阅读说明：本技术 一种氮掺杂碳包裹的钨氧氮纳米线阵的制备方法 (Preparation method of nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array ) 是由 彭根英 于 2021-01-13 设计创作，主要内容包括：本发明公开了一种氮掺杂碳包裹的钨氧氮纳米线阵的制备方法,通过水热的方法在碳布合成了氧化钨的纳米线阵列,然后在二氰二胺的惰性氛围中高温热解氧化钨的纳米线阵列制备目标产物。本发明通过简单地调控分解温度以及二氰二胺的量控制碳层的厚度,保证在钨氧氮纳米线上均匀的包裹上碳层,同时预先搭建的纳米线阵列结构也能有效避免金属粒子的团聚。本发明制备的WON@NC NWs/CC,在全pH范围内,展现出了优异的化学活性,氮掺杂到碳外层中提高电极材料的导电性,从而加速传质效率。同时有效的减缓内核中的WON溶解。此外,氮元素掺杂到氧化钨结构中不仅能显著的调节钨原子的电子结构,还能进一步增强WON@NC NWs/CC的稳定性。(The invention discloses a preparation method of a nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array. According to the invention, the thickness of the carbon layer is controlled by simply regulating and controlling the decomposition temperature and the dicyanodiamine, so that the carbon layer is uniformly wrapped on the tungsten oxygen nitrogen nanowire, and meanwhile, the pre-built nanowire array structure can effectively avoid the agglomeration of metal particles. The WON @ NC NWs/CC prepared by the method shows excellent chemical activity in the full pH range, and nitrogen is doped into the carbon outer layer to improve the conductivity of the electrode material, so that the mass transfer efficiency is accelerated. And simultaneously, the WON dissolution in the kernel is effectively slowed down. In addition, nitrogen is doped into the tungsten oxide structure, so that the electronic structure of tungsten atoms can be remarkably adjusted, and the stability of WON @ NC NWs/CC can be further enhanced.)

1. A preparation method of a nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array is characterized by comprising the following steps: the method specifically comprises the following steps:

s1, firstly, preparing an oxide nanowire array on a carbon cloth (WO)₃NWs/CC), dissolving sodium tungstate dihydrate into ultrapure water, and after the sodium tungstate dihydrate is completely dissolved, continuously dropwise adding hydrochloric acid with a certain concentration to adjust the pH value to a certain value to obtain a solution;

s2, adding oxalic acid into the solution prepared in the step S1 while diluting the solution, and finally adding ammonium sulfate. Then transferring the solution into a reaction kettle, simultaneously putting a small piece of carbon cloth, putting the reaction kettle into an oven at 180 ℃ for reacting for 16h to obtain WO₃ NWs/CC；

S3, followed by WO₃Soaking NWs/CC in N, N-dimethylformamide solution containing dicyanodiamide and polyvinylpyrrolidone, taking out the mixture after the mixture is completely wetted, and placing the mixture in a tubular furnace containing dicyanodiamide;

s4, heating the mixture to the temperature of 10 ℃/min in a tube furnace, keeping the mixture for 2 hours, heating the mixture to the temperature of two at the heating speed of 5 ℃/min, and keeping the mixture for 2 hours;

s5, and finally, waiting for the tube furnace to cool naturally to obtain the nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array (WON @ NC NWs/CC).

2. The method for preparing the N-doped C-coated W-N nanowire array as claimed in claim 1, wherein the N-doped C-coated W-N nanowire array is prepared by the following steps: the certain concentration of the hydrochloric acid in the step S1 is 3 mol/L.

3. The method for preparing the N-doped C-coated W-N nanowire array as claimed in claim 1, wherein the N-doped C-coated W-N nanowire array is prepared by the following steps: the constant pH value in step S1 was 1.2.

4. The method for preparing the N-doped C-coated W-N nanowire array as claimed in claim 1, wherein the N-doped C-coated W-N nanowire array is prepared by the following steps: the first temperature in step S4 is 500 ℃.

5. The method for preparing the N-doped C-coated W-N nanowire array as claimed in claim 1, wherein the N-doped C-coated W-N nanowire array is prepared by the following steps: the second temperature in step S4 is 700 ℃.

Technical Field

The invention relates to the technical field of preparation of nano catalysts, in particular to a preparation method of a nitrogen-doped carbon-coated tungsten oxygen nitrogen nano-wire array.

Background

For a long time, tungsten-based nano materials are widely applied to catalyzing electrolysis of water to generate hydrogen. However, the activity of the tungsten-based nano material is not ideal, and researchers have been dedicated to solving the disadvantages of poor conductivity and poor corrosion resistance of the tungsten-based nano material in order to achieve higher catalytic efficiency. The carbon material encapsulation strategy can significantly slow the dissolution of the nanomaterial, for example, the Pt/C composite nanomaterial used commercially is the best evidence of the effectiveness of this strategy. In addition, the wettability and the conductivity of the carbon material can be further optimized by the hetero atom doping, so that the charge transfer speed of an electrode/electrolyte interface is increased, and the transfer of protons and electrons in the electrolytic water reaction process is improved. The Wangyong subject group coats glucosamine hydrochloride containing carbon and nitrogen on cobalt ions by a hydrothermal auxiliary method, and then obtains the nitrogen-doped carbon-coated cobalt and cobalt oxide composite material with high catalytic activity by high-temperature calcination. However, the hydrothermal assisted coating method may cause the problem of non-uniform carbon coating, so that cobalt particles are agglomerated due to insufficient carbon coating in the subsequent pyrolysis process or active cobalt sites cannot be exposed due to too thick carbon coating.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a preparation method of a nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array, which solves the problem of non-uniform carbon coating of a nitrogen-doped carbon-coated metal oxide composite material.

In order to achieve the purpose, the invention is realized by the following technical scheme: a preparation method of a nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array specifically comprises the following steps:

s1, firstly, preparing an oxide nanowire array on a carbon cloth (WO)₃NWs/CC), dissolving sodium tungstate dihydrate into ultrapure water, and after the sodium tungstate dihydrate is completely dissolved, continuously dropwise adding hydrochloric acid with a certain concentration to adjust the pH value to a certain value to obtain a solution;

s2, adding oxalic acid into the solution prepared in the step S1 while diluting the solution, and finally adding ammonium sulfate. Then transferring the solution into a reaction kettle, simultaneously putting a small piece of carbon cloth, putting the reaction kettle into an oven at 180 ℃ for reacting for 16h to obtain WO₃ NWs/CC；

S3, followed by WO₃Soaking NWs/CC in N, N-dimethylformamide solution containing dicyanodiamide and polyvinylpyrrolidone, taking out the mixture after the mixture is completely wetted, and placing the mixture in a tubular furnace containing dicyanodiamide;

s4, heating the mixture to the temperature of 10 ℃/min in a tube furnace, keeping the mixture for 2 hours, heating the mixture to the temperature of two at the heating speed of 5 ℃/min, and keeping the mixture for 2 hours;

s5, and finally, waiting for the tube furnace to cool naturally to obtain the nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array (WON @ NC NWs/CC).

Preferably, the certain concentration of the hydrochloric acid in the step S1 is 3 mol/L.

Preferably, the constant pH in step S1 is 1.2.

Preferably, the temperature in step S4 is 500 ℃.

Preferably, the second temperature in step S4 is 700 ℃.

Advantageous effects

The invention provides a preparation method of a nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array. Compared with the prior art, the method has the following beneficial effects: according to the preparation method of the nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array, a nanowire array of tungsten oxide is synthesized on carbon cloth through a hydrothermal method, and then the nanowire array of tungsten oxide is pyrolyzed at high temperature in an inert atmosphere of dicyanodiamine to prepare a target product. According to the invention, the thickness of the carbon layer is controlled by simply regulating and controlling the decomposition temperature and the dicyanodiamine, so that the carbon layer is uniformly wrapped on the tungsten oxygen nitrogen nanowire, and meanwhile, the pre-built nanowire array structure can effectively avoid the agglomeration of metal particles. The WON @ NC NWs/CC prepared by the method shows excellent chemical activity in the full pH range, and nitrogen is doped into the carbon outer layer to improve the conductivity of the electrode material, so that the mass transfer efficiency is accelerated. And simultaneously, the WON dissolution in the kernel is effectively slowed down. In addition, nitrogen is doped into the tungsten oxide structure, so that the electronic structure of tungsten atoms can be remarkably adjusted, and the stability of WON @ NC NWs/CC can be further enhanced.

Drawings

FIG. 1 is a scanning electron microscope image at different magnifications of WON @ NC NWs/CC of the present invention;

FIG. 2 shows WO of the present invention₃X-ray diffraction patterns of NWs/CC and WON @ NC NWs/CC;

FIG. 3 shows (A) a high resolution transmission electron micrograph and (B) a selected area diffraction pattern of WON @ NC NWs/CC according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, the embodiment of the present invention provides three technical solutions: a preparation method of a nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array specifically comprises the following steps:

example 1

S1, firstly, preparing an oxide nanowire array on a carbon cloth (WO)₃NWs/CC), dissolving 2mmol of sodium tungstate dihydrate in 18ml of ultrapure water, and after the sodium tungstate dihydrate is completely dissolved, continuously dropwise adding 3mol/L hydrochloric acid to adjust the pH value to 1.2 to obtain a solution;

s2, then adding 6mmol oxalic acid into the solution prepared in the step S1 while diluting the solution to 45ml, and finally adding 2g ammonium sulfate. Then transferring the solution into a reaction kettle, simultaneously putting a small piece of carbon cloth, putting the reaction kettle into an oven at 180 ℃ for reacting for 16h to obtain WO₃ NWs/CC；

S3, followed by WO₃NWs/CC was immersed in a solution of N, N-dimethylformamide containing 1.8g of dicyanodiamide and 0.2g of polyvinylpyrrolidone, and after the mixture was completely wetted, it was taken out and placed in a tube furnace containing 1.8g of dicyanodiamide;

s4, heating to 500 ℃ at a speed of 10 ℃/min in a tube furnace, keeping for 2h, heating to 700 ℃ at a speed of 5 ℃/min, and keeping for 2 h;

s5, and finally, waiting for the tube furnace to cool naturally to obtain the nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array (WON @ NC NWs/CC).

Example 2

S1, firstly, preparing an oxide nanowire array on a carbon cloth (WO)₃NWs/CC), dissolving 3mmol of sodium tungstate dihydrate in 25ml of ultrapure water, and after the sodium tungstate dihydrate is completely dissolved, continuously dropwise adding 3mol/L hydrochloric acid to adjust the pH value to 1.2 to obtain a solution;

s2, adding 8mmol oxalic acid into the solution prepared in the step S1 while diluting the solution to 60ml, and adding 3g ammonium sulfate. Then transferring the solution into a reaction kettle, simultaneously putting a small piece of carbon cloth, putting the reaction kettle into an oven at 180 ℃ for reacting for 16h to obtain WO₃ NWs/CC；

S3, followed by WO₃NWs/CC is immersed in a solution of N, N-dimethylformamide containing 3g of dicyanodiamide and 0.3g of polyvinylpyrrolidone, and after the mixture is completely wetted, the mixture is taken out and placed in a tube furnace containing 3g of dicyanodiamide;

s4, heating to 500 ℃ at a speed of 10 ℃/min in a tube furnace, keeping for 2h, heating to 700 ℃ at a speed of 5 ℃/min, and keeping for 2 h;

s5, and finally, waiting for the tube furnace to cool naturally to obtain the nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array (WON @ NC NWs/CC).

Example 3

S1, firstly, preparing an oxide nanowire array on a carbon cloth (WO)₃NWs/CC), dissolving 4mmol of sodium tungstate dihydrate in 30ml of ultrapure water, and after the sodium tungstate dihydrate is completely dissolved, continuously dropwise adding 3mol/L hydrochloric acid to adjust the pH value to 1.2 to obtain a solution;

s2, adding 10mmol oxalic acid into the solution prepared in the step S1 while diluting the solution to 70ml, and adding 4g ammonium sulfate. Then transferring the solution into a reaction kettle, simultaneously putting a small piece of carbon cloth, putting the reaction kettle into an oven at 180 ℃ for reacting for 16h to obtain WO₃ NWs/CC；

S3, followed by WO₃NWs/CC is immersed in a N, N-dimethylformamide solution containing 4g of dicyanodiamide and 0.5g of polyvinylpyrrolidone, and after the mixture is completely wetted, the mixture is taken out and placed in a tube furnace containing 4g of dicyanodiamide;

s4, heating to 500 ℃ at a speed of 10 ℃/min in a tube furnace, keeping for 2h, heating to 700 ℃ at a speed of 5 ℃/min, and keeping for 2 h;

s5, and finally, waiting for the tube furnace to cool naturally to obtain the nitrogen-doped carbon-coated tungsten oxygen nitrogen nanowire array (WON @ NC NWs/CC).

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.