CN114976052A

CN114976052A - Preparation method of grain boundary-rich ultrathin rhodium nanosheet electrocatalyst

Info

Publication number: CN114976052A
Application number: CN202210627462.0A
Authority: CN
Inventors: 杨晓冬; 孙一强; 葛雪宁; 曹文文; 史传鑫
Original assignee: University of Jinan
Current assignee: University of Jinan
Priority date: 2022-06-06
Filing date: 2022-06-06
Publication date: 2022-08-30

Abstract

The invention relates to a grain boundary-rich ultrathin rhodium nanosheet electrocatalyst and a preparation method thereof, belonging to the field of preparation of novel nano catalytic materials. The synthesis method of the material used in the invention is a solvothermal method. The method comprises the following specific steps: firstly, dispersing polyvinylpyrrolidone and rhodium triacetylacetone into ethylene glycol, adding a formaldehyde solution into a mixed solution, fully mixing, transferring the solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and putting the kettle into a constant-temperature air-blast drying box for heating reaction. And centrifuging, washing and drying the obtained product to obtain a black powdery solid, namely the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst. The preparation method is simple and easy to implement, the synthesized catalytic material has stable performance, the experimental conditions are green and environment-friendly, and the experimental conditions are mild and suitable for large-scale production.

Description

Preparation method of grain boundary-rich ultrathin rhodium nanosheet electrocatalyst

Technical Field

The invention relates to a preparation method of a grain boundary-rich ultrathin rhodium nanosheet electrocatalyst, belonging to the technical field of novel functional materials.

Background

With the proposal of the strategy of 'double carbon', China continuously promotes the adjustment of industrial structure and energy structure, and develops renewable energy energetically. Hydrogen energy is recognized as the most promising energy carrier for development due to its high energy density, high heat of combustion and the fact that the combustion products are water only. Among the various ways of utilizing hydrogen energy, the hydrogen-oxygen fuel cell is considered to be the most important and safest and green form of power generation.

In recent years, a series of key materials and technologies such as alkaline membranes have been developed in a breakthrough manner, and in recent years, anion exchange membrane fuel cells are gradually attracted by people, so that the advantage of fast cathode oxygen reduction reaction kinetics of the traditional alkaline fuel cells is inherited, and the service life of the cells is prolonged due to the low-corrosivity alkaline environment. However, the slow kinetics of the hydrogen oxidation reaction in alkaline environments and the disadvantage of the susceptibility of the catalyst to carbon monoxide poisoning limit its development. Therefore, research on corresponding catalysts to improve reaction efficiency is urgently required.

Grain boundaries are typically present in two-dimensional polycrystalline materials, which are often described as line defects, and play a key role in improving the properties of two-dimensional materials, such as mechanical strengthening, photovoltaics, and catalysis. In recent years, two-dimensional materials have been widely used in energy conversion reactions such as electrocatalysis, photocatalysis, supercapacitors, fuel cells, etc. due to their enhanced electronic and optical properties, higher electron mobility and carrier concentration, and adjustable bandgap structure. Therefore, the introduction of the grain boundary defects into the two-dimensional material can optimize the electronic structure of the material and effectively improve the corresponding electrocatalytic activity of the material. Rhodium is considered as one of The most promising platinum alternatives in hydrogen oxidation/hydrogen evolution reactions (N Bronstov J K, Bligaard T, Logadottir A, et al. Trends in The exchange current for hydrogen evolution [ J ]. Journal of The Electrochemical Society, 2005, 152(3): J23.) according to calculated hydrogen adsorption energy volcano plots and experimental measurements of exchange currents based on different transition metals and noble metals.

However, in combination with the advantages of the catalyst, no report has been made on a method for preparing grain boundary-rich ultrathin rhodium nanosheets.

The invention prepares the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst with the thickness of less than 2 nanometers in one pot by a solvothermal method. The grain boundary defect is constructed on the ultrathin two-dimensional rhodium nanosheet, so that the intrinsic activity of the rhodium nanosheet is improved, and the electronic structure of the rhodium nanosheet is regulated and controlled, thereby effectively improving the electrocatalytic performance of the rhodium nanosheet and providing a wide prospect for construction of a fuel cell anode catalyst.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a preparation method of a grain boundary-rich ultrathin rhodium nanosheet electrocatalyst, which is a solvothermal method, and the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst with the thickness of less than 2 nanometers is prepared in one pot. The preparation process is simple, rapid and efficient, and is suitable for large-scale industrial production.

The purpose of the invention is realized by the following technical scheme:

1) weighing polyvinylpyrrolidone (-360000) and rhodium triacetylacetone in a beaker according to a certain molar ratio;

2) adding ethylene glycol into the beaker used in the step 1), and carrying out ultrasonic treatment to promote polyvinylpyrrolidone (-360000) and rhodium triacetylacetone to the ethylene glycol to form a light yellow mixed solution;

3) adding the formaldehyde solution into the beaker in the step 2) and stirring to enable the formaldehyde solution and the original solution to be mutually soluble;

4) transferring the mixed solution obtained in the step 3) into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and placing the reaction kettle in a 220 ^o C, reacting for 6 hours in a constant-temperature air-blast drying box;

5) centrifuging the reaction mixture obtained in step 4), washing with ethanol 3-4 times, and then washing at 60 deg.C ^o And C, vacuum drying to obtain a final product.

The invention has the beneficial effects that:

1. the invention provides a preparation method of a grain boundary-rich ultrathin rhodium nanosheet electrocatalyst, which is simple and easy to operate, does not need special equipment, is suitable for large-scale preparation, can prepare the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst through one-time reaction, and can meet the requirements of practical application;

2. the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst prepared by the method is high in preparation speed and product purity, and the preparation efficiency is improved;

3. the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst prepared by the invention has a good catalytic effect on a hydrogen oxidation reaction;

4. the method of the invention is simple and easy to implement, and does not need special equipment.

Drawings

FIG. 1 is a macroscopic TEM image of a grain boundary-rich ultrathin rhodium nanosheet electrocatalyst;

FIG. 2 is a high-power TEM image of a grain-boundary-rich ultrathin rhodium nanosheet electrocatalyst;

FIG. 3 is an X-ray diffraction (XRD) pattern of the grain boundary-rich ultrathin rhodium nanosheet prepared by the method, wherein the pattern shows that the diffraction peak position and peak shape in the experimental spectrogram and the simulated spectrogram are well matched, and the two structures are proved to be consistent, so that the prepared sample has good purity;

FIG. 4 is a photograph taken by a high-angle annular dark field image scanning transmission electron microscope of the grain boundary-rich ultrathin rhodium nanosheet prepared by the method of the present invention, and the sample can be seen as the grain boundary-rich ultrathin nanosheet.

Detailed Description

The present invention will be described in further detail with reference to the following specific embodiments, which are not intended to limit the scope of the present invention.

Example 1

Firstly, respectively weighing 0.9 mmol of polyvinylpyrrolidone (-360000) and 0.05 mmol of rhodium triacetylacetone to dissolve into 6 mL of ethylene glycol, adding 1.3 mL of formaldehyde solution into the mixed solution to dissolve the mixture mutually to form a light yellow mixed solution, transferring the solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and putting the high-pressure reaction kettle into the high-pressure reaction kettle with a 220. about.220. about. ^o C reacting for 6 hours in a constant temperature air-blast drying oven, then centrifugally separating, ultrasonically cleaning for 3-4 times by using ethanol, and then cleaning at 60 degrees ^o And C, drying under vacuum drying to prepare the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst.

Example 2

Firstly, respectively weighing 1.8 mmol of polyvinylpyrrolidone (-360000) and 0.1 mmol of rhodium triacetylacetone, dissolving the polyvinylpyrrolidone and the rhodium triacetylacetone in 6 mL of ethylene glycol, adding 1.3 mL of formaldehyde solution into the mixed solution to dissolve the formaldehyde solution mutually to form a light yellow mixed solution, transferring the solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and putting the high-pressure reaction kettle into a reaction kettle with a 220. sup. th mol of formaldehyde solution ^o C, reacting for 6 hours in a constant-temperature air-blast drying oven, then centrifugally separating, ultrasonically cleaning for 3-4 times by using ethanol, and then cleaning at 60 DEG C ^o And C, drying under vacuum drying to obtain the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst.

Example 3

Firstly, respectively weighing 0.9 mmol of polyvinylpyrrolidone (-360000) and 0.05 mmol of rhodium triacetylacetone, dissolving the polyvinylpyrrolidone and the rhodium triacetylacetone in 6 mL of ethylene glycol, adding 1.3 mL of formaldehyde solution into the mixed solution to be mutually dissolved to form a light yellow mixed solution, transferring the mixed solution to a high-pressure reaction kettle with a polytetrafluoroethylene lining, and putting the high-pressure reaction kettle into a reactor with a 220. sup. th micrometer ^o C, reacting in a constant-temperature air-blast drying oven for 12 hours, then centrifugally separating, ultrasonically cleaning for 3-4 times by using ethanol, and then cleaning at 60 DEG C ^o And C, drying under vacuum drying to prepare the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst.

Claims

1. The catalyst is an ultrathin nanosheet with a surface rich in grain boundaries, and the thickness of the catalyst is less than 2 nanometers.

2. A preparation method of a grain boundary-rich ultrathin rhodium nanosheet electrocatalyst is characterized by comprising the following steps:

1) weighing polyvinylpyrrolidone (360000) and rhodium triacetylacetone in a certain molar ratio, and dispersing the polyvinylpyrrolidone and the rhodium triacetylacetone into ethylene glycol;

2) adding a formaldehyde solution into the mixed solution obtained in the step 1), mixing, transferring to a high-pressure reaction kettle with a polytetrafluoroethylene lining, and carrying out heating reaction in a constant-temperature air-blast drying oven;

3) centrifuging, washing and drying to obtain a black powdery product.

3. The grain boundary-rich ultrathin rhodium nanosheet electrocatalyst according to claim 2, wherein the solvent used is ethylene glycol and the rhodium salt used is rhodium triacetylacetonate.

4. The preparation method of the grain boundary-rich ultrathin rhodium nanosheet electrocatalyst according to claim 2, wherein the reaction temperature in step 2) is 220% ^o C, the reaction time is 6 to 12 hours.