CN115224294B - PtM intermetallic compound catalyst, preparation method and application - Google Patents
PtM intermetallic compound catalyst, preparation method and application Download PDFInfo
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- CN115224294B CN115224294B CN202211000875.2A CN202211000875A CN115224294B CN 115224294 B CN115224294 B CN 115224294B CN 202211000875 A CN202211000875 A CN 202211000875A CN 115224294 B CN115224294 B CN 115224294B
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- 239000003054 catalyst Substances 0.000 title claims abstract description 150
- 229910000765 intermetallic Inorganic materials 0.000 title claims abstract description 81
- 238000002360 preparation method Methods 0.000 title claims abstract description 29
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 84
- 239000000243 solution Substances 0.000 claims abstract description 63
- 238000010438 heat treatment Methods 0.000 claims abstract description 60
- 238000001132 ultrasonic dispersion Methods 0.000 claims abstract description 48
- 239000000843 powder Substances 0.000 claims abstract description 47
- 239000002243 precursor Substances 0.000 claims abstract description 46
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 44
- 150000003839 salts Chemical class 0.000 claims abstract description 32
- 229910021642 ultra pure water Inorganic materials 0.000 claims abstract description 32
- 239000012498 ultrapure water Substances 0.000 claims abstract description 32
- 239000007788 liquid Substances 0.000 claims abstract description 28
- 239000006185 dispersion Substances 0.000 claims abstract description 26
- 239000002253 acid Substances 0.000 claims abstract description 22
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 22
- 150000003624 transition metals Chemical class 0.000 claims abstract description 22
- 238000005406 washing Methods 0.000 claims abstract description 22
- 230000003197 catalytic effect Effects 0.000 claims abstract description 15
- 238000001291 vacuum drying Methods 0.000 claims abstract description 14
- 238000004108 freeze drying Methods 0.000 claims abstract description 12
- 239000003446 ligand Substances 0.000 claims abstract description 11
- 239000011259 mixed solution Substances 0.000 claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000007306 functionalization reaction Methods 0.000 claims abstract description 8
- 238000000227 grinding Methods 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 8
- UEUXEKPTXMALOB-UHFFFAOYSA-J tetrasodium;2-[2-[bis(carboxylatomethyl)amino]ethyl-(carboxylatomethyl)amino]acetate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-]C(=O)CN(CC([O-])=O)CCN(CC([O-])=O)CC([O-])=O UEUXEKPTXMALOB-UHFFFAOYSA-J 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims description 31
- 238000004519 manufacturing process Methods 0.000 claims description 16
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 12
- 229910052760 oxygen Inorganic materials 0.000 claims description 12
- 239000001301 oxygen Substances 0.000 claims description 12
- 238000003756 stirring Methods 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 11
- LHIJANUOQQMGNT-UHFFFAOYSA-N aminoethylethanolamine Chemical compound NCCNCCO LHIJANUOQQMGNT-UHFFFAOYSA-N 0.000 claims description 10
- 238000005530 etching Methods 0.000 claims description 9
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 7
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 7
- 125000000524 functional group Chemical group 0.000 claims description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims description 7
- 238000010301 surface-oxidation reaction Methods 0.000 claims description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- 239000007789 gas Substances 0.000 claims description 6
- 238000005554 pickling Methods 0.000 claims description 5
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 4
- 229910052700 potassium Inorganic materials 0.000 claims description 4
- 239000011591 potassium Substances 0.000 claims description 4
- FBEIPJNQGITEBL-UHFFFAOYSA-J tetrachloroplatinum Chemical compound Cl[Pt](Cl)(Cl)Cl FBEIPJNQGITEBL-UHFFFAOYSA-J 0.000 claims description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 3
- 229910002651 NO3 Inorganic materials 0.000 claims description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 18
- 238000009210 therapy by ultrasound Methods 0.000 abstract 1
- 239000002245 particle Substances 0.000 description 34
- 229910002837 PtCo Inorganic materials 0.000 description 20
- 229960001484 edetic acid Drugs 0.000 description 17
- 238000012360 testing method Methods 0.000 description 17
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 16
- 230000015572 biosynthetic process Effects 0.000 description 14
- 229910052799 carbon Inorganic materials 0.000 description 14
- 238000009826 distribution Methods 0.000 description 11
- 230000002776 aggregation Effects 0.000 description 10
- 238000002441 X-ray diffraction Methods 0.000 description 9
- 238000003786 synthesis reaction Methods 0.000 description 9
- 239000000446 fuel Substances 0.000 description 8
- 238000000967 suction filtration Methods 0.000 description 7
- 238000005054 agglomeration Methods 0.000 description 6
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 6
- 229910002836 PtFe Inorganic materials 0.000 description 5
- 238000003917 TEM image Methods 0.000 description 5
- 238000001889 high-resolution electron micrograph Methods 0.000 description 5
- 238000011068 loading method Methods 0.000 description 5
- 230000010287 polarization Effects 0.000 description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 5
- 238000004321 preservation Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 229910019029 PtCl4 Inorganic materials 0.000 description 4
- 238000004220 aggregation Methods 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000011160 research Methods 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000004817 gas chromatography Methods 0.000 description 3
- LMSDCGXQALIMLM-UHFFFAOYSA-N 2-[2-[bis(carboxymethyl)amino]ethyl-(carboxymethyl)amino]acetic acid;iron Chemical compound [Fe].OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O LMSDCGXQALIMLM-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 239000010411 electrocatalyst Substances 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000009827 uniform distribution Methods 0.000 description 2
- YTSDVWYUJXKXCC-UHFFFAOYSA-L zinc;2-[2-[carboxylatomethyl(carboxymethyl)amino]ethyl-(carboxymethyl)amino]acetate Chemical compound [Zn+2].OC(=O)CN(CC([O-])=O)CCN(CC(O)=O)CC([O-])=O YTSDVWYUJXKXCC-UHFFFAOYSA-L 0.000 description 2
- 229910021591 Copper(I) chloride Inorganic materials 0.000 description 1
- -1 EDTA ions Chemical class 0.000 description 1
- 229920000557 Nafion® Polymers 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- OXBLHERUFWYNTN-UHFFFAOYSA-M copper(I) chloride Chemical compound [Cu]Cl OXBLHERUFWYNTN-UHFFFAOYSA-M 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000000840 electrochemical analysis Methods 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 229910021397 glassy carbon Inorganic materials 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 231100000344 non-irritating Toxicity 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000009777 vacuum freeze-drying Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
- H01M4/921—Alloys or mixtures with metallic elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
- H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
- H01M4/926—Metals of platinum group supported on carriers, e.g. powder carriers on carbon or graphite
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
- H01M2004/8689—Positive electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Catalysts (AREA)
Abstract
The invention provides a PtM intermetallic compound catalyst, a preparation method and application, wherein the preparation method comprises the following steps: s1, dissolving Pt precursor salt in ultrapure water, and adding N-containing molecular ligand to obtain a first solution; s2, dissolving precursor salt of transition metal M in ultrapure water, and adding EDTA tetrasodium salt to obtain a second solution; s3, dispersing the carbon powder into ultrapure water after functionalization treatment to obtain carbon powder dispersion liquid; s4, mixing the first solution and the second solution, adding carbon powder dispersion liquid after ultrasonic dispersion, and continuing ultrasonic treatment to obtain mixed liquid; s5, freeze-drying the mixed solution to obtain precursor freeze-dried powder; s6, performing heat treatment on the precursor freeze-dried powder in a reducing atmosphere to obtain powder; s7, acid washing, water washing, vacuum drying and grinding to obtain the PtM intermetallic compound catalyst. The catalyst in the invention shows the ORR catalytic activity superior to Pt/C, the mass specific activity is improved by nearly 4 times, and the catalyst also shows outstanding durability.
Description
Technical Field
The invention belongs to the field of synthesis of fuel cell nano electrocatalyst, and particularly relates to a PtM intermetallic compound catalyst, a preparation method and application.
Background
Ordered Pt-M intermetallic compounds (PtM-IMC) are used as ORR electrocatalysts with high activity and high stability, are concerned by the research in the field of fuel cells, and have unique Pt and M atomic structures which are periodically distributed, so that the effective regulation and control of Pt electronic structures can be more effectively realized, the great promotion of Pt intrinsic catalytic activity is promoted, and meanwhile, transition metal M can be effectively stabilized, so that dissolution is difficult to occur, and the structural stability of PtM is ensured.
However, the existing PtM-IMC synthesis method adopts a two-step method, wherein disordered PtM alloy is formed in the first step, and the disordered PtM alloy is calcined at high temperature in the second step, so that the transformation from disordered to ordered structure is realized, and the PtM-IMC catalyst is constructed. Although the synthesis strategy can realize the formation of an ordered structure, a long-time conversion process is usually required at high temperature to obtain a PtM-IMC structure with high ordered degree, which can lead to easy agglomeration and growth of PtM particles and uneven particle distribution, thereby greatly reducing the active area and catalytic activity of PtM.
Therefore, how to directly and efficiently prepare PtM-IMC catalysts with high ordering degree and smaller particle size is a key scientific and technical problem to be solved in the present urgent need.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a PtM intermetallic compound catalyst, a preparation method and an application thereof, which are used for solving the problem that the PtM intermetallic compound catalyst with high order degree, smaller particle size and uniform distribution cannot be directly and efficiently prepared in the prior art.
To achieve the above and other related objects, the present invention provides a method for preparing a PtM intermetallic compound catalyst, comprising the steps of:
S1, dissolving Pt precursor salt in ultrapure water, adding a certain amount of N-containing molecular ligand, and performing ultrasonic dispersion to carry out molecular coordination to obtain a first solution;
S2, dissolving precursor salt of transition metal M in ultrapure water, adding ethylene diamine tetraacetic acid tetrasodium salt, and carrying out molecular coordination under ultrasonic dispersion to obtain a second solution;
s3, carrying out functionalization treatment on the carbon powder, and then dispersing the carbon powder in ultrapure water by ultrasonic to obtain carbon powder dispersion liquid;
s4, mixing the first solution and the second solution, ultrasonically dispersing for a period of time, then adding the carbon powder dispersion liquid, and continuing ultrasonic dispersion to obtain a mixed liquid;
S5, performing freeze drying treatment on the mixed solution to obtain precursor freeze-dried powder;
S6, carrying out heat treatment on the precursor freeze-dried powder in a reducing atmosphere to obtain powder;
and S7, sequentially carrying out acid washing and water washing on the powder, and then grinding after vacuum drying to obtain the PtM intermetallic compound catalyst.
Preferably, the molar ratio between the Pt precursor salt and the N-containing molecular ligand in step S1 is 1:2 to 1:4.
Preferably, the Pt precursor salt in step S1 is one or a combination of chloroplatinic acid, potassium chloroplatinic acid, and platinum tetrachloride.
Preferably, the N-containing molecular ligand in step S1 is ethylenediamine or hydroxyethyl ethylenediamine.
Preferably, the time of ultrasonic dispersion in step S1 is 1 to 4 hours.
Preferably, the molar ratio between the transition metal M and the tetra sodium salt of ethylenediamine tetraacetic acid in step S2 is 1:1.
Preferably, the transition metal M in step S2 is one of Fe, co, cu, zn.
Preferably, the precursor salt in step S2 is one or a combination of chloride, nitrate, acetate or sulfate.
Preferably, the time of ultrasonic dispersion in step S2 is 1 to 4 hours.
Preferably, the functionalization treatment in step S3 is doping or surface oxidation treatment; wherein, the carbon powder doping treatment comprises the following steps: placing carbon powder in a tubular furnace, heating to 700-950 ℃, and etching for 20-90 min under the condition that NH 3 is introduced at the flow rate of 50-200 sccm to realize N doping of the carbon powder to obtain N doped carbon powder; the method for carrying out surface oxidation treatment on the carbon powder comprises the following steps: dispersing carbon powder in 2-8 mol/L nitric acid solution, heating to 60-85 deg.c, stirring for 1-4 hr, water washing and filtering to obtain carbon powder with grafted oxygen-containing functional group.
Preferably, in the step S3, the carbon powder is one or a combination of XC-72, XC-72R, EC-300, KB-600 and BP-2000; and the ultrasonic dispersion time in the step S3 is 2-5 h.
Preferably, after the first solution and the second solution are mixed in the step S4, the first solution and the second solution are ultrasonically dispersed for 1 to 3 hours; and after adding the carbon powder dispersion liquid, continuing ultrasonic dispersion for 2-4 hours.
Preferably, the reducing atmosphere in the step S6 is H 2/Ar mixed gas.
Preferably, the heat treatment in step S6 specifically includes the steps of: raising the temperature to 500-750 ℃ at the heating rate of 7 ℃/min, preserving the heat for 0.5-8 h, and naturally cooling to room temperature.
Preferably, the pickling in step S7 specifically includes the following steps: pouring the powder into an acid solution, and stirring for 12-18 h at 60-80 ℃; wherein the acid solution is one or a combination of sulfuric acid, hydrochloric acid and nitric acid, and the concentration of the acid solution is 0.1 mol/L-5 mol/L.
Preferably, the washing in step S7 is performed 3 to 5 times with ultrapure water.
Preferably, the temperature of the vacuum drying in the step S7 is 60 ℃, and the time of the vacuum drying is 12-24 hours.
The invention also provides a PtM intermetallic compound catalyst, which is prepared by the preparation method of the PtM intermetallic compound catalyst.
In order to better understand the PtM intermetallic compound catalyst and the preparation method, the invention also provides application of the PtM intermetallic compound catalyst in the ORR catalytic process, wherein the PtM intermetallic compound catalyst is prepared by the preparation method of the PtM intermetallic compound catalyst.
As described above, the PtM intermetallic compound catalyst, the preparation method and the application of the invention have the following beneficial effects:
The invention provides a preparation method of a PtM intermetallic compound catalyst with high degree of ordering, uniform and controllable particle size and uniform particle distribution, and application of the PtM intermetallic compound catalyst in an ORR catalytic process, which provides a new solution for developing a new generation of high-activity and long-durability fuel cell cathode PtM intermetallic compound catalyst, and can realize high dispersion of Pt and M precursor substances on a carbon carrier by utilizing a research strategy of water-soluble metal-organic coordination molecule pairs, and simultaneously pull up the space distance between Pt and transition metal M atoms, thereby providing a premise for efficiently realizing PtM ordered structures; by adopting a direct high-temperature and short-time heat treatment mode, the formation of the highly ordered PtM intermetallic compound catalyst can be realized, and meanwhile, the heat treatment time is greatly shortened and the agglomeration of particles is inhibited, so that the synthesis of the catalyst with high order degree is realized; the functionalized carbon carrier, such as N-doped or surface grafted oxygen-containing functional groups, can not only realize the efficient adsorption of Pt and M organic complex ions on the carbon carrier, but also effectively inhibit the aggregation of PtM particles in the heat treatment process.
The PtM intermetallic compound catalyst prepared by the method shows the ORR catalytic activity superior to that of commercial Pt/C, and particularly the mass specific activity is improved by nearly 4 times; in addition, the catalyst also shows outstanding durability, and after 10000 circles of acceleration tests, the mass activity of the PtM-IMC catalyst only declines by about 20%, so that the use requirement of the commercial catalyst of the PEMFC is met, and an advanced synthesis strategy is provided for preparing the ORR catalyst of a new generation fuel cell in the future.
Drawings
FIG. 1 shows a flow chart of the preparation process of the PtM intermetallic catalyst of the invention.
FIG. 2 shows XRD contrast patterns of different catalysts PtCo-IMC-T-T prepared in examples 1 to 6 of the present invention.
FIG. 3 shows a comparison of electrochemical ORR polarization curves of test electrodes prepared with different catalysts of examples 1-6 of the present invention in 0.1mol/L HClO 4 solution.
FIG. 4 shows a comparison of mass specific activities at 0.9V/RHE for the different catalysts of examples 1 to 6 according to the invention.
FIG. 5 shows, from left to right, a transmission electron micrograph, a high resolution electron micrograph, a particle size distribution map, and a fast Fourier transform diffraction pattern of the 33% -PtCo-IMC-700-2.5 catalyst prepared in example 3 of the present invention, respectively.
FIG. 6 shows, from left to right, a transmission electron micrograph, a high resolution electron micrograph, a particle size distribution map, and a fast Fourier transform diffraction pattern map of the 33% -PtCo-IMC-700-4.0 catalyst prepared in example 4 of the present invention, respectively.
FIG. 7 shows the XRD pattern of the 50% -PtCo-IMC-700-1 catalyst prepared in example 5 of the present invention.
FIG. 8 shows a graph of electrochemical ORR polarization in a 0.1mol/L HClO 4 solution for a test electrode made of the 50% -PtCo-IMC-700-1 catalyst prepared in example 5 of the present invention.
FIG. 9 shows, from left to right, a transmission electron micrograph, a high resolution electron micrograph, a particle size distribution map, and a fast Fourier transform diffraction pattern map, respectively, of the 50% -PtCo-IMC-700-1 catalyst prepared in example 5 of the present invention.
FIG. 10 shows the XRD pattern of the 50% -1:1.5-PtCo-IMC-700-1 catalyst prepared in example 6 of the invention.
FIG. 11 shows a graph of electrochemical ORR polarization in a 0.1mol/L HClO 4 solution for a test electrode made of the 50% -1:1.5-PtCo-IMC-700-1 catalyst prepared in example 6 of the invention.
FIG. 12 shows XRD patterns of PtZn-IMC-T catalysts prepared at different heat treatment temperatures in examples 7 to 10 of the present invention.
FIG. 13 shows the XRD pattern of the PtCu-IMC catalyst prepared in example 11 of the present invention.
FIG. 14 shows the XRD pattern of the PtFe-IMC catalyst prepared in example 12 of the present invention.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Please refer to fig. 1-14. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
The invention provides a preparation method of a PtM intermetallic compound catalyst with high degree of ordering, uniform and controllable particle size and uniform particle distribution, and application of the PtM intermetallic compound catalyst in an ORR catalytic process, which provides a new solution for developing a new generation of high-activity and long-durability fuel cell cathode PtM intermetallic compound catalyst, and can realize high dispersion of Pt and M precursor substances on a carbon carrier by utilizing a research strategy of water-soluble metal-organic coordination molecule pairs, and simultaneously pull up the space distance between Pt and transition metal M atoms, thereby providing a premise for efficiently realizing PtM ordered structures; by adopting a direct high-temperature and short-time heat treatment mode, the formation of the highly ordered PtM intermetallic compound catalyst can be realized, and meanwhile, the heat treatment time is greatly shortened and the agglomeration of particles is inhibited, so that the synthesis of the catalyst with high order degree is realized; the functionalized carbon carrier, such as N-doped or surface grafted oxygen-containing functional groups, can not only realize the efficient adsorption of Pt and M organic complex ions on the carbon carrier, but also effectively inhibit the aggregation of PtM particles in the heat treatment process; the PtM intermetallic compound catalyst prepared by the method shows the ORR catalytic activity superior to that of commercial Pt/C, and particularly the mass specific activity is improved by nearly 4 times; in addition, the catalyst also shows outstanding durability, and after 10000 circles of acceleration tests, the mass activity of the PtM-IMC catalyst only declines by about 20%, so that the use requirement of the commercial catalyst of the PEMFC is met, and an advanced synthesis strategy is provided for preparing the ORR catalyst of a new generation fuel cell in the future.
Referring to fig. 1, the present invention provides a preparation method of a PtM intermetallic compound catalyst, the preparation method comprising the steps of:
S1, dissolving Pt precursor salt in ultrapure water, adding a certain amount of N-containing molecular ligand, and performing ultrasonic dispersion to carry out molecular coordination to obtain a first solution;
S2, dissolving precursor salt of transition metal M in ultrapure water, adding Ethylene Diamine Tetraacetic Acid (EDTA) tetrasodium salt, and carrying out molecular coordination under ultrasonic dispersion to obtain a second solution;
s3, carrying out functionalization treatment on the carbon powder, and then dispersing the carbon powder in ultrapure water by ultrasonic to obtain carbon powder dispersion liquid;
s4, mixing the first solution and the second solution, ultrasonically dispersing for a period of time, then adding carbon powder dispersion liquid, and continuing ultrasonic dispersion to obtain mixed liquid;
s5, performing freeze drying treatment on the mixed solution to obtain precursor freeze-dried powder;
s6, performing heat treatment on the precursor freeze-dried powder in a reducing atmosphere to obtain powder;
And S7, sequentially carrying out acid washing and water washing on the powder, and grinding after vacuum drying to obtain the PtM intermetallic compound catalyst.
Specifically, water-soluble Pt coordination molecules with positive charges are formed in the step S1, water-soluble transition metal coordination molecules with negative charges are formed in the step S2, and the carbon powder after the functionalization treatment in the carbon powder dispersion liquid obtained in the step S3 is uniformly dispersed in ultrapure water; in the step S4, because the metal-organic coordination molecules of the two molecules have positive and negative charges, the mutual collision between Pt and the transition metal M can be improved due to the electrostatic effect, so that the high dispersion of Pt and M precursor substances on the carbon carrier is realized, and meanwhile, the space distance between Pt and M atoms of the transition metal is shortened, and a precondition is provided for efficiently realizing the PtM ordered structure; in the step S5, the mixed solution is placed in a freeze dryer for vacuum freeze drying, so that dispersed Pt and M coordination molecules are quickly frozen, intermolecular agglomeration is inhibited, and high-efficiency load of the molecules on a carbon carrier is realized; in the step S6, the precursor freeze-dried powder is placed in a porcelain boat and slowly placed in a tube furnace for high-temperature heat treatment, and particularly, before the high-temperature heat treatment, vacuumizing operation is needed, the air in the tube furnace is thoroughly discharged, and then programmed heating is carried out.
As an example, the molar ratio between the Pt precursor salt and the N-containing molecular ligand in step S1 is 1:2 to 1:4.
Specifically, the molar ratio between the Pt precursor salt and the N-containing molecular ligand in step S1 may include any value within any range of 1:2, 1:3, 1:4, etc., and may be specifically adjusted according to the actual implementation.
As an example, the Pt precursor salt in step S1 is one or a combination of chloroplatinic acid, potassium chloroplatinic acid, and platinum tetrachloride.
Specifically, the Pt precursor salt is water-soluble, and is any one of chloroplatinic acid, potassium chloroplatinic acid and platinum tetrachloride, or a mixture of any two or a mixture of three.
As an example, the N-containing molecular ligand in step S1 is ethylenediamine or hydroxyethylethylenediamine (AEEA).
Specifically, ethylenediamine or hydroxyethyl ethylenediamine is a coordination molecule with amino group, and under ultrasonic dispersion, the ethylenediamine or hydroxyethyl ethylenediamine is subjected to molecular coordination with Pt precursor salt to form a water-soluble Pt coordination molecule with positive charge; wherein, ethylenediamine (ETHYLENEDIAMINE), EDA for short, has a chemical formula of C 2H8N2; hydroxyethyl ethylenediamine, AEEA for short, has a molecular formula of C 4H12ON2 and a structural formula of: h 2NCH2CH2NHCH2CH2 OH, the appearance is light yellow to yellow viscous liquid with ammonia smell, and the liquid is non-irritating.
As an example, the time of ultrasonic dispersion in step S1 is 1 to 4 hours.
Specifically, the time of ultrasonic dispersion in step S1 may include values in any range of 1h, 2h, 3h, 4h, etc., and may be specifically adjusted according to the actual situation.
As an example, the molar ratio between the transition metal M and the tetra sodium salt of ethylenediamine tetraacetic acid in step S2 is 1:1.
Specifically, the tetra-sodium salt of ethylenediamine tetraacetic acid is referred to as EDTA tetra-sodium salt.
As an example, the transition metal M in step S2 is one of Fe, co, cu, zn.
As an example, the precursor salt in step S2 is one or a combination of chloride, nitrate, acetate or sulfate, which has a valence state of +2.
As an example, the time of ultrasonic dispersion in step S2 is 1 to 4 hours.
Specifically, the transition metal M in the transition metal M precursor salt coordinates with EDTA ions, and the water-soluble transition metal coordination molecules with negative charges are formed by ultrasonic dispersion, wherein the coordination speed of the step is high, and the ultrasonic dispersion time in the step S2 can comprise values in any range of 1h, 2h, 3h, 4h and the like, and can be specifically adjusted according to actual practice.
As an example, the manner of the functionalization treatment in step S3 is doping or surface oxidation treatment; the carbon powder doping treatment comprises the following steps: placing carbon powder in a tubular furnace, heating to 700-950 ℃, and etching for 20-90 min under the condition that NH 3 is introduced at the flow rate of 50-200 sccm to realize N doping of the carbon powder to obtain N doped carbon powder;
The method for carrying out surface oxidation treatment on the carbon powder comprises the following steps: dispersing carbon powder in 2-8 mol/L nitric acid solution, heating to 60-85 deg.c, stirring for 1-4 hr, water washing and filtering to obtain carbon powder with grafted oxygen-containing functional group.
Specifically, when carbon powder is doped, the etching temperature can include values in any range of 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃, 950 ℃ and the like, and can be specifically adjusted according to actual conditions; the flow rate of NH 3 can comprise values in any range of 50sccm, 100sccm, 150sccm, 200sccm, etc., and can be specifically adjusted according to the actual situation; the etching time can comprise any value in any range of 20min, 30min, 40min, 50min, 60min, 70min, 80min, 90min and the like, and can be specifically adjusted according to actual practice.
When the carbon powder is subjected to surface oxidation treatment, the concentration of the nitric acid solution adopted can comprise values in any range of 2mol/L, 3mol/L, 4mol/L, 5mol/L, 6mol/L, 7mol/L, 8mol/L and the like, and the concentration can be specifically adjusted according to actual practice; the heating temperature can comprise values in any range of 60 ℃, 65 ℃,70 ℃, 75 ℃, 80 ℃, 85 ℃ and the like, and can be specifically adjusted according to actual conditions; the stirring time can comprise values in any range of 1h, 2h, 3h, 4h and the like, and can be specifically adjusted according to actual practice.
In this embodiment, a functionalized carbon carrier, such as carbon powder doped with N or carbon powder grafted with an oxygen-containing functional group on the surface, is used, so that not only can efficient adsorption of Pt and M organic complex ions on the carbon carrier be realized, but also aggregation of PtM particles can be effectively inhibited in the heat treatment process.
As an example, the carbon powder in step S3 is one or a combination of XC-72, XC-72R, EC-300, KB-600, BP-2000; and the ultrasonic dispersion time in the step S3 is 2-5 h.
Specifically, the carbon powder is commercial carbon powder, and specifically selected from XC-72, XC-72R, EC-300, KB-600 and BP-2000 model carbon powder; and the time of ultrasonic dispersion can comprise values in any range of 2h, 3h, 4h, 5h and the like, and can be specifically adjusted according to actual practice.
As an example, after the first solution and the second solution are mixed in step S4, ultrasonic dispersion is performed for 1 to 3 hours; and after adding the carbon powder dispersion liquid, continuing ultrasonic dispersion for 2-4 hours.
Specifically, after the first solution and the second solution are mixed in step S4, the time of ultrasonic dispersion may include values in any range of 1h, 1.5h, 2h, 2.5h, 3h, etc., and may be specifically adjusted according to the actual situation; after adding the carbon powder dispersion liquid, the time for continuing ultrasonic dispersion can comprise values in any range of 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours and the like, and can be specifically adjusted according to actual practice.
In addition, when the first solution and the second solution are mixed, the two metal-organic coordination molecules have large positive and negative charges, so that the mutual collision and the molecular distance between Pt and transition metal M molecules can be improved due to the electrostatic effect, then carbon powder dispersion liquid is added, and the loading of the Pt and M coordination molecules and a carbon carrier is promoted in a form of weak interaction force.
As an example, the reducing atmosphere in step S6 is H 2/Ar mixture.
As an example, the heat treatment in step S6 specifically includes the steps of: raising the temperature to 500-750 ℃ at the heating rate of 7 ℃/min, preserving the heat for 0.5-8 h, and naturally cooling to room temperature.
Specifically, the temperature at the time of the heat treatment in step S6 may include values in any range of 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, etc., and may be specifically adjusted according to the actual use; the heat preservation time can comprise values in any range of 0.5h, 1h, 2h, 4h, 6h, 8h and the like, and can be specifically adjusted according to actual practice; in the step, a direct high-temperature and short-time heat treatment mode is adopted, so that the formation of the highly ordered PtM intermetallic compound catalyst can be realized, and meanwhile, the heat treatment time is greatly shortened, and agglomeration of particles is inhibited, so that the synthesis of the catalyst with high order degree is realized.
As an example, the pickling in step S7 specifically includes the steps of: pouring the powder into an acid solution, and stirring for 12-18 h at 60-80 ℃; wherein the acid solution is one or a combination of sulfuric acid, hydrochloric acid and nitric acid, and the concentration of the acid solution is 0.1 mol/L-5 mol/L.
Specifically, the temperature during pickling in step S7 may include values in any range of 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃ and the like, and may be specifically adjusted according to the actual use; the stirring time can comprise values in any range of 12h, 13h, 14h, 15h, 16h, 17h, 18h and the like, and can be specifically adjusted according to actual practice; the concentration of the acid solution may include values in any range of 0.1mol/L, 0.5mol/L, 1mol/L, 2mol/L, 3mol/L, 4mol/L, 5mol/L, etc., and may be specifically adjusted according to the actual use.
As an example, the washing with ultrapure water in step S7 is performed 3 to 5 times.
Specifically, ultrapure water is used for washing 3 times, 4 times or 5 times, in this embodiment, when the washed powder solution is subjected to water washing treatment, a suction filtration device is used for washing, residual salt, unstable transition metal M and anions in the powder are thoroughly washed by the ultrapure water, and the washed powder solution is subjected to suction filtration by the suction filtration device to obtain a washed filter cake.
As an example, the temperature of the vacuum drying in step S7 is 60 ℃, and the time of the vacuum drying is 12 to 24 hours.
Specifically, the product after pickling and washing is dried in vacuum, and the drying time at 60 ℃ can comprise values in any range of 12h, 14h, 16h, 18h, 20h, 22h, 24h and the like, and can be specifically adjusted according to the actual situation.
The invention also provides a PtM intermetallic compound catalyst, which is prepared by adopting the preparation method of the PtM intermetallic compound catalyst.
In order to better understand the PtM intermetallic compound catalyst and the preparation method, the invention provides application of the PtM intermetallic compound catalyst, and the PtM intermetallic compound catalyst is applied to an ORR catalytic process, wherein the PtM intermetallic compound catalyst is prepared by the preparation method of the PtM intermetallic compound catalyst.
The PtM intermetallic catalyst, the preparation method and the use of the present invention will now be described with reference to specific examples, which are intended to be illustrative only and not limiting in any way.
Example 1
The present embodiment provides a preparation method of a PtCo intermetallic compound catalyst, the preparation method comprising the steps of:
S1, dissolving 163.5mg of K 2PtCl4 powder into 20ml of ultrapure water, adding 82mg of hydroxyethyl ethylenediamine (AEEA), and performing ultrasonic dispersion for 6 hours to perform molecular coordination to obtain a Pt-AEEA complex; wherein, the mole ratio of Pt precursor salt to AEEA is 1:2;
S2, dissolving 51.1mg of CoCl 2 powder into 20ml of ultrapure water, adding 178.1mg of ethylenediamine tetraacetic acid (EDTA) tetrasodium salt, and performing ultrasonic dispersion for 6 hours to carry out molecular coordination to obtain a Co-EDTA complex; wherein, the mole ratio of Co to EDTA is 1:1, a step of;
S3, placing carbon powder (XC-72R) in a tube furnace, heating to 850 ℃ under Ar protection, then etching for 40min under the condition of introducing NH 3 at the flow rate of 100sccm, naturally cooling to obtain N-doped carbon powder (N-XC-72R), then ultrasonically dispersing 200mg of N-XC-72R in 10ml of ultrapure water, and ultrasonically dispersing for 1h to obtain uniformly dispersed carbon powder dispersion; wherein the mass ratio of carbon powder to PtCo metal is 2:1, namely the loading amount of target PtCo is 33wt%;
s4, mixing the Pt-AEEA complex and the Co-EDTA complex, performing ultrasonic dispersion for 2 hours, adding carbon powder dispersion liquid, and continuing ultrasonic dispersion for 3 hours to obtain a mixed liquid;
S5, placing the mixed solution in a freeze drying instrument for freeze drying to obtain precursor freeze-dried powder;
S6, placing the precursor freeze-dried powder in a high-temperature tube furnace, vacuumizing, fully removing oxygen in the tube, continuously introducing H2/Ar mixed gas, heating to 700 ℃ at a heating rate of 7 ℃/min, preserving heat for 0.5H, and naturally cooling to obtain powder;
S7, pouring the powder into a sulfuric acid solution with the concentration of 0.5mol/L, stirring for 12 hours at the temperature of 65 ℃, washing for 3 meters by suction filtration, and grinding after vacuum drying at the temperature of 60 ℃ to obtain the PtCo intermetallic compound catalyst which is recorded as 33% -PtCo-IMC-700-0.5.
The present embodiment also provides a PtCo intermetallic compound catalyst prepared by the above preparation method of the PtCo intermetallic compound catalyst.
Example 2
This example provides a method for producing a PtCo intermetallic compound catalyst, which differs from example 1 in that: the heat preservation time in the step S6 is set to be 1h; other steps and methods are the same as those in embodiment 1, and will not be described here again.
This example also provides a PtCo intermetallic catalyst, which is correspondingly labeled 33% -PtCo-IMC-700-1.
Example 3
This example provides a method for producing a PtCo intermetallic compound catalyst, which differs from example 1 in that: the heat preservation time in the step S6 is set to be 2.5 hours; other steps and methods are the same as those in embodiment 1, and will not be described here again.
This example also provides a PtCo intermetallic catalyst, which is correspondingly labeled 33% -PtCo-IMC-700-2.5.
Referring to fig. 5, from left to right, there are a transmission electron micrograph, a high resolution electron micrograph, a particle size distribution map, and a fast fourier transform diffraction pattern map of the 33% -PtCo-IMC-700-2.5 catalyst prepared in this example, respectively, it is clear that the particles of the 33% -PtCo-IMC-700-2.5 catalyst prepared in this example are uniformly distributed, the particle size is uniform and controllable, the particle size is about 8nm, and the catalyst in this example is an ordered intermetallic compound crystal structure.
Example 4
This example provides a method for producing a PtCo intermetallic compound catalyst, which differs from example 1 in that: the heat preservation time in the step S6 is set to be 4 hours; other steps and methods are the same as those in embodiment 1, and will not be described here again.
This example also provides a PtCo intermetallic catalyst, which is correspondingly labeled 33% -PtCo-IMC-700-4.
Referring to fig. 6, from left to right, there are a transmission electron micrograph, a high resolution electron micrograph, a particle size distribution map, and a fast fourier transform diffraction pattern of the 33% -PtCo-IMC-700-4 catalyst prepared in this example, respectively, and it is understood that the catalyst in this example has a uniform distribution of particles and an intermetallic compound crystal structure, as compared with example 3, since the particles become larger by extending the heat treatment time.
Example 5
This example provides a method for producing a PtCo intermetallic compound catalyst, which differs from example 1 in that: in the step S3, the mass of the N-XC-72R is 100mg, and the loading amount of the obtained target PtCo is 50wt%; s6, setting the heat preservation time to be 1h; other steps and methods are the same as those in embodiment 1, and will not be described here again.
This example also provides a PtCo intermetallic catalyst, which is correspondingly labeled 50% -PtCo-IMC-700-1.
Referring to FIG. 7, which shows the XRD pattern of the 50% -PtCo-IMC-700-1 catalyst prepared in this example, the catalyst has a clear superlattice, indicating that the PtCo is an ordered alloy.
Referring to FIG. 8, there is shown a graph of electrochemical ORR polarization in a 0.1mol/L HClO 4 solution for a test electrode made from the 50% -PtCo-IMC-700-1 catalyst prepared in this example, as can be seen from the graph, the 50% -PtCo-IMC-700-1 catalyst prepared in this example shows excellent ORR catalytic activity, and the half-wave point is close to 0.9V.
Referring to fig. 9, from left to right, there are a transmission electron microscope image, a high resolution electron microscope image, a particle size distribution diagram, and a fast fourier transform diffraction pattern image of the 50% -PtCo-IMC-700-1 catalyst prepared in this example, and it is known that the 50% -PtCo-IMC-700-1 catalyst prepared in this example has uniform particle distribution, uniform and controllable particle size, and particle size of about 7.5nm, and the catalyst in this example has an ordered intermetallic compound crystal structure.
Example 6
This example provides a method for producing a PtCo intermetallic compound catalyst, which differs from example 1 in that: the molar ratio of Pt in the step S1 to Co in the step S2 is 1:1.5, namely 76.65mg of CoCl 2 powder is weighed in the step S2 and dissolved in 20ml of ultrapure water, and 267.15mg of Ethylene Diamine Tetraacetic Acid (EDTA) tetrasodium salt is added; in the step S3, the mass of the N-XC-72R is 100mg, and the loading amount of the target PtCo is 50wt%; other steps and methods are the same as those in embodiment 1, and will not be described here again.
This example also provides a PtCo intermetallic catalyst, which is correspondingly labeled 50% -1:1.5-PtCo-IMC-700-1.
Referring to FIG. 2, which shows XRD contrast patterns of the different catalysts 33% -PtCo-IMC-700-0.5, 33% -PtCo-IMC-700-1, 33% -PtCo-IMC-700-2.5, 33% -PtCo-IMC-700-4, 50% -PtCo-IMC-700-1 and 50% -1:1.5-PtCo-IMC-700-1 prepared in examples 1 to 6, it is understood that the ordered intermetallic structure can be formed when the heat treatment temperature is 600 ℃, but the superlattice is not obvious, the prepared catalyst presents obvious superlattice as the temperature is increased to 700 ℃, which indicates that the prepared PtCo is ordered alloy, and the longer the heat treatment time, the higher the ordering degree is, but the particle size is obviously increased.
Experimental example
The catalysts prepared in examples 1 to 6 above were prepared into test electrodes, specifically comprising the steps of: preparing an electrochemical test ink solution, then dropwise adding 8 mu L of ink solution onto a pre-polished GC (gas chromatography) with a selected glassy carbon electrode head (GC) diameter of 5mm, and naturally airing to prepare a test electrode, wherein the Pt loading amount is 10 mu g (Pt)cm-2. Wherein, the ink solution formula is as follows: an ink solution was prepared by ultrasonic dispersion of 2mg of the catalyst, 25. Mu.L of a 5% Nafion solution, 1.5mL of isopropyl alcohol and 0.475mL of ultrapure water for 2 hours.
The test electrodes made of the catalysts in examples 1 to 6 were subjected to oxygen reduction performance test, respectively:
the method comprises the following specific steps: a certain amount of 0.1mol/L HClO 4 solution is put into a five-port electrolytic cell, N 2 is introduced for half an hour to saturate the solution, and CV and LSV tests are carried out by using an electrochemical workstation of Shanghai Chen Hua CHI730 e. Wherein, the scanning speed is 50mVs -1, the scanning is 40 circles, and the voltage range is 0.05-1V/RHE during CV test; in the linear scanning test, the scanning speed is 10mVs -1, and the scanning range is 0-1V RHE. Referring to FIG. 3, which shows a comparison of electrochemical ORR polarization curves of the test electrodes prepared with the different catalysts of examples 1 to 6 in 0.1mol/L HClO 4 solution, it is clear that the ORR catalytic activities of the prepared catalysts are different at different heat treatment temperatures and heat treatment times, wherein the 33% -PtCo-IMC-700-2.5 catalyst prepared at the heat treatment temperature of 700 ℃ for 2.5 hours shows the optimal ORR catalytic activity.
After O 2 is introduced for half an hour to reach saturation, LSV test is carried out similarly, and a curve is recorded; calculating kinetic current at 0.9V/RHE according to a K-L equation by utilizing an LSV curve, and finally calculating the mass specific activity (MA) of the catalyst; referring to FIG. 4, which shows the mass specific activity comparison of the catalysts of examples 1 to 6, it is understood that the mass specific activity of the 33% -PtCo-IMC-700-2.5 catalyst prepared by the heat treatment at 700℃for 2.5 hours is highest.
The Accelerated Durability Test (ADT) is to scan CV in the voltage range of 0.6-1.1V/RHE, the scanning speed is 100mVs -1, the scanning circle number is 10000, and the CV curve before and after the ADT test, the LSV curve and the MA front and back comparison are recorded.
Example 7
The present embodiment provides a method for producing a PtZn intermetallic compound catalyst, comprising the steps of:
S1, dissolving 163.5mg of K 2PtCl4 powder into 20ml of ultrapure water, adding 82mg of hydroxyethyl ethylenediamine (AEEA), and performing ultrasonic dispersion for 6 hours to perform molecular coordination to obtain a Pt-AEEA complex; wherein, the mole ratio of Pt precursor salt to AEEA is 1:2;
S2, dissolving 63.7mg of ZnCl 2 powder into 20ml of ultrapure water, adding 178.1mg of ethylenediamine tetraacetic acid (EDTA) tetrasodium salt, and performing ultrasonic dispersion for 6 hours to carry out molecular coordination to obtain a Zn-EDTA complex; wherein, the mol ratio of Zn to EDTA is 1:1, a step of;
S3, placing carbon powder (XC-72R) in a tube furnace, heating to 850 ℃ under Ar protection, then etching for 40min under the condition of introducing NH 3 at the flow rate of 100sccm, naturally cooling to obtain N-doped carbon powder (N-XC-72R), then ultrasonically dispersing 200mg of N-XC-72R in10 ml of ultrapure water, and ultrasonically dispersing for 1h to obtain uniformly dispersed carbon powder dispersion; s4, mixing the Pt-AEEA complex and the Zn-EDTA complex, performing ultrasonic dispersion for 2 hours, adding carbon powder dispersion liquid, and continuing ultrasonic dispersion for 3 hours to obtain a mixed liquid;
S5, placing the mixed solution in a freeze drying instrument for freeze drying to obtain precursor freeze-dried powder;
s6, placing the precursor freeze-dried powder in a high-temperature tube furnace, vacuumizing, fully removing oxygen in the tube, continuously introducing H2/Ar mixed gas, heating to 450 ℃ at a heating rate of 7 ℃/min, preserving heat for 0.5H, and naturally cooling to obtain powder;
S7, pouring the powder into a sulfuric acid solution with the concentration of 0.5mol/L, stirring for 12 hours at the temperature of 65 ℃, washing for 3 meters by suction filtration, and grinding after vacuum drying at the temperature of 60 ℃ to obtain the PtZn intermetallic compound catalyst, which is named as PtZn-IMC-450.
The present embodiment also provides a PtZn intermetallic compound catalyst prepared by the above preparation method of a PtZn intermetallic compound catalyst.
Example 8
This example provides a method for producing a PtZn intermetallic compound catalyst, which differs from example 7 in that: the temperature of the heat treatment in the step S6 is 500 ℃; other steps and methods are the same as in example 7, and will not be described here again.
This example also provides a PtZn intermetallic catalyst, which is labeled PtZn-IMC-500.
Example 9
This example provides a method for producing a PtZn intermetallic compound catalyst, which differs from example 7 in that: the temperature of the heat treatment in the step S6 is 550 ℃; other steps and methods are the same as in example 7, and will not be described here again.
This example also provides a PtZn intermetallic catalyst, which is correspondingly labeled PtZn-IMC-550.
Example 10
This example provides a method for producing a PtZn intermetallic compound catalyst, which differs from example 7 in that: the temperature of the heat treatment in the step S6 is 600 ℃; other steps and methods are the same as in example 7, and will not be described here again.
This example also provides a PtZn intermetallic catalyst, which is labeled PtZn-IMC-600.
Referring to FIG. 12, which shows XRD patterns of PtZn-IMC-450, ptZn-IMC-500, ptZn-IMC-550, ptZn-IMC-600 catalysts prepared at different heat treatment temperatures in examples 7 to 10, it can be seen that the particle size of the prepared catalyst increases significantly with increasing heat treatment temperature, and the ordered structure is also more apparent; and the ordered PtZn structure can be formed at the lower heat treatment temperature of 450 ℃.
Example 11
The present embodiment provides a preparation method of a PtCu intermetallic compound catalyst, the preparation method comprising the steps of:
S1, dissolving 163.5mg of K 2PtCl4 powder into 20ml of ultrapure water, adding 82mg of hydroxyethyl ethylenediamine (AEEA), and performing ultrasonic dispersion for 6 hours to perform molecular coordination to obtain a Pt-AEEA complex; wherein, the mole ratio of Pt precursor salt to AEEA is 1:2;
S2, dissolving 62.9mg of CuCl 2 powder into 20ml of ultrapure water, adding 178.1mg of ethylenediamine tetraacetic acid (EDTA) tetrasodium salt, and performing ultrasonic dispersion for 6 hours to carry out molecular coordination to obtain a Cu-EDTA complex; wherein, the mol ratio of Cu to EDTA is 1:1, a step of;
S3, placing carbon powder (XC-72R) in a tube furnace, heating to 850 ℃ under Ar protection, then etching for 40min under the condition of introducing NH 3 at the flow rate of 100sccm, naturally cooling to obtain N-doped carbon powder (N-XC-72R), then ultrasonically dispersing 200mg of N-XC-72R in 10ml of ultrapure water, and ultrasonically dispersing for 1h to obtain uniformly dispersed carbon powder dispersion; s4, mixing the Pt-AEEA complex and the Cu-EDTA complex, performing ultrasonic dispersion for 2 hours, adding carbon powder dispersion liquid, and continuing ultrasonic dispersion for 3 hours to obtain a mixed liquid;
S5, placing the mixed solution in a freeze drying instrument for freeze drying to obtain precursor freeze-dried powder;
S6, placing the precursor freeze-dried powder in a high-temperature tube furnace, vacuumizing, fully removing oxygen in the tube, continuously introducing H2/Ar mixed gas, heating to 600 ℃ at a heating rate of 7 ℃/min, preserving heat for 0.5H, and naturally cooling to obtain powder;
S7, pouring the powder into a sulfuric acid solution with the concentration of 0.5mol/L, stirring for 12 hours at the temperature of 65 ℃, washing for 3 meters by suction filtration, and grinding after vacuum drying at the temperature of 60 ℃ to obtain the PtCu intermetallic compound catalyst which is marked as PtCu-IMC.
The present embodiment also provides a PtCu intermetallic compound catalyst prepared by the above-mentioned method for preparing a PtCu intermetallic compound catalyst.
Referring to FIG. 13, which shows the XRD pattern of PtCu-IMC prepared in this example, it can be seen that a more distinct ordered PtCu intermetallic structure is formed after heat treatment at 600 ℃.
Example 12
The present embodiment provides a method for preparing a PtFe intermetallic catalyst, including the steps of:
S1, dissolving 163.5mg of K 2PtCl4 powder into 20ml of ultrapure water, adding 82mg of hydroxyethyl ethylenediamine (AEEA), and performing ultrasonic dispersion for 6 hours to perform molecular coordination to obtain a Pt-AEEA complex; wherein, the mole ratio of Pt precursor salt to AEEA is 1:2;
S2, 59.39mg of FeCl 2 powder is dissolved in 20ml of ultrapure water, 178.1mg of Ethylene Diamine Tetraacetic Acid (EDTA) tetrasodium salt is added, and the mixture is subjected to ultrasonic dispersion for 6 hours to carry out molecular coordination, so as to obtain an Fe-EDTA complex; wherein, the mol ratio of Fe to EDTA is 1:1, a step of;
S3, placing carbon powder (XC-72R) in a tube furnace, heating to 850 ℃ under Ar protection, then etching for 40min under the condition of introducing NH 3 at the flow rate of 100sccm, naturally cooling to obtain N-doped carbon powder (N-XC-72R), then ultrasonically dispersing 200mg of N-XC-72R in 10ml of ultrapure water, and ultrasonically dispersing for 1h to obtain uniformly dispersed carbon powder dispersion;
S4, mixing the Pt-AEEA complex and the Fe-EDTA complex, performing ultrasonic dispersion for 2 hours, adding carbon powder dispersion liquid, and continuing ultrasonic dispersion for 3 hours to obtain a mixed liquid;
S5, placing the mixed solution in a freeze drying instrument for freeze drying to obtain precursor freeze-dried powder;
S6, placing the precursor freeze-dried powder in a high-temperature tube furnace, vacuumizing, fully removing oxygen in the tube, continuously introducing H2/Ar mixed gas, heating to 650 ℃ at a heating rate of 7 ℃/min, preserving heat for 0.5H, and naturally cooling to obtain powder;
S7, pouring the powder into a sulfuric acid solution with the concentration of 0.5mol/L, stirring for 12 hours at the temperature of 65 ℃, washing for 3 meters by suction filtration, and grinding after vacuum drying at the temperature of 60 ℃ to obtain the PtFe intermetallic compound catalyst which is marked as PtFe-IMC.
The present embodiment also provides a PtFe intermetallic catalyst prepared by the above preparation method of PtFe intermetallic catalyst.
Referring to FIG. 14, which shows the XRD pattern of PtFe-IMC prepared in this example, it can be seen that ordered PtFe intermetallic catalysts were efficiently prepared in this example.
In summary, the invention provides a preparation method of a PtM intermetallic compound catalyst with high degree of ordering, uniform and controllable particle size and uniform particle distribution, and application of the PtM intermetallic compound catalyst in an ORR catalytic process, which provides a new solution for developing a new generation of high-activity and long-durability fuel cell cathode PtM intermetallic compound catalyst, and can realize high dispersion of Pt and M precursor substances on a carbon carrier by utilizing a research strategy of water-soluble metal-organic coordination molecule pairs, and simultaneously pull up the space distance between Pt and transition metal M atoms, thereby providing a premise for efficiently realizing PtM ordered structures; by adopting a direct high-temperature and short-time heat treatment mode, the formation of the highly ordered PtM intermetallic compound catalyst can be realized, and meanwhile, the heat treatment time is greatly shortened and the agglomeration of particles is inhibited, so that the synthesis of the catalyst with high order degree is realized; the functionalized carbon carrier, such as N-doped or surface grafted oxygen-containing functional groups, can not only realize the efficient adsorption of Pt and M organic complex ions on the carbon carrier, but also effectively inhibit the aggregation of PtM particles in the heat treatment process; the PtM intermetallic compound catalyst prepared by the method shows the ORR catalytic activity superior to that of commercial Pt/C, and particularly the mass specific activity is improved by nearly 4 times; in addition, the catalyst also shows outstanding durability, and after 10000 circles of acceleration tests, the mass activity of the PtM-IMC catalyst only declines by about 20%, so that the use requirement of the commercial catalyst of the PEMFC is met, and an advanced synthesis strategy is provided for preparing the ORR catalyst of a new generation fuel cell in the future. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (10)
1. A method for preparing a PtM intermetallic compound catalyst, comprising the steps of:
S1, dissolving Pt precursor salt in ultrapure water, adding a certain amount of N-containing molecular ligand, and performing ultrasonic dispersion to carry out molecular coordination to obtain a first solution;
S2, dissolving precursor salt of transition metal M in ultrapure water, adding ethylene diamine tetraacetic acid tetrasodium salt, and carrying out molecular coordination under ultrasonic dispersion to obtain a second solution;
s3, carrying out functionalization treatment on the carbon powder, and then dispersing the carbon powder in ultrapure water by ultrasonic to obtain carbon powder dispersion liquid;
s4, mixing the first solution and the second solution, ultrasonically dispersing for a period of time, then adding the carbon powder dispersion liquid, and continuing ultrasonic dispersion to obtain a mixed liquid;
S5, performing freeze drying treatment on the mixed solution to obtain precursor freeze-dried powder;
S6, carrying out heat treatment on the precursor freeze-dried powder in a reducing atmosphere to obtain powder;
and S7, sequentially carrying out acid washing and water washing on the powder, and then grinding after vacuum drying to obtain the PtM intermetallic compound catalyst.
2. The method for producing a PtM intermetallic compound catalyst according to claim 1, wherein: step S1 includes one or a combination of the following conditions:
the molar ratio between the Pt precursor salt and the N-containing molecular ligand is 1:2-1:4;
the Pt precursor salt is one or a combination of chloroplatinic acid, potassium chloroplatinic acid and platinum tetrachloride;
The N-containing molecular ligand is ethylenediamine or hydroxyethyl ethylenediamine;
The ultrasonic dispersion time is 1-4 h.
3. The method for producing a PtM intermetallic compound catalyst according to claim 1, wherein: step S2 includes one or a combination of the following conditions:
the molar ratio between the transition metal M and the ethylene diamine tetraacetic acid tetrasodium salt is 1:1;
the transition metal M is one of Fe, co, cu, zn;
the precursor salt is one or a combination of chloride, nitrate, acetate or sulfate;
The ultrasonic dispersion time is 1-4 h.
4. The method for producing a PtM intermetallic compound catalyst according to claim 1, wherein: the mode of the functionalization treatment in the step S3 is doping or surface oxidation treatment;
Wherein, the carbon powder doping treatment comprises the following steps: placing carbon powder in a tubular furnace, heating to 700-950 ℃, and etching for 20-90 min under the condition that NH 3 is introduced at the flow rate of 50-200 sccm to realize N doping of the carbon powder to obtain N doped carbon powder;
The method for carrying out surface oxidation treatment on the carbon powder comprises the following steps: dispersing carbon powder in 2-8 mol/L nitric acid solution, heating to 60-85 deg.c, stirring for 1-4 hr, water washing and filtering to obtain carbon powder with grafted oxygen-containing functional group.
5. The method for producing a PtM intermetallic compound catalyst according to claim 1, wherein: in the step S3, the carbon powder is one or a combination of XC-72, XC-72R, EC-300, KB-600 and BP-2000; and the ultrasonic dispersion time in the step S3 is 2-5 h.
6. The method for producing a PtM intermetallic compound catalyst according to claim 1, wherein: s4, after the first solution and the second solution are mixed, performing ultrasonic dispersion for 1-3 hours; and after adding the carbon powder dispersion liquid, continuing ultrasonic dispersion for 2-4 hours.
7. The method for producing a PtM intermetallic compound catalyst according to claim 1, wherein: step S6 includes one or a combination of the following conditions:
the reducing atmosphere is H 2/Ar mixed gas;
The heat treatment specifically comprises the following steps: raising the temperature to 500-750 ℃ at the heating rate of 7 ℃/min, preserving the heat for 0.5-8 h, and naturally cooling to room temperature.
8. The method for producing a PtM intermetallic compound catalyst according to claim 1, wherein: step S7 includes one or a combination of the following conditions:
The pickling specifically comprises the following steps: pouring the powder into an acid solution, and stirring for 12-18 h at 60-80 ℃; wherein the acid solution is one or a combination of sulfuric acid, hydrochloric acid and nitric acid, and the concentration of the acid solution is 0.1 mol/L-5 mol/L;
The water washing is carried out by adopting ultrapure water for 3-5 times;
the temperature of the vacuum drying is 60 ℃, and the time of the vacuum drying is 12-24 hours.
9. A PtM intermetallic catalyst characterized by: the PtM intermetallic compound catalyst is prepared by the preparation method of the PtM intermetallic compound catalyst according to any one of claims 1 to 8.
10. The application of the PtM intermetallic compound catalyst is characterized in that the PtM intermetallic compound catalyst is applied to an ORR catalytic process, wherein the PtM intermetallic compound catalyst is prepared by the preparation method of the PtM intermetallic compound catalyst in any one of claims 1 to 8.
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