阅读说明：本技术 一种还原氧化石墨烯负载的二维珊瑚片状钯纳米催化剂及其制备方法 (Reduced graphene oxide loaded two-dimensional coral sheet-shaped palladium nano-catalyst and preparation method thereof ) 是由 白雪峰 崔泽琳 吕宏飞 徐虹 刘洋 于 2020-06-05 设计创作，主要内容包括：本发明涉及一种还原氧化石墨烯负载的二维珊瑚片状钯纳米催化剂及其制备方法,属于催化剂及其制备领域。为解决现有钯催化剂催化活性低,制备过程较为复杂的问题,本发明提供了一种还原氧化石墨烯负载的二维珊瑚片状钯纳米催化剂,其为二维珊瑚片状形貌的颗粒,存在枝状孔道结构,粒径为30～100nm,钯负载量为20～40wt％。其制备方法为：将一定质量摩尔比的氧化石墨烯载体、CTAB溶液、AA溶液和钯前驱体溶液混合,通过超声处理使其进行还原反应,对溶液进行离心干燥处理。该钯纳米催化剂的制备方法简单,且该催化剂为二维珊瑚片状结构,存在枝状孔道结构,为反应提供了更多的活性位点,在氧还原反应中具有更高的催化活性。(The invention relates to a reduced graphene oxide loaded two-dimensional coral sheet-shaped palladium nano-catalyst and a preparation method thereof, belonging to the field of catalysts and preparation thereof. In order to solve the problems of low catalytic activity and complex preparation process of the existing palladium catalyst, the invention provides a two-dimensional coral sheet-shaped palladium nano-catalyst loaded by reduced graphene oxide, which is particles with two-dimensional coral sheet-shaped appearance and has a dendritic pore structure, the particle size is 30-100 nm, and the palladium loading amount is 20-40 wt%. The preparation method comprises the following steps: mixing a graphene oxide carrier, a CTAB solution, an AA solution and a palladium precursor solution in a certain mass molar ratio, performing reduction reaction by ultrasonic treatment, and performing centrifugal drying treatment on the solution. The preparation method of the palladium nano catalyst is simple, the catalyst is of a two-dimensional coral sheet structure, and has a dendritic pore structure, so that more active sites are provided for the reaction, and the catalyst has higher catalytic activity in the oxygen reduction reaction.)

1. The reduced graphene oxide loaded two-dimensional coral sheet-shaped palladium nano-catalyst is characterized in that the palladium nano-catalyst is particles with two-dimensional coral sheet-shaped morphology, a dendritic pore structure exists, the particle size is 30-100 nm, and the palladium loading capacity is 20-40 wt%.

2. The preparation method of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nano-catalyst as claimed in claim 1, comprising the steps of:

preparing a graphene oxide carrier, a CTAB solution, an AA solution and a palladium precursor solution in a certain mass molar ratio, adding the graphene oxide carrier into deionized water, performing ultrasonic dispersion treatment in a greenhouse to form a clear solution, adding the CTAB solution and the AA solution into the obtained solution under the conditions of ultrasonic treatment and magnetic stirring, adding the palladium precursor solution at a certain sample introduction speed, performing reduction reaction on the system at a certain temperature, stopping ultrasonic treatment after the palladium precursor solution is subjected to sample introduction, curing the obtained solution for a certain time under magnetic stirring, and performing centrifugation and drying treatment to obtain the reduced graphene oxide loaded two-dimensional coral-shaped palladium nanosheet catalyst.

3. The preparation method of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nano-catalyst as claimed in claim 2, wherein the mass molar ratio of the graphene oxide support, the CTAB solution, the AA solution and the palladium precursor solution is 133.3-266.7 g: 1-20 mol: 2-6 mol: 0.5 to 2 mol.

4. The preparation method of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nano-catalyst as claimed in claim 2 or 3, wherein the palladium precursor solution comprises the following components: na (Na)₂PdCl₄、K₂PdCl₄、H₂PdCl₄Or Pd (NO)₃)₂。

5. The preparation method of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nano-catalyst as claimed in claim 4, wherein the ultrasonic power obtained by ultrasonic dispersion treatment is 300W.

6. The preparation method of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nano-catalyst as claimed in claim 5, wherein the ultrasonic power of the ultrasonic treatment is 300-700W, and the stirring speed of the magnetic stirring in the ultrasonic process is 300-600 rpm.

7. The preparation method of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nano-catalyst as claimed in claim 6, wherein the sample injection speed of the palladium precursor solution is 3-7 mL/h.

8. The preparation method of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nano-catalyst as claimed in claim 7, wherein the temperature of the reduction reaction is 25-45 ℃.

9. The preparation method of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nano-catalyst as claimed in claim 8, wherein the volume of the solution obtained after the palladium precursor solution is injected is 80-120 mL.

10. The preparation method of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nano-catalyst as claimed in claim 9, wherein the curing time under magnetic stirring is 0.5-4 h, and the stirring speed of the magnetic stirring during the curing process is 300-600 rpm.

Technical Field

The invention belongs to the field of catalysts and preparation thereof, and particularly relates to a two-dimensional coral sheet-shaped palladium nano-catalyst loaded with reduced graphene oxide and a preparation method thereof.

Background

In the face of today's increasingly severe energy and environmental crisis, fuel cells play a crucial role in the field of energy development and conversion. Among them, the Oxygen Reduction Reaction (ORR) has received much attention as a basic step in fuel cells. Platinum nanocatalysts are the most commonly used efficient, stable, durable ORR catalysts, but are expensive. Therefore, it is of great significance to develop a catalyst with high catalytic activity, high stability, low cost and easy availability. Palladium as platinum group metal has similar chemical properties, but has poor electrocatalytic activity, and the specific surface area of the palladium nano-particle is increased by improving the surface structure of the palladium nano-particle, so that the palladium nano-particle has potential for further improving the electrocatalytic performance of the palladium nano-particle. However, most of the existing palladium nano-catalysts are spherical particles, and have low activity and catalytic activity in ORR reaction and complex preparation process.

Disclosure of Invention

In order to solve the problems of low catalytic activity and complex preparation process of the existing palladium catalyst, the invention provides a two-dimensional coral sheet-shaped palladium nano-catalyst loaded by reduced graphene oxide and a preparation method thereof.

The technical scheme of the invention is as follows:

a two-dimensional coral sheet-shaped palladium nano-catalyst loaded with reduced graphene oxide is provided, wherein the palladium nano-catalyst is particles with two-dimensional coral sheet-shaped appearance, has a dendritic pore structure, has a particle size of 30-100 nm, and has a palladium loading amount of 20-40 wt%.

A preparation method of a reduced graphene oxide loaded two-dimensional coral sheet-shaped palladium nano-catalyst comprises the following steps:

preparing a graphene oxide carrier, a CTAB (cetyl trimethyl ammonium bromide) solution, an AA (ascorbic acid) solution and a palladium precursor solution in a certain mass molar ratio, adding the graphene oxide carrier into deionized water, performing ultrasonic dispersion treatment in a greenhouse to form a clarified solution, adding the CTAB solution and the AA solution into the obtained solution under the conditions of ultrasonic treatment and magnetic stirring, adding the palladium precursor solution at a certain sample introduction speed, performing reduction reaction on the system at a certain temperature, stopping ultrasonic treatment after the sample introduction of the palladium precursor solution is finished, aging the obtained solution under magnetic stirring for a certain time, and performing centrifugation and drying treatment to obtain the reduced graphene oxide loaded two-dimensional coral-shaped palladium nanosheet catalyst.

Further, the mass molar ratio of the graphene oxide carrier to the CTAB solution to the AA solution to the palladium precursor solution is 133.3-266.7 g: 1-20 mol: 2-6 mol: 0.5 to 2 mol.

Further, the palladium precursor solution comprises the following components: na (Na)₂PdCl₄、K₂PdCl₄、H₂PdCl₄Or Pd (NO)₃)₂。

Further, the ultrasonic power obtained by ultrasonic dispersion treatment is 300W.

Further, the ultrasonic power of ultrasonic treatment is 300-700W, and the stirring speed of magnetic stirring in the ultrasonic process is 300-600 rpm.

Furthermore, the sampling speed of the palladium precursor solution is 3-7 mL/h.

Further, the temperature of the reduction reaction is 25-45 ℃.

Furthermore, the volume of the solution obtained after the palladium precursor solution is injected is 80-120 mL.

Further, the curing time under magnetic stirring is 0.5-4 h, and the stirring speed of the magnetic stirring in the curing process is 300-600 rpm.

The invention has the beneficial effects that:

1. the palladium nano catalyst prepared by the invention is of a two-dimensional coral sheet structure, is uniformly dispersed, has a dendritic pore structure, has more defects on the surface, provides more active sites for the reaction, and has higher catalytic activity in the oxygen reduction reaction.

2. According to the invention, the preparation of the two-dimensional coral sheet-shaped palladium nano-catalyst loaded with the reduced graphene oxide is realized by an ultrasonic-assisted method, with CTAB (cetyl trimethyl ammonium bromide) as a protective agent and AA (ascorbic acid) as a reducing agent, the operation is simple, and the preparation efficiency of the catalyst is improved.

Drawings

FIG. 1 is a 40000-fold TEM photograph of the reduced graphene oxide-supported two-dimensional coral sheet-like palladium nanocatalyst prepared in example 1;

FIG. 2 is a 400000-fold TEM photograph of the reduced graphene oxide-supported two-dimensional coral sheet-like palladium nanocatalyst prepared in example 1;

FIG. 3 is an HRTEM photograph of the reduced graphene oxide supported two-dimensional coral sheet-like palladium nanocatalyst prepared in example 1;

FIG. 4 is an XRD pattern of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nanocatalyst prepared in example 1;

FIG. 5 is an LSV curve of oxygen reduction of the reduced graphene oxide supported two-dimensional coral sheet-shaped palladium nanocatalyst prepared in example 1;

FIG. 6 is an oxygen reduction LSV curve for the commercial Pd/C catalyst described in comparative example 1;

FIG. 7 is a K-L equation fitting curve of oxygen for the reduced graphene oxide-supported two-dimensional coral sheet-shaped palladium nanocatalyst prepared in example 1;

FIG. 8 is a K-L equation fitted curve for the commercial Pd/C catalyst described in comparative example 1.

Detailed Description

The technical solutions of the present invention are further described below with reference to the following examples, but the present invention is not limited thereto, and any modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.