CN114335563B - Mono-atom iron catalyst and preparation method thereof - Google Patents
Mono-atom iron catalyst and preparation method thereof Download PDFInfo
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 440
- 239000003054 catalyst Substances 0.000 title claims abstract description 167
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 125
- 238000002360 preparation method Methods 0.000 title abstract description 12
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 63
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 61
- 239000001301 oxygen Substances 0.000 claims abstract description 60
- 239000007788 liquid Substances 0.000 claims abstract description 23
- 238000009210 therapy by ultrasound Methods 0.000 claims abstract description 23
- 239000006185 dispersion Substances 0.000 claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 17
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 239000000843 powder Substances 0.000 claims description 66
- 238000000034 method Methods 0.000 claims description 31
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 22
- 239000011259 mixed solution Substances 0.000 claims description 17
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 claims description 11
- 229960004543 anhydrous citric acid Drugs 0.000 claims description 11
- 239000000243 solution Substances 0.000 claims description 11
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 7
- 239000005457 ice water Substances 0.000 claims description 6
- 125000000524 functional group Chemical group 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- 238000004108 freeze drying Methods 0.000 claims description 4
- 235000011187 glycerol Nutrition 0.000 claims description 4
- 239000002096 quantum dot Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 1
- 230000003197 catalytic effect Effects 0.000 abstract description 14
- 230000007704 transition Effects 0.000 abstract description 6
- 238000006722 reduction reaction Methods 0.000 abstract description 4
- 230000002708 enhancing effect Effects 0.000 abstract description 2
- 238000001179 sorption measurement Methods 0.000 abstract description 2
- 238000012360 testing method Methods 0.000 description 23
- 239000012467 final product Substances 0.000 description 21
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 20
- 230000005540 biological transmission Effects 0.000 description 15
- 239000010406 cathode material Substances 0.000 description 14
- 239000000446 fuel Substances 0.000 description 13
- 239000002135 nanosheet Substances 0.000 description 13
- 238000010521 absorption reaction Methods 0.000 description 12
- 238000001228 spectrum Methods 0.000 description 10
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 9
- 239000000758 substrate Substances 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 229910017135 Fe—O Inorganic materials 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 5
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 5
- 229920000557 Nafion® Polymers 0.000 description 5
- 238000007605 air drying Methods 0.000 description 5
- 230000005415 magnetization Effects 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 239000002064 nanoplatelet Substances 0.000 description 5
- 229910021642 ultra pure water Inorganic materials 0.000 description 5
- 239000012498 ultrapure water Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 150000002505 iron Chemical class 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 238000011056 performance test Methods 0.000 description 4
- 239000010405 anode material Substances 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
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- 238000005260 corrosion Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
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- 238000001994 activation Methods 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 239000012621 metal-organic framework Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 239000012692 Fe precursor Substances 0.000 description 1
- 239000011865 Pt-based catalyst Substances 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- DSVGQVZAZSZEEX-UHFFFAOYSA-N [C].[Pt] Chemical compound [C].[Pt] DSVGQVZAZSZEEX-UHFFFAOYSA-N 0.000 description 1
- 238000000952 abberration-corrected high angular annular dark-field scanning transmission electron microscopy Methods 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000003011 anion exchange membrane Substances 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000010411 electrocatalyst Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000006056 electrooxidation reaction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 150000003141 primary amines Chemical class 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
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- 229920006395 saturated elastomer Polymers 0.000 description 1
- 150000003335 secondary amines Chemical class 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- VLCQZHSMCYCDJL-UHFFFAOYSA-N tribenuron methyl Chemical compound COC(=O)C1=CC=CC=C1S(=O)(=O)NC(=O)N(C)C1=NC(C)=NC(OC)=N1 VLCQZHSMCYCDJL-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- 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
Abstract
The invention relates to a single-atom iron catalyst and a preparation method thereof, belonging to the technical field of electrocatalysis. The catalyst consists of PQD-Fe and oxygen end MXene, wherein the coordination configuration of Fe central atom in the PQD-Fe is FeN 3 O, fe in the PQD-Fe is connected with oxygen of an oxygen end MXene through a covalent bond, so that the PQD-Fe is loaded on the oxygen end MXene; in the catalyst, the mass ratio of oxygen end MXene, PQD and Fe atoms is 1 (1-2) to 0.04-0.1. And uniformly dispersing the oxygen end MXene in water, then adding the PQD-Fe dispersion liquid, uniformly mixing, and carrying out ultrasonic treatment to obtain the catalyst. The catalyst induces the transition from a low spin state to a high spin state of Fe central atoms by introducing an axial Fe-O-M bridging bond into an Fe active center, and enhances the adsorption force of the catalyst on oxygen molecules, thereby enhancing the catalytic activity of the oxygen reduction reaction.
Description
Technical Field
The invention relates to a single-atom iron catalyst and a preparation method thereof, belonging to the technical field of electrocatalysis.
Background
Oxygen Reduction Reactions (ORR) are currently important cathode reactions in sustainable energy storage and conversion devices, such as the cathode reactions of fuel cells or metal-air cells. However, because of the slow kinetics of ORR, a catalyst is required to accelerate the reaction.
Currently, in ORR, the catalysts that enable commercial applications are mainly platinum (Pt) based catalysts. However, due to factors such as limited Pt resources, high price, poor stability, etc., it is necessary to develop a transition metal-based catalyst which is rich in resources, low in price, and environmentally friendly.
Monoatomic catalysts (SACs) because they have the highest atomsBy utilizing the coordination environment of the efficiency and the active center unsaturation, the method ensures that the active center is in O 2 Or H 2 Precipitation reaction of CO 2 Or N 2 Has higher catalytic activity and selectivity in the electrocatalytic process such as reduction reaction. SACs are promising alternatives to the Pt-based catalysts described above, in particular monoatomic iron catalysts. Currently, the work of the single-atom iron catalyst is mostly focused on improving the catalytic performance by increasing the loading of metallic iron, however, the ORR catalytic performance of the single-atom iron catalyst obtained by the regulation means is still insufficient for application to practical energy equipment. Thus, there is also a need to improve the ORR catalytic performance of single-atom iron catalysts.
In addition, nanomaterials such as carbonaceous substrates, metal oxides, metal Organic Frameworks (MOFs) and the like are considered to be ideal substrate materials for SACs. At present, SACs are loaded on the surface of a carbonaceous substrate, but electrochemical corrosion of the carbonaceous substrate occurs in ORR, so that catalytic metal atoms migrate and merge and are even separated from a catalyst system, and the performance of the catalyst is affected.
The two-dimensional ultrathin MXene material comprises Ti 3 C 2 T x ，TiNbCT x ，Ti 3 CN x T x ，Ta 4 C 3 T x ，Nb 2 CT x ，V 2 CT x ，Nb 4 C 3 T x ，Mo 2 CT x Etc., wherein: x is any positive integer, and has been attracting attention in various fields such as energy storage and conversion, sensors and multifunctional polymer composites in recent years due to its unique physicochemical properties. In the research aspect of the current MXene for preparing the electrocatalyst, the research thought mainly comprises the step of exposing the outer surface of the MXene and metal vacancies to anchor high-density active center atoms so as to improve the catalytic activity. MXene is used as a substrate material to regulate the spin state of an active center atom so as to further improve the intrinsic activity of the catalyst, and has not been reported at present.
Therefore, how to change the spin state of the central atom to further improve the catalytic activity of the monoatomic iron catalyst, and solve the problem that the substrate material of SACs is not corrosion-resistant at the same time, is a technical problem to be solved in the field.
Disclosure of Invention
In view of the above, the present invention aims to provide a monoatomic iron catalyst and a preparation method thereof.
In order to achieve the purpose of the invention, the following technical scheme is provided.
A single-atom Fe catalyst is composed of iron-containing quantum dot (PQD-Fe) and oxygen end MXene, and the coordination configuration of Fe central atom in PQD-Fe is FeN 3 O, fe in the PQD-Fe is connected with oxygen of an oxygen end MXene through a covalent bond, so that the PQD-Fe is loaded on the oxygen end MXene; wherein the oxygen-terminal MXene is an oxygen-rich functional group-rich MXene.
In the catalyst, the mass ratio of the oxygen end MXene to the quantum dots (PQD) in the PQD-Fe and the Fe atoms is 1 (1-2) (0.04-0.1), namely the mass ratio of the oxygen end MXene, the PQD and the Fe atoms is 1 (1-2) (0.04-0.1).
Preferably, the mass ratio of the oxygen end MXene, the PQD and the Fe is 1:2:0.1.
Preferably, the oxygen-terminal MXene is Ti 3 C 2 O x X is any positive integer.
The preparation method of the monatomic iron catalyst comprises the following steps:
uniformly dispersing the oxygen end MXene in water, then adding PQD-Fe dispersion liquid, uniformly mixing, and performing ultrasonic treatment with the power of 600W, the frequency of 40kHZ and the treatment time of 0.5-2 h to obtain the monoatomic iron catalyst.
The PQD-Fe dispersion is obtained by uniformly dispersing PQD-Fe in water.
Preferably, the PQD-Fe dispersion liquid is prepared by the following method:
(1) Uniformly dispersing diethylenetriamine and anhydrous citric acid in the mixed solution, and then reacting for 2-5 min under the microwave with the power of 300W to obtain PQD powder;
the mass ratio of the diethylenetriamine to the anhydrous citric acid is 1 (1.84-1.86); the mixed solution is prepared from glycerin and water according to the volume ratio of (1) - (4); the ratio of the sum (g) of the masses of diethylenetriamine and anhydrous citric acid to the volume (mL) of the mixed solution is (0.7-0.8): 1.
(2) Uniformly dispersing PQD powder in water, and adding FeCl 3 ·6H 2 And O, uniformly mixing, and performing ultrasonic treatment, wherein the power of the ultrasonic treatment is 600W, the frequency is 40kHZ, and the treatment time is 1h, so as to obtain the PQD-Fe dispersion liquid.
Wherein the volume of water (mL), the mass of PQD powder (mg) and FeCl 3 ·6H 2 The proportion relation of the mass (mg) of O is 1 (1-2): 0.2-0.5;
preferably, the oxygen-terminal MXene is prepared by the following method: and (3) carrying out heat treatment on the MXene for 1-4 hours at the temperature of 250-400 ℃ in an air atmosphere to obtain the oxygen end MXene.
The MXene can be prepared by the disclosed methods, preferably by the following methods: dispersing LiF in 9mol/L HCl solution, uniformly stirring in ice water bath, adding MAX phase, stirring at 35-40 ℃ for 24-72 h, wherein the mass ratio of LiF to HCl is (0.35-0.36): 1, and the mass ratio of LiF to MAX phase is (1.6-1.7): 1; and (3) washing, when the pH value of the liquid to be washed is more than or equal to 7 and less than 8, taking the liquid, carrying out ultrasonic treatment on the liquid in an ice water bath, wherein the ultrasonic treatment power is 600W, the frequency is 40kHZ, the treatment time is 20-60 min, and freeze-drying to obtain the MXene.
Advantageous effects
(1) The invention provides a single-atom iron catalyst, which takes two-dimensional ultrathin oxygen end MXene as a substrate, wherein Fe in PQD-Fe and oxygen in the oxygen end MXene are connected through a covalent bond, and an axial Fe-O-M bridging bond is formed between the PQD-Fe and the oxygen end MXene, wherein M is a metal element in the oxygen end MXene, generally a transition metal element such as Cr, nb, ti and the like. The invention adopts the oxygen end MXene as a substrate material to realize the regulation and control of the spin state of the active center atom Fe, and introduces an axial Fe-O-M bridging bond in the active center of Fe to induce the transition from the low spin state to the high spin state of the Fe center atom, thereby enhancing the adsorption force of the Fe center atom on oxygen molecules and further improving the catalytic activity of the oxygen reduction reaction of the catalyst. Specifically, dz in the high spin state electron configuration of Fe 2 Electronic (t) 2g 4e g 1)Can easily penetrate the reverse bond pi-orbit of oxygen molecules, thus having higher ORR catalytic activity.
In the catalyst, the mass ratio of the oxygen end MXene, the PQD and the Fe is 1: (1-2): (0.04-0.1), and the content relation of the three ensures the catalytic performance of the catalyst.
The oxygen end MXene material has good conductivity and corrosion resistance, and overcomes the defect that a single-atom catalyst substrate in the prior art is not corrosion-resistant.
The catalyst is used as a cathode material of a battery, can exert excellent electrochemical performance, and has good application potential in the fields of fuel cells, metal-air cells, biosensing, supercapacitors and the like.
(2) The invention provides a preparation method of a monatomic iron catalyst, which is characterized in that an oxygen end MXene nano sheet and PQD-Fe are compounded by a non-pyrolysis simple method, the treatment time is 0.5 h-2 h, the Shan Yuanzi iron catalyst is obtained, and the catalyst has good electrocatalytic performance. The method is simple, low in cost and suitable for large-scale production.
(3) The invention provides a preparation method of a single-atom iron catalyst, which adopts a preparation method of a PQD-Fe dispersion liquid, and adopts the dosage of diethylenetriamine, anhydrous citric acid and mixed solution to influence the quantity of oxygen-containing functional groups (such as carboxyl groups) and nitrogen-containing functional groups (such as primary amine and secondary amine) in the PQD, wherein the functional groups provide high-density bonding sites for Fe ions, prevent the aggregation of Fe precursors and facilitate the preparation of the Shan Yuanzi iron catalyst. In addition, after the MXene is subjected to heat treatment in the air, the surface of the MXene is rich in oxygen functional groups to form an oxygen end MXene, which is favorable for compounding with PQD-Fe.
Drawings
Fig. 1 is a test result of an aberration-corrected high-angle annular dark field scanning transmission electron microscope (AC HAADF-STEM) of the monoatomic iron catalyst prepared in example 1.
FIG. 2 is a transmission electron microscopic image of the monoatomic iron catalyst prepared in example 1.
FIG. 3 is an X-ray photoelectron spectroscopy (XPS) O1s spectrum of the PQD-Fe powder and the monoatomic iron catalyst prepared in example 1.
FIG. 4 is an X-ray photoelectron spectroscopy (XPS) N1s spectrum of the PQD-Fe powder and the monoatomic iron catalyst prepared in example 1.
FIG. 5 is a Fourier transform plot and corresponding R-space fit curve of the X-ray absorption fine structure spectrum of the Fe K-side of the PQD-Fe powder prepared in example 1.
FIG. 6 is a Fourier transform plot and corresponding K-space fitting curve of the X-ray absorption fine structure spectrum of the Fe K-side of the PQD-Fe powder prepared in example 1.
FIG. 7 is a Fourier transform plot and corresponding R space fit curve of the Fe K-side X-ray absorption fine structure spectrum of the monoatomic iron catalyst prepared in example 1.
FIG. 8 is a Fourier transform plot and corresponding K-space fit curve of the Fe K-side X-ray absorption fine structure spectrum of the monoatomic iron catalyst prepared in example 1.
FIG. 9 is a graph showing the magnetization curves of the PQD-Fe powder and the monoatomic iron catalyst obtained in example 1 according to the change in temperature.
FIG. 10 is a transmission electron microscopic image of the monoatomic iron catalyst prepared in example 2.
FIG. 11 is a transmission electron microscopic image of the monoatomic iron catalyst prepared in example 3.
FIG. 12 is a transmission electron microscopic image of the monoatomic iron catalyst prepared in example 4.
FIG. 13 shows ORR performance test results of the single-atom iron catalysts prepared in examples 1 to 4 in 0.1mol/L KOH.
Fig. 14 is a performance test result of the single-atom iron catalyst prepared in example 1 for zinc-air batteries.
Fig. 15 is a performance test result of using the monoatomic iron catalyst prepared in example 1 for an oxyhydrogen fuel cell.
Detailed Description
The invention will be further described with reference to the following detailed description, wherein the processes are conventional, unless otherwise indicated, and wherein the starting materials are commercially available or prepared from the literature, unless otherwise indicated.
In the following examples:
the forced air drying oven is derived from Shanghai-Heng science instruments Co., ltd and has the model number DHG-9070A.
The aberration-corrected high angle annular dark field scanning transmission electron microscope was available from Japanese electronics, inc. under the model ARM-200CF.
The transmission electron microscope was obtained from FEI company, netherlands, model Tecnai G2F 30.
The X-ray photoelectron spectrometer is derived from the company of Sieimer Feichi technology (China), and the model number is K-Alpha.
The Beijing synchrotron radiation device is a device with the model of a beamline BL07A1 of the national synchrotron radiation research center.
The SQUID-VSM magnetic measurement system is derived from QUANTUM Quantum science instruments trade (Beijing) Inc., and is model MPMS-3.
The model of the Shanghai Chenhua electrochemical workstation is CHI760E.
The rotating ring plate electrode was derived from U.S. Pine Research Instrumentation, model E7R9 model.
The blue battery test system is derived from blue electric electronic Co., ltd, and is model LAND-CT2001A.
The 850e fuel cell test system was derived from us Scribner Associates company.
Example 1
(1) 540. Mu.L of diethylenetriamine (density 0.9586 g/cm) 3 ) And 0.9606g of anhydrous citric acid are dispersed in 2mL of mixed solution, and then react for 5min under the microwave with the power of 300W to obtain PQD powder; the mixed solution is prepared from glycerin and ultrapure water according to the volume ratio of 1:3.
(2) Dispersing 20mg of PQD powder in 10mL of ultrapure water, and carrying out ultrasonic treatment to uniformly disperse the PQD powder in the ultrapure water, wherein the ultrasonic treatment power is 600W, the frequency is 40kHZ, and the time is 20min; then 5mg of FeCl is added 3 ·6H 2 O, stirring uniformly, performing ultrasonic treatment with power of 600W and frequencyThe rate was 40kHZ and the time was 1h, to obtain a PQD-Fe dispersion.
(3) 3.32g of LiF was dispersed in 40mL of a 9mol/L hydrochloric acid solution and stirred in an ice-water bath, and 2g of Ti was added 3 AlC 2 Stirring at 35 ℃ for 24 hours to obtain a suspension, wherein the mass ratio of LiF to HCl is 0.3556:1, and the mass ratio of LiF to MAX phase is 1.66:1; centrifuging the suspension liquid for several times with a centrifuge, detecting the pH value of the upper liquid obtained after each centrifuging and washing with pH test paper, retaining the upper liquid after centrifuging and washing when the pH value of the upper liquid after centrifuging and washing is more than or equal to 7 and less than 8, performing ultrasonic treatment in ice water bath with the power of 600W, the frequency of 40kHZ and the time of 30min, and freeze-drying at the temperature of minus 40 ℃ to obtain Ti 3 C 2 T x The nano-sheet, x is any positive integer.
(4) Ti is mixed with 3 C 2 T x The nano-sheet is placed in a tubular furnace with two open ends, and is heat treated for 2 hours at 250 ℃ in the air atmosphere to obtain Ti 3 C 2 O x The nano-sheet, x is any positive integer.
(5) 10mg of said Ti 3 C 2 O x Dispersing the nanosheets in 10mL of ultrapure water, and performing ultrasonic treatment to ensure that Ti is 3 C 2 O x The nanosheets are uniformly dispersed in ultrapure water, the power of the ultrasonic treatment is 600W, the frequency is 40kHZ, and the time is 20min; then adding all the PQD-Fe dispersion liquid prepared in the step (2), stirring for 30min to uniformly mix, and carrying out ultrasonic treatment, wherein the power of the ultrasonic treatment is 600W, the frequency is 40kHZ, and the time is 45min; and freeze-drying at-40deg.C to obtain final product.
The PQD-Fe dispersion prepared in this example was dried in a forced air drying oven at 60℃for 10 hours to obtain a PQD-Fe powder; the PQD-Fe powder was then tested with the final product prepared in this example as follows:
(1) The atomic-level morphology of the final product was observed with an aberration-corrected high-angle annular dark field scanning transmission electron microscope, and the results are shown in fig. 1, and the appearance of the white bright spot area in fig. 1 indicates that Fe atoms are uniformly dispersed in the catalyst in the final product, and indicates that the final product is a monoatomic iron catalyst. The morphology of the Shan Yuanzi iron catalyst was then observed with a transmission electron microscope at an operating voltage of 300kV, and the test results are shown in fig. 2. As can be seen from fig. 2, the Shan Yuanzi iron catalyst exhibits a two-dimensional platelet morphology.
(2) Further, the PQD-Fe powder and the single-atom iron catalyst prepared in this example were tested by X-ray photoelectron spectroscopy (XPS), the test results are shown in FIG. 3 and FIG. 4, and the peak separation of O1s and N1s was performed by XPSP 4 software, and the results in FIG. 3 and FIG. 4 indicate that both the PQD-Fe powder and the single-atom iron catalyst prepared in this example exist in Fe-N x And Fe-O x The characteristic peaks of (2) indicate that Fe in the PQD-Fe powder and the single-atom iron catalyst forms chemical bonds with nitrogen and oxygen, and that the PQD-Fe powder and the single-atom iron catalyst form Fe-N x And Fe-O x A chemical bond.
(3) Further, the fine structure spectrum of the X-ray absorption of the PQD-Fe powder and the single-atom iron catalyst was tested by a Beijing synchrotron radiation device, and the R space curve and the k space curve of the extended X-ray near-edge absorption structure were obtained by Athena software, see FIGS. 5 to 8. As can be seen from FIGS. 5 and 6, the coordination environment of Fe in the PQD-Fe powder is FeN 3 The O configuration, i.e., the Fe center atom coordinates 3N atoms and 1O atom. As can be seen from FIGS. 7 and 8, in the Shan Yuanzi iron catalyst, the coordination environment of Fe is FeN 3 O-Ti configuration, i.e. the Fe central atom is coordinated with 3N atoms and 2O atoms, one of which is derived from PQD-Fe powder and the other of which is derived from Ti 3 C 2 O x The method comprises the steps of carrying out a first treatment on the surface of the It is further illustrated that the catalyst achieves the introduction of axial Fe-O-Ti bridging bonds in the Fe active sites.
Thus, it was confirmed from the test results of (1) to (3) that the final product was a monoatomic iron catalyst according to the invention, i.e., the catalyst was composed of iron quantum dots (PQD-Fe) and Ti 3 C 2 O x The nanosheets (namely oxygen end MXene) are formed, and the coordination configuration of Fe central atoms in the PQD-Fe is FeN 3 Fe and Ti in O, PQD-Fe 3 C 2 O x The oxygen of the nano-sheet is connected by covalent bond to make the PQD-Fe load on Ti 3 C 2 O x On the nanoplatelets, wherein x is any positive integer.
(4) The PQD-Fe powder and the single-atom iron catalyst prepared in the embodiment are tested by a SQUID-VSM magnetic measurement system to obtain magnetization curves of the two along with the change of temperature, the result is shown in figure 9, the Curie-Vis law is utilized to linearly fit the curve with the temperature of more than 150K, and the effective magnetic moment value of Fe of the PQD-Fe powder is calculated to be 1.69 mu according to the fitting result B The effective magnetic moment value of Fe of the monoatomic Fe catalyst is 3.65 mu B Which is significantly higher than the effective magnetic moment value of Fe of the PQD-Fe powder; therefore, the transition from the low spin state to the high spin state of the Fe central atom in the monoatomic iron catalyst is known from the effective magnetic moment value.
Example 2
Unlike example 1, the amount of PQD powder used in step (2) was 10mg, feCl 3 ·6H 2 The dosage of O is 2mg; ti in step (5) 3 C 2 O x The amount of (C) was 10mg. The rest of the procedure was the same as in example 1.
The PQD-Fe dispersion prepared in this example was dried in a forced air drying oven at 60℃for 10 hours to obtain a PQD-Fe powder; the PQD-Fe powder was then tested with the final product prepared in this example as follows:
(1) And observing the atomic-level morphology of the final product by using an aberration-corrected high-angle annular dark field scanning transmission electron microscope, wherein the appearance of a region with white bright spots in a test result indicates that Fe atoms are uniformly dispersed in the catalyst in the final product, and indicates that the final product is a monoatomic iron catalyst.
The morphology of the Shan Yuanzi iron catalyst was observed under 300kV working voltage by a transmission electron microscope, and the test result is shown in fig. 10. As can be seen from fig. 10, the Shan Yuanzi iron catalyst presents a two-dimensional flaky morphology.
(2) Further, the PQD-Fe powder and the monoatomic iron catalyst prepared in the example were tested by an X-ray photoelectron spectrometer (XPS), and the peaks of O1s and N1s were separated by XPSP 4 software; according toAs a result, it was found that the PQD-Fe powder and the single-atom iron catalyst prepared in this example both had Fe-N x And Fe-O x The characteristic peaks of (2) indicate that Fe in the PQD-Fe powder and the single-atom iron catalyst forms chemical bonds with nitrogen and oxygen, and that the PQD-Fe powder and the single-atom iron catalyst form Fe-N x And Fe-O x A chemical bond.
(3) Further, the X-ray absorption fine structure spectrum of the PQD-Fe powder and the single-atom iron catalyst is tested by a Beijing synchronous radiation device, and an R space curve and a k space curve of an extended X-ray near-edge absorption structure are obtained by Athena software; as a result, it was found that the coordination environment of Fe in the PQD-Fe powder was FeN 3 The O configuration, i.e., the Fe center atom coordinates 3N atoms and 1O atom. In the Shan Yuanzi iron catalyst, the coordination environment of Fe is FeN 3 O-Ti configuration, i.e. the Fe central atom is coordinated with 3N atoms and 2O atoms, one of which is derived from PQD-Fe powder and the other of which is derived from Ti 3 C 2 O x The method comprises the steps of carrying out a first treatment on the surface of the It is further illustrated that the catalyst achieves the introduction of axial Fe-O-Ti bridging bonds in the Fe active sites.
Thus, it was confirmed from the test results of (1) to (3) that the final product was a monoatomic iron catalyst according to the invention, i.e., the catalyst was composed of iron quantum dots (PQD-Fe) and Ti 3 C 2 O x The nanosheets (namely oxygen end MXene) are formed, and the coordination configuration of Fe central atoms in the PQD-Fe is FeN 3 Fe and Ti in O, PQD-Fe 3 C 2 O x The oxygen of the nano-sheet is connected by covalent bond to make the PQD-Fe load on Ti 3 C 2 O x On the nanoplatelets, wherein x is any positive integer.
(4) The PQD-Fe powder and the monoatomic iron catalyst prepared in the embodiment are tested through a SQUID-VSM magnetic measurement system to obtain a magnetization curve of the two along with the change of temperature, the Curie-Vis law is utilized to linearly fit the curve with the temperature of more than 150K, and the effective magnetic moment values of Fe of the PQD-Fe powder and the monoatomic iron catalyst are respectively calculated through the fitting result; according to the calculation result, the effective magnetic moment value of Fe of the monoatomic iron catalyst is obviously higher than that of Fe of the PQD-Fe powder; therefore, the transition from the low spin state to the high spin state of the Fe central atom in the monoatomic iron catalyst is known from the effective magnetic moment value.
Example 3
Unlike example 1, in step (5), ti is 3 C 2 O x And after being uniformly mixed with the PQD-Fe dispersion liquid, the mixture is subjected to ultrasonic treatment for 1h. The rest of the procedure was the same as in example 1.
The PQD-Fe dispersion prepared in this example was dried in a forced air drying oven at 60℃for 10 hours to obtain a PQD-Fe powder; the PQD-Fe powder was then tested with the final product prepared in this example as follows:
(1) And observing the atomic-level morphology of the final product by using an aberration-corrected high-angle annular dark field scanning transmission electron microscope, wherein the appearance of a region with white bright spots in a test result indicates that Fe atoms are uniformly dispersed in the catalyst in the final product, and indicates that the final product is a monoatomic iron catalyst.
The morphology of the Shan Yuanzi iron catalyst was observed under 300kV working voltage by a transmission electron microscope, and the test result is shown in fig. 11, and as can be seen from fig. 11, the Shan Yuanzi iron catalyst presents a two-dimensional flaky morphology.
(2) Further, the PQD-Fe powder and the monoatomic iron catalyst prepared in the example were tested by an X-ray photoelectron spectrometer (XPS), and the peaks of O1s and N1s were separated by XPSP 4 software; as can be seen from the results, the PQD-Fe powder and the single-atom iron catalyst prepared in this example both had Fe-N x And Fe-O x The characteristic peaks of (2) indicate that Fe in the PQD-Fe powder and the single-atom iron catalyst forms chemical bonds with nitrogen and oxygen, and that the PQD-Fe powder and the single-atom iron catalyst form Fe-N x And Fe-O x A chemical bond.
(3) Further, the X-ray absorption fine structure spectrum of the PQD-Fe powder and the single-atom iron catalyst is tested by a Beijing synchronous radiation device, and an R space curve and a k space curve of an extended X-ray near-edge absorption structure are obtained by Athena software; as a result, it was found that the coordination environment of Fe in the PQD-Fe powder was FeN 3 The O configuration, i.e., the Fe center atom coordinates 3N atoms and 1O atom. In the Shan Yuanzi iron catalyst, the coordination environment of Fe is FeN 3 O-Ti configuration, i.e. the Fe central atom is coordinated with 3N atoms and 2O atoms, one of which is derived from PQD-Fe powder and the other of which is derived from Ti 3 C 2 O x The method comprises the steps of carrying out a first treatment on the surface of the It is further illustrated that the catalyst achieves the introduction of axial Fe-O-Ti bridging bonds in the Fe active sites.
Thus, it was confirmed from the test results of (1) to (3) that the final product was a monoatomic iron catalyst according to the invention, i.e., the catalyst was composed of iron quantum dots (PQD-Fe) and Ti 3 C 2 O x The nanosheets (namely oxygen end MXene) are formed, and the coordination configuration of Fe central atoms in the PQD-Fe is FeN 3 Fe and Ti in O, PQD-Fe 3 C 2 O x The oxygen of the nano-sheet is connected by covalent bond to make the PQD-Fe load on Ti 3 C 2 O x On the nanoplatelets, wherein x is any positive integer.
(4) The PQD-Fe powder and the monoatomic iron catalyst prepared in the embodiment are tested through a SQUID-VSM magnetic measurement system to obtain a magnetization curve of the two along with the change of temperature, the Curie-Vis law is utilized to linearly fit the curve with the temperature of more than 150K, and the effective magnetic moment values of Fe of the PQD-Fe powder and the monoatomic iron catalyst are respectively calculated through the fitting result; according to the calculation result, the effective magnetic moment value of Fe of the monoatomic iron catalyst is obviously higher than that of Fe of the PQD-Fe powder; therefore, the transition from the low spin state to the high spin state of the Fe central atom in the monoatomic iron catalyst is known from the effective magnetic moment value.
Example 4
Unlike example 1, in step (5), ti is 3 C 2 O x And after being uniformly mixed with the PQD-Fe dispersion liquid, the mixture is subjected to ultrasonic treatment for 0.5h. The rest of the procedure was the same as in example 1.
The PQD-Fe dispersion prepared in this example was dried in a forced air drying oven at 60℃for 10 hours to obtain a PQD-Fe powder; the PQD-Fe powder was then tested with the final product prepared in this example as follows:
(1) And observing the atomic-level morphology of the final product by using an aberration-corrected high-angle annular dark field scanning transmission electron microscope, wherein the appearance of a region with white bright spots in a test result indicates that Fe atoms are uniformly dispersed in the catalyst in the final product, and indicates that the final product is a monoatomic iron catalyst.
The morphology of the Shan Yuanzi iron catalyst was observed under 300kV working voltage by a transmission electron microscope, and the test result is shown in fig. 12, and as can be seen from fig. 12, the Shan Yuanzi iron catalyst presents a two-dimensional flaky morphology.
(2) Further, the PQD-Fe powder and the monoatomic iron catalyst prepared in the example were tested by an X-ray photoelectron spectrometer (XPS), and the peaks of O1s and N1s were separated by XPSP 4 software; as can be seen from the results, the PQD-Fe powder and the single-atom iron catalyst prepared in this example both had Fe-N x And Fe-O x The characteristic peaks of (2) indicate that Fe in the PQD-Fe powder and the single-atom iron catalyst forms chemical bonds with nitrogen and oxygen, and that the PQD-Fe powder and the single-atom iron catalyst form Fe-N x And Fe-O x A chemical bond.
(3) Further, the X-ray absorption fine structure spectrum of the PQD-Fe powder and the single-atom iron catalyst is tested by a Beijing synchronous radiation device, and an R space curve and a k space curve of an extended X-ray near-edge absorption structure are obtained by Athena software; as a result, it was found that the coordination environment of Fe in the PQD-Fe powder was FeN 3 The O configuration, i.e., the Fe center atom coordinates 3N atoms and 1O atom. In the Shan Yuanzi iron catalyst, the coordination environment of Fe is FeN 3 O-Ti configuration, i.e. the Fe central atom is coordinated with 3N atoms and 2O atoms, one of which is derived from PQD-Fe powder and the other of which is derived from Ti 3 C 2 O x The method comprises the steps of carrying out a first treatment on the surface of the It is further illustrated that the catalyst achieves the introduction of axial Fe-O-Ti bridging bonds in the Fe active sites.
Thus, it was confirmed from the test results of (1) to (3) that the final product was a monoatomic iron catalyst according to the invention, i.e., the catalyst was composed of iron quantum dots (PQD-Fe) and Ti 3 C 2 O x Nanoplatelets (i.e.)Oxygen-terminal MXene), the coordination configuration of Fe central atom in PQD-Fe is FeN 3 Fe and Ti in O, PQD-Fe 3 C 2 O x The oxygen of the nano-sheet is connected by covalent bond to make the PQD-Fe load on Ti 3 C 2 O x On the nanoplatelets, wherein x is any positive integer.
(4) The PQD-Fe powder and the monoatomic iron catalyst prepared in the embodiment are tested through a SQUID-VSM magnetic measurement system to obtain a magnetization curve of the two along with the change of temperature, the Curie-Vis law is utilized to linearly fit the curve with the temperature of more than 150K, and the effective magnetic moment values of Fe of the PQD-Fe powder and the monoatomic iron catalyst are respectively calculated through the fitting result; according to the calculation result, the effective magnetic moment value of Fe of the monoatomic iron catalyst is obviously higher than that of Fe of the PQD-Fe powder; therefore, the transition from the low spin state to the high spin state of the Fe central atom in the monoatomic iron catalyst is known from the effective magnetic moment value.
Example 5
Mono-atom iron catalysts prepared in examples 1 to 4 and Ti were tested by Shanghai Chen Hua electrochemical workstation 3 C 2 T x Polarization current curve in 0.1mol/L KOH. The specific conditions for the test are: adopting a rotary ring plate electrode as a working electrode, a saturated calomel electrode as a reference electrode and a carbon rod as a counter electrode, wherein the Shan Yuanzi iron catalyst and Ti 3 C 2 T x The ink is prepared by the following steps: with monoatomic iron catalysts or Ti 3 C 2 T x Dispersing in a mixed solution composed of water, isopropanol and 5wt% Nafion solution (5 wt% Nafion solution is produced by DuPont company of U.S.) according to the volume ratio of 1:2:0.06, and allowing the single-atom iron catalyst or Ti in the ink to be contained in the mixed solution 3 C 2 T x The concentration of (C) was 2mg/mL. Then the ink is dripped on the surface of the disk electrode of the rotating ring disk electrode (the area of the disk electrode is 0.2475 cm) 2 The area of the ring electrode is 0.1866cm 2 ) Drying the ink on the surface of the rotating ring plate electrode to form a film, wherein the single-atom iron catalyst or Ti on the surface of the rotating ring plate electrode 3 C 2 T x Is 0.65mg/cm 2 . Placing a rotating ring plate electrode, a saturated calomel electrode and a carbon rod in a reactor to be filled with O 2 Saturated 0.1mol/L KOH solution, regulating the rotating speed of a rotating ring plate electrode to 1600r/min, and setting electrochemical workstation parameters: the scanning speed is 30mV/s, the voltage range is 1.16V-0.04V vs. RHE, and the electrochemical activation process is carried out under the condition. After the electrochemical activation process is finished, the parameters of the electrochemical workstation are changed as follows: the scanning speed is 0.05mV/s, the voltage range is 0.2V-1V vs. RHE to carry out polarization current test, the test result is shown in figure 13, and according to figure 13, the potential values (half-wave potential values) of the monoatomic iron catalysts prepared in examples 1-4 at half of the limiting current density value are all obviously higher than Ti 3 C 2 T x The half-wave potential values of (2) indicate that the single-atom iron catalysts prepared in examples 1-4 all have good ORR catalytic performance under the KOH of 0.1 mol/L.
Example 6
The single-atom iron catalyst prepared in example 1 and a commercial platinum carbon (Pt/C) catalyst manufactured by beijing enoki technologies co were assembled as cathode materials into a zinc-air battery, respectively, and the performance of the two zinc-air batteries was tested, the commercial Pt/C catalyst being a Pt/C catalyst having a mass fraction of platinum of 20 wt%.
The zinc-air battery adopts a zinc plate as an anode material; the Shan Yuanzi iron catalyst and the Pt/C catalyst are respectively used as cathode materials. The preparation method of the cathode material comprises the following steps: dispersing the Shan Yuanzi iron catalyst or the Pt/C catalyst in a mixed solution consisting of ethanol, water and 5wt% Nafion solution (5 wt% Nafion solution is produced by DuPont company of U.S.) according to a volume ratio of 1:11:0.105 to obtain ink, wherein the concentration of the single-atom iron catalyst or the Pt/C catalyst in the ink is 5mg/mL; the ink is dripped on the surface of the carbon paper on a heating plate at 45 ℃, and the cathode material is obtained after complete drying, wherein the loading capacity of the two catalysts in the cathode material is 1mg/cm respectively 2 . With 6mol/L KOH and 0.2mol/L Zn (OAc) 2 As electrolyte. At room temperature, the discharge electrode polarization current curves of two zinc-air batteries are measured by using a blue electric battery test system, and the test parameters are as follows: scanning speedThe degree is 5mV/s, the initial voltage is 1.55V, and the end voltage is 0.2V. As a result, as shown in FIG. 14, the maximum power density value of the zinc-air cell using the Shan Yuanzi iron catalyst as a cathode material was 158.2mW/cm 2 Whereas the maximum power density value of the zinc-air cell employing the Pt/C catalyst as the cathode material was 83.5mW/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the This shows that the monatomic iron catalyst prepared in example 1 has good ORR catalytic activity and gives zinc-air cells with the Shan Yuanzi iron catalyst as cathode material good performance. Since the low spin state of the Fe central atoms in the monatomic iron catalysts prepared in examples 2 to 4 also changed to the high spin state, the monatomic iron catalysts prepared in examples 2 to 4 also enable the zinc-air battery to have good performance when used as a cathode material for the zinc-air battery.
Example 7
The monoatomic iron catalyst prepared in example 1 was assembled as a cathode material into an oxyhydrogen fuel cell, which may also be written as H 2 /O 2 A fuel cell in which the Shan Yuanzi iron catalyst is dispersed into ink and coated on carbon paper as a cathode material, the ink being prepared by: 40mg of the Shan Yuanzi iron catalyst was dispersed in 20mL of a mixed solution consisting of ethanol, water and 5wt% Nafion in a volume ratio of 1:11:0.105. Spraying a single-atom iron catalyst on the surface of carbon paper, wherein the loading capacity of the single-atom iron catalyst is 3mg/cm 2 . In addition, 40wt% of Pt/C catalyst, which is 40wt% of Pt/C catalyst by platinum mass fraction, manufactured by beijing enoki technology limited, was dispersed as an ink and coated on carbon paper as an anode material. The preparation method of the ink comprises the following steps: 30mg of 40wt% Pt/C catalyst was dispersed in 20mL of a mixed solution of isopropyl alcohol and AS-4 solution (the AS-4 solution is 30wt% AS-4 solution manufactured by Tokuyama Co., ltd., japan) at a volume ratio of 1:0.05. Spraying a Pt/C catalyst on the surface of the carbon paper, wherein the loading capacity of the Pt/C catalyst is 0.1mg/cm 2 . An A201 anion exchange membrane manufactured by Tokuyama corporation of Japan is clamped between the cathode material and the anode material, and the three materials are prepared into a membrane by a hot pressing method; by H 2 And O 2 Respectively are provided withAs an anode raw material and a cathode raw material of a fuel cell, the H 2 And O 2 The relative humidity of (C) was 100%, the back pressure was 150kPa, and the flow rate was 0.5L/min. H was measured at 80℃using a 850e fuel cell test system 2 /O 2 The fuel cell was subjected to a discharge electrode current performance test. The test results are shown in FIG. 15, said H 2 /O 2 The fuel cell had a maximum power density value of 407.5mW/cm at 80 DEG C 2 Indicating the H 2 /O 2 The fuel cell has good cell performance, further showing that the single-atom iron catalyst prepared in example 1 has good ORR catalytic activity. Since the low spin state of the Fe central atom in the monatomic iron catalysts prepared in examples 2 to 4 was also changed to the high spin state, the monatomic iron catalysts prepared in examples 2 to 4 were used as H 2 /O 2 In the case of a cathode material for a fuel cell, H can be also made 2 /O 2 The fuel cell has good performance.
The invention includes, but is not limited to, the above embodiments, any equivalent or partial modification made under the principle of the spirit of the invention, shall be considered as being within the scope of the invention.
Claims (9)
1. A monatomic iron catalyst characterized by: the catalyst consists of PQD-Fe and oxygen end MXene, wherein the coordination configuration of Fe central atom in the PQD-Fe is FeN 3 O, fe in the PQD-Fe is connected with oxygen of an oxygen end MXene through a covalent bond, so that the PQD-Fe is loaded on the oxygen end MXene; wherein the PQD-Fe is an iron-containing quantum dot, and the oxygen terminal MXene is an oxygen-rich functional group MXene;
in the catalyst, the mass ratio of oxygen end MXene, PQD and Fe atoms is 1 (1-2) to 0.04-0.1.
2. A monoatomic iron catalyst according to claim 1, characterised in that: the mass ratio of the oxygen end MXene, the PQD and the Fe is 1:2:0.1.
3. A monoatomic iron catalyst according to claim 1, characterised in that: the oxygen isEnd MXene is Ti 3 C 2 O x X is any positive integer.
4. A monoatomic iron catalyst according to claim 1, characterised in that: the mass ratio of the oxygen end MXene, the PQD and the Fe is 1:2:0.1;
the oxygen end MXene is Ti 3 C 2 O x X is any positive integer.
5. The method for producing a monoatomic iron catalyst according to any one of claims 1 to 4, characterized in that: the method comprises the following steps:
uniformly dispersing an oxygen end MXene in water, adding a PQD-Fe dispersion liquid, uniformly mixing, and performing ultrasonic treatment with the power of 600W, the frequency of 40kHZ and the treatment time of 0.5-2 h to obtain a monoatomic iron catalyst; the PQD-Fe dispersion is obtained by uniformly dispersing PQD-Fe in water.
6. The method for preparing the monoatomic iron catalyst according to claim 5, wherein the method comprises the following steps: the PQD-Fe dispersion liquid is prepared by the following method:
(1) Uniformly dispersing diethylenetriamine and anhydrous citric acid in the mixed solution, and then reacting for 2-5 min under the microwave with the power of 300W to obtain PQD powder;
the mass ratio of the diethylenetriamine to the anhydrous citric acid is 1 (1.84-1.86); the mixed solution is prepared from glycerin and water according to the volume ratio of (1) - (4); the ratio of the sum (g) of the masses of the diethylenetriamine and the anhydrous citric acid to the volume (mL) of the mixed solution is (0.7-0.8): 1;
(2) Uniformly dispersing PQD powder in water, and adding FeCl 3 ·6H 2 O, uniformly mixing, and performing ultrasonic treatment, wherein the power of the ultrasonic treatment is 600W, the frequency is 40kHZ, and the treatment time is 1h, so as to obtain PQD-Fe dispersion liquid;
wherein the volume of water (mL), the mass of PQD powder (mg) and FeCl 3 ·6H 2 The proportion relation of the mass (mg) of O is 1 (1-2) to 0.2-0.5.
7. The method for preparing the monoatomic iron catalyst according to claim 5, wherein the method comprises the following steps: the oxygen end MXene is prepared by the following method: and (3) carrying out heat treatment on the MXene for 1-4 hours at the temperature of 250-400 ℃ in an air atmosphere to obtain the oxygen end MXene.
8. The method for preparing the monoatomic iron catalyst according to claim 5, wherein the method comprises the following steps: the PQD-Fe dispersion liquid is prepared by the following method:
(1) Uniformly dispersing diethylenetriamine and anhydrous citric acid in the mixed solution, and then reacting for 2-5 min under the microwave with the power of 300W to obtain PQD powder;
the mass ratio of the diethylenetriamine to the anhydrous citric acid is 1 (1.84-1.86); the mixed solution is prepared from glycerin and water according to the volume ratio of (1) - (4); the ratio of the sum (g) of the masses of the diethylenetriamine and the anhydrous citric acid to the volume (mL) of the mixed solution is (0.7-0.8): 1;
(2) Uniformly dispersing PQD powder in water, and adding FeCl 3 ·6H 2 O, uniformly mixing, and performing ultrasonic treatment, wherein the power of the ultrasonic treatment is 600W, the frequency is 40kHZ, and the treatment time is 1h, so as to obtain PQD-Fe dispersion liquid;
wherein the volume of water (mL), the mass of PQD powder (mg) and FeCl 3 ·6H 2 The proportion relation of the mass (mg) of O is 1 (1-2): 0.2-0.5;
the oxygen end MXene is prepared by the following method: and (3) carrying out heat treatment on the MXene for 1-4 hours at the temperature of 250-400 ℃ in an air atmosphere to obtain the oxygen end MXene.
9. The method for preparing a monoatomic iron catalyst according to claim 7 or 8, wherein: the MXene is prepared by the following method: dispersing LiF in 9mol/L HCl solution, uniformly stirring in ice water bath, adding MAX phase, stirring at 35-40 ℃ for 24-72 h, wherein the mass ratio of LiF to HCl is (0.35-0.36): 1, and the mass ratio of LiF to MAX phase is (1.6-1.7): 1; and (3) washing, when the pH value of the liquid to be washed is more than or equal to 7 and less than 8, taking the liquid, carrying out ultrasonic treatment on the liquid in an ice water bath, wherein the ultrasonic treatment power is 600W, the frequency is 40kHZ, the treatment time is 20-60 min, and freeze-drying to obtain the MXene.
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