatile metal to the noble metal is 1 (0.5-1); the mass ratio of the soluble carbon nitrogen compound to the noble metal is 1 (1-10).
Further, the carbonization temperature is 700-900 ℃, and the time is 1-3h.
Furthermore, nitric acid with the concentration range of 0.1-5M is adopted during acid washing, and the acid washing temperature range is 50-90 ℃.
Further, the temperature of the second carbonization is 50-100 ℃ lower than the carbonization temperature, and the time is 20-40min.
Further, the carbonization conditions are as follows: in nitrogen atmosphere, firstly preserving heat for 1-3h at 180-300 ℃, and then preserving heat for 1-3h at 700-900 ℃.
A microporous carbon-coated platinum nanoparticle electrocatalyst prepared as described above.
Compared with the prior art, the method can load the noble metal Pt catalyst coated with porous carbon on the carbon substrate in situ, as shown in figure 1, can inhibit the fusion of adjacent platinum particles in a long circulation process on the premise of not sacrificing the stability of the catalyst, and overcomes the problem that the activity and the stability of the conventional Pt/C catalyst are difficult to obtain simultaneously. In addition, the method also provides reference for preparing other high-activity and high-stability porous carbon-coated noble metal catalysts.
Drawings
FIG. 1 is a conceptual comparison of carbon coating with microporous carbon coating according to the present invention;
FIG. 2 is a BET plot comparing the materials of example 1 and comparative example 1;
FIG. 3 is a comparison of LSV for the materials of example 1 and comparative example 1;
FIG. 4 is a comparison of LSV before and after 10000 CV cycles for the material of example 1.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.
A microporous carbon-coated platinum nanoparticle electrocatalyst and a preparation method thereof comprise the following steps:
(1) Adding Pt and Zn ion solution into the carbon substrate solution, and performing ultrasonic treatment to uniformly disperse the Pt and Zn ion solution; the noble metal ion solution is an aqueous solution of platinum tetrachloride, chloroplatinic acid or potassium chloroplatinate, and the volatile metal ion solution is an aqueous solution of zinc chloride, zinc sulfate, zinc nitrate or zinc acetate; adding platinum precursor according to the theoretical platinum content of 20-50wt% of the catalyst. The mass ratio of Zn to Pt is 1 (0.5-1).
(2) Adding a soluble carbon nitrogen compound solution into the solution obtained in the step (1), uniformly mixing, and freeze-drying; the soluble carbon nitrogen compound solution is dicyandiamide or a melamine aqueous solution; the mass ratio of the soluble carbon nitrogen compound to the Pt is 1 (1-10).
(3) Carbonizing the product obtained in the step (2) in an inert atmosphere to obtain microporous carbon-coated platinum-zinc nanoparticles; the carbonization condition is that the temperature is kept at 180-300 ℃ for 1-3 hours under the nitrogen atmosphere, and then the temperature is kept at 700-900 ℃ for 1-3 hours.
(4) And (4) pickling the product obtained in the step (3) and then carbonizing again to obtain the microporous carbon-coated platinum nano-particle electrocatalyst, namely the microporous carbon-coated Pt/C. The acid is nitric acid, the concentration range of the nitric acid is 0.1-5M, and the pickling temperature range is 50-90 ℃.
Example 1
A microporous carbon-coated platinum nanoparticle electrocatalyst and a preparation method thereof comprise the following steps:
(1) And dispersing 30mg of carbon aerogel in 20ml of deionized water, and uniformly dispersing the carbon aerogel by ultrasonic treatment for 30 minutes to obtain a carbon substrate solution.
(2) Slowly adding 1.5ml of 1mol/L chloroplatinic acid aqueous solution and 1.5ml of 2mol/L zinc chloride aqueous solution into the solution obtained in the step (1), and performing ultrasonic treatment for 30 minutes to uniformly disperse the chloroplatinic acid aqueous solution and the zinc chloride aqueous solution
(3) To the solution obtained in step (2), 3ml of a 1mol/L aqueous solution of dicyandiamide was slowly added, stirred for 4 hours, and then lyophilized.
(4) And (4) putting the precursor obtained in the step (3) into a tube furnace for pyrolysis to obtain the microporous carbon-coated Pt-Zn nano-particles. The pyrolysis condition is that the temperature is kept at 180 ℃ for 3 hours under the argon atmosphere, the temperature is kept at 750 ℃ for 2 hours, at the moment, pt and Zn ions are reduced into metal or alloy, carbon nitride compounds are carbonized to form a carbon layer to be coated on the metal surface, and partial Zn volatilizes to form micropores on the coated carbon layer.
(5) And (3) placing the microporous carbon-coated Pt-Zn nanoparticles obtained in the step (4) at 85 ℃ and stirring with 0.5M dilute nitric acid for 2 hours, and then filtering and washing with deionized water for 3 times.
(6) And (6) drying the solid obtained in the step (5) and then carbonizing again to obtain the microporous carbon-coated Pt nanoparticle electrocatalyst.
Comparative example 1
The difference from example 1 is that the carbon-coated platinum nanoparticle electrocatalyst, i.e., carbon-coated Pt/C, was obtained in the same manner as the microporous carbon-coated Pt/C catalyst except that no metal Zn was added and no acid wash was performed.
And (3) testing conditions are as follows:
preparation of a reagent slurry: 6mg of the catalyst and 40. Mu.L of the Nafion membrane solution were dispersed in 960. Mu.L of a water-isopropanol mixed solution (volume ratio: 3.
LSV test: the electrochemical performance of the synthesized catalyst is evaluated on a CHI 760E electrochemical workstation in Shanghai province by adopting a traditional three-electrode system, and the electrolyte is 0.1M HClO 4 The platinum carbon electrode is a working electrode, and the reference electrode and the counter electrode are SCE and a graphite rod respectively. 10 mu L of catalyst slurry is measured by a liquid transfer gun and is dripped on the surface of a platinum-carbon electrode, and the platinum-carbon electrode is naturally air-dried at room temperature to form a thin electrode film on the surface. Charging high purity O into the cell for at least 0.5h prior to ORR testing 2 Until the electrolyte is at O 2 A saturated state. And (3) carrying out a Linear Sweep Voltammetry (LSV) test in a certain voltage interval to obtain the ORR performance of the catalyst. The sweep rate of the LSV was set at 5mV/s. And in the test process, the electrochemical workstation carries out automatic solution compensation.
And (3) stability testing: samples tested for LSV were cycled 10000 cycles over a potential range of 0.6-1.0V vs RHE at a scan rate of 20mV/s.
FIG. 2 is a BET plot of microporous carbon coated Pt/C versus carbon coated Pt/C, and from FIG. 2 it can be seen that the micropore content of the microporous carbon coated Pt/C catalyst is much greater than the carbon coated Pt/C catalyst, indicating that the introduction of zinc is effective in introducing micropores at the surface of the microporous carbon.
FIG. 3 is a comparison of LSV for microporous carbon coated Pt/C and carbon coated Pt/C. As can be seen in FIG. 3, the half-wave potential of the microporous carbon-coated Pt/C catalyst is higher than that of the carbon-coated Pt/C, indicating that the microporous carbon-coated Pt/C catalyst is superior in activity to the carbon-coated Pt/C catalyst.
FIG. 4 is a comparison of LSV before and after 10000 cycles of CV for microporous carbon-coated Pt/C catalyst. As can be seen from fig. 4, the half-wave potential of the microporous carbon-coated Pt/C catalyst did not change significantly after 10000 cycles, indicating that the microporous carbon-coated Pt/C catalyst has excellent stability.
Example 2
A microporous carbon-coated platinum nanoparticle electrocatalyst and a preparation method thereof comprise the following steps:
(1) 40mg of ketjen black was dispersed in 20ml of deionized water, and uniformly dispersed by ultrasonic treatment for 30 minutes to obtain a carbon base solution.
(2) Slowly adding 1.5ml of 1mol/L chloroplatinic acid aqueous solution and 1.5ml of 2mol/L zinc chloride aqueous solution into the solution obtained in the step (1), and performing ultrasonic treatment for 30 minutes to uniformly disperse the chloroplatinic acid aqueous solution and the zinc chloride aqueous solution
(3) To the solution obtained in step (2), 3ml of a 1mol/L aqueous solution of dicyandiamide was slowly added, stirred for 4 hours, and then lyophilized.
(4) And (4) putting the precursor obtained in the step (3) into a tube furnace for pyrolysis to obtain the microporous carbon-coated Pt-Zn nano-particles. The pyrolysis condition is that the temperature is kept at 180 ℃ for 3 hours under the argon atmosphere, the temperature is kept at 750 ℃ for 2 hours, at the moment, pt and Zn ions are reduced into metal or alloy, a carbon nitride compound is carbonized to form a carbon layer to be coated on the surface of the metal, and partial Zn is volatilized on the coated carbon layer to form micropores.
(5) And (3) placing the microporous carbon-coated PtZn nanoparticles obtained in the step (4) at 85 ℃ and stirring with 0.5M dilute nitric acid for 2 hours, and then filtering and washing with deionized water for 3 times.
(6) And (5) drying the solid obtained in the step (5) and then carbonizing again to obtain the microporous carbon-coated Pt nano-particles.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.
Claims (10)
1. A method for preparing a microporous carbon-coated platinum nanoparticle electrocatalyst, comprising the steps of:
adding a noble metal ion solution and a volatile metal ion solution into the carbon substrate solution, and uniformly dispersing;
adding soluble carbon nitrogen compound solution, mixing uniformly and freeze-drying;
carbonizing the product in an inert atmosphere to obtain microporous carbon-coated nano particles;
and (4) pickling the product, and carbonizing again to obtain the microporous carbon-coated platinum nanoparticle electrocatalyst.
2. The method of claim 1, wherein the volatile metal is a metal that is volatile at 700-900 ℃, and comprises zinc.
3. The method of claim 2, wherein the pore former precursor is a zinc salt solution comprising an aqueous solution of zinc chloride, zinc sulfate, zinc nitrate, or zinc acetate.
4. The method of claim 1, wherein the carbon substrate comprises carbon aerogel or ketjen black; the noble metal ion solution comprises a water solution of platinum tetrachloride, chloroplatinic acid or potassium chloroplatinate; the soluble carbon nitrogen compound solution is dicyandiamide or a melamine aqueous solution.
5. The method of claim 1, wherein the noble metal content of the catalyst is 20-50wt%; the mass ratio of the volatile metal to the noble metal is 1 (0.5-1); the mass ratio of the soluble carbon nitrogen compound to the noble metal is 1 (1-10).
6. A method of preparing a microporous carbon-coated platinum nanoparticle electrocatalyst according to claim 1, wherein the temperature of the carbonization is 700-900 ℃ for 1-3h.
7. The method of claim 1, wherein the acid washing is performed using nitric acid at a concentration ranging from 0.1 to 5M and at a temperature ranging from 50 to 90 ℃.
8. The method of claim 7, wherein the re-carbonization temperature is 50-100 ℃ lower than the carbonization temperature for 20-40min.
9. The method of claim 7, wherein the carbonizing is performed under the following conditions: in nitrogen atmosphere, firstly preserving heat for 1-3h at 180-300 ℃, and then preserving heat for 1-3h at 700-900 ℃.
10. A microporous carbon-coated platinum nanoparticle electrocatalyst prepared according to the method of any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211641253.8A CN115863679A (en) | 2022-12-20 | 2022-12-20 | Microporous carbon-coated platinum nanoparticle electrocatalyst and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211641253.8A CN115863679A (en) | 2022-12-20 | 2022-12-20 | Microporous carbon-coated platinum nanoparticle electrocatalyst and preparation method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115863679A true CN115863679A (en) | 2023-03-28 |
Family
ID=85674480
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211641253.8A Pending CN115863679A (en) | 2022-12-20 | 2022-12-20 | Microporous carbon-coated platinum nanoparticle electrocatalyst and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115863679A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117174927A (en) * | 2023-07-25 | 2023-12-05 | 鸿基创能科技(广州)有限公司 | Fuel cell catalyst wrapped by microporous carbon layer and preparation method and application thereof |
-
2022
- 2022-12-20 CN CN202211641253.8A patent/CN115863679A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117174927A (en) * | 2023-07-25 | 2023-12-05 | 鸿基创能科技(广州)有限公司 | Fuel cell catalyst wrapped by microporous carbon layer and preparation method and application thereof |
| CN117174927B (en) * | 2023-07-25 | 2024-02-13 | 鸿基创能科技(广州)有限公司 | Fuel cell catalyst wrapped by microporous carbon layer and preparation method and application thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN114293223B (en) | Method for preparing superfine cerium dioxide supported metal monoatomic catalyst from cluster-based framework material | |
| CN112652780B (en) | Fe/Fe 3 Preparation method of C nano-particle loaded porous nitrogen-doped carbon-based oxygen reduction catalyst | |
| CN112968185A (en) | Preparation method of plant polyphenol modified manganese-based nano composite electrocatalyst with supermolecular network framework structure | |
| WO2021114056A1 (en) | Fuel cell cathode catalyst and preparation method therefor, membrane electrode and fuel cell | |
| CN112133933A (en) | Preparation method of iron-cobalt-platinum-loaded three-dimensional network surface hollow carbon sphere compound, product and application thereof | |
| CN114108004A (en) | Ruthenium-based alloy catalyst and preparation method and application thereof | |
| CN115863679A (en) | Microporous carbon-coated platinum nanoparticle electrocatalyst and preparation method thereof | |
| CN109731599B (en) | 2D oxygen reduction catalyst Fe3O4Preparation method of @ FeNC nanosheet | |
| CN108963279B (en) | Nitrogen-doped carbon microsphere/Pd composite catalyst and preparation method and application thereof | |
| WO2022099793A1 (en) | Orr catalyst material, preparation method therefor, and use thereof | |
| CN110600752B (en) | H2Method for preparing carbon-supported Pt alloy catalyst by gas-phase thermal reduction | |
| CN115570143B (en) | Low-platinum high-entropy alloy nano-particle and preparation method and application thereof | |
| CN115395026B (en) | Fe single-atom-supported N-doped carbon aerogel electrocatalyst and preparation method and application thereof | |
| CN112510217B (en) | Carbon-supported platinum yttrium catalyst and preparation method and application thereof | |
| CN113809344B (en) | High-stability nano platinum-based intermetallic compound direct methanol fuel cell electrocatalyst and preparation method thereof | |
| CN116130686A (en) | Mono-atom catalyst based on functionalized MOF, and preparation method and application thereof | |
| CN110224148B (en) | Pt or Au modified porous PdFe intermetallic compound and preparation method and application thereof | |
| JP2006092957A (en) | Cathode catalyst for solid polymer fuel cell, cathode electrode equipped with catalyst, solid polymer fuel cell equipped with electrode, and manufacturing method of catalyst | |
| CN110931808A (en) | Pd-WO3Anode electrocatalyst of/C proton exchange membrane fuel cell and its preparing method and use | |
| CN113054211B (en) | Coating catalytic material for proton exchange membrane fuel cell and preparation method and application thereof | |
| CN116565240B (en) | PtLn alloy catalyst supported by rare earth metal Ln doped NC carrier, and preparation method and application thereof | |
| CN114843532B (en) | Preparation method of high-activity Pt/C catalyst | |
| CN115161695B (en) | Non-noble metal catalyst and preparation method and application thereof | |
| CN117497787A (en) | Noble metal nanoparticle synergistic transition metal monoatomic catalyst, preparation and application | |
| CN115881982A (en) | N and P codoped porous carbon nanosheet loaded FeCo hollow nanosphere dual-functional electrocatalyst and preparation method and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |