CN116344845A - FeTe diatomic catalyst and preparation method thereof - Google Patents

FeTe diatomic catalyst and preparation method thereof Download PDF

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CN116344845A
CN116344845A CN202211395342.9A CN202211395342A CN116344845A CN 116344845 A CN116344845 A CN 116344845A CN 202211395342 A CN202211395342 A CN 202211395342A CN 116344845 A CN116344845 A CN 116344845A
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fete
solution
catalyst
diatomic
tellurium
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雷永鹏
郑焕然
熊禹
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Central South University
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Central South University
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    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M12/00—Hybrid cells; Manufacture thereof
    • H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
    • H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode
    • 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
    • H01M4/88—Processes of manufacture
    • 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
    • H01M4/9041—Metals or alloys

Abstract

An FeTe diatomic catalyst and a preparation method thereof, wherein the FeTe diatomic catalyst is in a rhombic dodecahedron structure, and iron tellurium diatomic atoms are evenly distributed in the rhombic dodecahedron nitrogen doped carbon in an atomic level. The invention also discloses a preparation method of the FeTe diatomic catalyst. The N-doped carbon polyhedral catalyst based on FeTe diatomic can efficiently catalyze the oxygen electroreduction reaction, and after being assembled into a zinc-air battery, the whole battery can take the current density of 50mA cm ‑2 Over 400 cycles, the performance is far better than that of commercial Pt/C+RuO 2 。

Description

FeTe diatomic catalyst and preparation method thereof
Technical Field
The invention relates to a preparation method of a catalyst, in particular to an FeTe diatomic catalyst and a preparation method thereof.
Background
Monoatomic catalysts (SACs) are a leading edge of catalytic science in recent years, and reduction of active species from nanoscale to atomic fraction size is an effective strategy to improve catalytic performance. On the one hand, it is theoretically possible to achieve 100% atomic utilization, fully expose the catalytically active sites, increase the number of active sites; on the other hand, the intrinsic activity of the reactive site can be improved by the effects of strong interaction between the metal monoatomic active center and the carrier, charge transfer, and the like. However, M-N represented by coordination of metal atom and nitrogen 4 The single-atom catalyst of the site still has the problems of insufficient reaction activity, poor stability and the like. Further modification and adjustment of the monoatomic catalyst is required. Currently, effective regulatory strategies can be broadly divided into four categories: (1) increasing the loading of monoatomic Fe; (2) Increase the specific surface area and expose more active sitesA dot; (3) By introducing auxiliary components, e.g. FeCo alloys, fe 3 C, etc.; (4) heteroatom localized doping.
The development of next generation energy conversion and storage devices, such as fuel cells and metal-air cells, relies heavily on the electrocatalytic Oxygen Reduction Reaction (ORR). Noble metal-based ORR catalysts, which are predominantly platinum (Pt) electrocatalysts, have been well developed and have higher activity. However, its high cost, scarce reserves and long-term stability problems greatly hamper large-scale commercial applications. Iron/nitrogen doped carbon (Fe/NC) catalysts have become a new generation of catalytic materials in recent years that are promising alternatives to noble metals. Although Fe-based ORR catalysts, and in particular iron single-atom catalysts, have experienced rapid development, the performance of these materials has remained difficult to meet the application needs.
In order to solve these problems, it is an effective strategy to reduce the active species of the catalyst from particles to atomic scale to improve the performance of the catalyst, and at the same time, designing diatomic catalysts (DACs) on atomic scale not only compensates for the defect of low SACs loading, but also improves the intrinsic activity of the active site by utilizing the strong interaction between diatomic and carrier, and in addition, the synergistic effect between metal diatomic has great auxiliary advantage for the cleavage of o—o bond.
Xing et al disclose an iron-cobalt diatomic catalyst that has 20 times the oxygen reduction performance of a monoatomic catalyst (Climbing the Apex of the ORR Volcano Plot via Binuclear Site Construction: electronic and Geometric Engineering, J.Am.chem.Soc.2019,44, 17763-1777); sun et al prepared Pt-Ru diatomic catalyst by atomic deposition method, showed very high hydrogen evolution quality activity and stability (Atomic layer deposited Pt-Ru dual-metal dimers and identifying their active sites for hydrogen evolution reactions. Nature communications.2019,10,4936). However, the above-described method has the following problems, (1) DACs and SACs commonly coexist; (2) In the preparation process of the carbon-supported SACs, the carbon carriers are easy to agglomerate, so that holes are blocked, and the mass transfer efficiency is reduced. Both hamper further improvement of the ORR performance of DACs.
Therefore, a preparation method of the diatomic catalyst, which has the advantages of good atomic fraction, good electrocatalytic oxygen reduction performance, better cycle performance than commercial Pt/C catalyst, simple synthesis process, high efficiency, low cost, strong universality and suitability for industrial production, needs to be developed.
Disclosure of Invention
The invention aims to solve the technical problems, overcome the defects in the prior art, and provide the noble metal-based catalyst which can efficiently catalyze ORR and has better assembled zinc-air battery performance than commercial Pt/C and the like.
The invention further solves the technical problems of overcoming the defects in the prior art, filling the blank of the tellurium-iron diatomic catalyst, and providing a method for synthesizing the tellurium-doped iron single-atom carbon polyhedral catalyst, which has the advantages of simple process, high efficiency, low cost, strong universality and suitability for industrial production.
The technical scheme adopted for solving the problems is as follows: based on an FeTe diatomic catalyst and a preparation method thereof, the tellurium-iron diatomic carbon polyhedral catalyst is a catalyst with a rhombic dodecahedron structure, wherein two atoms of iron and tellurium are uniformly distributed in the carbon polyhedral in the form of atom pairs;
the method comprises the following steps: ORR generally undergoes a 2-electron or 4-electron catalytic pathway, with Fe-based SACs having higher catalytic ORR activity, stability, and reaction progress approaching that of 4 electrons compared to non-Fe-based SACs. The preparation of the iron single-atom catalyst with high catalytic activity and high stability on the nitrogen-doped carbon carrier can obtain the ORR catalytic activity with excellent performance, and is a process based on a 'host-guest strategy' and high-temperature heat treatment. Sodium tellurite is reduced to the corresponding negative anion (Te) by reaction of strong reducing agent and sodium tellurite 2- ) While Te is 2- Easy to bond with iron single atoms to form a stable FeTe double-atom catalyst. According to the invention, feTe diatomic is synthesized by a hydrothermal method, wherein an iron monatom is anchored by a nitrogen atom and a carbon atom (Fe-N-C), and a tellurium atom is coordinated with the iron monatom and exists in the form of an iron-tellurium diatomic pair. The FeTe diatomic catalyst is a rhombic dodecahedron structure, and the rhombic dodecahedron structure can expose more catalytic ORR active sitesIn some cases, the internally developed pores may also facilitate coordination of tellurium atoms with iron monoatoms during synthesis to further enhance ORR catalytic activity.
Preferably, the doping amount of N in the catalyst is 0.01-1.00%, which is more favorable for anchoring iron monoatoms.
Preferably, the mass percentage of iron in the catalyst is 0.01-5.00%, and agglomeration of iron single atoms in the carbon polyhedron can be avoided.
Preferably, the mass percent of tellurium in the catalyst is 0.01-3.00%, and the ORR reaction activity can be enhanced without forming metal tellurium compounds and weakening the ORR reaction activity.
Preferably, the average particle size of the catalyst is 200-500 nm, which facilitates exposure of more bifunctional reactive sites and facilitates adsorption and desorption of the reaction intermediates.
Preferably, the simple substance tellurium comprises tellurium powder; the tellurium-containing salt comprises one or more of sodium tellurite and sodium tellurite. More preferably, the tellurium-comprising salt is sodium tellurite, which is easily reduced to negative anions by a strong reducing agent.
The technical scheme adopted by the invention for further solving the technical problems is as follows, namely a preparation method of an FeTe diatomic catalyst, which comprises the following steps:
(1) Firstly, stirring and dissolving metal salt and zinc nitrate in a methanol solvent to obtain a solution A, stirring and dissolving an N-containing organic ligand in the methanol solvent to obtain a solution B, stirring and mixing the solution A and the solution B, standing for ageing, centrifuging, filtering and washing, and vacuum drying to obtain precursor powder;
(2) Carrying out primary heat treatment on the precursor powder obtained in the step (1) under the protection of inert atmosphere, and cooling along with a furnace to obtain black powder; the temperature of the primary heat treatment is 600-1000 ℃;
(3) Dissolving a strong reducing agent in deoxidized ultrapure water until the solution is clear and transparent to obtain a solution C, adding a tellurium simple substance or salt containing tellurium elements into the solution C, and oscillating until the solution is clear again to obtain a precursor solution D;
(4) Adding the black powder obtained in the step (2) into the precursor solution D obtained in the step (3), performing ultrasonic dispersion, performing hydrothermal reaction, centrifuging, filtering, washing, and freeze-drying to obtain sample powder; the mass volume ratio of the black powder to the tellurium simple substance or the salt containing tellurium element is 0.1 g/1 mL-10 mL; the molar concentration of the ferric salt solution is 0.05-0.50 mol/L;
(5) Under the protection of inert atmosphere, carrying out secondary heat treatment on the sample powder obtained in the step (4), and cooling along with a furnace to obtain an FeTe diatomic catalyst; the temperature of the secondary heat treatment is 300-600 ℃.
Preferably, in step (1), the mass ratio of the iron salt to zinc nitrate is 1:8 to 50 (more preferably 1:10 to 30). The zinc ions are used as metal nodes, form a molecular cage with the N-containing organic ligand through chemical coordination, the metal salt is used as a guest molecule, and the metal salt, the zinc nitrate and the N-containing organic ligand are packaged in a cavity of the molecular cage to form a Metal Organic Framework (MOF), so that the metal-organic framework (MOF) has high controllability, is favorable for the dispersion of metal atoms and prevents aggregation of the metal atoms in the pyrolysis process. Zn is an essential element constituting a metal-organic framework. The mass ratio of the metal salt to the zinc nitrate is limited to be in the range of 1:8-50, so that the agglomeration of excessive metal is prevented, the generation of corresponding oxidized metal, carbonized metal or metal nano particles is avoided, the utilization rate of metal atoms is reduced, and the electrochemical activity is reduced.
Preferably, in the solution A of the step (1), the mass-volume ratio (g/mL) of the sum of the mass of the iron salt and the zinc nitrate to the methanol solvent is 1:20-200 (more preferably 1:25-100). If the amount of the methanol solvent is too small, the MOF size becomes too large, and if the amount of the methanol solvent is too large, the yield of the product becomes greatly reduced.
Preferably, in the step (1), the iron salt comprises one or more of carbonyl iron, acetylacetonate iron, acetate iron, chloride iron, sulfate iron or nitrate iron.
Preferably, in the step (1), the mass ratio of the zinc nitrate to the N-containing organic ligand is 1:0.6-3.0 (more preferably 1:0.8-2.0). The N-containing organic ligand mainly provides a precursor containing both C and N, and forms a regular polyhedral shape by coordination with metal salt. If the amount of the N-containing organic ligand is too large, the MOF size becomes too large, and if the amount of the N-containing organic ligand is too small, the yield of the product becomes significantly low.
Preferably, in the solution B of the step (1), the mass-to-volume ratio (g/mL) of the N-containing organic ligand to the methanol solvent is 1:20-200 (more preferably 1:21-100). If the amount of the methanol solvent is too small, the MOF size is too large, and if the amount of the methanol solvent is too large, the yield of the product is greatly reduced.
Preferably, in the step (1), the N-containing organic ligand includes one or more of dimethyl imidazole, hexamethylenetetramine, ethylenediamine tetraacetic acid and the like.
Preferably, in the step (1), the stirring and dissolving temperatures are all room temperature, and the stirring and dissolving time is 10-30 min.
Preferably, in the step (1), the temperature of the stirring and mixing is room temperature to 140 ℃ and the time is 1 to 6 hours.
Preferably, in the step (1), the temperature of the standing aging is between room temperature and 140 ℃ and the time is between 6 and 24 hours. The standing aging is used for completely and chemically coordinating the metal salt and the N-containing organic ligand to obtain Zn 2+ And complexes containing N organic ligands.
Preferably, in the step (1), the vacuum drying pressure is 0.05-0.5 MPa, and the time is 12-72 h.
Preferably, in the step (1), the filtering and washing means that the precipitate is filtered and washed with N, N-dimethylformamide and methanol respectively for more than or equal to 2 times. The obtained precipitate is firstly washed by N-N Dimethylformamide (DMF) and then washed by methanol, and the purpose is to better dissolve metal salts which do not completely react in DMF, and methanol can effectively dissolve residual DMF in the precipitate. According to the method, through a two-step organic solvent washing process, the MOF-derived carbon carrier has a very high specific surface area, a large porosity and a three-dimensional interconnected pore structure, and is beneficial to full exposure of metal active sites.
Preferably, in the step (2), the time of one heat treatment is 1 to 6 hours. During the heat treatment, N is contained inDecomposing the machine ligand to generate an N-doped C polyhedron in situ, wherein an iron atom is coordinated with the doped N atom; at the same time, zn volatilizes, resulting in the formation of a large number of micropores. After one heat treatment, the MOF can be allowed to undergo complete conversion. The inert atmosphere is nitrogen, argon and the volume fraction is 5%H 2 /95％N 2 Is 5%H by volume fraction 2 Mixture of 95% Ar.
Preferably, the deoxidized ultra-pure water in the step (3) is obtained by introducing inert gas such as argon, nitrogen and the like, more preferably argon, to the ultra-pure water to remove oxygen dissolved in the ultra-pure water and prevent Te from being oxidized by the oxygen dissolved in the water 2- 。
Preferably, the strong reducing agent in step (3) comprises one or more of sodium borohydride or hydrazine hydrate. More preferably, the strong reducing agent is an aqueous solution of hydrazine hydrate with a mass fraction of 80%.
Preferably, the simple substance tellurium in the step (3) comprises tellurium powder, and the salt containing tellurium element comprises one or more of sodium tellurite and sodium tellurite. More preferably, the tellurium-comprising salt is sodium tellurite. Compared with other methods, the method uses hydrazine hydrate to directly reduce sodium tellurite in aqueous solution, and can efficiently and quickly synthesize Te 2- 。
Preferably, in the step (3), the temperature of the oscillation is 20-40 ℃ and the oscillation time is 10-30 min; the concentration of the strong reducing agent in the solution C is 1-4 mol/L.
Preferably, in the step (3), the concentration of the tellurium simple substance or the salt containing tellurium element in the solution D is 0.05 to 0.50mol/L.
Preferably, in the step (3), the molar ratio of the strong reducing agent to the tellurium simple substance is 2-80:1, or the molar ratio of the strong reducing agent to the salt containing tellurium element is 2-80:1.
Preferably, in the step (4), the filtering and washing means that the precipitate is filtered and washed with water and ethanol respectively for more than or equal to 2 times.
Preferably, in the step (4), the temperature of the hydrothermal reaction is 160-220 ℃ and the time is 12-48 h. Te in the hydrothermal treatment process 2- Can bond with the bare iron single atoms on the surface to form iron-tellurium atom pairs.
Preferably, in the step (4), the rotation speed of the centrifugation is 6000-10000 r/min, and the centrifugation time is 1.5-5 min.
Preferably, in the step (4), the temperature of the freeze drying is between-10 ℃ and-30 ℃ and the time is between 12 and 72 hours. Under the freeze-drying condition, the water can be removed from the frozen sample, and the appearance of the frozen sample can be well maintained, so that the frozen sample can not be agglomerated or collapsed.
Preferably, in the step (4), the time of the secondary heat treatment is 1-6 hours, so that agglomeration of iron monoatoms is prevented from being formed due to too high annealing temperature and too long heat preservation time.
Preferably, in the step (4), the inert atmosphere is nitrogen, argon and the volume fraction is 5%H 2 /95％N 2 Is 5%H by volume fraction 2 Mixture of 95% Ar.
Preferably, in the step (1), the rotation speed of the centrifugation is 4000-10000 r/min, and the time is 0.5-10 min.
Preferably, in the step (1), the temperature of the vacuum drying is room temperature to 80 ℃, the pressure is 0.05 to 0.5MPa, and the time is 12 to 72 hours.
An FeTe diatomic catalyst prepared by a method as described in any of the preceding claims.
Use of an FeTe diatomic catalyst as described above in ORR catalytic reactions.
The beneficial effects of the invention are as follows:
(1) The invention is based on an FeTe diatomic catalyst and a preparation method thereof, the catalyst is in a rhombic dodecahedron structure, and the average grain diameter is 300-500 nm, wherein the iron monoatoms are uniformly distributed in a carbon polyhedron in an atomic level; the method comprises the steps of carrying out a first treatment on the surface of the
(2) The FeTe diatomic catalyst and the preparation method thereof show the characteristics of high half-wave potential (0.946V) and high durability in an alkaline medium (0.1 mol/L KOH), almost no loss of half-wave potential after 10000 cycles of cyclic voltammetry acceleration circulation, and can be used as a high-efficiency ORR electrocatalyst for replacing a Pt/C noble metal catalyst in the alkaline medium;
(3) The invention is based onFeTe diatomic catalyst and preparation method thereof, after being assembled into quasi-solid zinc-air battery, at 50 mAcm -2 Can stably circulate 435 circles under the current density which is far higher than that of a commercial Pt/C+Ir/C catalyst, and has better high-current circulation performance;
(4) The method has the advantages of simple synthesis process, high efficiency, low cost and strong universality, and is suitable for industrial production.
Drawings
FIG. 1 is an SEM image of a FeTe-DAC of example 1 of the present invention;
FIG. 2 is a TEM image of the FeTe-DAC of example 1 of the present invention;
FIG. 3 is an XRD pattern for FeTe-DAC of example 1 of the present invention;
FIG. 4 is an AC-HAADF-STEM diagram of a FeTe-DAC of example 1 of the present invention;
FIG. 5 is a graph of nitrogen adsorption/desorption for FeTe-DAC of example 1 of the present invention;
FIG. 6 is an N1s XPS spectrum of the FeTe-DAC of example 1 of the present invention;
FIG. 7 is a spectrum of Fe 2p XPS of FeTe-DAC of example 1 of the present invention;
FIG. 8 is a Te 3d XPS spectrum of FeTe-DAC of example 1 of the present invention;
FIG. 9 is a LSV plot of the electrocatalytic oxygen reduction reaction of FeTe-DAC and noble metal catalyst Pt/C in 0.1mol/L KOH according to example 1 of the present invention;
FIG. 10 is a LSV graph of the electrocatalytic oxygen reduction reaction at various rotational speeds for FeTe-DAC of example 1 of the present invention;
FIG. 11 is a LSV stability profile of an electrocatalytic oxygen reduction reaction of example 1FeTe-DAC of this invention in 0.1mol/L KOH before and after 10000 CV cycles;
FIG. 12 is the cycling performance of the FeTe-DAC and Pt/C noble metal catalysts of example 1 of the present invention in a quasi-solid zinc-air cell;
FIG. 13 is a LSV plot of an electrocatalytic oxygen reduction reaction of a FeTe-DAC and Pt/C noble metal catalyst of example 2 of the present invention in 0.1mol/L KOH;
FIG. 14 is a LSV plot of an electrocatalytic oxygen reduction reaction of FeTe-DAC and Pt/C noble metal catalyst of example 3 of the present invention in 0.1mol/L KOH;
FIG. 15 is a Te 3d XPS spectrum of the sample obtained in comparative example 4;
FIG. 16 is a LSV stability curve of the samples of comparative example 4 after 10000 CV cycles in 0.1mol/L KOH, after which the electrocatalytic oxygen reduction reaction was carried out.
Detailed Description
The invention is further described below with reference to examples and figures.
The protective atmosphere used in the embodiment of the invention is high-purity atmosphere with purity more than or equal to 99.9 percent. The materials or chemicals used in the examples of the present invention, unless otherwise specified, were obtained by conventional commercial means.
Example 1 based on FeTe diatomic catalyst
The FeTe-based diatomic catalyst (marked as FeTe-DAC) is a catalyst with a rhombic dodecahedron structure, wherein the iron monoatoms and tellurium atoms are uniformly distributed in the form of atom pairs (diatomic) in the carbon polyhedron; the doping amount of N in the FeTe-DAC is 0.35%; the mass percentage of the iron monoatoms in the FeTe-DAC is 1.46%; the mass percentage of the tellurium element in the FeTe-DAC is 0.62%; the average particle size of the FeTe-DAC is 378nm;
(1) Firstly, 150mg of ferric acetylacetonate and 1190mg of zinc nitrate are dissolved in 30mL of methanol solvent under stirring for 15min at room temperature to obtain solution A, 1314mg of dimethyl imidazole is dissolved in 30mL of methanol solvent under stirring for 15min at room temperature to obtain solution B, then the solution A and the solution B are stirred and mixed for 15min at room temperature, then are stood for aging for 12h, are centrifuged for 3min under the rotating speed of 7500r/min, the precipitate is filtered and washed for 3 times by using N, N-dimethyl acetamide and methanol successively, and are dried in vacuum for 8h under the temperature of 25 ℃ and the pressure of 0.05-0.5 MPa to obtain precursor powder;
(2) Heating the precursor powder obtained in the step (1) to 900 ℃ at a speed of 5 ℃/min under the protection of high-purity nitrogen atmosphere, maintaining for 3 hours, performing primary annealing heat treatment, and cooling along with a furnace to obtain 50mg of black powder SA-Fe/NC;
(3) 2mL of deoxidized ultrapure water prepared by hydrazine hydrate aqueous solution (151.3 mg,0.005 mol) is used to form solution C, 110.8mg of sodium tellurite is added into the solution C, and the solution is slightly oscillated for 30min at 25 ℃ until the solution is clear, so as to obtain precursor solution D;
(4) Dispersing the black powder SA-Fe/NC obtained in the step (2) in the precursor solution D obtained in the step (3) by ultrasonic, performing hydrothermal reaction for 24 hours at 200 ℃, centrifuging for 3 minutes at the rotating speed of 9000r/min, filtering and washing the precipitate for 3 times by using de-oxygenated ultrapure water and ethanol sequentially, and then freeze-drying for 24 hours at the temperature of minus 35 ℃;
(5) And (3) heating the powder obtained in the step (4) to 500 ℃ at a speed of 5 ℃/min under the protection of high-purity nitrogen atmosphere, maintaining for 1h, performing secondary annealing heat treatment, and cooling along with a furnace to obtain the FeTe-DAC.
As shown in FIG. 1, the FeTe-DAC of the embodiment of the invention has a rhombic dodecahedron structure, is well dispersed and does not agglomerate.
As shown in FIG. 2, the FeTe-DAC of the embodiment of the invention has a rhombic dodecahedron structure, is well dispersed and does not agglomerate.
As shown in FIG. 3, in the FeTe-DAC of the embodiment of the present invention, only a broad carbon peak is present, and no other impurity peak appears, which means that there is no impurity peak such as Te or other compounds.
As shown in fig. 4, in the FeTe-DAC of the embodiment of the present invention, there are abundant isolated iron-tellurium atom pairs (bright spot portions), which indicate that the iron-tellurium atom pairs are all atomically dispersed and exist in the form of diatomic atoms.
As shown in FIG. 5, in the FeTe-DAC of the embodiment of the present invention, the specific surface area is as high as 920m 2 /g。
As shown in fig. 6, in the FeTe-DAC of the embodiment of the present invention, N doping type is mainly pyridine nitrogen, pyrrole nitrogen and graphite nitrogen.
As shown in FIG. 7, in the FeTe-DAC of the embodiment of the present invention, the valence of Fe is +3.
As shown in FIG. 8, in the FeTe-DAC of the embodiment of the present invention, the valence of Te is +4.
To evaluate the performance of the FeTe-DAC obtained by the method of the present invention, the following tests were performed:
(1) Electrocatalytic ORR performance test:
configuration of catalyst slurry: 6mg of FeTe-DAC of the embodiment of the invention is weighed and transferred into a 5mL centrifuge tube, and then 5%40 mu L of nafion membrane solution and 960 mu L of isopropanol/water mixed solution (v: v=1:3) are sequentially dripped into the centrifuge tube, and the catalyst slurry is obtained by ultrasonic treatment for 1 h.
Electrocatalytic performance test: in a three-electrode system. Taking 10 mu L of catalyst slurry by a liquid-transferring gun, dripping the catalyst slurry onto the surface of a glassy carbon electrode, and drying the catalyst slurry at room temperature to serve as a working electrode; graphite rod is used as a counter electrode; saturated Calomel Electrode (SCE) as reference electrode; the electrolyte is 0.1mol/L KOH solution; the test environment was room temperature and pressure. The linear sweep voltammogram was done on an electrochemical workstation of the Shanghai Chenhua CHI 630E.
The electrochemical test conditions were: before the electrocatalytic reaction, introducing 0.5h of high-purity oxygen into the reaction system to enable the oxygen in the reaction system to reach a saturated state.
As shown in fig. 9, in the FeTe-DAC of the embodiment of the present invention, the half-wave potential is as high as 0.946V, the limiting current density is gradually increased with increasing rotation speed, and the process is a typical four-electron process, which is obtained through linear fitting, and has higher ORR reactivity compared with the noble metal catalyst Pt/C. Because the atomic radius of Te is far greater than that of Fe, the introduction of Te increases the distortion degree of the iron monoatomic local environment, adjusts the electronic structure of the material, optimizes the adsorption and desorption process of the reaction intermediate, and further improves the catalytic performance of the material.
As shown in fig. 10, in the FeTe-DAC according to the embodiment of the present invention, as the rotation speed increases, the limiting current density also increases gradually, and the linear fitting results in that the process is a typical four-electron process.
As shown in FIG. 11, the FeTe-DAC of the embodiment of the invention has almost no loss of half-wave potential after 10000 cycles of cyclic voltammetry acceleration cycles compared with the first cycle of LSV curve, which proves that the FeTe-DAC of the embodiment of the invention has very high electrocatalytic ORR stability.
(2) Quasi-solid zinc-air cell cycle performance test:
air electrode preparation: 60mg of FeTe-DAC and 10mg of acetylene black according to the embodiment of the invention are weighed and put into a mortar, 1mL of ethanol is dripped for grinding to form mixed slurry, 40 mu L of 60% polytetrafluoroethylene emulsion is dripped into the mixed slurry by a pipette, 1mL of ethanol is dripped again, and the mixture is fully ground to obtain a flaky catalytic layer. The foam nickel, the waterproof breathable film and the catalyst are fixed in this sequence, and the three are pressed into a whole on a roller press, namely the air electrode.
Assembly of quasi-solid zinc-air cells: and (3) placing the organic gel electrolyte between the zinc cathode and the air electrode according to a sandwich structure, and fixing the organic gel electrolyte by adopting a special battery clamp so that the gel electrolyte is in close contact with the zinc cathode and the air electrode to assemble the quasi-solid zinc-air battery. The test was performed under room temperature pressure. The charge-discharge circulation current density is 50mA cm -2 。
As shown in FIG. 12, the FeTe-DAC and noble metal Pt/C of the embodiment of the invention are at 50mA cm -2 The battery charge-discharge cycle performance of the noble metal Pt/C from the 200 th turn, and the FeTe-DAC from the 420 th turn, which shows that the cycle performance of the FeTe-DAC of the embodiment of the invention is higher than that of commercial Pt/C, and the cycle performance of the FeTe-DAC is better.
Example 2
This embodiment 2 differs from embodiment 1 only in that: the temperature of the primary heat treatment was 600℃and the temperature of the secondary heat treatment was 300 ℃.
In order to evaluate the catalytic performance of the FeTe-DAC of the present invention, the test was performed according to the following methods:
(1) Electrocatalytic ORR performance test: as in example 1.
As shown in fig. 13, the half-wave potential of the FeTe-DAC of the embodiment of the present invention is 0.833V, and the limiting current density is gradually increased with increasing rotation speed, and the linear fitting results from the linear fitting, and the process is a typical four-electron process, and has poorer ORR reactivity compared with the noble metal catalyst Pt/C.
(2) Quasi-solid zinc-air cell cycle performance test: as in example 1. FeTe-DAC of example 2 at 50mA cm -2 The battery cycle performance of (2) is lower than commercial Pt/C, with worse charge-discharge cycle performance.
Example 3
This embodiment 3 differs from embodiment 1 only in that: the temperature of the primary heat treatment was 1000℃and the temperature of the secondary heat treatment was 600 ℃.
In order to evaluate the catalytic performance of the FeTe-DAC of the present invention, the test was performed according to the following methods:
(1) Electrocatalytic ORR performance test: as in example 1.
As shown in FIG. 14, the half-wave potential of the FeTe-DAC of the embodiment of the invention is 0.919V, the limiting current density is gradually increased along with the increase of the rotating speed, and the limiting current density is obtained through linear fitting, and the process is a typical four-electron process and has higher ORR reactivity compared with a noble metal catalyst Pt/C.
(2) Quasi-solid zinc-air cell cycle performance test: as in example 1. FeTe-DAC of example 2 at 50mA cm -2 The battery cycle performance of the catalyst is higher than that of commercial Pt/C, and the catalyst has better charge-discharge cycle performance.
Comparative example 1
This comparative example differs from example 1 only in that: in the step (1), the mass of the ferric acetylacetonate is 300.0mg; in the step (2), an N-doped carbon polyhedral catalyst loaded with an elemental iron and iron carbide is obtained; the operations of the steps (3) and (4) are not performed. Example 1 was followed.
Through detection, the carbon polyhedral catalyst loaded with the iron simple substance and the iron carbide, which is obtained in the comparative example 1, has diffraction peaks of crystalline phase nano iron simple substance and iron carbide particles.
To evaluate the performances of the carbon polyhedral catalyst supporting elemental iron and iron carbide obtained in this comparative example, the following tests were conducted:
(1) Electrocatalytic ORR performance test:
as in example 1.
The ORR activity of the elemental iron and iron carbide loaded carbon polyhedral catalyst obtained in this comparative example was significantly lower than that of FeTe-DAC and commercial Pt/C catalysts obtained in example 1 of the process of the present invention.
Through detection, after 10000 cycles of cyclic voltammetry acceleration circulation, the curve is obviously shifted to the left, which proves that the carbon polyhedral catalyst ORR loaded with the iron simple substance and the iron carbide obtained in the comparative example has poor stability.
(2) Quasi-solid zinc-air cell cycle performance test:
as in example 1.
The test shows that the comparative example is 50mA cm -2 The battery charge-discharge cycle performance of (C) was significantly worse than that of commercial Pt/C, indicating that the cycle performance of this comparative example was poor.
In summary, it is demonstrated that increasing the loading of iron salt reduces the electrochemical activity of the catalyst.
Comparative example 2
This comparative example differs from example 1 only in that: in the step (1), ferric acetylacetonate is not added; in the step (2), an N-doped carbon polyhedral catalyst is obtained; the operations of the steps (3) and (4) are not performed. Example 1 was followed.
According to detection, no diffraction peak of crystalline phase iron particles is found in the N-doped carbon polyhedral catalyst obtained by the method embodiment of the invention, and amorphous carbon is the main material.
To evaluate the performance of the N-doped carbon polyhedral catalyst obtained in this comparative example, the following test was performed:
(1) Electrocatalytic ORR performance test:
as in example 1.
Through detection, after 10000 cycles of cyclic voltammetry acceleration cycle, the curve is obviously shifted to the left, which proves that the stability of the N-doped carbon polyhedral catalyst ORR obtained in the comparative example is poor.
(2) Quasi-solid zinc-air cell cycle performance test:
as in example 1.
The test shows that the comparative example is 50mA cm -2 The battery charge-discharge cycle performance of (C) was significantly worse than that of commercial Pt/C, indicating that the cycle performance of this comparative example was poor.
In conclusion, it is demonstrated that the electrochemical performance is reduced since comparative example 2 is not loaded with iron monoatoms.
Comparative example 3
This comparative example differs from example 1 only in that: the black powder obtained in the step (2) is the carbon polyhedral catalyst loaded with iron single atoms; the operations of the steps (3) and (4) are not performed. Example 1 was followed.
No diffraction peak of crystalline phase iron particles was found in the iron single atom-supported carbon polyhedral catalyst.
To evaluate the performance of the iron single atom-supported carbon polyhedral catalyst obtained in this comparative example, the following test was performed:
(1) Electrocatalytic ORR performance test:
as in example 1.
Through detection, after 10000 cycles of cyclic voltammetry acceleration cycle, the curve is obviously shifted to the left, which proves that the stability of the N-doped carbon polyhedral catalyst ORR obtained in the comparative example is poor.
(2) Quasi-solid zinc-air cell cycle performance test:
as in example 1.
The test shows that the comparative example is 50mA cm -2 The battery charge-discharge cycle performance of (C) was slightly better than that of commercial Pt/C, but was inferior to that of example 1, indicating that the cycle performance of this comparative example was insufficient.
Taken together, it is demonstrated that the electrochemical performance is insufficient due to the comparative example 3 having no formation of iron-tellurium diatomic.
Comparative example 4
This comparative example differs from example 1 only in that: the black powder obtained in the step (2) is the carbon polyhedral catalyst loaded with iron single atoms; and (4) performing no operation of the step (4). Example 1 was followed.
As shown in FIG. 15, the sample obtained in this comparative example 4 has abundant F-Te coordination bonds, which proves that Te after the second hydrothermal reaction 2- Reacts with iron monoatoms to form Fe-Te coordination bonds.
No diffraction peak of crystalline phase iron particles was found in the iron single atom-supported carbon polyhedral catalyst.
The diffraction peak and other impurity peaks of the metal telluride are not found in the Fe-Te diatomic catalyst which is not calcined after the hydrothermal reaction.
To evaluate the performance of the uncalcined iron-tellurium diatomic catalyst obtained in this comparative example, the following tests were performed:
(1) Electrocatalytic ORR performance test:
as in example 1.
As shown in FIG. 16As shown, the half-wave potential of the sample obtained in this comparative example 4 was 0.89V, which is inferior to the FeTe DAC performance after the secondary calcination. After 10000 cycles of cyclic voltammetry acceleration circulation, the curve is obviously shifted to the left, which proves that the stability of the N-doped carbon polyhedral catalyst ORR obtained in the comparative example is poor. Description if only hydrothermal treatment is performed without secondary calcination, te 2- Although weak coordination is formed with bare iron monoatoms, te is due to 2- Not doped with nitrogen in the vicinity of the iron monoatoms with carbon C&N coordinates, poor conductivity, and influences electron transfer in the reaction process, which in turn leads to no improvement in reactivity.
(2) Quasi-solid zinc-air cell cycle performance test:
as in example 1.
The test shows that the comparative example is 50mA cm -2 The battery charge-discharge cycle performance of (C) was slightly better than that of commercial Pt/C, but was inferior to that of example 1, indicating that the cycle performance of this comparative example was insufficient.
In conclusion, it is explained that the electrocatalytic oxygen reduction reaction performance is insufficient due to the absence of the calcined hydrothermal iron-tellurium diatomic catalyst of comparative example 4.

Claims (10)

1. The preparation method of the FeTe diatomic catalyst is characterized by comprising the following steps:
(1) Firstly, stirring and dissolving ferric salt and zinc nitrate in a methanol solvent to obtain a solution A, stirring and dissolving an N-containing organic ligand in the methanol solvent to obtain a solution B, stirring and mixing the solution A and the solution B, standing for ageing, centrifuging, filtering and washing, and vacuum drying to obtain precursor powder;
(2) Performing primary heat treatment on the precursor powder obtained in the step (1) under the protection of inert atmosphere to obtain black powder; the temperature of the primary heat treatment is 600-1000 ℃;
(3) Dissolving a strong reducing agent in deoxidized ultrapure water until the solution is clear and transparent to obtain a solution C, adding a tellurium simple substance or salt containing tellurium elements into the solution C, and oscillating until the solution is clear again to obtain a precursor solution D;
(4) Ultrasonically dispersing the black powder obtained in the step (2) in the precursor solution D obtained in the step (3), carrying out hydrothermal treatment, centrifuging, filtering and washing, and freeze-drying the black precipitate to obtain sample powder; the mass volume ratio of the black powder to the tellurium simple substance or the salt containing tellurium element is 0.1 g/1 mL-10 mL; the molar concentration of the tellurium simple substance or the salt containing tellurium element in the precursor solution D is 0.05-0.50 mol/L;
(5) Carrying out secondary heat treatment on the sample powder obtained in the step (4) under the protection of inert atmosphere to obtain a FeTe diatomic catalyst; the temperature of the secondary heat treatment is 300-600 ℃.
2. The method for preparing the FeTe diatomic catalyst as claimed in claim 1, wherein: in the step (1), the mass ratio of the ferric salt to the zinc nitrate is 1:8-50; the mass volume ratio of the sum of the iron salt and the zinc nitrate in the solution A to the methanol solvent is 1g:20 mL-200 mL; the ferric salt is one or more of carbonyl iron, ferric acetylacetonate, ferric acetate, ferric chloride or ferric nitrate; the mass ratio of the zinc nitrate to the N-containing organic ligand is 1:0.8-2.0; the mass volume ratio of the N-containing organic ligand to the methanol solvent in the solution B is 1g:20 mL-200 mL; the N-containing organic ligand is one or more of dimethyl imidazole, hexamethylenetetramine or ethylenediamine tetraacetic acid; the temperature of stirring and dissolving is room temperature, and the time is 10-30 min;
in the step (3), the tellurium simple substance comprises tellurium powder, and the salt containing tellurium element comprises one or more of sodium tellurite and sodium tellurite.
3. The method for preparing the FeTe diatomic catalyst as claimed in claim 1, wherein: in the step (1), the temperature of stirring and mixing is between room temperature and 140 ℃ and the time is between 1 and 6 hours; the temperature of the standing aging is between room temperature and 140 ℃ and the time is between 6 and 24 hours; the vacuum drying pressure is 0.05-0.5 MPa, and the time is 12-72 h.
4. The method for preparing the FeTe diatomic catalyst as claimed in claim 1, wherein: in the step (2), the time of the primary heat treatment is 1-6 h, and inert gas is usedThe atmosphere is nitrogen, argon and the volume fraction is 5%H 2 /95％N 2 Is 5%H by volume fraction 2 Mixed gas of/95% Ar.
5. The method for preparing the FeTe diatomic catalyst as claimed in claim 1, wherein: the strong reducing agent is one or more of sodium borohydride or hydrazine hydrate; the deoxidized ultrapure water is deoxidized ultrapure water for discharging oxygen in the ultrapure water by argon.
6. The method for preparing a FeTe diatomic catalyst according to any one of claims 1 to 5, characterized in that: in the step (3), the temperature of oscillation is 20-40 ℃ and the oscillation time is 10-30 min; the concentration of the strong reducing agent in the solution C is 1-4 mol/L.
7. The method for preparing a FeTe diatomic catalyst according to any one of claims 1 to 5, characterized in that: in the step (4), the hydrothermal time is 12-48 h, and the hydrothermal temperature is 160-220 ℃; the rotational speed of the centrifugation is 6000-10000 r/min, and the centrifugation time is 1.5-5 min; the freeze drying temperature is-10 to-30 ℃ and the time is 12 to 72 hours.
8. The method for preparing a FeTe diatomic catalyst according to any one of claims 1 to 5, characterized in that: in the step (5), the time of the secondary heat treatment is 1-6 h, the inert atmosphere is nitrogen, argon and the volume fraction is 5%H 2 /95％N 2 Is 5%H by volume fraction 2 Mixture of 95% Ar.
9. A FeTe diatomic catalyst prepared by the method of any one of claims 1-8.
10. Use of the FeTe diatomic catalyst of claim 9 in ORR catalytic reactions.
CN202211395342.9A 2022-11-09 2022-11-09 FeTe diatomic catalyst and preparation method thereof Pending CN116344845A (en)

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