CN113636555A

CN113636555A - Ti3C2TxOxygen vacancy anchoring single-atom material and preparation method and application thereof

Info

Publication number: CN113636555A
Application number: CN202111003511.5A
Authority: CN
Inventors: 宫勇吉; 张江江
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2021-08-30
Filing date: 2021-08-30
Publication date: 2021-11-12
Anticipated expiration: 2041-08-30
Also published as: CN113636555B

Abstract

The invention belongs to the field of new materials, and discloses Ti₃C₂T_xAn oxygen vacancy anchored monatomic material and a method for making the same, comprising the steps of: a single layer of Ti₃C₂T_xPreparing a solution with a metal complex or a metal salt; freeze drying to obtain a precursor with a two-dimensional lamellar structure; then in the environment of hydrogen-argon mixture gas, the Ti is obtained by rapid heat treatment reaction₃C₂T_xThe oxygen vacancies anchor the monoatomic material. Anchored to Ti with a previously prepared monoatomic atom₃C₂T_xThe single atom provided by the invention isAnchored to Ti₃C₂T_xThe material on the oxygen vacancy is more beneficial to the desorption reaction of hydrogen. The preparation process is simple and suitable for large-scale production; prepared Ti₃C₂T_xThe oxygen vacancy anchoring monatomic material can be directly applied to the field of electrochemical catalytic hydrogen production.

Description

Ti3C2TxOxygen vacancy anchoring single-atom material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of new materials, and particularly relates to Ti₃C₂T_xAn oxygen vacancy anchored monatomic material, a method for its preparation and its use.

Background

Monatomic materials have been in the leading-edge field of electrocatalytic hydrogen production due to their highest atomic utilization. However, the monoatomic material must be attached to a conductive substrate to exert its greatest advantage. Meanwhile, the form of the attachment of the monoatomic atom to the substrate also affects the performance of the catalytic performance of the monoatomic atom. Graphene and other two-dimensional materials and the like have been used to support monoatomic atoms to date, and despite some advances, finding suitable substrates and modulating the interactions between monoatomic atoms and substrates to further improve catalytic activity remains a research hotspot in the field of hydrogen production. In addition, adjusting the coordination environment of a monatomic catalyst has proven to be an effective way to increase its catalytic activity. Two-dimensional MXene has attracted attention as a novel two-dimensional material because of its excellent properties such as a very large specific surface area and a rich surface functional group. Compared with graphene and other two-dimensional materials, the surface functional group rich in MXene provides more possibilities for adjusting the coordination environment of the MXene-based single-atom catalyst. The monatomic material has excellent catalytic performance in the field of electrocatalytic hydrogen production, but the MXene oxygen vacancy anchoring monatomic material has not been successfully prepared.

Disclosure of Invention

The technical problem that the catalyst based on monoatomic atoms is difficult to prepare is solved, and the invention aims to provide Ti₃C₂T_xPreparation method of oxygen vacancy anchoring metal monoatomic material, which can prepare Ti simply and easily₃C₂T_xThe oxygen vacancies anchor the monoatomic material.

One aspect of the present invention provides a Ti₃C₂T_xA method for preparing an oxygen vacancy anchored monatomic material, comprising the steps of:

mixing: mixing raw material Ti₃C₂T_xMixing the material with a solution of a metal complex or metal salt, and freeze-drying to obtain the final productDriving a body; a heat treatment step: heating the precursor to a predetermined temperature in an atmosphere containing a reducing gas to perform heat treatment to obtain Ti₃C₂T_xOxygen vacancy anchoring single atom materials; wherein, the raw material Ti₃C₂T_xThe surface of the material has oxygen-containing functional groups; the heating rate of the heat treatment is between 40 ℃/min and 50 ℃/min.

In some embodiments, the above metal complex is selected from a carbonyl complex or an amino complex of a metal; the metal salt is selected from chloride or nitrate of metal; preferably, the metal element is selected from one or more of platinum, iron, cobalt, nickel, copper, zinc, gallium, germanium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tungsten, rhenium, iridium, gold, lead or bismuth.

In some embodiments, the predetermined temperature is between 400 ℃ and 500 ℃.

In some embodiments, the mixing step further comprises mixing the above raw material Ti₃C₂T_xCarrying out ultrasonic treatment on the material and a metal complex or a metal salt solution under the conditions of argon and ice bath; and/or the above raw material Ti₃C₂T_xThe material passing MAX phase Ti₃AlC₂Etching the material in a mixed solution of hydrochloric acid and lithium fluoride to obtain the material; and/or the above raw material Ti₃C₂T_xThe material is a single-layer material, or the thickness is between 1nm and 2 nm.

In some embodiments, the atmosphere further comprises an inert gas; preferably, the volume fraction of the reducing gas is between 1% and 20%.

In some embodiments, the reducing gas is hydrogen or ammonia.

In some embodiments, the resulting Ti₃C₂T_xThe loading of a single atom in the single atom material with an oxygen vacancy anchor is 0.01 wt.% to 10 wt.%.

The invention also provides Ti obtained by the preparation method₃C₂T_xThe oxygen vacancies anchor the monoatomic material of platinum, iron, cobalt, nickel, copper, zinc, gallium, germanium,One or more of ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tungsten, rhenium, iridium, gold, lead or bismuth atoms.

The invention also comprises a catalytic hydrogen production device containing the Ti obtained by the preparation method₃C₂T_xMXene material with oxygen vacancies anchored to a single atom.

The invention also provides Ti obtained by the preparation method₃C₂T_xOxygen vacancy anchoring monatomic materials have applications in the fields of catalysis, sensors or batteries.

Compared with the prior art, the preparation method of the invention utilizes Ti₃C₂T_xThe oxygen-containing functional group on the surface of the material adopts a rapid heat treatment technology under a reducing atmosphere to realize Ti₃C₂T_xThe preparation method of the oxygen vacancy anchoring monatomic material is simple and feasible, is suitable for industrial large-scale production, and provides a new technical route for the preparation of the monatomic catalyst.

Ti prepared by the invention₃C₂T_xOxygen vacancy anchored monatomic material is anchored to Ti due to the monatomic anchoring₃C₂T_xThe oxygen vacancy can reduce the hydrogen bonding energy and the hybrid strength, promote the dynamic process of hydrogen adsorption-desorption and greatly improve the catalytic performance; when used in catalytic hydrogen production electrodes, exhibit low overpotentials, high mass activity and high conversion efficiency, about 16 times higher than 20 wt.% Pt/C industrial catalysts, and have shown great commercial utility.

Drawings

FIG. 1 shows Ti in example 1 of the present invention₃C₂T_xAnd Ti₃C₂T_x-Pt_SAFourier transform infrared spectrogram of (1);

FIG. 2 shows Ti in example 1 of the present invention₃C₂T_xScanning electron microscope (a) and transmission electron microscope (b);

FIG. 3 shows Ti in example 1 of the present invention₃C₂T_xThe atomic force microscope photograph of (1);

FIG. 4 shows Ti in example 1 of the present invention₃C₂T_x-Pt_SAScanning electron microscope (a) and transmission electron microscope (b);

FIG. 5 shows Ti in example 1 of the present invention₃C₂T_x-Pt_SAHigh Angle Annular Dark Field (HAADF) -STEM and Ti, C, O, Pt element distribution images of (a), where bright spots appear as single platinum atoms;

FIG. 6 shows Ti in example 1 of the present invention₃C₂T_x-Pt_SAElectron paramagnetic resonance spectrum of the material;

FIG. 7 shows Ti in example 1 of the present invention₃C₂T_x-Pt_SAFourier transform-expanded X-ray absorption fine structure diagram of the material;

FIG. 8 shows Ti in comparative example 1 of the present invention₃C₂T_xPt-loaded particle high angle annular dark field photo (HAADF) -STEM;

FIG. 9 shows Ti in example 2 of the present invention₃C₂T_x-N-Pt_SATransmission electron micrographs (a, b) and scanning transmission electron micrographs (c, d) of the material;

FIG. 10 shows Ti in example 7 of the present invention₃C₂T_x(a)、Ti₃C₂T_x-N-Pt_SA(b)、Ti₃C₂T_x-Pt_SA(c) And a photograph of a Pt/C (d) material after analysis of a water contact angle test curve by circular model fitting;

FIG. 11 shows Ti in example 7 of the present invention₃C₂T_x,Ti₃C₂T_x-N-Pt_SA,Ti₃C₂T_x-Pt_SAAnd linear sweep voltammograms of Pt/C;

FIG. 12 shows Ti in example 7 of the present invention₃C₂T_x-Pt_SACompared with the overpotentials of recently reported MXene-based and Pt-based catalysts;

FIG. 13 shows Ti in example 7 of the present invention₃C₂T_x、Ti₃C₂T_x-N-Pt_SA、Ti₃C₂T_x-Pt_SAAnd Tafel plot of Pt/C;

FIG. 14 shows Ti in example 7 of the present invention₃C₂T_x-Pt_SA、Ti₃C₂T_x-N-Pt_SAAnd mass activity profile of the Pt/C catalyst;

FIG. 15 shows Ti in example 7 of the present invention₃C₂T_x-Pt_SA、Ti₃C₂T_x-N-Pt_SAAnd a plot of conversion efficiency for the Pt/C catalyst;

FIG. 16 shows Ti in example 7 of the present invention₃C₂T_x-Pt_SAThe hydrogen production stability test of (1), comprising: ti₃C₂T_x-Pt_SALinear sweep voltammetry graphs before and after 1000 cycles of cyclic voltammetry; ti₃C₂T_x-Pt_SACurrent-time graph of (a).

Detailed Description

The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.

The technical solution of the present invention will be described below by way of specific examples. It is to be understood that one or more of the steps mentioned in the present invention does not exclude the presence of other methods or steps before or after the combined steps, or that other methods or steps may be inserted between the explicitly mentioned steps. It should also be understood that these examples are intended only to illustrate the invention and are not intended to limit the scope of the invention. Unless otherwise indicated, the numbering of the method steps is only for the purpose of identifying the method steps, and is not intended to limit the arrangement order of each method or the scope of the implementation of the present invention, and changes or modifications of the relative relationship thereof may be regarded as the scope of the implementation of the present invention without substantial technical change.

The raw materials and apparatuses used in the examples are not particularly limited in their sources, and may be purchased from the market or prepared according to a conventional method well known to those skilled in the art.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

Raw material Ti of the present invention₃C₂T_xThe material is transition metal carbide with a two-dimensional lamellar structure, at present, single-layer Ti₃C₂T_xThe material is prepared by mixing Ti with hydrochloric acid and lithium fluoride₃AlC₂The surface of the compound is rich in surface functional groups. T is_xRefers to surface functional groups including-F, -OH, and-O; however, the-F functional group is less stable than the-O functional group, so that Ti₃C₂T_xThe surface functional groups of (a) are present mainly in the form of-O and/or-OH. A similar conclusion is also confirmed in our work in fourier transform infrared spectroscopy figure 1. Ti₃C₂T_xAnd N₂H₈PtCl₆Under the mixed atmosphere of hydrogen and argon, the catalyst Ti is formed by heat treatment₃C₂T_x-Pt_SAThe functional group is converted from-OH to-O. From FIG. 1 to Ti₃C₂T_x-

Pt

_SA3433, 2925 and 1630cm^-1The significant reduction of the vibration peak was confirmed.

Ti provided by the invention₃C₂T_xA method for preparing an oxygen vacancy anchored monatomic material, comprising the steps of:

1) mixing: mixing raw material Ti₃C₂T_xThe material is mixed with a solution of a metal complex or a metal salt and then is frozen and dried to obtain a precursor with the metal complex or the metal salt dispersed on the MXene; wherein, the raw material Ti₃C₂T_xThe surface of the material has oxygen-containing functional groups (such as-OH and/or-O);

2) a heat treatment step: heating the precursor to a preset temperature at a heating rate of 40-50 ℃/min in an atmosphere containing reducing gas, and then cooling to normal temperature to obtain the Ti₃C₂T_xOxygen vacancy anchoring single atom materials; in thatIn this step, Ti is first heated by a rapid temperature rise process in an atmosphere containing a reducing gas₃C₂T_xOxygen-containing functional groups on the surface are reduced to form oxygen vacancies, and simultaneously, the metal complex or metal salt is thermally decomposed to form metal atoms occupying the oxygen vacancies to obtain Ti₃C₂T_xThe oxygen vacancies anchor the monoatomic material.

In some embodiments, the metal complex is selected from a carbonyl complex or an amino complex of a metal; alternatively, the metal salt is selected from chloride or nitrate salts of the metal; during the heat treatment of the metal complexes or metal salts, the decomposition products, metal atoms and gaseous compounds can avoid the doping of impurities into the generated products.

In some embodiments, the metal species in the metal complex or metal salt is selected from one or more of platinum, iron, cobalt, nickel, copper, zinc, gallium, germanium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tungsten, rhenium, iridium, gold, lead, bismuth, or the like, and Ti is obtained by the preparation method of the present invention₃C₂T_xThe oxygen vacancies anchor the corresponding monatomic material.

In some embodiments, the reducing gas comprises hydrogen or ammonia, and the atmosphere further comprises an inert gas (a gas that does not participate in the reaction, such as argon, helium, etc.); preferably, the volume fraction of the reducing gas is between 1% and 20%.

Example 1

This example provides a Ti₃C₂T_xProcess for the preparation of an oxygen-vacancy-anchored monatomic material, wherein T_xRefers to a surface functional group formed by mixing Ti with a mixed solution of hydrochloric acid and lithium fluoride₃AlC₂The medium is obtained by extracting weaker aluminum-bit element. Fourier transform infrared spectroscopy shown in FIG. 1 confirmed Ti₃C₂T_xThe surface functional groups of (a) include-F, -OH, and-O; however, since the-F functional group is less stable than the-O functional group, Ti₃C₂T_xThe surface functional groups of (a) are present mainly in the form of-O and/or-OH.

The preparation method of the embodiment comprises the following steps:

step 1): 20mL of 0.25mM N₂H₈PtCl₆The aqueous solution was slowly added to 1mg mL^–1Single layer of Ti₃C₂T_xIn solution, wherein Pt is loaded with Ti₃C₂T_x-Pt_SA0.84 wt.% of the material, and then sonicated for 3h under argon and ice bath protection, in order to make N₂H₈PtCl₆At Ti₃C₂T_xUniform dispersion on the lamella while avoiding N induced by sonication₂H₈PtCl₆To obtain Ti₃C₂T_xAnd N₂H₈PtCl₆The mixed solution of (1);

step 2): pre-freezing the solution obtained in the step 1) at-66 ℃ for 24h, and then placing the frozen solution in a freeze dryer for drying for 38h to obtain a precursor with a two-dimensional lamellar structure;

step 3): putting the precursor in the step 2) into a tube furnace filled with 10% hydrogen-argon mixed gas for rapid heat treatment, heating to 400 ℃ in 10min (the heating rate is 40 ℃/min), and aiming at obtaining the Ti monolayer₃C₂T_xGenerating oxygen vacancy in the surface functional group to enable Pt atoms to occupy the oxygen vacancy, cooling to room temperature after the reaction is finished to obtain a target product Ti₃C₂T_xOxygen vacancy anchoring Pt monoatomic, hereinafter denoted as Ti₃C₂T_x-Pt_SA。

1mg mL in step 1)^–1Single layer of Ti₃C₂T_xIn solution, freeze-drying to obtain Ti₃C₂T_xFor comparison, the following is marked Ti₃C₂T_xTo Ti₃C₂T_xScanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Atomic Force Microscope (AFM) measurements were performed, with the results shown in FIG. 2 as a, b and FIG. 3, for a single layer of Ti₃C₂T_xAlmost transparent, with a thickness of about 1.5 nm.

To identify Ti₃C₂T_x-Pt_SASheet inLayer Ti₃C₂T_xPt monoatomic atom anchored on oxygen vacancy to the target product Ti obtained in step 3)₃C₂T_x-Pt_SAScanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) measurements were taken with Ti as shown in FIGS. 4 a and b, and visible in FIG. 4₃C₂T_x-Pt_SAThe morphology of (1) is similar to that of the substrate Ti₃C₂T_xThe material, the surface remained smooth and no Pt particles appeared. It can be seen that Ti was obtained by freeze-drying₃C₂T_x-Pt_SACapable of holding a substrate Ti₃C₂T_xAnd (3) the appearance characteristics of the two-dimensional sheet layer of the material.

To further evaluate the single layer of Ti₃C₂T_xIn the form of Pt atoms, to the product Ti₃C₂T_x-Pt_SAA spherical aberration corrected TEM measurement was performed. Some bright spots were observed in the High Angle Annular Dark Field (HAADF) -STEM image (as shown in fig. 5), indicating a monolayer of Ti₃C₂T_xHeavy atoms are present in the structure, and it is known that the relative atomic mass (195) of Pt in the periodic table is heavier than that of Ti (47), C (12) elements. Therefore, high density bright spots in HAADF-STEM images (FIG. 5b) should be assigned to Pt atoms to verify Ti₃C₂T_xFormation of Pt monoatomic atoms on the nano-sheet. In addition, for the product Ti₃C₂T_x-Pt_SAElectron paramagnetic resonance spectroscopy (EPR) measurements, as shown in figure 6, demonstrated Ti₃C₂T_x-Pt_SAIn which oxygen vacancies exist. With Ti₃C₂T_xIn contrast, Ti₃C₂T_x-Pt_SAA sharper peak appears at g-2.003, indicating that hydrogen heat treatment can generate more oxygen vacancies, which is 634cm in comparison with the Ti-O bond observed in FT-IR in FIG. 1^-1The peak intensity becomes uniform. For product Ti₃C₂T_x-Pt_SAThe expanded X-ray absorption fine structure of (2) is subjected to Fourier transform FT-EXAFS, as shown in FIG. 7a, in which Pt atom occupies oxygen vacancy and coordinates with three Ti atoms₃C₂T_x-Pt_SATo form Pt-Ti bonds (see FIGS. 7b, c). Ti is measured by an atomic spectrometer (ICP-OES)₃C₂T_x-Pt_SAThe content of Pt in the product was 0.84 wt.%.

Comparative example 1

This comparative example differs from example 1 in that:

step 3): putting the precursor in the step 2) into a tube furnace filled with argon gas environment for rapid heat treatment, and obtaining a target product marked as Ti in the same way as the example 1₃C₂T_x-Pt。

For the target product Ti obtained in the step 3)₃C₂T_xHigh Angle Annular Dark Field (HAADF) -STEM measurements were carried out on Pt, the results are shown in FIG. 8, and it can be seen that the heat treatment atmosphere was Ti after exchanging argon for hydrogen-argon mixture₃C₂T_xA large amount of Pt particles appear on the sheet layer, and the resultant Ti can be judged to be Ti₃C₂T_xSupporting the Pt particle composite material. This comparative example illustrates that argon gas cannot reduce oxygen functional groups, i.e., cannot form oxygen vacancies, i.e., cannot fix N, during rapid thermal treatment due to the absence of reducing gas (hydrogen gas)₂H₈PtCl₆The formed Pt atoms are decomposed and agglomerated to form Pt particles.

Comparative example 2

This comparative example differs from example 1 in that:

step 3): putting the precursor in the step 2) into a tube furnace filled with 10% hydrogen-argon mixed gas for rapid heat treatment, heating to 200 ℃ within 5min, cooling to room temperature after the reaction is finished, and obtaining the target product Ti in the same way as the example 1₃C₂T_xPt-Supported, hereinafter denoted as Ti₃C₂T_xPt, Ti determination by ICP-OES₃C₂T_x-Pt content in Pt 0.01 wt.%. It can be seen that in this comparative example, the heat treatment temperature was too low, oxygen vacancies were reduced, and the monatomic Pt loading was very low.

Comparative example 3

This comparative example differs from example 1 in that:

step 3): putting the precursor in the step 2) into a tube furnace filled with 10% hydrogen-argon mixed gas for rapid heat treatment, heating to 600 ℃ for 15min, cooling to room temperature after the reaction is finished, and obtaining the target product Ti in the same way as the example 1₃C₂T_xPt-carrying particles, hereinafter denoted as Ti₃C₂T_x-Pt₃And (3) Ti. In this comparative example, the heat treatment temperature was too high, oxygen vacancies increased, and Pt was easily formed₃Ti particles.

Comparative example 4

This comparative example differs from example 1 in that:

step 3): putting the precursor in the step 2) into a tube furnace filled with 10% hydrogen-argon mixed gas for heat treatment, heating to 400 ℃ in 40min (the heating rate is 10 ℃/min), cooling to room temperature after the reaction is finished, and obtaining the target product Ti in the same way as the example 1 except that₃C₂T_xMedium-loaded Pt particles show that the temperature rise speed is too slow in heat treatment, and the metal complex N₂H₈PtCl₆The decomposed Pt atoms are easy to agglomerate to form Pt particles.

In another embodiment, the target product Ti is obtained by heating to 400 ℃ in step 3) through 20min (heating rate 20 ℃/min), cooling to room temperature after the reaction is completed, and the rest is the same as in example 1₃C₂T_xAlso contains Pt-loaded particles. Illustrating the rate of temperature rise in the heat treatment step for the formation of Ti₃C₂T_xThe oxygen vacancy anchoring monoatomic material is vital, and under the rapid heating rate, the metal monoatomic material generated by the thermal decomposition of the metal complex or the metal salt can occupy the oxygen vacancy; if the temperature rise rate is too slow, the metal monoatomic atoms formed by thermal decomposition are easily agglomerated into metal particles, and Ti is obtained₃C₂T_xSupporting the metal particle material.

Comparative example 5

This comparative example differs from example 1 in that:

in the step 2), drying the product in vacuum for 48h at 40 ℃ to obtain a precursor; the rest(s)The same as in example 1. In this comparative example, Ti was caused due to vacuum drying₃C₂T_xThe sheet layer generates a serious agglomeration phenomenon, and the reducing gas cannot be sufficiently reduced in the heat treatment step.

Example 2

This example provides a nitrogen doped Ti₃C₂T_xThe preparation method of the oxygen vacancy anchored single-atom material is similar to that of example 1, except that after the hydrogen gas in the 10% hydrogen-argon mixed gas is replaced by the ammonia gas for rapid heat treatment in step 3), the prepared product is marked as Ti₃C₂T_x-N-Pt_SA. As shown by a, b, c and d in FIG. 9, it can be seen that nitrogen-doped Ti is obtained by measurement using a transmission electron microscope and a scanning transmission electron microscope₃C₂T_xThe oxygen vacancies anchor the Pt monatomic material and do not produce Pt particles, since ammonia gas can also act to reduce the oxygen functional groups to form oxygen vacancies.

Example 3

This example provides a Ti₃C₂T_xThe preparation method of the oxygen vacancy anchored single-atom material is similar to that of the embodiment 1, and is characterized in that the precursor in the step 2) is placed into a tube furnace filled with 10% hydrogen-argon mixed gas in the step 3) to be subjected to heat treatment, the temperature is increased to 500 ℃ (the temperature increase rate is 50 ℃/min) in 10min, the temperature is reduced to room temperature after the reaction is finished, and the rest is the same as that of the embodiment 1, so that the target product is obtained.

The target product obtained by measuring the target product obtained at a temperature rise rate of 50 ℃/min in this example by high-angle annular dark field (HAADF) -STEM measurement was Ti, which was the same as that in example 1₃C₂T_xThe oxygen vacancies anchor the Pt monatomic material.

Example 4

This example provides a Ti₃C₂T_xPreparation of an oxygen vacancy anchored monatomic material, similar to example 1, with the exception that the concentration of the metal complex was varied to obtain Ti₃C₂T_xOxygen vacancy anchoring of varying contents of Pt monatomic material, in particularThe ground is: in step 1), 20mL of N at 0.5mM, 1.0mM, 1.5mM, 2.0mM and 2.5mM, respectively₂H₈PtCl₆The aqueous solution was slowly added to 1mg mL^–1Single layer of Ti₃C₂T_xIn the solution, the target product Ti was obtained in the same manner as in example 1₃C₂T_xOxygen vacancies anchored at different levels of Pt monoatomic atoms, and Ti determined by ICP-OES₃C₂T_xThe content of Pt in Pt was 2.0 wt.%, 4.0 wt.%, 6.0 wt.%, 8.0 wt.% and 10.08 wt.%, respectively.

In the target product obtained by observation of a spherical aberration electron microscope, no obvious Pt particles appeared in the samples with Pt contents of 2.0 wt.%, 4.0 wt.%, 6.0 wt.% and 8.0 wt.%, indicating that Pt is anchored to Ti in a monoatomic form₃C₂T_xOn oxygen vacancies, small amounts of Pt particles appear in the target product with a Pt content of 10.08 wt.%. Therefore, in the preparation method of the present invention, the loading of the metal atom is preferably between 0.01 wt.% and 10.0 wt.%.

Example 5

This example provides a Ti₃C₂T_xA process for the preparation of an oxygen-vacancy-anchored monatomic material, similar to that of example 1, except that, in step 1), N₂H₈PtCl₆Replacement of aqueous solution with FeCl₃To obtain a target product Ti₃C₂T_xThe oxygen vacancies anchor the Fe monatomic material.

In another embodiment, N₂H₈PtCl₆The aqueous solution may also be replaced by Fe (NO)₃)₃To obtain a target product Ti₃C₂T_xThe oxygen vacancies anchor the Fe monatomic material.

Example 7

This example provides a catalytic hydrogen production device, more specifically, a catalytic hydrogen production catalytic electrode, in this example Ti₃C₂T_x-Pt_SAAnd Ti₃C₂T_x-N-Pt_SAThe target products obtained in examples 1 and 2, respectively, this catalytic preparationThe preparation method of the hydrogen electrode comprises the following steps:

4mg of Ti₃C₂T_x-Pt_SA700 mul deionized water, 300 mul ethanol and 80 mul 5 wt.% Nafion solution, and carrying out ultrasonic treatment for 3h to uniformly mix the solution and obtain the solution with the concentration of 4 mg.mL^-1Ti of (A)₃C₂T_x-Pt_SAAnd (3) spraying the dispersion liquid on the surface of an L-glassy carbon electrode (L-GCE, the diameter of which is 3 mm) by using a liquid transfer gun, and evaporating water on the surface of the L-GCE to finally obtain the catalytic hydrogen production electrode.

Ti on the surface of the catalytic Hydrogen production electrode obtained in this example₃C₂T_x-Pt_SAContact Angle test with Water, Ti as a control₃C₂T_x、Ti₃C₂T_x-N-Pt_SAAnd 20 wt% Pt/C. The contact angle test uses a surface interfacial tensiometer (DCAT21), and the curve of the contact angle test is analyzed by circular model fitting as shown in FIG. 10, from which it can be seen that Ti₃C₂T_xThe interfacial hydrophilicity of the base catalyst is stronger than that of Pt/C.

Carrying out hydrogen evolution reaction on the obtained catalytic hydrogen production electrode in a three-electrode system, wherein Ag/AgCl (saturated KCl solution) is used as a reference electrode, a graphite rod is used as a counter electrode, the prepared catalytic hydrogen production electrode is used as a working electrode, and electrolyte is 0.5M H₂SO₄0.5M H saturated with argon₂SO₄Measure electrocatalytic HER activity. The Ag/AgCl reference electrode was calibrated by a Reversible Hydrogen Electrode (RHE), E_RHE＝E_Ag/AgCl+0.0591 × pH + 0.197V. Wherein Ti₃C₂T_x-Pt_SA、Ti₃C₂T_x-N-Pt_SAAnd 20 wt.% Pt/C catalyst loading on L-GCE of 0.2857, 0.2857, and 0.5714mg cm, respectively^-2。

Mixing Ti₃C₂T_x、Ti₃C₂T_x-N-Pt_SA、Ti₃C₂T_x-Pt_SAAnd Pt/C at a scanning rate of 5mV s^-1Performing Linear Sweep Voltammetry (LSV) measurementsTest, as shown in FIG. 11, from which it can be seen that comparative sample Ti₃C₂T_xAnd Ti₃C₂T_x-N-Pt_SAThe overpotential of (a) is 241mV and 86mV, respectively, Ti₃C₂T_x-Pt_SAHas a low overpotential (38mV) comparable to Pt/C.

FIG. 12 shows Ti₃C₂T_x-Pt_SAComparison with the recently reported overpotentials for MXene-based and Pt-based catalysts illustrates Ti₃C₂T_x-Pt_SAThe catalyst has excellent catalytic performance.

FIG. 13 shows Ti₃C₂T_x、Ti₃C₂T_x-N-Pt_SA、Ti₃C₂T_x-Pt_SAAnd Tafel curves of Pt/C, from which it can be seen that Ti₃C₂T_x-Pt_SATafel slope of 45mV dec^-1Has fast Pt-like kinetics, close to commercial 20 wt% Pt/C (32mV dec)^-1) A value of (A) is much lower than that of Ti₃C₂T_x(135mV dec^-1) And Ti₃C₂T_x-N-Pt_SA(61mV dec^-1) The value of (A) also indicates Ti₃C₂T_x-Pt_SAThe catalyst is suitable for the Volmer-Heyrovsky mechanism, which is the rate limiting step in the hydrogen evolution process.

Mass activity is another commonly used evaluation criterion for characterizing catalyst performance, and Ti is given in FIG. 14₃C₂T_x-Pt_SA、Ti₃C₂T_x-N-Pt_SAAnd mass activity curves of Pt/C catalyst, from which it can be seen that Ti₃C₂T_x-Pt_SAMass activity ratio of catalyst Ti₃C₂T_x-N-Pt_SAAnd Pt/C catalysts are preferred. At an over potential of 0.1V, Ti₃C₂T_x-Pt_SAThe mass activity of the product can reach 23.21A mg_Pt ^–1Respectively is greater than Ti₃C₂T_x-N-Pt_SA(5.66A mg_Pt ^–1) And Pt/C (1.46A mg)_Pt ^–1) 4 times and 16 times higher.

The intrinsic activity of the catalyst is generally expressed in terms of conversion efficiency (TOF), and Ti is given in FIG. 15₃C₂T_x-Pt_SA、Ti₃C₂T_x-N-Pt_SAAnd conversion efficiency curve of Pt/C catalyst, from which it can be seen that at 0.1V, Ti₃C₂T_x-Pt_SAAnd Ti₃C₂T_x-N-Pt_SARespectively, of 23.45 and 5.62s^-1Far better than commercial 20 wt% Pt/C (1.48 s)^-1) Even beyond the latest electrocatalysts reported in the literature.

Mixing Ti₃C₂T_x-Pt_SAThe obtained catalytic hydrogen production electrode has the scanning speed of 50mV s^-1Cyclic Voltammetry (CV) measurements were performed over a potential window from 0.097 to-0.403V, repeatedly scanned for 1000 cycles, and then scanned at a rate of 5mV s^-1LSV testing was performed, as shown in FIG. 16, illustrating a single layer of Ti₃C₂T_xThe stability of the oxygen vacancy anchoring Pt monatomic catalyst is good.

Ti is given from the inset in FIG. 16₃C₂T_x-Pt_SACurrent-time curve of (a), further illustrating monolayer Ti₃C₂T_xThe stability of the oxygen vacancy anchoring Pt monatomic catalyst is good.

As can be seen from the above-mentioned test of catalytic performance of the electrode for catalytic hydrogen production, the Ti of the present invention is contained₃C₂T_xOxygen vacancy anchoring metal monoatomic material Ti₃C₂T_x-Pt_SAAnd Ti₃C₂T_x-N-Pt_SAAll show better catalytic performance and have great industrial practical value, which can be attributed to two aspects: one is the presence of a reducing gas (hydrogen or ammonia) to the Ti during the heat treatment₃C₂T_xReducing the oxygen-containing functional group to obtain an oxygen vacancy; second, metal monoatomic anchoring to Ti₃C₂T_xOn the oxygen vacancy, the hydrogen bonding energy and the hybrid strength can be reduced, and the reaction is promotedThe dynamic process of adsorption-desorption of hydrogen is carried out, thus greatly improving the catalytic performance.

By comparison of the catalytic properties, Ti can be seen₃C₂T_x-Pt_SAThe mass activity of the catalyst is superior to that of Ti₃C₂T_x-N-Pt_SAAnd Pt/C catalyst, as shown by density functional theory calculation, relative to Ti₃C₂T_xAnd Ti₃C₂T_x-N-Pt_SAHydrogen is selected as the product Ti of the reducing gas₃C₂T_x-Pt_SAThe medium Pt monoatomic group reduces the binding energy and the hybridization strength of hydrogen atoms and carriers, and further shows better catalytic performance, particularly shows low overpotential, high mass activity and high conversion efficiency, is about 16 times higher than that of a 20 wt.% Pt/C industrial catalyst, and shows great commercial practical value. Therefore, a more preferable embodiment of the present invention is to use hydrogen gas as the reducing gas in the heat treatment step.

Ti in the invention₃C₂T_xWhen the material with the oxygen vacancy anchoring single atom is used as a hydrogen production catalyst, the more the content of the anchoring metal single atom is, the more the active sites equivalent to catalysis are, the better the catalytic performance in the hydrogen evolution process is, and preferably, the Ti of the invention₃C₂T_xThe Pt monoatomic content at which oxygen vacancies can be anchored is 0.01 to 10 wt.%, more preferably, 0.8 to 2 wt.%.

By adopting the method of the invention, Ti can be obtained by changing experimental conditions₃C₂T_xIt is presumed that, when these metal elements exist in a monoatomic state, they also have a promoting effect on hydrogen evolution, and that, since these metal elements have a promoting effect on hydrogen evolution, and Ti is present in a monoatomic state₃C₂T_xThe material has abundant surface functional groups according toThe calculation of the first sex principle shows that Ti₃C₂T_xThe oxygen vacancy anchoring single-atom material has excellent catalytic performance in the field of electrocatalytic hydrogen production. Therefore, it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the inventive concept of the present invention, and these modifications and improvements are within the scope of the present invention.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims

1. Ti₃C₂T_xA method for producing an oxygen vacancy anchored monatomic material, comprising the steps of:

mixing: mixing raw material Ti₃C₂T_xMixing the material with a metal complex or a metal salt solution, and then freeze-drying to obtain a precursor;

a heat treatment step: heating the precursor to a predetermined temperature in an atmosphere containing a reducing gas to perform heat treatment to obtain the Ti₃C₂T_xOxygen vacancy anchoring single atom materials;

wherein the raw material Ti₃C₂T_xThe surface of the material has oxygen-containing functional groups; the heating rate of the heat treatment is between 40 ℃/min and 50 ℃/min.

2. The process according to claim 1, wherein the metal complex is selected from a carbonyl complex or an amino complex of a metal;

the metal salt is selected from chloride or nitrate of metal; preferably, the metal is selected from one or more of platinum, iron, cobalt, nickel, copper, zinc, gallium, germanium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tungsten, rhenium, iridium, gold, lead or bismuth.

3. The method of claim 1, wherein the predetermined temperature is between 400 ℃ and 500 ℃.

4. The method of claim 1, wherein the mixing step further comprises: the raw material Ti₃C₂T_xCarrying out ultrasonic treatment on the material and the metal complex or the solution of the metal salt under the conditions of argon and ice bath; and/or the presence of a gas in the gas,

the raw material Ti₃C₂T_xThe material passing MAX phase Ti₃AlC₂Etching the material in a mixed solution of hydrochloric acid and lithium fluoride to obtain the material; and/or the presence of a gas in the gas,

the raw material Ti₃C₂T_xThe material is a single-layer material, or the thickness is between 1nm and 2 nm.

5. The method of claim 1, wherein the atmosphere further comprises an inert gas; preferably, the volume fraction of the reducing gas is between 1% and 20%.

6. The method according to claim 1, wherein the reducing gas is hydrogen gas or ammonia gas.

7. The method according to any one of claims 1 to 6, wherein the Ti obtained is₃C₂T_xThe loading of the metal monoatomic species in the oxygen vacancy anchoring metal monoatomic material is 0.01 wt.% to 10 wt.%.

8. Ti produced by the production method according to any one of claims 1 to 7₃C₂T_xOxygen vacancy anchorA monoatomic material, wherein the monoatomic atom is one or more of platinum, iron, cobalt, nickel, copper, zinc, gallium, germanium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tungsten, rhenium, iridium, gold, lead, or bismuth atoms.

9. A catalytic hydrogen production apparatus comprising Ti obtained by the production method according to any one of claims 1 to 7₃C₂T_xThe oxygen vacancies anchor the monoatomic material.

10. Ti obtained by the production method according to any one of claims 1 to 7₃C₂T_xOxygen vacancy anchoring monatomic materials have applications in the fields of catalysis, sensors or batteries.