阅读说明：本技术 一种空心碳管复合材料及其制备方法与应用 (Hollow carbon tube composite material and preparation method and application thereof ) 是由 董红军 洪士欢 李春梅 宋宁 肖梦雅 朱达强 左延 于 2020-11-27 设计创作，主要内容包括：本发明属于材料制备技术领域,具体涉及一种空心碳管复合材料及其制备方法与应用。本发明采用高温煅烧法制备负载Co纳米粒子的空心碳管复合材料,原材料棉花经高温烧制后形成规则的空心碳管状形貌,具有独特的中空结构,具有较大的表面积,较强的传质能力。过渡金属Co比Pt便宜得多,Co对氢离子和含氧中间体均具有优异的吸附能力。所制备的空心碳管复合材料是一种OER和HER双功能高活性电催化剂,可以加速电解质在催化剂表面的渗透性,可用于电催化碱性环境全水解。在能源及环境领域有良好的应用前景。本发明工艺简单、操作方便、反应时间较短,降低能耗和生产成本,便于批量生产,无毒无害,符合环境友好要求。(The invention belongs to the technical field of material preparation, and particularly relates to a hollow carbon tube composite material, and a preparation method and application thereof. The invention adopts a high-temperature calcination method to prepare the hollow carbon tube composite material loaded with the Co nano particles, and the raw material cotton forms a regular hollow carbon tube-shaped appearance after being calcined at high temperature, has a unique hollow structure, and has larger surface area and stronger mass transfer capacity. The transition metal Co is much cheaper than Pt, and Co has excellent adsorption capacity to hydrogen ions and oxygen-containing intermediates. The prepared hollow carbon tube composite material is an OER and HER bifunctional high-activity electrocatalyst, can accelerate the permeability of electrolyte on the surface of the catalyst, and can be used for full hydrolysis in an electrocatalytic alkaline environment. Has good application prospect in the fields of energy and environment. The method has the advantages of simple process, convenient operation, short reaction time, reduced energy consumption and production cost, convenient batch production, no toxicity and harmlessness, and environmental friendliness.)

1. The hollow carbon tube composite Co/KF loaded with Co nano particles is characterized in that the Co/KF is of a hollow structure, and the Co nano particles are loaded on the outer wall of the hollow carbon tube.

2. A preparation method of hollow carbon tube composite Co/KF loaded with Co nano-particles is characterized in that,

the method comprises the following steps:

(1) adding cotton into NaClO₂In the solution, after magnetic stirring, refluxing the obtained suspension at a certain temperature, performing suction filtration, washing and drying to obtain hollow carbon tube cotton;

(2) immersing the hollow carbon tube cotton obtained in the step (1) into CoCl₂Soaking in the solution for a period of time, drying, and heating and calcining in a hydrogen-argon mixed gas to obtain the Co nanoparticle-loaded hollow carbon tube composite Co/KF.

3. Preparation according to claim 2The method is characterized in that NaClO is used in the step (1)₂The concentration of the solution is l-3 wt%.

4. The preparation method according to claim 2, wherein the certain temperature in the step (1) is 100 to 150 ℃, and the refluxing time is 3 to 5 hours.

5. The preparation method according to claim 2, wherein the drying temperature in the step (1) is 50-60 ℃, and the drying time is more than or equal to 8 h.

6. The method according to claim 2, wherein the CoCl is present in step (2)₂The concentration of the solution is 3-5 wt%, and the hollow carbon tube cotton and CoCl are₂The dosage ratio of the solution is 0.9 g: 10 to 21 ml.

7. The method according to claim 2, wherein the heating and calcining in step (2) is performed by heating from room temperature to 700-900 ℃ in a mixed gas of hydrogen and argon at a heating rate of 2-5 ℃ min "1 for 3-5 hours.

8. The hollow carbon tube composite Co/KF loaded with Co nanoparticles as claimed in claim 1 is applied in the field of total hydrolysis.

9. The hollow carbon tube composite Co/KF loaded with Co nanoparticles as claimed in claim 1 is applied to full hydrolysis in electrocatalytic alkaline environment.

Technical Field

The invention belongs to the technical field of material preparation, and particularly relates to a hollow carbon tube composite material, and a preparation method and application thereof.

Background

With the increasing global energy crisis, hydrogen energy has attracted attention due to its high energy density and clean, pollution-free characteristics. In the existing hydrogen production technology, water electrolysis is a carbon-free, high-purity and sustainable hydrogen production way. In recent years, non-noble metal catalysts have been used for Oxygen Evolution Reaction (OER) and Hydrogen Evolution Reaction (HER) in order to avoid the use of expensive and scarce noble metal catalysts (noble metals such as Pt, Ir, and Ru) for water electrolysis. However, the power consumption of the total hydrolysis is a bottleneck of about 1.8V, which is much higher than the theoretical value of 1.23V, and the efficiency of the non-noble metal catalyst is still very low. It is well known that the reason for affecting the sufficient water decomposition is caused by the slow anode OER and the rather easy cathode HER. Therefore, in order to practically apply the perhydrolysis process to hydrogen production, careful design of an OER and HER bifunctional electrocatalyst having high activity, excellent stability, low cost and easy synthesis is urgently required.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art.

The invention aims to provide a hollow carbon tube composite material loaded with Co nano particles, and a preparation method and application thereof. According to the invention, Co nano particles are loaded on the surface of the cotton which is fired at high temperature, so that the hollow carbon tube composite Co/KF with a unique hollow structure is formed. Is an OER and HER bifunctional high-activity electrocatalyst.

The invention provides a hollow carbon tube composite Co/KF loaded with Co nano particles, wherein the Co/KF is of a hollow structure, and the Co nano particles are loaded on the outer wall of the hollow carbon tube.

The invention also provides a preparation method of the hollow carbon tube composite Co/KF loaded with Co nano particles, which comprises the following steps:

(1) adding cotton into NaClO₂In the solution, after magnetic stirring, refluxing the obtained suspension at a certain temperature, performing suction filtration, washing and drying to obtain hollow carbon tube cotton;

(2) immersing the hollow carbon tube cotton obtained in the step (1) into CoCl₂In solutionAnd soaking for a period of time, drying, and heating and calcining in a hydrogen-argon mixed gas to obtain the Co nanoparticle-loaded hollow carbon tube composite Co/KF.

Further, NaClO is used in the step (1)₂The concentration of the solution is l-3 wt%.

The certain temperature in the step (1) is 100-150 ℃, and the refluxing time is 3-5 h.

The drying temperature in the step (1) is 50-60 ℃, and the drying time is more than or equal to 8 hours.

The CoCl in the step (2)₂The concentration of the solution is 3-5 wt%, and the hollow carbon tube cotton and CoCl are₂The dosage ratio of the solution is 0.9 g: 10 to 21 ml.

In the step (2), the heating and calcining are carried out in a hydrogen-argon mixed gas at the temperature of 2-5 ℃ for min^-1The temperature rising rate is that the mixture is heated from room temperature to 700-900 ℃ and calcined for 3-5 h.

The invention also provides the application of the hollow carbon tube composite Co/KF loaded with the Co nano particles in the field of total hydrolysis. Further, the application is full hydrolysis in an electrocatalytic alkaline environment.

Compared with the prior art, the invention has the beneficial effects that:

the Co nano particle loaded hollow carbon tube composite material is prepared by a high-temperature calcination method, and the raw material cotton is non-toxic, cheap and rich, and contains about 87-90% of cellulose and 5-8% of water. The cotton is fired at high temperature to form a regular hollow carbon tube shape, has a unique hollow structure, a larger surface area and stronger mass transfer capacity. The transition metal cobalt (Co) is much cheaper than Pt and has excellent adsorption capacity for both hydrogen ions and oxygen-containing intermediates. The prepared hollow carbon tube composite material is an OER and HER bifunctional high-activity electrocatalyst, can accelerate the permeability of electrolyte on the surface of the catalyst, and can be used for full hydrolysis in an electrocatalytic alkaline environment. Has good application prospect in the fields of energy and environment. The method has the advantages of simple process, convenient operation, short reaction time, reduced energy consumption and production cost, convenient batch production, no toxicity and harmlessness, and environmental friendliness.

Drawings

FIG. 1 is an XRD diffraction pattern of a Co/KF composite;

FIG. 2 is a field emission scanning electron microscope image of the prepared hollow carbon tube materials KF and Co/KF; wherein, (a) and (b) are hollow carbon tube material KF, and (c) and (d) are Co/KF;

FIG. 3 is a plot of linear sweep voltammograms LSV and Tafel for Co/KF, KF and Pt/C; in the figure, (a) is a linear sweep voltammogram comparison graph, and (b) is a tafel plot comparison graph;

FIG. 4 shows Co/KF, KF and RuO₂LSV and Tafel plots of linear sweep voltammograms of (a); in the figure, (a) is a linear sweep voltammogram comparison graph, and (b) is a tafel plot comparison graph;

FIG. 5 shows Co/KF, KF and Pt/C RuO₂The LSV and Tafel plots of total hydrolysis of (a) are linear sweep voltammograms versus (b) are Tafel plots.

Detailed Description

The present invention will be further described by the following examples, however, the scope of the present invention is not limited to the following examples. The present invention has been described generally and/or specifically with respect to materials used in testing and testing methods. The following examples are examples of experimental methods not indicating specific conditions, and the detection is usually carried out according to conventional conditions or according to the conditions recommended by the manufacturers.

Example 1: preparation of Co nano particle loaded hollow carbon tube composite Co/KF

(1) 150 ml of NaClO was added to 2.0 g of cotton (KF)₂(1 wt%) solution, after magnetically stirring for 10 minutes, refluxing the suspension at 120 ℃ for 4 hours to remove the wax protective layer attached to the surface of the cotton, then performing suction filtration separation, washing with distilled water for multiple times, and drying at 60 ℃ overnight to obtain the hollow carbon tube material KF.

(2) 0.9g of the hollow carbon tube material KF prepared in step (1) was dipped in 10 ml of CoCl₂(5 wt%) in the solution, the hollow carbon tube material KF completely absorbs CoCl₂Drying the solution at 60 deg.C overnight, placing in a tube furnace under hydrogen-argon mixed gas for 5 deg.C min^-1Heating rate of (2) from room temperature to 8Calcining for 4 hours at the temperature of 00 ℃ to obtain the final product Co/KF composite material.

And performing characterization analysis on the prepared product Co/KF. FIG. 1 is an XRD diffraction pattern of a Co/KF composite; as shown in fig. 1, Co nanoparticles were successfully loaded on the hollow carbon tube material KF. FIG. 2 is a field emission scanning electron microscope image of the prepared hollow carbon tube materials KF and Co/KF; wherein, (a) and (b) are hollow carbon tube material KF, and (c) and (d) are Co/KF; as shown in fig. 2, the prepared hollow carbon tube material KF has a regular carbon tube shape and a hollow structure, and the Co nanoparticles in the Co/KF material are loaded on the outer wall of the hollow carbon tube KF, so that the thickness of the carbon tube wall is reduced, and the hollow structure is still maintained.

Example 2: preparation of Co nano particle loaded hollow carbon tube composite Co/KF

(1) Adding 4.0 g cotton (KF) to 300 ml NaClO₂(2 wt%) solution, after magnetically stirring for 10 minutes, refluxing the suspension at 100 ℃ for 5 hours to remove the wax protective layer on the surface of the cotton, then performing suction filtration separation, washing with distilled water for multiple times, and drying at 50 ℃ for 12 hours to obtain the processed hollow carbon tube material KF.

(2) 0.9g of the hollow carbon tube material KF prepared in step (1) was dipped in 12ml of CoCl₂(5 wt%) in the solution, the hollow carbon tube material KF completely absorbs CoCl₂Drying the solution at 70 deg.C overnight, placing in a tube furnace under hydrogen-argon mixed gas for 2 deg.C min^-1The temperature is raised from room temperature to 900 ℃, and the final product Co/KF composite material is obtained after calcining for 3 h.

Example 3: preparation of Co nano particle loaded hollow carbon tube composite Co/KF

(1) 150 ml of NaClO was added to 2.0 g of cotton (KF)₂(3 wt%) solution, after magnetically stirring for 10 minutes, refluxing the suspension at 150 ℃ for 3 hours to remove the wax protective layer on the surface of the cotton, then performing suction filtration separation, washing with distilled water for multiple times, and drying overnight at 60 ℃ to obtain the processed hollow carbon tube material KF.

(2) 0.9g of the hollow carbon tube material KF prepared in step (1) was dipped in 21 ml of CoCl₂(3 wt%) in the solution, the hollow carbon tube material KF completely absorbs CoCl₂Solutions ofDrying at 60 deg.C overnight, placing in a tube furnace, and heating at 5 deg.C for min^-1The temperature is raised from room temperature to 700 ℃, and the final product Co/KF composite material is obtained after calcining for 5 hours.

Example 4: electrochemical characteristics of Co nano particle loaded hollow carbon tube composite Co/KF

5 mg of Co/KF prepared in example 1 was mixed with 40. mu.L of perfluorosulfonic acid (Nafion) and 960. mu.L of ethanol and ultrasonically dispersed to obtain an electrocatalyst mixture, and then 60. mu.L of the electrocatalyst mixture was applied to 2.5 mm by 2.5 mm carbon paper and dried to prepare a working electrode. And platinum sheet and Hg/HgO were used as counter and reference electrodes, respectively, as Pt/C, RuO in 1M KOH electrolyte, respectively, at room temperature₂、Pt/C||RuO₂Electrochemical testing was performed on a conventional three-electrode system.

FIG. 3 is a graph of LSV and Tafel linear sweep voltammograms for Co/KF, KF and Pt/C (currently the control ideal electrocatalytic hydrogen evolution catalyst, available from Maxin Biotechnology Ltd., China); in the figure, (a) is a linear sweep voltammogram versus (b) is a tafel plot versus. As can be seen from FIG. 3, the prepared Co nanoparticle-loaded hollow carbon tube composite material reaches 10 mA cm in Hydrogen Evolution Reaction (HER)^-2The working electrode only needs 100 mV of overpotential. Tafel curves for different catalysts, Tafel slope of Co/KF in HER test (37.0 mV dec) were measured^-1) Indicating its excellent HER kinetics.

FIG. 4 shows Co/KF, KF and RuO₂(ideal electrocatalytic oxygen evolution catalyst for comparison, available from mcelin biochemical technologies, ltd., china) linear sweep voltammogram LSV and Tafel plots; in the figure, (a) is a linear sweep voltammogram comparison graph, and (b) is a tafel plot comparison graph; as can be seen from FIG. 4, the prepared Co nanoparticle-loaded hollow carbon tube composite material reaches 10 mA cm in Oxygen Evolution Reaction (OER)^-2The working electrode only needs 158 mV of overpotential. Tafel slope of Co/KF in OER test (69.0 mV dec)^-1) Indicating its excellent OER kinetics.

FIG. 5 shows Co/KF, KF and Pt/C RuO₂(Pt/C andRuO₂ used as anode and cathode, respectively) LSV and Tafel plots of total hydrolysis; in the figure, (a) is a linear sweep voltammogram versus (b) is a tafel plot versus. As can be seen from FIG. 5, the alkaline electrolyzer was assembled using Co nanoparticles loaded hollow carbon tube composites as both anode and cathode, and was subjected to total hydrolysis in 1M KOH electrolyte, showing that the Co/KF system was at 10 mA cm^-2While providing a voltage of 1.540V, corresponding to a Tafel slope (138 mV dec)^-1) And is also smaller. Based on the facts, the Co nanoparticle-loaded hollow carbon tube composite Co/KF prepared by the invention is an effective water decomposition catalyst, has excellent OER and HER activities, and can be used for full hydrolysis in an electrocatalytic alkaline environment.

The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.