CN113846352B

CN113846352B - Preparation method of crystalline orthorhombic phase cobalt diselenide amorphous cobalt phosphide heterojunction

Info

Publication number: CN113846352B
Application number: CN202111427710.9A
Authority: CN
Inventors: 申士杰; 张欢欢; 钟文武; 林志萍; 王宗鹏
Original assignee: Taizhou University
Current assignee: Taizhou University
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2022-08-30
Anticipated expiration: 2041-11-29
Also published as: CN113846352A

Abstract

The invention discloses a preparation method of a crystalline orthorhombic phase cobalt diselenide amorphous cobalt phosphide heterojunction. The prepared crystalline state orthorhombic cobalt diselenide amorphous cobalt phosphide heterojunction has excellent electro-catalytic hydrogen evolution performance.

Description

Preparation method of crystalline orthorhombic phase cobalt diselenide amorphous cobalt phosphide heterojunction

Technical Field

The invention relates to a preparation method of a crystalline orthorhombic phase cobalt diselenide amorphous cobalt phosphide heterojunction.

Technical Field

In recent years, since amorphous electrocatalysts have, in many cases, more excellent electrocatalytic hydrogen evolution properties than crystalline electrocatalysts, they have attracted considerable research attention. Currently, various amorphous electrocatalysts based on transition metals, such as those containing Co, Ni, Fe, Mo, etc., have been found to have good activity. The construction of heterojunctions is another strategy to increase the electrocatalytic hydrogen evolution activity, since they tend to have better physicochemical properties than their single counterparts. Many transition metal compound heterojunctions, such as transition metal phosphide heterojunctions, transition metal oxide heterojunctions and noble metal heterojunctions, have been extensively studied. However, the above-mentioned heterojunction is mostly a crystalline-crystalline heterojunction. There has been little research on crystalline-amorphous heterojunctions, although the latter may combine the features of an amorphous structure with superior performance. Therefore, it is an urgent problem to develop a simple process for preparing a novel crystalline-amorphous heterojunction with excellent properties.

Disclosure of Invention

The invention aims to provide a crystalline orthorhombic cobalt diselenide amorphous cobalt phosphide heterojunction electrocatalyst with simple process and excellent performance and a preparation method thereof.

The said one crystalline orthorhombic phaseThe preparation method of the cobalt diselenide amorphous cobalt phosphide heterojunction is characterized by comprising the following steps: dissolving 1mmol of cobalt nitrate hexahydrate and 1mmol of sodium selenite in 38mL of ethylene glycol, stirring for twenty minutes, placing the solution in a high-pressure kettle with the volume of 50mL, keeping the solution at 180 ℃ for 1 day, cooling to room temperature, washing and drying precipitates in the high-pressure kettle to obtain Co _0.85 Se precursor; ② respectively mixing 40mg of Co _0.85 Se precursor and 800mg sodium hypophosphite are dispersed in a quartz boat, the Se precursor is arranged at the downstream of the airflow in the tube furnace, the Se precursor is arranged at the upstream of the airflow, and the airflow is high-purity argon; thirdly, heating the tubular furnace to 350 ℃ at the speed of 2 ℃/min, keeping the temperature for 2 hours, and cooling the tubular furnace to room temperature to obtain a crystalline state orthorhombic cobalt diselenide amorphous cobalt phosphide heterojunction sample.

Compared with the prior art, the sample provided by the invention has the following advantages: the prepared electro-catalyst has excellent performance and simple preparation process.

Drawings

Fig. 1 is XRD patterns of the example sample and the comparative example sample.

FIG. 2 is a spherical aberration electron microscope image of the example.

Fig. 3 is a fourier transform plot of synchrotron radiation absorption data for the example and comparative example samples.

Fig. 4 is a linear voltammogram of example and comparative samples.

Detailed Description

The following describes the implementation of the present invention in detail with reference to specific embodiments.

The preparation method of the crystalline orthorhombic phase cobalt diselenide amorphous cobalt phosphide heterojunction is characterized by comprising the following steps of: dissolving 1mmol of cobalt nitrate hexahydrate and 1mmol of sodium selenite in 38mL of ethylene glycol, stirring for twenty minutes, placing the solution in a 50 mL-volume autoclave, keeping the autoclave at 180 ℃ for 1 day, cooling to room temperature, washing and drying precipitates in the solution to obtain Co _0.85 Se precursor; ② respectively mixing 40mg of Co _0.85 Se precursor and 800mg sodium hypophosphite are dispersed in a quartz boat, the former is arranged at the downstream of the airflow in the tube furnace, the latter is arranged at the upstream, and the gasThe flow is high purity argon; thirdly, heating the tubular furnace to 350 ℃ at the speed of 2 ℃/min, keeping the temperature for 2 hours, and cooling the tubular furnace to room temperature to obtain a crystalline state orthorhombic cobalt diselenide amorphous cobalt phosphide heterojunction sample.

For convenience of description, the above-mentioned crystalline orthorhombic cobalt diselenide amorphous cobalt phosphide heterojunction is abbreviated as CoSe hereinafter and in the accompanying drawings ₂ /a-CoP。

To illustrate the technical effect of the example sample, a comparative example sample was prepared as follows: dissolving 1mmol of cobalt nitrate hexahydrate and 1mmol of sodium selenite in 38mL of ethylene glycol, stirring for twenty minutes, placing the solution in a 50 mL-volume autoclave, keeping the autoclave at 180 ℃ for 1 day, cooling to room temperature, washing and drying precipitates in the solution to obtain Co _0.85 Se precursor; ② respectively adding 40mg of Co _0.85 Se precursor and 800mg sodium hypophosphite are dispersed in a quartz boat, the Se precursor is arranged at the downstream of the airflow in the tube furnace, the Se precursor is arranged at the upstream of the airflow, and the airflow is high-purity argon; thirdly, heating the tubular furnace to 550 ℃ at the speed of 2 ℃/min and keeping the temperature for 2 hours, and cooling the tubular furnace to room temperature to obtain a crystalline state orthorhombic cobalt diselenide crystalline state cobalt phosphide heterojunction sample.

For convenience of description, the above-described crystalline cobalt orthorhombic diselenide crystalline cobalt phosphide heterojunction is abbreviated as CoSe hereinafter and in the accompanying drawings ₂ /c-CoP。

To illustrate the technical effect of the example sample, a comparative example sample was prepared as follows: 90mg of Co (OH) ₂ And 160mg of Se powder dispersed in 24mL of N, N-dimethylformamide; stirring for twenty minutes, putting the solution into a reaction kettle with a volume of 50ml, and keeping the solution at 200 ℃ for 1 day; after cooling to room temperature, the precipitate was washed and dried to obtain orthorhombic CoSe ₂ And (3) sampling. For convenience of description, the above-described orthorhombic CoSe is hereinafter and in the accompanying drawings ₂ Sample direct writing as CoSe ₂ 。

In order to illustrate the technical effects of the present example, the example samples and the comparative example samples were characterized. Figure 1 is an XRD pattern. Diffraction peaks and orthorhombic CoSe of the samples can be seen for the example samples ₂ (PDF # 53-0449) standard data match, without CThe diffraction peak of the oP suggests that the CoP is amorphous. While the diffraction peak and orthorhombic CoSe of the first sample of the comparative example ₂ (PDF # 53-0449) and CoP (PDF # 29-0497) standard data match, illustrating CoSe therein ₂ And CoP are both crystalline forms. Diffraction Peak and Quadrature phase CoSe of comparative example No. two ₂ (PDF # 53-0449) standard data match, which indicates that it is quadrature phase CoSe ₂ 。

FIG. 2 is a spherical aberration electron microscope image of the example. The upper half (FIG. 2 a) is a high resolution dark field image, from which it can be seen that the amorphous CoP portion shows white floc with no lattice fringes, indicating that it is amorphous, while CoSe ₂ Partially present obvious lattice stripes, the lattice stripe spacing and orthorhombic CoSe ₂ (PDF # 53-0449) is lattice matched by (111). Crystalline CoSe ₂ And amorphous CoP presents sharp boundaries. The lower half (fig. 2 b) is an element scan, from which it can be seen that Co and P are uniformly distributed throughout the material, and Se is distributed in the bright part of the figure. This indicates that three elements of Co, P, and Se are actually present in the material.

Fig. 3 is a fourier transform plot of synchrotron radiation absorption data for the example sample and the comparative example sample. It can be seen that for CoSe ₂ Co-Se bonds can be observed, while CoSe of the examples ₂ the/a-CoP has a Co-P bond in addition to the Co-Se bond, and has a bond length corresponding to that of the CoP (PDF # 29-0497). The above results further confirm that the amorphous material in the examples is CoP.

The example and comparative samples were tested for their electrocatalytic hydrogen evolution overpotentials with a 0.5M sulfuric acid solution as the electrolyte. FIG. 4 is a linear voltammogram of the example and comparative samples, from which the electrocatalytic hydrogen evolution overpotential (10 mA/cm) of the example samples can be seen ² Time) was 65mV versus the electrocatalytic hydrogen evolution overpotential (10 mA/cm) for the comparative example one sample ² Time) was 127mV, the electrocatalytic hydrogen evolution overpotential (10 mA/cm) of the comparative example two sample ² When the concentration is higher than the standard value), the concentration is 173 mV. The results show that CoSe ₂ the/a-CoP has more excellent electro-catalytic hydrogen evolution performance.

It should be noted that the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above examples. It is to be understood that other modifications and variations, which may be directly derived or suggested to one skilled in the art without departing from the basic concept of the invention, are to be considered as included within the scope of the invention.

Claims

1. A preparation method of a crystalline orthorhombic phase cobalt diselenide amorphous cobalt phosphide heterojunction is characterized by comprising the following steps: dissolving 1mmol of cobalt nitrate hexahydrate and 1mmol of sodium selenite in 38mL of ethylene glycol, stirring for twenty minutes, placing the solution in a 50 mL-volume autoclave, keeping the autoclave at 180 ℃ for 1 day, cooling to room temperature, washing and drying precipitates in the solution to obtain Co _0.85 Se precursor; ② respectively mixing 40mg of Co _0.85 Se precursor and 800mg sodium hypophosphite are dispersed in a quartz boat, the Se precursor is arranged at the downstream of the airflow in the tube furnace, the Se precursor is arranged at the upstream of the airflow, and the airflow is high-purity argon; thirdly, heating the tubular furnace to 350 ℃ at the speed of 2 ℃/min, keeping the temperature for 2 hours, and cooling the tubular furnace to room temperature to obtain a crystalline state orthorhombic cobalt diselenide amorphous cobalt phosphide heterojunction sample.

2. A crystalline orthorhombic cobalt diselenide amorphous cobalt phosphide heterojunction prepared by the method of claim 1.

3. The use of the crystalline cobalt orthorhombic diselenide amorphous cobalt phosphide heterojunction as claimed in claim 2 in the field of electrocatalytic hydrogen evolution.