阅读说明：本技术 一种CuSe/g-C3N4电催化材料的制备方法及其用途 (CuSe/g-C3N4Preparation method and application of electrocatalytic material ) 是由 尹晓红 张�浩 穆曼曼 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种复合材料,在六边形CuSe纳米片上复合g-C-3N-4纳米层,我们做了一系列比例包括10％,30％,50％,70％比例的CuSe/g-C-3N-4的复合材料,其中,50％的CuSe/g-C-3N-4具有最优异的电催化性能,在-1.2Vvs.RHE下CO的法拉第效率可以达到85.28％,并且电流密度为-10.125mA/cm～2。本发明具有选择性高且产物单一、稳定的特点,并且材料价格低廉且易制取获得,具有显著的应用前景,并且符合绿色发展的理念。(The invention discloses a composite material, which is formed by compounding g-C on a hexagonal CuSe nano-sheet 3 N 4 The nano-layer is formed by preparing a series of CuSe/g-C with the proportion of 10%, 30%, 50% and 70% 3 N 4 The composite material of (1), wherein 50% of CuSe/g-C 3 N 4 Has the most excellent electrocatalytic performance, the Faraday efficiency of CO can reach 85.28 percent under-1.2 Vvs. RHE, and the current density is-10.125 mA/cm 2 . The invention has the characteristics of high selectivity, single and stable product, low material price, easy preparation and acquisition, obvious application prospect and accordance with the concept of green development.)

1. CuSe nanosheet compounded in g-C₃N₄The formation of heterostructures between two-dimensional and two-dimensional materials of the preparation method of the composite catalyst on the nano layer is beneficial to increasing the active surface area, and can improve the electron transfer rate, thereby improving the CO₂Performance of electrocatalytic reduction.

2. A CuSe/g-C according to claim 1₃N₄The preparation method of the composite material is characterized by comprising the following steps:

(1) synthesizing hexagonal CuSe nanosheets by a hydrothermal method:

10mL of 0.1M CuSO₄·5H₂The O solution and 10mL of 0.1M EDTA-2Na solution were added to a 100mL beaker. After stirring for 30 minutes, a 1M NaOH solution was added dropwise to the above mixed solution to adjust the pH to 12. Then, 10mL of 0.1M Na was added under stirring₂SeSO₃The solution was added to the above solution, and the mixture was transferred to a stainless steel autoclave (100mL) with a teflon liner and heated at 160 ℃ for 12 h. After natural cooling to room temperature, the suspension was centrifuged at 5000rpm, and the black precipitate was washed 3 times with water and absolute ethanol and dried at 60 ℃ for 6 h.

Wherein Na is used as Se source₂SeSO₃Is prepared by the following steps: adding 0.01mol of Na₂SO₃Added to a 100ml round bottom flask containing 50ml of distilled water and stirred to dissolve. Then, 0.005mol of Se powder was added to the above solution, and an oil bath reaction was performed at 95 ℃ with the whole experiment being protected from light and stirred for 30 minutes. Finally, the obtained product was washed with water and absolute ethanol by centrifugation 3 times to remove unreacted Se powder, and the product was sealed and stored in the dark.

(2) Preparation of g-C by calcination₃N₄Nano-layer:

g-C is synthesized by taking urea as raw material₃N₄The nanolayer, 25g of urea was first weighed into a ceramic crucible and heated in a muffle furnace at a rate of 5 ℃/min to 550 ℃ for 4 h. Then it was cooled to room temperature at the same rate of 5 ℃/min, after cooling the yellowish product was removed and further ground to a powder for use.

(3) Synthesis of CuSe/g-C by hydrothermal method₃N₄The composite material comprises the following components:

firstly, weighing the CuSe nanosheets prepared in the step (1), determining the synthetic weight of the CuSe nanosheets, and then taking the synthetic weight as a standard value. The prepared g-C₃N₄NSs are put into a hydrothermal kettle for growing CuSe according to different mass ratios, and the CuSe/g-C with the weight ratio of X percent is prepared at the temperature of 160 DEG C₃N₄Heterostructure materials (X ═ 10, 30, 50, 70) were synthesized and the properties of these materials were compared under the same conditions.

3. The CuSe/g-C of claim 1₃N₄Synthesis method of composite material and application of composite material with electrocatalytic reduction of CO under potential condition₂Resulting in applications in CO performance.

Technical Field

The invention belongs to the technical field of catalytic materials, and particularly relates to a catalyst applied to electrocatalytic reduction of CO₂The preparation method and the application of the composite catalyst.

Background

With the promotion of social civilization and the rapid development of industrialization, a series of activities and CO of human beings₂Emissions are also becoming increasingly more closely related. Up to now, the conversion of energy has been mainly achieved by burning fossil fuel, but primary fossil energy represented by coal, oil, and natural gas is short of energy due to non-regenerability thereof, and CO in air is generated after burning₂The drastic rise in content all leads to the limitation of the use of primary fossil energy in today's society. Therefore, how to develop new energy to gradually replace fossil fuel to reduce atmospheric CO₂Has become a hot issue.

In recent years, two-dimensional (2D) materials, especially klockmann phase CuSe nanoplates, have become a hotspot for electrocatalytic research due to their fast electron transport capabilities and more active sites on the surface. However, simple CuSe nanosheets are prone to agglomeration, preventing CO from being formed₂Diffusion over the catalyst, in turn, hinders CO₂Electrocatalytic properties of RR. Recently, various strategies for compounding CuSe with semiconductors have been proposed, which are very important for improving electrocatalytic performance.

g-C₃N₄The nano layer is a plane structure with a small number of layers and a large surface area, and can enable the catalytic material loaded on the surface to be more dispersed. In addition, a larger surface may provide more active sites for anchoring to, for example, amino functional groups, etc. Thus, take part in CO₂The number of reduced electrons increases and the transfer speed is faster. The conductivity of such semiconductors is relatively increased. Therefore, some strategies, particularly semiconductor doping and loading, are considered as methods for improving performance.

Disclosure of Invention

The invention provides a preparation method and application of a novel electrocatalyst for CO₂The reduction to CO has higher selectivity, good stability is kept in a long-time electrolytic process, the preparation process is simple, the cost is low, and a new research and development idea is provided for the development of a novel catalyst.

In order to solve the technical problems, the invention adopts the following technical scheme:

Drawings

FIG. 1 shows CuSe/g-C prepared by the present invention₃N₄The X-ray diffraction (XRD) patterns of the composite with two pure catalysts, i.e. the XRD pattern of example 2;

FIG. 2 is a Scanning Electron Microscope (SEM) image of a hexagonal CuSe nanosheet catalyst prepared in accordance with the present invention, i.e., the SEM image of example 1;

FIG. 3 shows a composite CuSe/g-C prepared by the present invention₃N₄(ii) a scanning electron micrograph and (b) a transmission electron micrograph of the catalyst, i.e., an SEM and TEM image of example 2;

FIG. 4 shows CuSe/g-C prepared according to the present invention in different ratios₃N₄Electrocatalytic reduction of CO by composite materials₂Is the faradaic efficiency of CO, i.e., performance test plots for example 1 and example 2;

FIG. 5 shows a composite CuSe/g-C prepared by the present invention₃N₄The stability test result chart of the catalyst, namely the stability performance test chart of the composite material of the example 2;

example 1:

with electrocatalytic reduction of CO₂Preparing a CuSe material with performance and testing the performance.

(1) Synthesizing hexagonal CuSe nanosheets by a hydrothermal method:

10mL of 0.1M CuSO₄·5H₂The O solution and 10mL of 0.1M EDTA-2Na solution were added to a 100mL beaker. After stirring for 30 minutes, a 1M NaOH solution was added dropwise to the above mixed solution to adjust the pH to 12. Then, 10mL of 0.1M Na was added under stirring₂SeSO₃The solution was added to the above solution, and the mixture was transferred to a stainless steel autoclave (100mL) with a teflon liner and heated at 160 ℃ for 12 h. After natural cooling to room temperature, the suspension was centrifuged at 5000rpm, and the black precipitate was washed 3 times with water and absolute ethanol and dried at 60 ℃ for 6 h.

Wherein Na is used as Se source₂SeSO₃Is prepared by the following steps: adding 0.01mol of Na₂SO₃Added to a 100ml round bottom flask containing 50ml of distilled water and stirred to dissolve. Then, 0.005mol of Se powder was added to the above solution, and an oil bath reaction was performed at 95 ℃ with the whole experiment being protected from light and stirred for 30 minutes. Finally, the obtained product was washed with water and absolute ethanol by centrifugation 3 times to remove unreacted Se powder, and the product was sealed and stored in the dark.

(2) Electrocatalytic reduction of CO by nano-electrocatalyst CuSe₂Study of Properties

Dissolving 5mg CuSe sample in 500ul ethanol, 500ul water and 100ul 5 wt% Nation solution, performing ultrasonic treatment for 30min to form uniform ink solution, and dripping 30ul solution to an area of 1 x 1cm²And then used as a working electrode. 0.1M KHCO was added prior to electrochemical testing₃(both chambers were filled with 70mL of electrolyte respectively) bubbling CO through the electrolyte₂The gas was allowed to flow for at least 30 minutes to remove other residual gases, and all tests were performed at room temperature and pressure. CO diversion Using gas flow valve (LZM-3MB)₂The gas was fed into an H-type cell at a rate of 20mL/min and the gas products were detected by an on-line gas chromatograph (GC-7920).Detecting the presence and concentration of CO using a Flame Ionization Detector (FID), and measuring H using a Thermal Conductivity Detector (TCD)₂。

Example 2

Has excellent electro-catalytic reduction of CO₂Nano composite photocatalyst CuSe/g-C with performance₃N₄And (4) preparing and testing the performance.

(1) Synthesis of CuSe/g-C by hydrothermal method₃N₄The composite material comprises the following components:

firstly, weighing the prepared CuSe nanosheets, determining the synthetic weight of the CuSe nanosheets, and then taking the synthetic weight as a standard value. The prepared g-C₃N₄The nano-layer is put into a hydrothermal kettle for growing CuSe according to different mass ratios, and the CuSe/g-C with the weight ratio of X percent is prepared at the temperature of 160 DEG C₃N₄Heterostructure materials (X ═ 10, 30, 50, 70) were synthesized and the properties of these materials were compared under the same conditions.

(2) Nano electro-catalyst CuSe/g-C₃N₄Electrocatalytic reduction of CO₂Study of Properties

Taking 5mg of CuSe/g-C₃N₄Dissolving the sample in 500ul ethanol, 500ul water and 100ul 5 wt% Nafion solution, performing ultrasonic treatment for 30min to form uniform ink solution, and dripping 30ul solution to 1 × 1cm area²And then used as a working electrode. 0.1M KHCO was added prior to electrochemical testing₃(both chambers were filled with 70mL of electrolyte respectively) bubbling CO through the electrolyte₂The gas was allowed to flow for at least 30 minutes to remove other residual gases, and all tests were performed at room temperature and pressure. CO diversion Using gas flow valve (LZM-3MB)₂The gas was fed into an H-type cell at a rate of 20mL/min and the gas products were detected by an on-line gas chromatograph (GC-7920). Detecting the presence and concentration of CO using a Flame Ionization Detector (FID), and measuring H using a Thermal Conductivity Detector (TCD)₂。

FIG. 1 shows the hexagonal CuSe nano-materials and composite CuSe/g-C prepared by hydrothermal method in examples 1 and 2₃N₄The crystal configuration of the compound is gradually changed along with the increase of the compound ratio.

Fig. 2 is a scanning electron microscope image of the hexagonal CuSe nanosheet obtained in example 1, and it can be seen from the image that the structure thereof is the shape of the nanosheet and the characteristic of the sheet-like structure of the composite two-dimensional material.

FIG. 3 shows that CuSe/g-C is obtained in example 2₃N₄SEM and TEM images of the composite material, and the lattice spacing of the CuSe nanometer material can be seen, which indicates the successful synthesis of the composite material.

FIG. 4 is a composite CuSe/g-C obtained in example 2₃N₄Results of the selectivity test of (1), X% CuSe/g-C in the figure₃N₄(X-10, 30, 50, 70) represents composite materials with different contents, and 50% of the composite material CuSe/g-C can be seen from the figure₃N₄The activity of the catalyst is obviously higher than that of other composite proportion catalysts for electrocatalytic reduction of CO₂The highest CO selectivity was achieved at-1.2V vs. RHE, 85.28%.

Fig. 5 shows the stability test results of the composite material after 14h of electrolysis under the applied potential of-1.2V vs. rhe, and the magnitude of the current density is basically in a stable state, which indicates that the catalyst has good stability.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are still within the protection scope of the technical solution of the present invention.

the specific embodiment is as follows:

the invention provides a preparation method of a novel electrocatalyst, which comprises the following steps:

(1) synthesizing hexagonal CuSe nanosheets by a hydrothermal method:

10mL of 0.1M CuSO₄·5H₂The O solution and 10mL of 0.1M EDTA-2Na solution were added to a 100mL beaker. After stirring for 30 minutes, a 1M NaOH solution was added dropwise to the above mixed solution to adjust the pH to 12. Then, 10mL of 0.1M Na was added under stirring₂SeSO₃Adding the solution into the above solution, addingThe mixture was transferred to a stainless steel autoclave (100mL) with a teflon liner and heated at 160 ℃ for 12 h. After natural cooling to room temperature, the suspension was centrifuged at 5000rpm, and the black precipitate was washed 3 times with water and absolute ethanol and dried at 60 ℃ for 6 h.

Wherein Na is used as Se source₂SeSO₃Is prepared by the following steps: adding 0.01mol of Na₂SO₃Added to a 100ml round bottom flask containing 50ml of distilled water and stirred to dissolve. Then, 0.005mol of Se powder was added to the above solution, and an oil bath reaction was performed at 95 ℃ with the whole experiment being protected from light and stirred for 30 minutes. Finally, the obtained product was washed with water and absolute ethanol by centrifugation 3 times to remove unreacted Se powder, and the product was sealed and stored in the dark.

(2) Preparation of g-C by calcination₃N₄Nano-layer:

g-C is synthesized by taking urea as raw material₃N₄The nanolayer, 25g of urea was first weighed into a ceramic crucible and heated in a muffle furnace at a rate of 5 ℃/min to 550 ℃ for 4 h. Then it was cooled to room temperature at the same rate of 5 ℃/min, after cooling the yellowish product was removed and further ground to a powder for use.

(3) Synthesis of CuSe/g-C by hydrothermal method₃N₄The composite material comprises the following components:

firstly, weighing the CuSe nanosheets prepared in the step (2), determining the synthetic weight of the CuSe nanosheets, and then taking the synthetic weight as a standard value. The prepared g-C₃N₄The nano-layer is put into a hydrothermal kettle for growing CuSe according to different mass ratios, and the CuSe/g-C with the weight ratio of X percent is prepared at the temperature of 160 DEG C₃N₄Heterostructure materials (X ═ 10, 30, 50, 70) were synthesized and the properties of these materials were compared under the same conditions.

II, nano electro-catalyst CuSe/g-C₃N₄Electrocatalytic reduction of CO₂The performance evaluation method comprises the following steps:

0.1M KHCO was added prior to electrochemical testing₃(both chambers were filled with 70mL of electrolyte respectively) and bubbling C into the electrolyteO₂The gas was allowed to flow for at least 30 minutes to remove other residual gases, and all tests were performed at room temperature and pressure. CO diversion Using gas flow valve (LZM-3MB)₂The gas was fed into an H-type cell at a rate of 20mL/min and the gas products were detected by an on-line gas chromatograph (GC-7920). Detecting the presence and concentration of CO using a Flame Ionization Detector (FID), and measuring H using a Thermal Conductivity Detector (TCD)₂。

Electrochemical performance tests were performed at an electrochemical workstation (CHI660E) which was used to adjust the applied potential. Electrochemical Impedance Spectroscopy (EIS) was conducted under conditions of an open circuit voltage of 0.352V, a frequency in the range of 0.01Hz to 100kHz, and an amplitude of 5 mV. In N₂Or CO₂Saturated KHCO₃In the electrolyte, a Linear Sweep Voltammetry (LSV) curve was tested over a potential interval of 0 to-1.4V vs. RHE, with a sweep rate of 20 mV/s. The electrochemically active surface area (ECSA) was evaluated by the double layer capacitance (Cdl) determined by measuring the capacitive current density related to the scan rate of the Cyclic Voltammetry (CV) curve. The values of the overpotential and the current density were determined from the LSV plot with a tafel slope.