F-doped Cu x O catalysts and methods for their preparation and use

Abstract

The application relates to the technical field of electrocatalytic materials, in particular to a F-doped Cu x O catalyst and a preparation method and application thereof, which takes a metal copper salt, ammonia water and sodium hydroxide as reactants, reacts to generate a blue solid powder sample precursor, and generates a F-doped CuO / Cu2O catalyst through F salt joule heating under a nitrogen environment; the catalyst can be used in the field of electrocatalytic CO2 reduction, exhibits relatively excellent catalytic activity, and can effectively increase the selectivity of C2 products; in addition, all the raw materials required in the application are cheap and easy to obtain, sample preparation time is short, the reaction is mild, energy consumption is low, and the application has very high practical value and application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electrocatalytic materials, and particularly relates to an F-doped Cu x O catalyst and a preparation method and application thereof. BACKGROUND

[0002] Carbon dioxide (CO2) is one of the greenhouse gases and has become an important driving factor for climate change and global warming. Human activities such as the combustion of fossil fuels and industrial emissions have led to large-scale CO2 emissions, and the pressure of global warming is increasing. Therefore, the capture, conversion and utilization of CO2 have become an important research direction in the field of global energy and environmental science. At present, most chemicals and energy in industry rely on fossil resources such as oil and natural gas, but the finiteness and environmental impact of these resources have prompted scientists to seek sustainable alternative paths. The electrocatalytic CO2 reduction reaction (CO2RR) is a promising technology that converts CO2 into useful chemicals and fuels through electrochemical methods. This not only can effectively reduce the concentration of CO2 in the atmosphere, but also can provide a new way for energy storage and distribution.

[0003] In the process of electrocatalytic CO2 conversion, different catalysts have different selectivity. Copper-based catalysts (such as copper thin films, copper nanoparticles, etc.) are particularly suitable for the generation of multi-carbon products due to their unique electronic structure and catalytic performance. The advantages of copper-based catalysts include: copper-based catalysts are different from other common catalysts (such as silver, gold, etc.), copper can not only reduce CO2 to carbon monoxide (CO), but also further convert CO into more complex multi-carbon compounds such as ethanol (C2H5OH), ethylene (C2H4), propylene (C3H8), etc. These multi-carbon products have wide application prospects in the chemical industry, so copper-based catalysts are concerned in the electrocatalytic CO2 reduction reaction. Copper-based catalysts have good electronic conductivity, which helps to improve the current density and reaction rate in the electrocatalytic process. Different copper surface morphologies and crystal faces (such as {111}, {100}, etc.) have different effects on the adsorption, activation of CO2 and the conversion of reaction intermediates, thereby regulating the selectivity of multi-carbon products. The selectivity of copper-based catalysts is a key advantage in the electrocatalytic CO2 reduction. By reasonably designing the morphology, surface structure and alloying strategy (such as alloying of copper with other metals) of the catalyst, the reaction pathway can be adjusted to improve the selectivity of specific multi-carbon products. For example, copper-based catalysts can promote the generation of ethanol and ethylene products by adjusting the generation and adsorption of CO intermediates.

[0004] The CO2 electro-reduction reaction (CO2RR) is a complex multi-step process involving multiple reaction intermediates and electron transfer processes. Copper-based catalysts interact with CO2 molecules through their surface catalytic active sites to decompose CO2 into multiple intermediates (such as CO, C2, etc.), which are then converted into multi-carbon products. The technology of electro-catalytic CO2 conversion, especially the application of copper-based catalysts, has broad prospects: converting CO2 into liquid fuels (such as ethanol, ethylene, etc.) can provide a new way for the storage of renewable energy, especially when there is excess electricity, which can be converted into chemical energy for storage. Multi-carbon products such as ethanol, propylene, ethylene, etc. can be widely used in the chemical industry for the production of plastics, solvents and other important chemical products.

[0005] However, Cu-based electro-catalysts have poor selectivity for catalyzing CO2 reduction products, and the ability to reduce multi-carbon products needs to be further improved. SUMMARY

[0006] The purpose of the present application is to provide a F-doped Cu x O catalyst and its preparation method and application. In order to overcome the shortcomings of Cu-based electro-catalysts for catalyzing CO2 reduction products with poor selectivity, a metal copper source, ammonia water and sodium hydroxide are mixed and precipitated, then mixed uniformly with sodium fluoride, and then subjected to a process of Joule heat treatment to obtain a F-doped CuO / Cu2O catalyst. The structure of the nanosheet obtained by this preparation method not only reduces the charge transfer resistance, but also greatly increases the number of exposed active sites of the catalyst, thereby improving the ability of electro-catalytic CO2 reduction to multi-carbon products.

[0007] To achieve the above purpose, the present application provides a F-doped Cu x O catalyst and its preparation method and application, comprising the following steps:

[0008] Weigh the copper sulfate pentahydrate and dissolve it in deionized water, and stir to form a uniform solution A;

[0009] Add ammonia water to the uniform solution A and stir for 20 min to form solution B;

[0010] Add sodium hydroxide solution to solution B, stir for 20 min, wash, filter, dry and collect to obtain a blue solid powder sample;

[0011] Mix the blue solid powder sample with NaF uniformly, and then heat it under a voltage of 30V and a current of 200A by Joule heating, and then wash, filter, dry and collect to obtain a F-doped Cu x O catalyst.

[0012] In the step of "weighing the copper sulfate pentahydrate and dissolving it in deionized water, and stirring to form a uniform solution A";

[0013] The amount of copper sulfate pentahydrate used is 1g to 2g; the amount of deionized water used is 20 to 40mL; and the stirring time is 15 to 30min.

[0014] Among them, in the sentence "Add ammonia water to a homogeneous solution A and stir for 20 minutes to form solution B";

[0015] The amount of ammonia water used is 1 to 5 mL.

[0016] Among them, in the sentence “Add sodium hydroxide solution to solution B, stir for 20 min, wash, filter, dry and collect to obtain a blue solid powder sample”;

[0017] The sodium hydroxide concentration is 0.2 mol / L, and the volume is 20 mL.

[0018] The process involved mixing a blue solid powder sample with NaF, heating it at 30V and 200A using Joule heating, followed by washing, filtering, drying, and collecting to obtain F-doped Cu. x In "O catalyst";

[0019] The amount of blue solid powder sample used is 0.3–0.5 g, and the amount of NaF used is 0.6–0.8 g.

[0020] The present invention also includes an F-doped Cu x O catalyst, using the aforementioned F-doped Cu x The O catalyst was prepared using a specific method.

[0021] The present invention also includes an F-doped Cu x The application of O catalysts is in the electrocatalytic reduction of CO2.

[0022] An F-doped Cu of the present invention x O catalysts, their preparation methods, and applications, with the following beneficial effects:

[0023] The electrode material prepared by the Joule heating method of this invention has the characteristics of simple operation steps, mild processing conditions, short reaction time, low energy consumption, and environmental friendliness. It is suitable for mass production and has certain application prospects.

[0024] Compared with existing technologies, the significant advantages of this invention are: it can effectively improve the poor selectivity of Cu-based electrocatalytic reduction of CO2; secondly, the in-situ pyrolysis method of this invention is simple and easy to implement, with good reproducibility, strong controllability, and is environmentally friendly, with mild synthesis conditions, which is conducive to large-scale preparation and application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0026] Figure 1 F-doped Cu prepared by the Joule heating method in Example 3 x XRD pattern of the F-doped Cu O catalyst.

[0027] Figure 2 F-doped Cu prepared by the Joule heating method in Example 3 x XPS pattern of the F element of the F-doped Cu O catalyst.

[0028] Figure 3 F-doped Cu prepared by the Joule heating method in Example 3 x SEM pattern of the F-doped Cu O catalyst.

[0029] Figure 4 F-doped Cu prepared by the Joule heating method in Example 3 x Electrocatalytic CO2 reduction performance graph of the F-doped Cu O catalyst.

[0030] Figure 5 Performance comparison graph of the catalyst materials in Examples 1, 2, and 3 for use in electrocatalytic CO2 to prepare multi-carbon products.

[0031] Figure 6 Current density comparison graph corresponding to the performance of the catalyst materials in Examples 1, 2, and 3 for use in electrocatalytic CO2 to prepare multi-carbon products.

[0032] Figure 7 F-doped Cu O catalyst of the present application x Flowchart of the preparation method of the F-doped Cu O catalyst of the present application. DETAILED DESCRIPTION

[0033] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, the embodiments described below by reference to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0034] F-doped Cu O catalyst of the present application x The preparation method of the F-doped Cu O catalyst of the present application comprises the following steps:

[0035] S101: weigh copper sulfate pentahydrate, dissolve in deionized water, and stir to form a uniform solution A;

[0036] S102: add ammonia water to the uniform solution A, and stir for 20 min to form solution B;

[0037] S103: add sodium hydroxide solution to solution B, stir for 20 min, wash, filter, dry, and collect to obtain a blue solid powder sample;

[0038] S104: The blue solid powder sample is mixed with NaF uniformly, and then is joule heated under a voltage of 30 V and a current of 200 A, and then is washed, filtered, dried, and collected to obtain F-doped Cu x O catalyst.

[0039] The experimental methods used in the following examples are conventional methods unless otherwise specified.

[0040] The materials, reagents, etc. used in the following examples can be obtained commercially unless otherwise specified.

[0041] Example 1: 1 g of copper sulfate pentahydrate is weighed, added to 20 mL of deionized water, and stirred for 15 min to obtain solution A, 1.08 mL of an ammonia water solution with a concentration of 28% is added to solution A, and stirred for 20 min to obtain solution B, 20 mL of a sodium hydroxide solution with a concentration of 0.2 M is added to solution B again, and stirred for 20 min before being centrifuged and dried to obtain Cu(OH)2electrocatalytic material.

[0042] Example 2: 1 g of copper sulfate pentahydrate is weighed, added to 20 mL of deionized water, and stirred for 15 min to obtain solution A, 1.08 mL of an ammonia water solution with a concentration of 28% is added to solution A, and stirred for 20 min to obtain solution B, 20 mL of a sodium hydroxide solution with a concentration of 0.2 M is added to solution B again, and stirred for 20 min before being centrifuged and dried to obtain a blue solid powder sample. 0.3 g of the obtained sample is joule heated under a nitrogen atmosphere for 10 s, and then washed, filtered, dried, and collected to obtain F-doped Cu x O catalyst (CuO / Cu2O electrocatalytic material).

[0043] Example 3: 1 g of copper sulfate pentahydrate is weighed, added to 20 mL of deionized water, and stirred for 15 min to obtain solution A, 1.08 mL of an ammonia water solution with a concentration of 28% is added to solution A, and stirred for 20 min to obtain solution B, 20 mL of a sodium hydroxide solution with a concentration of 0.2 M is added to solution B again, and stirred for 20 min before being centrifuged and dried to obtain a blue solid powder sample. 0.3 g of the obtained sample is joule heated under a nitrogen atmosphere for 10 s, and then washed, filtered, dried, and collected to obtain F-doped Cu x O catalyst (CuO / Cu2O electrocatalytic material).

[0044] The structure test of the prepared sample is completed on a German Bruker D8 type ray diffraction instrument (XRD Cu-Kα ray, scanning rate is 7° min-1, and the range is 10°-80°) and a Japanese Shimadzu AXIS type X-ray photoelectron spectrometer (XPS monochromatic Al Kα source, energy is 1486.6 eV). ​

[0045] As Figure 1 (XRD) and Figure 2 (XPS) clearly indicated that the phase of the prepared sample was F-doped CuO / Cu2O, indicating the successful preparation of the composite catalyst.

[0046] Figure 3 For the SEM spectrum of the F-doped CuO / Cu2O electrocatalytic material in Example 3, we can see the nano-cluster-shaped catalyst material.

[0047] Electrocatalytic activity test: The electrocatalytic CO2 reduction performance test of the synthesized sample was carried out in a CHI 660E electrochemical workstation produced by Shanghai Chenhua Company.

[0048] After the electrocatalyst material prepared in the example was ground into powder, 2 mg was taken into a mixed solution composed of 250 μL of anhydrous ethanol, 250 μL of deionized water and 10 μL of Nafion, and ultrasonic oscillation was carried out for 30 min to make the catalyst powder completely suspended in the solution. The gas diffusion electrode sheet was cut into a size of 1*2.5 cm, and the cut gas diffusion electrode sheet was placed on a heating table. After the temperature was stabilized at 80°C, 500 μL of the catalyst suspension was uniformly coated on the gas diffusion electrode sheet and used as the working electrode. A saturated Ag / AgCl electrode and a Pt electrode were used as the reference electrode and the counter electrode, respectively, and the electrolyte was 1.0 M potassium hydroxide solution. The electrochemical measurement was carried out using a Shanghai CHI 660E electrochemical workstation (CH Instruments Inc.). Before each electrochemical measurement, an activation process was carried out at a potential of -1.2 to -2.6 V vs. Ag / AgCl. Linear sweep voltammetry (LSV) was used to determine the activity range in 1.0 M KOH solution at a scan rate of 100 mV s-1. Current-time (i-t) was used to determine the performance in 1.0 M KOH solution at -1.6 to -2.6 V vs. Ag / AgCl.

[0049] Figure 4 For the activity graph of the electrocatalytic CO2 reduction in Example 3.

[0050] Figure 5 For the performance comparison graph of the catalyst material for the electrocatalytic CO2 preparation of multi-carbon products in Examples 1, 2, and 3.

[0051] Figure 6 For the current comparison graph corresponding to the performance of the catalyst material for the electrocatalytic CO2 preparation of multi-carbon products in Examples 1, 2, and 3, it can be seen from the graph that the F-doped CuO / Cu2O catalyst nano-catalyst prepared according to Example 3 exhibits excellent performance in the electrocatalytic CO2 reduction to multi-carbon products.

[0052] Figure 7 Preparation of F-doped Cu x Flow chart of the method for preparing the O catalyst.

[0053] The above disclosure only represents one or more preferred embodiments of the present application, and cannot limit the scope of the present application. Those skilled in the art can understand that the implementation of all or part of the above processes, and the equivalent changes made according to the claims of the present application, still belong to the scope covered by the present application.

Claims

1. An F-doped Cu x The method for preparing the O catalyst is characterized in that, Includes the following steps: Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and stir to form a homogeneous solution A; Add ammonia water to a homogeneous solution A and stir for 20 minutes to form solution B; Add sodium hydroxide solution to solution B, stir for 20 min, wash, filter, dry and collect to obtain a blue solid powder sample; The blue solid powder sample was mixed evenly with NaF, heated by Joule heating at 30 V and 200 A, and then washed, filtered, dried and collected to obtain the F-doped CuO / Cu2O catalyst.

2. The F-doped Cu as described in claim 1 x The method for preparing the O catalyst is characterized in that, The copper sulfate pentahydrate was weighed, dissolved in deionized water, and stirred to form a homogeneous solution A; The amount of copper sulfate pentahydrate used is 1g~2g; the amount of deionized water used is 20~40mL; the stirring time is 15~30min.

3. The F-doped Cu as described in claim 1 x The method for preparing the O catalyst is characterized in that, Ammonia water is added to the homogeneous solution A and stirred for 20 minutes to form solution B; The amount of ammonia water used is 1~5 mL.

4. The F-doped Cu as described in claim 1 x The method for preparing the O catalyst is characterized in that, Sodium hydroxide solution was added to solution B, stirred for 20 min, washed, filtered, dried, and collected to obtain a blue solid powder sample. The sodium hydroxide concentration is 0.2 mol / L, and the volume is 20 mL.

5. The F-doped Cu as described in claim 1 x The method for preparing the O catalyst is characterized in that, The blue solid powder sample was mixed uniformly with NaF, then Joule heated at 30 V and 200 A, followed by washing, filtering, drying, and collection to obtain F-doped Cu. x In O catalyst; The amount of blue solid powder sample used is 0.3~0.5 g, and the amount of NaF used is 0.6~0.8 g.

6. An F-doped CuO / Cu2O catalyst, characterized in that, Using F-doped Cu as described in any one of claims 1-5 x The O catalyst was prepared using a specific method.

7. An application of an F-doped CuO / Cu2O catalyst, employing the F-doped CuO / Cu2O catalyst as described in claim 6, characterized in that, It is used for electrocatalytic CO2 reduction.

Images