阅读说明：本技术 单原子催化剂及其制备方法和微电极及其制备方法和应用 (Monoatomic catalyst and preparation method thereof, microelectrode and preparation method and application thereof ) 是由 毛兰群 高小龙 马文杰 于萍 于 2021-08-06 设计创作，主要内容包括：本发明涉及一种单原子催化剂,包括石墨相氮化碳作为载体,以及负载于载体上的铜单原子作为活性组分；其中,所述活性组分在所述单原子催化剂中的原子百分含量为0.07-0.2％；所述石墨相氮化碳为mpg-C-(3)N-(4)。本发明还涉及一种微电极,包括电极、涂覆在电极表面的复合物层以及用于覆盖所述复合物层的聚合物层,其中,所述复合物层包含所述单原子催化剂或者所述单原子催化剂和碳材料的混合。本发明的单原子催化剂比表面积较大,活性组分含量较低,对过氧化氢的选择性高,稳定性好。本发明的微电极采用具有高选择性的单原子催化剂作为电催化剂,在该电极上实现了过氧化氢的精确检测,同时不受氧气及脑内其他多数物质的干扰。(The invention relates to a monatomic catalyst, which comprises graphite-phase carbon nitride as a carrier and copper monatomic as an active component, wherein the copper monatomic is loaded on the carrier; wherein the atom percentage content of the active component in the monatomic catalyst is 0.07-0.2%; the graphite phase carbon nitride is mpg-C 3 N 4 . The invention also relates to a microelectrode which comprises an electrode, a compound layer coated on the surface of the electrode and a polymer layer for covering the compound layer, wherein the compound layer contains the monatomic catalyst or the mixture of the monatomic catalyst and the carbon material. The monatomic catalyst of the invention has larger specific surface area and lower active component content,high selectivity to hydrogen peroxide and good stability. The microelectrode of the invention adopts the monatomic catalyst with high selectivity as the electrocatalyst, and the accurate detection of the hydrogen peroxide is realized on the microelectrode without being interfered by oxygen and other substances in the brain.)

1. A monatomic catalyst characterized by comprising graphite-phase carbon nitride as a carrier and a copper monatomic supported on the carrier as an active component;

wherein the atom percentage content of the active component in the monatomic catalyst is 0.07-0.2%;

the graphite phase carbon nitride is mpg-C₃N₄。

2. The monatomic catalyst of claim 1 wherein the active component is present in the monatomic catalyst at a concentration of 0.1-0.2 atomic percent.

3. The method for preparing a monatomic catalyst according to claim 1 or 2, which comprises:

preparing graphite phase carbon nitride dispersion liquid; the graphite phase carbon nitride is mpg-C₃N₄；

Adding a copper salt solution into the graphite-phase carbon nitride dispersion liquid, stirring, separating and drying to obtain a catalyst precursor; and

reacting said catalyst precursor in H₂Calcining in a mixed atmosphere of inert gas or in H₂Roasting in atmosphere, and cooling to obtain the monatomic catalyst.

4. The method of claim 3, wherein the mpg-C is₃N₄The preparation method comprises the following steps: uniformly mixing the precursor with silicon dioxide colloid, removing solvent, roasting, grinding, placing the obtained powder in etching liquid for etching, separating, washing and drying to obtain mpg-C₃N₄(ii) a The precursor comprises any one or more of the following: cyanamide, dicyandiamide, melamine and urea.

5. The method of claim 3, wherein the copper salt comprises any one or more of: nitrates, nitrites, acetates, sulfates, chlorides and bromides.

6. The production method according to claim 3, wherein the inert gas is argon, helium or nitrogen; h in the mixed atmosphere₂The content of (B) is preferably 5 to 10% by volume.

7. A micro-electrode comprising an electrode, a composite layer coated on a surface of the electrode, and a polymer layer for covering the composite layer, wherein the composite layer comprises a monoatomic catalyst according to claim 1 or 2 or a monoatomic catalyst obtained by the production method according to any one of claims 3 to 6, or a mixture of the monoatomic catalyst and a carbon material.

8. The microelectrode of claim 7, wherein the carbon material comprises carbon nanotubes, graphene, nitrogen-doped graphene and other electrically conductive carbon materials; the mass ratio of the monatomic catalyst to the carbon material is (0.5-5) to 1; the polymer layer is preferably a perfluorosulfonic acid resin; the electrode is preferably a carbon fiber electrode, a platinum microelectrode or a gold microelectrode.

9. The method for producing a microelectrode according to claim 7 or 8, comprising:

dispersing a monatomic catalyst and an optional carbon material in a solvent to obtain a dispersion liquid;

coating the electrode tip with the dispersion, followed by drying; and

and immersing the tip of the dried electrode into a polymer solution, taking out and drying to obtain the microelectrode.

10. Use of the microelectrode according to claim 7 or 8 or of the microelectrode obtained by the production method according to claim 9 for determining a hydrogen peroxide concentration, in particular in the brain.

Technical Field

The invention relates to the field of materials and electroanalytical chemistry, in particular to a monatomic catalyst, a preparation method thereof, a microelectrode containing the monatomic catalyst, a preparation method and application of the monatomic catalyst.

Background

In cerebral neurochemistry, H₂O₂As a Reactive Oxygen Species (ROS), it is generally considered a potential toxin because it can be converted into highly reactive OH radicals under certain conditions, thereby destroying structures of proteins, DNA, lipids, etc. In addition, hydrogen peroxide also plays an important role in signal transduction as a neuromodulator, and has received increasing attention in the study of brain cell function. Thus, high-spatial-temporal resolution in vivo hydrogen peroxide monitoring is of great significance in both physiological and pathological studies. Although there are many electrochemical techniques available to detect hydrogen peroxide by electrocatalytic hydrogen peroxide reduction (HPRR), in vivo analysis of hydrogen peroxide still has many problems. For example, conventional electrocatalysts represented by Pt are often subjected to O₂Etc., resulting in a catalyst that is not highly selective for hydrogen peroxide.

Therefore, it is urgently needed to develop a catalyst with high selectivity to meet the requirement of in-situ detection of hydrogen peroxide concentration in a living body.

Disclosure of Invention

The object of the present invention is to overcome the disadvantages of the prior art and to provide a monatomic catalyst which has a high selectivity for hydrogen peroxide.

The second object of the present invention is to provide a process for preparing the above monatomic catalyst.

It is a third object of the present invention to provide a micro-electrode comprising the above monatomic catalyst. The microelectrode can quantitatively measure the in vivo/in vitro hydrogen peroxide concentration, particularly the in-situ detection of the concentration of the hydrogen peroxide in the brain without being interfered by oxygen and other most substances in the brain. The microelectrode has high detection stability, good repeatability and good application prospect.

It is a fourth object of the present invention to provide a method for producing the above-mentioned micro-electrode.

In order to achieve the above object, the present invention provides the following technical solutions.

A single atom catalyst comprises graphite phase carbon nitride as a carrier and copper single atoms loaded on the carrier as an active component;

wherein the atom percentage content of the active component in the monatomic catalyst is 0.07-0.2%;

the graphite phase carbon nitride is mpg-C₃N₄。

Preferably, the atomic percentage of the active component in the monatomic catalyst is 0.1 to 0.2%.

The preparation method of the monatomic catalyst comprises

Preparing graphite phase carbon nitride dispersion liquid; the graphite phase carbon nitride is mpg-C₃N₄；

Adding a copper salt solution into the dispersion liquid, stirring, separating and drying to obtain a catalyst precursor; and

reacting said catalyst precursor in H₂Calcining in a mixed atmosphere of inert gas or in H₂Roasting in atmosphere, and cooling to obtain the monatomic catalyst.

Preferably, said mpg-C₃N₄Can be prepared by the following method: uniformly mixing the precursor with silicon dioxide colloid, removing solvent, roasting, grinding, placing the obtained powder in etching liquid for etching, separating, washing and drying to obtain mpg-C₃N₄. The precursor may comprise any one or more of: cyanamide, dicyandiamide, melamine and urea. Preferably, the solvent is removed by evaporation to dryness. The roasting step can comprise roasting for 2-6 hours at a temperature rise rate of 2-5 ℃/min to 500-650 ℃ in a certain atmosphere, wherein the atmosphere preferably comprises any one of the following: air, nitrogen, argon, helium. The etching liquid can comprise any one of the following components: hydrofluoric acid, ammonium hydrogen fluoride (NH)₄HF₂) Solution, sodium hydroxide solution and potassium hydroxide solution. Preferably, the etching time can be 8-48 h. The separation can be carried out by a conventional separation means such as centrifugation and filtration.

Preferably, the step of preparing the graphite phase carbon nitride dispersion liquid includes adding graphite phase carbon nitride into a solvent to be uniformly dispersed. The dispersion may be carried out using ultrasound, mechanical agitation or a combination thereof. The solvent can be one or more of water, methanol, ethanol, isopropanol, acetone, acetonitrile, dimethylformamide and dimethyl sulfoxide. The concentration of the graphite phase carbon nitride dispersion may be 1-10 mg/mL.

Preferably, the copper salt comprises any one or more of: nitrates, nitrites, acetates, sulfates, chlorides and bromides. The concentration of the copper salt solution may be 1-25 mg/mL.

Preferably, in the step of preparing the catalyst precursor, the stirring time may be 12 to 24 hours. The separation can be carried out by a conventional separation means such as centrifugation and filtration. Washing with water and ethanol is preferred. The drying temperature can be 60-100 deg.C, and the drying time can be more than 6 h.

Preferably, in the step of calcining the catalyst precursor, the catalyst precursor is preferably in H₂And inert gas, wherein the mixed atmosphere can be H and any one of argon, helium and nitrogen₂In a mixed atmosphere of H₂The content of (B) is preferably 5 to 10% by volume. The roasting temperature is 300-450 ℃, and the roasting time is 1-5 h. Preferably, the step of calcining the catalyst precursor comprises: reacting said catalyst precursor in H₂And inert gas at a temperature rise rate of 2-5 ℃/min to 300-400 ℃ for 2 hours.

The invention also provides a microelectrode which comprises an electrode, a compound layer coated on the surface of the electrode and a polymer layer for covering the compound layer, wherein the compound layer contains the monatomic catalyst or the monatomic catalyst and the carbon material.

Preferably, the carbon material can be Carbon Nano Tube (CNT), graphene, nitrogen-doped graphene and other conductive carbon materials, and the mass ratio of the single-atom catalyst to the carbon material is (0.5-5): 1. The polymer layer is preferably a perfluorosulfonic acid resin.

Preferably, the electrode is a carbon fiber electrode, a platinum microelectrode or a gold microelectrode.

In addition, the invention also provides a preparation method of the microelectrode, which comprises the following steps:

dispersing a monatomic catalyst and an optional carbon material in a solvent to obtain a dispersion liquid;

coating the electrode tip with the dispersion, followed by drying; and

and immersing the tip of the dried electrode into a polymer solution, taking out and drying to obtain the microelectrode.

Preferably, in the step of preparing the dispersion, the dispersion may be performed using ultrasonic waves, mechanical stirring, or a combination thereof. The solvent is a conventional solvent including, but not limited to, water, ethanol, acetone, N-dimethylformamide, and dimethylsulfoxide. Preferably, the concentration of the monatomic catalyst in the dispersion may be 0.5 to 5 mg/mL. In the case where carbon nanotubes are present in the dispersion, the concentration of the carbon nanotubes may be 0.5 to 5 mg/mL.

Preferably, the polymer solution is a perfluorosulfonic acid resin solution.

The above-mentioned microelectrode or the microelectrode prepared by the above-mentioned method can be used for measuring the hydrogen peroxide concentration, particularly in the brain.

The invention has the following beneficial effects:

1. the monatomic catalyst has the advantages of large specific surface area and low active component content, and the active components are distributed on the surface of the catalyst, so that the exposure of catalytic active sites is facilitated, the mass transfer of a solution, a reactant and a product is facilitated, and the catalytic performance is further improved. The monatomic catalyst provided by the invention has high selectivity and good stability to hydrogen peroxide.

2. The preparation method of the monatomic catalyst is simple to operate, easy to implement and suitable for large-scale industrial production.

3. The microelectrode of the invention adopts the monatomic catalyst with high selectivity as the electrocatalyst, and the accurate detection of the hydrogen peroxide is realized on the microelectrode without being interfered by oxygen and other substances in the brain.

The microelectrode adopts a monatomic catalyst material with high stability as an electrocatalyst, and the long-time stability of the microelectrode is utilized to realize the construction of a tolerant hydrogen peroxide sensor.

The microelectrode is coated on a carbon fiber electrode after uniformly mixing the carbon nanotube with high conductivity and the monatomic catalyst, so that the conductivity of an electrode material and the dispersibility of the catalyst material are improved, and the response current of the electrode and the sensitivity of hydrogen peroxide detection are improved.

The microelectrode can quantitatively measure the in vivo/in vitro hydrogen peroxide concentration, particularly the in-situ detection of the concentration of the hydrogen peroxide in brain, and has high stability and good repeatability. The microelectrode solves the problems that a hydrogen peroxide electrode is easily interfered by oxygen and other substances, has poor stability and the like in the aspect of chemical design, is expected to become a simple and accurate microsensor for measuring hydrogen peroxide, has important significance for researching the concentration change of the hydrogen peroxide in brain and related physiological and pathological processes, and has wide application prospect in the field of brain neurochemistry research.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 shows a monoatomic catalyst Cu according to example 1 of the present invention₁/mpg-C₃N₄A Scanning Electron Microscope (SEM) image of (a);

FIG. 2 shows a monoatomic catalyst Cu according to example 1 of the present invention₁/mpg-C₃N₄A Transmission Electron Microscope (TEM) image of (a);

FIG. 3A is a scanning electron micrograph of a carbon fiber electrode according to example 1 of the present invention;

FIG. 3B is a scanning electron microscope image of the carbon fiber electrode modified by the monatomic catalyst and the carbon nanotubes in example 1 of the present invention;

FIG. 4A is a current-time curve of a hydrogen peroxide selectivity experiment by the hydrogen peroxide microelectrode of example 2 of the present invention;

FIG. 4B is a histogram of the current response of the hydrogen peroxide microelectrode in example 2 of the present invention to a hydrogen peroxide selectivity test;

FIG. 5 is a current-time curve showing the long-term response of the hydrogen peroxide microelectrode of example 2 of the present invention to hydrogen peroxide;

FIG. 6A is the result of in-situ detection of exogenous hydrogen peroxide in brain by the hydrogen peroxide microelectrode of example 2 of the present invention;

FIG. 6B is the result of in-brain in-situ detection of hydrogen peroxide levels in vivo after dynamic drug regulation by the hydrogen peroxide microelectrode of example 2 of the present invention.

Detailed Description

In order to facilitate understanding of the present invention, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto. Reagents, equipment, or procedures not described herein are routinely determinable by one of ordinary skill in the art.

Example 1

Monoatomic catalyst Cu₁/mpg-C₃N₄The preparation of (1):

cyanamide (5g) andAS-40 silica gel (12.5g) was mixed and stirred until the suspension became transparent. The mixture was heated at 100 ℃ for several hours until the water evaporation was complete and a white solid formed. The white solid was then ground to a powder, transferred to a crucible, raised to 550 ℃ in air at a ramp rate of 2.3 ℃/min, and then treated at 550 ℃ for 4 h. After the temperature is reduced, 4mol/L NH is added into the obtained yellow powder₄HF₂The solution was stirred for 2 days. Then, the precipitate was centrifuged, and washed with distilled water and ethanol. The centrifuged yellow compound was dried overnight under vacuum at 120 ℃ to give mpg-C₃N₄。

Adding Cu (NO)₃)₂The solution (10mg/mL) was added mpg-C₃N₄The dispersion (4mg/mL) was stirred for about 24 hours and centrifuged to obtain Cu (NO)₃)₂/mpg-C₃N₄. Then theThe precipitate was washed several times with water and ethanol and finally dried under vacuum at 70 ℃. The prepared powder was transferred to a porcelain boat and the boat was placed in a tube furnace and then in a flowing 5% H₂Heating to 400 ℃ at a heating rate of 3 ℃/min in an Ar atmosphere, keeping for 2 hours, and naturally cooling to obtain the monoatomic catalyst Cu₁/mpg-C₃N₄The topography is shown in fig. 1 and 2. The obtained monatomic catalyst was in an amorphous state. The BET specific surface area of the obtained monatomic catalyst was determined to be 117.3434m by a nitrogen adsorption and desorption experiment²(ii) in terms of/g. The atomic percentage of copper monatomic in the monatomic catalyst obtained was 0.135 ± 0.037%, as determined by X-ray photoelectron spectroscopy.

Preparing a carbon fiber electrode:

the glass capillary (outer diameter 1.5mm, length 100mm) is placed on a microelectrode drawing device (WD-1, China Sichuan Chengdu instrument factory) and is drawn into two glass capillaries with the tip diameters of 30-50 mu m. A carbon fiber was attached to a copper wire, the copper wire was inserted into a drawn glass capillary, the capillary containing carbon fiber and copper wire was encapsulated with 1:1 epoxy and ethylene diamine, and dried at 100 ℃ for 2 hours. Before use, the exposed carbon fibers are cut to 200 to 500 μm under a microscope. The electrode was then electrochemically treated by first immersing the prepared carbon fiber electrode in 0.5M H₂SO₄In solution, at +2.0V Ampere method for 30 seconds, at-1.0V Ampere method for 10 seconds, then at 0 to 1.0V cyclic voltammetry treatment, scan rate of 0.1V/s, until a stable cyclic voltammogram is obtained. The above treatments were all carried out in a three-electrode system, with the working electrode being the fabricated carbon fiber electrode, the reference electrode being the Ag/AgCl electrode, and the counter electrode being the platinum wire electrode. The scanning electron micrograph of the resulting carbon fiber electrode is shown in fig. 3A.

Preparation of a hydrogen peroxide microelectrode:

first, 1mg/mL of Cu was prepared₁/mpg-C₃N₄And a CNT dispersion liquid sonicated to be uniformly dispersed. Mixing two kinds of dispersion liquid with equal volume, and performing ultrasonic treatment to obtain Cu₁/mpg-C₃N₄A CNT dispersion. Dropping the dispersion on a cover glassThe carbon fiber electrode tips were placed on top and rotated to coat the composite layer, and then dried under a baking lamp. The scanning electron microscope image of the carbon fiber electrode modified by the monatomic catalyst and the carbon nanotube is shown in fig. 3B. And (3) immersing the tip of the dried carbon fiber electrode into 0.5% Nafion solution, taking out after a few seconds, naturally airing, and repeating for a plurality of times to obtain the hydrogen peroxide microelectrode.

Example 2

In-situ measurement of Hydrogen peroxide concentration Using the micro-electrode obtained in example 1

1. To verify the selectivity of the microelectrode to hydrogen peroxide in vitro, the inventors compared the response of interfering substances commonly found in the brain on the electrodes. Referring to FIGS. 4A and 4B, a voltage of 0V is applied to the working electrode, and after the current is stabilized, an electrolyte (here, artificial cerebrospinal fluid, abbreviated as aCSF, having a composition of NaCl (126mmol/L), KCl (2.4mmol/L), KH is supplied to the electrolyte₂PO₄(0.5mmol/L)，MgCl₂(0.85mmol/L)，NaHCO₃(27.5mmol/L)，Na₂SO₄(0.5mmol/L)，CaCl₂(1.1mmol/L) for simulating cerebrospinal fluid environment, adding 10. mu. mol/L Dopamine (DA) solution, 10. mu. mol/L dihydroxyphenylacetic acid (DOPAC) solution, 10. mu. mol/L serotonin (5-HT) solution, 10. mu. mol/L Norepinephrine (NE) solution, 10. mu. mol/L Uric Acid (UA) solution, and 50. mu. mol/L oxygen (O)₂) Solutions, none of which produced a significant current response, were supplemented with 5. mu. mol/L hydrogen peroxide (H)₂O₂) After the solution, the current is remarkably increased, which shows that the electrode has good selectivity to hydrogen peroxide. To verify the stability of the in vitro microelectrodes, the inventors carried out experiments on the long-term response of hydrogen peroxide on the microelectrodes. Referring to fig. 5, a 5 μmol/L hydrogen peroxide solution was added to the electrolyte (aCSF), and a voltage of 0V was applied to the working electrode, and it was found that the response current of the electrode was substantially constant within 20000s, indicating that the electrode had high stability. In the amperometric determination process, a hydrogen peroxide microelectrode is used as a working electrode, a reference electrode is an Ag/AgCl electrode, and a counter electrode is a Pt electrode in a three-electrode system.

2. In order to prove that the obtained microelectrode was able to monitor hydrogen peroxide in a practical system, the electrode was usedThe detection is carried out in real time when the epizoon is placed in the brain of the ragmouse, and the brain area to be detected is the cortex brain area (the three-dimensional positioning: AP: -4.2mm, ML: -2.5mm and V: -1 mm). Referring to FIG. 6A, when 100. mu. mol/L hydrogen peroxide was microinjected, the current increased, confirming the response of the microelectrode to hydrogen peroxide in vivo. Referring to fig. 6B, upon microinjection of thiomalate (MCS), a drug that causes hydrogen peroxide accumulation in vivo, the electrode response current increases; whereas if glutathione ethyl ester (GSOEt, a glutathione precursor) is injected first, H can be inhibited₂O₂Horizontal), MCS was reinjected, and the response current was still increased, but the increase was significantly less than injecting only the same concentration of MCS.

From the above examples it is evident that the monatomic catalyst Cu used in the present invention₁/mpg-C₃N₄The carbon fiber electrode compositely modified with the CNT has good selectivity for accurately measuring hydrogen peroxide in vivo. The microelectrode solves the problems that a hydrogen peroxide electrode is easily interfered by oxygen and other substances, has poor stability and the like in the aspect of chemical design, is expected to become a simple and accurate microsensor for measuring hydrogen peroxide, has important significance for researching the concentration change of the hydrogen peroxide in brain and related physiological and pathological processes, and has wide application prospect in the field of brain neurochemistry research.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.