阅读说明：本技术 杂原子掺杂碳包覆金属双功能分解水纳米材料及其制备方法 (Heteroatom-doped carbon-coated metal bifunctional water decomposition nano material and preparation method thereof ) 是由 郑耿锋 况敏 于 2020-06-21 设计创作，主要内容包括：本发明属于纳米材料技术领域,具体为杂原子掺杂碳包覆金属双功能分解水纳米材料及其制备方法。本发明通过共沉淀法制备金属前驱体纳米材料；然后在该金属前驱体纳米材料表面生长金属有机骨架；最后通过限域热转换,制得杂原子掺杂碳包覆金属双功能分解水纳米材料。本发明利用金属有机骨架高的比表面积和孔隙结构来限制金属离子在高温热处理过程中的扩散过程,使金属离子均匀分布在杂原子掺杂的碳材料中；在热处理的过程中形成更多的金属-杂原子化合键,提高碳材料中杂原子的掺杂含量。本发明制备的材料结构规整有序、分散性好、比表面积大、导电性能优异、机械和化学稳定性好,本发明工艺简洁,成本低,安全可靠,便于规模化制备。(The invention belongs to the technical field of nano materials, and particularly relates to a heteroatom-doped carbon-coated metal bifunctional water decomposition nano material and a preparation method thereof. The invention prepares the metal precursor nanometer material by a coprecipitation method; then growing a metal organic framework on the surface of the metal precursor nano material; finally, preparing the heteroatom-doped carbon-coated metal bifunctional water decomposition nanometer material through limited-area thermal conversion. The invention utilizes the high specific surface area and the pore structure of the metal organic framework to limit the diffusion process of metal ions in the high-temperature heat treatment process, so that the metal ions are uniformly distributed in the heteroatom-doped carbon material; more metal-heteroatom chemical bonds are formed in the heat treatment process, and the doping content of heteroatoms in the carbon material is improved. The material prepared by the invention has the advantages of regular and ordered structure, good dispersibility, large specific surface area, excellent conductivity, good mechanical and chemical stability, simple process, low cost, safety, reliability and convenience for large-scale preparation.)

1. A preparation method of a heteroatom-doped carbon-coated metal bifunctional water decomposition nanometer material is characterized in that a metal precursor nanometer material is prepared by a coprecipitation method; then growing a metal organic framework on the surface of the metal precursor nano material; finally, preparing the heteroatom-doped carbon-coated metal bifunctional decomposed water nanometer material through limited-domain thermal conversion; the method comprises the following specific steps:

(1) preparation of Metal precursors

Adding metal salt and ethylene glycol into the aqueous solution, and carrying out ultrasonic stirring treatment for 1-200 min to obtain a solution I; adding an alkali solution into the solution I, centrifuging and removing a supernatant, wherein a lower-layer precipitate is a metal precursor;

(2) preparation of metal/metal organic framework composite material

Dissolving the metal precursor prepared in the step (1), metal salt and polyvinylpyrrolidone into an organic solution, and carrying out ultrasonic treatment for 1-200 min to obtain a dispersion liquid I; dissolving dimethyl imidazole in an organic solvent, and carrying out ultrasonic treatment for 1-200 min to obtain a dispersion liquid II; adding the dispersion liquid II into the dispersion liquid I, reacting for 0.1-72 h, centrifuging and removing supernatant, wherein the lower-layer precipitate is the metal/metal organic framework composite material;

the metal salt in the step (2) is different from the metal salt in the step (1);

(3) preparation of heteroatom doped carbon-coated metal nano material

And (3) heating the metal/metal organic framework composite material prepared in the step (2) to 600-1000 ℃ at a heating rate of 0.5-50 ℃/min, and carrying out heat treatment for 0.1-5 h in an inert atmosphere to prepare the heteroatom doped carbon coated bifunctional decomposition water nanometer material.

2. The preparation method according to claim 1, wherein the metal salt in step (1) is one or more of copper chloride, nickel chloride, cobalt chloride or ferric chloride.

3. The preparation method according to claim 1, wherein the mass ratio of the metal salt to the ethylene glycol in the step (1) is 1:1 to 1: 10; the volume ratio of the metal salt solution to the alkali solution is 1: 1-1: 10.

4. The method according to claim 1, wherein the metal salt in the step (2) is one of cobalt nitrate and zinc nitrate.

5. The preparation method according to claim 1, wherein the mass ratio of the metal precursor to the metal salt in the step (2) is 1:0.5 to 1: 10.

6. A heteroatom-doped carbon-coated metal bifunctional water splitting nano material obtained by the preparation method of any one of claims 1 to 6.

Technical Field

The invention belongs to the technical field of nano materials, and particularly relates to a heteroatom-doped carbon-coated metal bifunctional water decomposition nano material and a preparation method thereof.

Background

The heteroatom-doped carbon-coated metal nano material has the advantages that the metal and the doped carbon have strong synergistic effect, so that the properties of the material in the aspect of electricity can be greatly improved, and the material is widely concerned by people.

The existing preparation method of heteroatom doped carbon-coated metal nano material mainly comprises the following steps: the method comprises the following steps of (1) simply and mechanically mixing, namely mechanically mixing the existing metal particles and the heteroatom-doped carbon material by a simple ultrasonic mode or a stirring mode. The disadvantages are that: poor uniformity, easy agglomeration, small synergistic effect and the like. ② in-situ sintering, wherein metal salt and carbon-containing precursor are uniformly mixed, and then heteroatom-doped carbon-coated material is obtained by high-temperature sintering, but the control of material in nano-scale is lacked, and metal particles are not uniform. And thirdly, self-assembling, namely obtaining various heteroatom-doped carbon-coated metal materials by utilizing a surfactant, polymer macromolecule surface modification, electrostatic attraction and the like in a self-assembling mode. The disadvantages of this method are: the material has poor conductivity, and the bonding force between the metal particles and the heteroatom-doped carbon material is weak, so that the metal particles and the heteroatom-doped carbon material are easily separated, the service life of the material is shortened, and the material is not favorable for further practical application. Deposition method, depositing carbon layer on the surface of metal particle through chemical vapor deposition, physical vapor deposition and electric deposition. The method has the disadvantages of long time consumption, expensive instrument and equipment and difficult batch production.

Therefore, the heteroatom-doped carbon-coated metal nanomaterial with a uniform structure is prepared by a practical and effective method, and has very important theoretical and practical significance in both basic scientific research and technical application.

Disclosure of Invention

The invention aims to provide a heteroatom-doped carbon-coated metal bifunctional decomposition water nanomaterial and a preparation method thereof, aiming at the problems that the fine structure of the heteroatom-doped carbon-coated metal nanomaterial is lack of effective control and the bifunctional decomposition water property is poor in the existing method.

The invention utilizes a limited-area thermal conversion method to prepare the heteroatom-doped carbon-coated metal nano material with excellent properties of fully decomposing water to generate hydrogen and generating oxygen. The method has the advantages of convenient operation, easy control, mass production and the like; and the obtained heteroatom doped carbon-coated metal nano material has excellent performances of good structural stability, strong synergistic effect, good conductivity and the like, and can be used as a functional material to be applied to the technology of preparing hydrogen by using an industrial water electrolyzer.

The invention provides a preparation method of a heteroatom-doped carbon-coated metal bifunctional water decomposition nanometer material, which comprises the steps of preparing a metal precursor nanometer material by a coprecipitation method; then growing a metal organic framework on the surface of the metal precursor nano material; finally, preparing the heteroatom-doped carbon-coated metal bifunctional decomposed water nanometer material through limited-domain thermal conversion; the method comprises the following specific steps:

(1) preparation of Metal precursors

Adding metal salt and ethylene glycol into the aqueous solution, and carrying out ultrasonic stirring treatment for 1-200 min to obtain a solution I; adding an alkali solution into the solution I, centrifuging and removing a supernatant, wherein a lower-layer precipitate is a metal precursor;

(2) preparation of metal/metal organic framework composite material

Dissolving the metal precursor prepared in the step (1), metal salt and polyvinylpyrrolidone into an organic solution, and carrying out ultrasonic treatment for 1-200 min to obtain a dispersion liquid I; dissolving dimethyl imidazole in an organic solvent, and carrying out ultrasonic treatment for 1-200 min to obtain a dispersion liquid II; adding the dispersion liquid II into the dispersion liquid I, reacting for 0.1-72 h, centrifuging and removing supernatant, wherein the lower-layer precipitate is the metal/metal organic framework composite material;

(3) preparation of heteroatom doped carbon-coated metal nano material

Heating the metal/metal organic framework composite material prepared in the step (2) to 600-1000 ℃ at a heating rate of 0.5-50 ℃/min, and carrying out inert atmosphere (such as N)₂Ar) performing heat treatment for 0.1-5 h to obtain the heteroatom-doped carbon-coated bifunctional water decomposition nano material.

In the present invention, the metal salt in the step (1) is a metal salt different from the metal salt in the step (2).

In the invention, the metal salt in the step (1) is one or more of copper chloride, nickel chloride, cobalt chloride or ferric chloride.

In the invention, the mass ratio of the metal salt to the ethylene glycol in the step (1) is 1: 1-1: 10; the volume ratio of the metal salt solution to the alkali solution is 1: 1-1: 10.

In the invention, the metal salt in the step (2) is one of cobalt nitrate or zinc nitrate.

In the invention, the mass ratio of the metal precursor to the metal salt in the step (2) is 1: 0.5-1: 10; the mass ratio of the metal salt to the dimethyl imidazole is 1: 1-1: 10.

According to the heteroatom-doped carbon-coated metal nano material prepared by the invention, because the thermal decomposition properties of the metal precursor and the metal organic framework are completely different, metal ions are limited in the pore structure of the metal framework in the heat treatment process so as to prevent the metal ions from self-aggregating at a higher calcination temperature; meanwhile, the introduction of metal ions can further reserve the heteroatoms in the organic framework and improve the doping amount of the heteroatoms. The metal nano material has the characteristics of large specific surface area, good conductivity, controllable components, good mechanical stability and the like, can better realize the synergistic effect between metal particles and the heteroatom doped carbon material compared with simple mechanical mixing, and is more convenient for the heteroatom doped carbon coated metal nano material to realize functional application. For example, the method can be applied to the field of hydrogen preparation by decomposing water in an electrolytic bath.

The invention has the advantages that:

1. the method adopts the procedures of chemical coprecipitation, in-situ heat conversion and the like, has simple process and convenient operation, is beneficial to large-scale production and is convenient to popularize and apply;

2. the method is easy to regulate and control, and the components and the structure can be controlled by simply changing the proportion of adding the metal salt; therefore, the method can be widely applied to the preparation of various heteroatom doped carbon-coated metal nano materials;

3. the invention adopts cheap transition metal elements, has low cost and is easy to realize large-scale production.

Drawings

FIG. 1 shows Cu (OH) prepared in example 1₂Transmission Electron Microscopy (TEM) images of cobalt metal organic framework precursors.

Fig. 2 is a TEM image of the nitrogen-doped carbon-coated copper-cobalt nanomaterial prepared in example 1.

Fig. 3 is a graph of hydrogen evolution performance by decomposition of the nitrogen-doped carbon-coated copper-cobalt nanomaterial prepared in example 1.

Fig. 4 is a graph of water decomposition and oxygen generation performance of the nitrogen-doped carbon-coated copper cobalt particle nano-material prepared in example 1.

Detailed Description

The technical solution of the present invention is further described below with reference to the specific embodiments.