阅读说明：本技术 一种新型氮掺杂碳负载铜掺杂磷化钴双层空心纳米粒子复合阵列材料及其制备方法 (Novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material and preparation method thereof ) 是由 黄海根 李映伟 沈葵 房瑞琪 于 2020-04-23 设计创作，主要内容包括：本发明公开了一种新型氮掺杂碳负载铜掺杂磷化钴双层空心纳米粒子复合阵列材料及其制备方法。该方法包括：以商业碳布作为自支撑模板导向剂,先在商业碳布模板表面定向生长铜掺杂的ZIFs前驱体,将含有前躯体的商业碳布模板在氩气气氛下高温热解,在相对较低的温度下氧化,磷化后得具有多孔结构的氮掺杂碳负载铜掺杂磷化钴双层空心纳米粒子复合阵列材料。该氮掺杂碳负载铜掺杂磷化钴空心纳米粒子复合阵列材料保留了ZIFs的基本骨架,其结构含有丰富规整的介孔和微孔,负载的铜掺杂磷化钴纳米颗粒具有开放性的双层空心结构。本发明的方法简单安全,所得产品纯度高,结构完整,机械强度好,适用于做电催化反应(析氢反应和析氧反应)的催化剂。(The invention discloses a novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material and a preparation method thereof. The method comprises the following steps: the method comprises the steps of taking commercial carbon cloth as a self-supporting template guiding agent, growing a copper-doped ZIFs precursor on the surface of a commercial carbon cloth template in a directional mode, pyrolyzing the commercial carbon cloth template containing the precursor at a high temperature in an argon atmosphere, oxidizing at a relatively low temperature, and phosphorizing to obtain the nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material with a porous structure. The nitrogen-doped carbon-loaded copper-doped cobalt phosphide hollow nanoparticle composite array material reserves the basic skeleton of ZIFs, the structure of the composite array material contains rich and regular mesopores and micropores, and the loaded copper-doped cobalt phosphide nanoparticles have an open double-layer hollow structure. The method of the invention is simple and safe, and the obtained product has high purity, complete structure and good mechanical strength, and is suitable for being used as a catalyst for electrocatalytic reactions (hydrogen evolution reaction and oxygen evolution reaction).)

1. A preparation method of a novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material is characterized by comprising the following steps:

(1) adding a metal precursor into water, and uniformly mixing to obtain a metal precursor solution;

(2) adding the ligand into water, and uniformly mixing to obtain a ligand solution;

(3) uniformly mixing the metal precursor solution and the ligand solution to obtain a mixed solution;

(4) soaking the commercial carbon cloth in an acid solution, taking out, washing and drying to obtain the pretreated commercial carbon cloth;

(5) soaking the pretreated commercial carbon cloth in the step (4) in the mixed solution in the step (3), taking out, washing, drying, and then heating in an argon atmosphere to perform high-temperature pyrolysis treatment to obtain a composite array material;

(6) heating the composite array material obtained in the step (5) for oxidation treatment to obtain an oxidized composite array material; mixing the oxidized composite array material with sodium hypophosphite to obtain a mixture; and heating the mixture in an argon atmosphere to carry out phosphating treatment to obtain the novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material.

2. The preparation method of the novel nitrogen-doped carbon-supported copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material according to claim 1, wherein the metal precursor in the step (1) is one of cobalt nitrate hexahydrate and copper nitrate trihydrate; the mass ratio of the metal precursor to water is 1: (30-120).

3. The preparation method of the novel nitrogen-doped carbon-supported copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material according to claim 1, wherein the mass ratio of the ligand in the step (2) to the metal precursor in the step (1) is (4.5-9): 1.

4. The preparation method of the novel nitrogen-doped carbon-supported copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material according to claim 1, wherein the ligand in the step (2) is 2-methylimidazole; the mass ratio of the ligand to the water is 1: (15-60).

5. The preparation method of the novel nitrogen-doped carbon-supported copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material according to claim 1, wherein the acidic solution in the step (4) is a mixture of concentrated sulfuric acid and concentrated nitric acid; the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is 1: 3.

6. The preparation method of the novel nitrogen-doped carbon-supported copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material as claimed in claim 1, wherein in the step (5), the time for soaking the pretreated commercial carbon cloth in the mixed solution is 2-8 hours.

7. The method for preparing the novel nitrogen-doped carbon-supported copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material as claimed in claim 1, wherein the temperature of the high-temperature pyrolysis treatment in the step (5) is 600-900 ℃, and the time of the high-temperature pyrolysis treatment is 1-5 h.

8. The preparation method of the novel nitrogen-doped carbon-supported copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material according to claim 1, wherein the temperature of the oxidation treatment in the step (6) is 250 ℃, and the time of the oxidation treatment is 0.5-2.5 h.

9. The preparation method of the novel nitrogen-doped carbon-supported copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material according to claim 1, wherein the mass ratio of the composite array material subjected to oxidation treatment in the step (6) to sodium hypophosphite is (20-50): 1; the temperature of the phosphating treatment is 300 ℃, and the time of the phosphating treatment is 0.5-3 h.

10. A novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material prepared by the preparation method of any one of claims 1-9.

Technical Field

The invention relates to the field of preparation of MOFs derived materials, in particular to a novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material and a preparation method thereof.

Background

ZIFs are MOFs materials of molecular sieve topological structures formed by self-assembly of 2-methylimidazole containing nitrogen groups and transition metal ions, the nitrogen content in a framework organic matter of the MOFs materials reaches 3-4 wt%, in addition, the ZIFs are used as precursors, the high-nitrogen-doped porous carbon materials can be prepared, due to good designability in the aspect of structures of the porous carbon materials, appropriate second metal elements can be introduced in the crystallization process of the porous carbon materials, the second metal elements, main body metals and ligands form a framework of the ZIFs, part of metal node positions are occupied, simple physical or chemical adsorption is not needed, and uniform dispersion of doped metals is facilitated to be introduced. The metal doped material can be further obtained through post-treatment, so that new defect sites are created, and active sites and the like are added (L.Yang, X.Zeng, W.Wang, D.Cao,. adv.Funct.Mater.2018,28,1704537; T.Liu, P.Li, N.Yao, T.G.Kong, G.Z.Cheng, S.L.Chen, W.Luo, Adv.Mater.2019, 1806672). However, although the varieties of ZIFs derived materials are numerous and exhibit excellent performance in many practical applications, most of the currently reported nanoparticles loaded with ZIFs derived materials have a closed solid structure, which is not favorable for forming a large amount of open structures, so that the number of exposed active sites is small, and internal atoms are wasted. This closed structure provides a relatively small reactive interface for HER and OER, which is detrimental to the timely diffusion of the generated gases and ions (a.aijaz, j.masa, C).Xia, P.Weide, A.J.R.Botz, R.A.Fischer, W.Schuhmann, M.Muhler, Angew.chem.int.Ed.2016,55, 4087-. In addition, most of the currently reported ZIFs-derived materials have single active sites and single functions (Y.Pan, K.Sun, S.Liu, X.Cao, K.Wu, W.C.Cheng, Z.Chen, Y.Wang, Y.Li, Y.Q.liu, D.S.Wang, Q.Peng, C.Chen, Y.D.Li, J.Am.chem.Soc. 2018,140, 2610-2618). Therefore, the novel hierarchical structure ZIFs-derived nitrogen-doped carbon-loaded hollow nanoparticle composite material suitable for electrocatalysis is prepared, so that the composite material has the characteristics superior to other MOFs-derived composite materials with single pore structures in the aspects of diffusion, mass transfer and the like, and the preparation method is a great problem faced by material workers. This is also a higher demand for social development demands in the field of MOFs-derived composites.

At present, many cobalt-based electrocatalysts reported at present have irregular pore channels or too small pore diameters, serious agglomeration of active components, less exposure of active sites, no access of electrolyte and poor mass transfer effect, so that the actual usable specific surface area is lower than the actual specific surface area of a material, and the conductivity of the catalyst is poor. In view of the problems and limitations presented by cobalt-based electrocatalysts, currently high performance cobalt-based electrocatalysts are mainly studied around two aspects: 1) optimizing the choice of carrier to create more active sites, increase the utilization of active centers and increase the conductivity of the catalyst itself (a. sivanantham, p. ganesan, l. estevez, b.p. mcgrail, r.k. motkuri, s.shanmugam, adv. energy mater.2018,8,1870065.); 2) multiple active sites with synergistic effect are formed by proper heteroatom doping, mainly including non-metal elements such as N, P, S and the like or proper metal element doping, so that the electronic configuration of the catalytic material and the electronic environment around the active sites and other aspects are adjusted and optimized, and the catalytic activity and stability of the material can be improved through reasonable material design (J.H.Song, C.Z.Zhu, B.Z.Xu, S.F.Fu, M.H.Engelhard, R.F.Ye, D.Du, S.P.Beckman, Y.H.Lin, adv.Energy Mater.2017,7,1601555; y.p.zhu, h.c.chen, c.s.hsu, t.s.lin, c.chang, s.c. Chang, l.d.tsai, h.m.chen, ACS Energy lett.2019,4,987-99.). However, all the reported methods cannot prepare a composite array material with a hierarchical pore structure and doping properties, and it is difficult to obtain a loaded nanoparticle with a double-layer hollow structure. Obviously, in order to further improve the application potential of the existing ZIFs-derived composite materials in many applications, the above bottleneck problems must be overcome, and a new route for preparing a novel multilevel structure nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material is provided.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material and a preparation method thereof.

The invention aims to overcome the defects of the existing ZIFs derivative material electrocatalyst, and provides a novel multilevel structure nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material derived from a copper-doped ZIFs array by directionally growing a commercial carbon cloth serving as a template and a method thereof.

The purpose of the invention is realized by at least one of the following technical solutions.

The invention provides a preparation method of a novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material, which comprises the following steps:

(1) adding a metal precursor into water, and uniformly mixing to obtain a metal precursor solution;

(2) adding the ligand into water, and uniformly mixing to obtain a ligand solution;

(3) uniformly mixing the metal precursor solution and the ligand solution to obtain a mixed solution;

(4) soaking the commercial carbon cloth in an acid solution, taking out, washing and drying to obtain the pretreated commercial carbon cloth;

(5) soaking the pretreated commercial carbon cloth in the step (4) in the mixed solution in the step (3) (standing at normal temperature, then crystallizing ZIFs and directionally growing on a self-supporting template commercial carbon cloth to prepare a leaf-shaped copper-doped ZIFs array material which is arranged on the commercial carbon cloth in order), taking out, washing, drying, heating in an argon atmosphere for high-temperature pyrolysis treatment to obtain a composite array material (the leaf-shaped ZIFs array-derived nitrogen-doped porous carbon loaded copper-doped metal cobalt nanoparticles composite array material which is arranged on the commercial carbon cloth in order);

(6) heating the composite array material obtained in the step (5) to carry out oxidation treatment (air atmosphere) to obtain an oxidized composite array material (the composite array material contains nitrogen-doped porous carbon loaded copper-doped cobaltosic oxide nanoparticles derived from leaf-shaped ZIFs arrays arranged on commercial carbon cloth); mixing the oxidized composite array material with sodium hypophosphite to obtain a mixture; and heating the mixture in an argon atmosphere to carry out phosphating treatment, thus obtaining the novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material (leaf-shaped ZIFs array-derived nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material containing regular commercial carbon cloth).

Further, the metal precursor in the step (1) is one of cobalt nitrate hexahydrate and copper nitrate trihydrate; the mass ratio of the metal precursor to the water is 1: (30-120).

Preferably, in the metal precursor in the step (1), the molar ratio of copper to cobalt is (0.05-0.2): 1.

preferably, the water in step (1) and step (2) is deionized water.

Further, the ligand in the step (2) is 2-methylimidazole; the mass ratio of the ligand to the water is 1: (15-60).

Preferably, the mass ratio of the ligand in the step (2) to the metal precursor in the step (1) is (4.5-9): 1.

Further, the acid solution in the step (4) is a mixture of concentrated sulfuric acid and concentrated nitric acid; the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is 1: 3.

Preferably, in the step (5), the pre-treated commercial carbon cloth is soaked in the mixed solution for 2 to 8 hours.

Further, the temperature of the high-temperature pyrolysis treatment in the step (5) is 600-900 ℃, and the time of the high-temperature pyrolysis treatment is 1-5 h.

Further, the temperature of the oxidation treatment in the step (6) is 250 ℃, and the time of the oxidation treatment is 0.5-2.5 h.

Preferably, the atmosphere of the oxidation treatment in the step (6) is an air atmosphere.

Further, the mass ratio of the composite array material subjected to oxidation treatment in the step (6) to the sodium hypophosphite is (20-80): 1; the temperature of the phosphating treatment is 300 ℃, and the time of the phosphating treatment is 0.5-3 h.

The invention provides a novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material prepared by the preparation method.

The nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material with the multilevel structure prepared by the preparation method keeps the basic skeleton of a copper-doped ZIFs array precursor with high quality and orderly arrangement, and the loaded nanoparticles have a double-layer hollow structure.

The preparation method provided by the invention takes commercial carbon cloth as a self-supporting template guiding agent, and the nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material with a porous structure can be obtained by directionally growing a precursor of copper-doped Zeolitic Imide Frameworks (ZIFs) on the surface of the commercial carbon cloth template, then pyrolyzing the commercial carbon cloth template containing the precursor at high temperature in an argon atmosphere, then oxidizing at relatively low temperature, and finally further phosphorizing.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material provided by the invention has a high specific surface area and a rich porous structure, and has a porous structure with a micropore-mesoporous carbon shell as a core, compared with the traditional carbon-based material, the rich mesopores can improve the reactant transmission efficiency, and the micropores are favorable for reaction ion adsorption and accumulation;

(2) the novel nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material provided by the invention has the structural advantages and the synergistic effect: the copper-doped hollow cobalt phosphide nano-particles are beneficial to forming a large number of open structures, so that more active sites are exposed, and the waste of internal atoms is avoided. This open structure provides a large reactive interface for HER and OER and facilitates the diffusion of the generated gases and ions in time. In addition, due to the synergistic effect, the copper-doped cobalt phosphide active site has better electrocatalytic performance than that of a single metal species active site;

(3) the preparation method provided by the invention has the advantages of simple preparation process, safety, controllability, less time consumption and energy consumption, and most importantly, the prepared multistage-structure nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticles have excellent catalytic performance on electrocatalytic reaction, and the catalytic activity of the prepared multistage-structure nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticles is far higher than that of a ZIF-67 derived composite material prepared by a traditional method when the multistage-structure nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticles.

Drawings

FIG. 1 is a scanning electron microscope photograph, a transmission electron microscope photograph and a partial transmission electron microscope photograph of a nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material prepared in example 5 of the present invention;

fig. 2 is a scanning electron microscope photograph, an XRD diffraction pattern, a transmission electron microscope photograph and a partial transmission electron microscope photograph of the nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material prepared in example 8 of the present invention;

fig. 3 is a scanning electron microscope photograph, a transmission electron microscope photograph and a partial transmission electron microscope photograph of the nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material prepared in example 10 of the present invention;

fig. 4 is a scanning electron microscope photograph, a transmission electron microscope photograph and a partial transmission electron microscope photograph of the nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material prepared in example 12 of the present invention;

FIG. 5 is a scanning electron micrograph, a transmission electron micrograph and a partial transmission electron micrograph of the nitrogen-doped carbon-loaded copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material prepared in example 14 of the present invention;

FIG. 6 is a scanning electron microscope photograph of a nitrogen-doped carbon-supported copper-doped cobalt phosphide double-layer hollow nanoparticle composite array material prepared in example 16 of the present invention; transmission electron micrographs and partial transmission electron micrographs.

Detailed Description

The following examples are presented to further illustrate the practice of the invention, but the practice and protection of the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art. The reagents or apparatus used are not indicated to the manufacturer, and are considered to be conventional products available by commercial purchase.