CN114635153B - A kind of defect-rich copper-based nanocatalyst and its preparation method and application - Google Patents

Abstract

The invention discloses a copper-based nano catalyst rich in defects, and a preparation method and application thereof. Placing the Wide alloy in an acid solution dissolved with a corrosion inhibitor for standing reaction, washing, filtering and vacuum drying after the reaction to obtain the copper-based nano catalyst rich in defects. The catalyst can be applied to electrocatalytic reduction of carbon dioxide into high carbon compounds (C2+). The invention adopts a very simple and controllable preparation process, prepares the copper-based nano catalyst rich in a large number of defects such as vacancies, steps, dislocation and the like by dealloying through a one-step chemical etching method, and has excellent performance on electrochemical reduction of carbon dioxide into ethylene and ethanol, and the selectivity of a C2 product is higher than 60 percent.

Description

A kind of defect-rich copper-based nanocatalyst and its preparation method and application

technical field

The invention belongs to the technical field of electrocatalysis, and in particular relates to a copper-based nano-catalyst rich in defects, a preparation method and application thereof.

Background technique

Since the industrial revolution, a large amount of fossil energy has been exploited and utilized, which has inevitably caused serious environmental problems and energy crises. Among them, the excessive emission of carbon dioxide has formed a serious greenhouse effect, threatening the survival and development of human beings in the future. Electrocatalytic carbon dioxide reduction technology can use renewable electric energy to electrocatalytically reduce carbon dioxide captured from the atmosphere into a series of chemicals and fuels (carbon monoxide, methane, formic acid, ethylene, ethanol, etc.) Close the cycle, which can not only alleviate the energy crisis and the greenhouse effect, but also convert intermittent renewable electrical energy into chemical energy containing carbon compounds for storage and transportation. The electrochemical reduction of carbon dioxide can generate a variety of carbon products, and those containing two or more carbons are considered to be multi-carbon compounds (C2+). Such carbon-containing compounds are regarded as high value-added products due to their high energy density, and have more great commercial value. Therefore, the electrocatalytic reduction of carbon dioxide to specific multi-carbon compounds is considered to be a promising technology path.

Carbon dioxide is an extremely stable molecule, so the core technology for the electrochemical reduction of carbon dioxide to high-carbon compounds is to develop electrochemical catalysts with high activity and high selectivity. Metal copper has attracted extensive attention and research because of its proper binding force to the reaction intermediates of high-carbon compounds and its unique catalytic performance. At present, a large number of copper-based materials such as oxidized copper, alloyed copper, doped copper, and alloyed copper have been prepared and studied. For example, the patented method for preparing carbon-containing compounds by electrocatalyzing carbon dioxide with a copper alloy material discloses an amorphous copper alloy material that can electrocatalyze carbon dioxide into alcohol or acid-like carbon products. In addition, precise control of alloy components is required, and the overall preparation conditions are more complicated. In the current research, no universal high-activity reaction sites and mature material development technology have been found, and the selectivity and activity of carbon dioxide electrocatalytic reduction of high-carbon compounds are still a huge challenge.

Recently, it has been shown that defect sites in copper-based materials can promote the adsorption of multicarbon compound *CO reaction intermediates and reduce the activation energy of C–C coupling reactions, resulting in high selectivity and activity for multicarbon compounds. For example, Zheng Gengfeng's research group prepared grain-boundary-rich cuprous oxide by rapid cooling (Yang C, Shen H, Guan A, et al. Fast cooling induced grain-boundary-rich copper oxide for electrocatalyticcarbon dioxide reduction to ethanol[J ].Journal of Colloid and InterfaceScience,2020,570:375-381.), the material shows better performance for high carbon compounds. However, the defect type of this catalyst is mainly the grain boundary, and its preparation process is also relatively complicated, including multiple steps such as oxidation, reduction, and liquid nitrogen cooling, and it is difficult to prepare on a large scale. Therefore, how to develop a stable, controllable, defect-rich, high-performance copper-based catalyst that can be produced on a large scale with a simple preparation method is an urgent problem to be solved in the field of carbon dioxide electrocatalytic reduction.

Contents of the invention

Based on the existing technical problems, the object of the present invention is to provide a defect-rich copper-based nanocatalyst and its preparation method and application. The defect-rich copper-based nanocatalyst is prepared through an extremely simple and controllable process technology, and the defect-rich copper-based nanocatalyst is used for efficiently electrocatalyzing the reduction of carbon dioxide to high-carbon compounds. The invention adopts a one-step chemical etching method to dealloy the pulverized Divide alloy particles with acid to prepare a copper-based nano-catalyst rich in a large number of defect sites (vacancies, steps, dislocations). The catalyst exhibits excellent selectivity and activity towards ethylene and ethanol in the electrochemical reduction of carbon dioxide.

In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

A method for preparing a copper-based nanocatalyst rich in defects, comprising the following steps:

(1) pulverize the Ti Weed alloy purchased with a pulverizer, and screen the Ti Weed alloy particles with uniform particle size;

(2) placing the sifted Tiweed alloy particles with uniform particle size in an acid solution containing a corrosion inhibitor, and heating for a period of time;

(3) washing the reacted particles, suction filtering, and drying in a vacuum environment to obtain a defect-rich copper-based nanocatalyst.

Further, the Ti Weed alloy described in step (1) is an aluminum-copper-zinc alloy.

Further, the mesh number of the Weed alloy particles in step (1) is 200-300 mesh.

Further, the acid solution in step (2) is at least one of hydrochloric acid solution, sulfuric acid solution, phosphoric acid solution, and perchloric acid solution.

Further, the mass fraction of the acid solution in step (2) is 5%-20%.

Further, the corrosion inhibitor in step (2) is at least one of benzotriazole, tolylbenzotriazole, and mercaptobenzothiazole.

Further, the mass percent content of the corrosion inhibitor in the acid solution containing the corrosion inhibitor in step (2) is 0.1%-1%.

Further, the temperature of the heating reaction in step (2) is 30-80° C., and the time of the heating reaction in step (2) is 1-12 hours.

The heating reaction time of step (2) is 1-6 hours.

Further, the particles after the reaction in step (3) are washed 2-6 times with water and ethanol respectively.

Further, the particles after the reaction in step (3) are washed three times with water and ethanol respectively.

Further, the drying in step (3) is drying in a vacuum oven at 20-80°C for 6-12h.

Further, the reacted particles in step (3) were washed and filtered with suction and then dried in a vacuum oven at 60° C. for 10 h.

The invention provides a defect-rich copper-based nano catalyst prepared by the preparation method.

The present invention also provides the application of the defect-rich copper-based nano-catalyst in the electrocatalytic reduction of carbon dioxide to high-carbon compounds (C2+).

Further, the defect-rich copper-based nanocatalyst was drop-coated on a glassy carbon electrode as a working electrode, silver-silver chloride was used as a reference electrode, a platinum sheet was used as a counter electrode, and potassium bicarbonate solution was used as an electrolyte. The electrocatalytic carbon dioxide reduction reaction was carried out in an electrolytic cell.

Further, the concentration of the potassium bicarbonate solution is 0.1M.

Compared with prior art, the beneficial effect of the present invention is:

(1) The present invention uses an acid solution, a corrosion inhibitor, and a Weed alloy as raw materials, and reacts statically to prepare a defect-rich copper-based nanocatalyst. The preparation method is extremely simple, the reaction condition is mild, the controllability is strong, the repeatability is high, and it is beneficial to large-scale production.

(2) The copper-based nanocatalyst prepared by the present invention contains a large number of defect sites such as vacancies, steps, and dislocations. These defect-rich copper-based nanocatalysts can be stored for a long time without special protection.

(3) The defect-rich copper-based nanocatalyst prepared by the present invention is beneficial to adsorb *CO reaction intermediates, reduce the activation energy of C-C coupling reaction, and exhibit high performance in the electrochemical reduction of carbon dioxide to high-carbon compounds.

Description of drawings

Fig. 1 is the SEM characterization diagram of the obtained 200-300 mesh Divide alloy particles (P-AlCuZn).

2 is a SEM characterization diagram of the defect-rich copper-based nanocatalyst (DeCu-3W) obtained in Example 1.

3 is a TEM characterization diagram of the defect-rich copper-based nanocatalyst ((DeCu-3W)) obtained in Example 1.

FIG. 4 is a SEM characterization diagram of the less defective copper-based nanocatalyst (DeCu-3WO) obtained in Comparative Example 1.

FIG. 5 is a TEM characterization diagram of the less defective copper-based nanocatalyst (DeCu-3WO) obtained in Comparative Example 1.

Fig. 6 shows the obtained 200-300 mesh Deweed alloy (P-AlCuZn) particles, the defect-rich copper-based nanocatalyst (DeCu-3W) obtained in Example 1, and the copper-based nanocatalyst (DeCu-3W) with less defects obtained in Comparative Example 1. XRD characterization pattern of the catalyst (DeCu-3WO).

Fig. 7 is the electrocatalytic _CO2 reduction product distribution diagram of the defect-rich copper-based nanocatalyst ((DeCu-3W)) obtained in Example 1.

Detailed ways

The present invention will be described in further detail below through specific examples. The following examples can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

A kind of preparation method of Weed alloy particle (P-AlCuZn), described preparation method comprises the following steps:

(1) Take by weighing 5g of Tiweed alloy purchased in a pulverizer, pulverize for 10s, and collect pulverized particles;

(2) Sieve the particles in step (1) sequentially with a standard sampling sieve, and screen out 200-300 mesh Alloy particles (P-AlCuZn).

Fig. 1 is the SEM image of the obtained 200-300 mesh Diweed alloy particles (P-AlCuZn), and it can be observed from Fig. 1 that the Diweed alloy particles present a smooth granular shape.

Example 1

The present embodiment provides a kind of preparation method of defect-rich copper-based nanocatalyst (DeCu-3W), and described preparation method comprises the following steps:

(1) preparation mass fraction is the hydrochloric acid solution of 10%, dissolves benzotriazole in the hydrochloric acid solution, obtains the hydrochloric acid solution containing benzotriazole, in the hydrochloric acid solution containing benzotriazole, benzotriazole The mass percentage of azole is 0.3%;

(2) Weigh 0.25g of 200-300 mesh Verde alloy particles (P-AlCuZn), pour the Verde alloy particles into the hydrochloric acid solution containing benzotriazole obtained in step (1), at 80°C Stand still and react for 3 hours;

(3) Pour off the remaining solution after the reaction stops, wash three times with deionized water and absolute ethanol, filter with suction, and dry the collected particles in a vacuum drying oven at 60°C for 10 hours to obtain defect-rich copper-based nanoparticles. Catalyst (DeCu-3W).

Fig. 2 is the scanning electron microscope (SEM) figure that is rich in the copper-based nanocatalyst (DeCu-3W) of the defect of embodiment 1 gained, can observe the copper-based nanocatalyst (DeCu-3W) that is rich in the defect of gained from Fig. 2 ) presents the shape of elliptical nanoparticles (approximately 250 nm) with cracks all over the surface. Fig. 3 is the transmission electron microscope (TEM) figure of the copper-based nanocatalyst (DeCu-3W) that is rich in the defect of embodiment 1 gained, as can be seen from Fig. 3, the surface of the copper-based nanocatalyst that is rich in the defect of gained There is a thin layer of Cu(OH) ₂ filled with crystal lattice, which contains three kinds of crystal plane orientations, namely (211), (012), (122) (see the mark on the upper left corner of b in Figure 3), and There are lattice defects such as steps and dislocations on the edge of the thin layer (see the upper right corner of b in Figure 3, the steps are marked by dots, and the dislocations are framed by boxes).

Example 2

The present embodiment provides a kind of preparation method of defect-rich copper-based nanocatalyst (DeCu-4W), and described preparation method comprises the following steps:

(1) preparation mass fraction is the hydrochloric acid solution of 20%, dissolves benzotriazole in the hydrochloric acid solution, obtains the hydrochloric acid solution containing benzotriazole, the hydrochloric acid solution containing benzotriazole in the benzotriazole The mass percentage of azole is 1%;

(2) Weigh 0.25g of 200-300 mesh Verde alloy particles (P-AlCuZn), pour the Verde alloy particles into the hydrochloric acid solution containing benzotriazole obtained in step (1), at 80°C Stand still and react for 1 hour;

(3) After the reaction stopped, the remaining solution was discarded, washed six times with deionized water and absolute ethanol, filtered with suction, and the collected particles were dried in a vacuum oven at 80°C for 6 hours.

Example 3

The present embodiment provides a kind of preparation method of defect-rich copper-based nanocatalyst (DeCu-6W), and described preparation method comprises the following steps:

(1) preparation mass fraction is the sulfuric acid solution of 5%, dissolves tolyl benzotriazole in the sulfuric acid solution, obtains the sulfuric acid solution containing tolyl benzotriazole, described containing tolyl benzotriazole The mass percentage of tolyltriazole in the sulfuric acid solution is 0.1%;

(2) take by weighing 0.25g 200-300 purpose Verde alloy particles (P-AlCuZn), the Verde alloy particles are poured into the sulfuric acid solution containing tolyl benzotriazole that step (1) obtains, in Stand at 30°C for 12 hours;

(3) Pour off the remaining solution after the reaction stops, wash three times with deionized water and absolute ethanol, filter with suction, and dry the collected particles in a vacuum drying oven at 20°C for 12 hours to obtain defect-rich copper-based nanoparticles. Catalyst (DeCu-6W).

Comparative example 1

The present embodiment provides a kind of preparation method of copper-based nano-catalyst (DeCu-3WO) with less defects, and described preparation method comprises the following steps:

(1) preparation mass fraction is the hydrochloric acid solution of 10%;

(2) Weigh 0.25g of 200-300 mesh Divide alloy particles (P-AlCuZn), pour the Divide alloy particles into the hydrochloric acid solution, and stand for reaction at 80°C for 3 hours;

(3) Pour off the remaining solution after the reaction stops, wash three times with deionized water and absolute ethanol, filter with suction, and dry the collected particles in a vacuum drying oven at 60°C for 10 hours to obtain a copper-based solution with fewer defects. Nanocatalyst (DeCu-3WO).

Fig. 4 is the SEM figure of the less defective copper-based nanocatalyst (DeCu-3WO) obtained in Comparative Example 1, from Fig. 4 it can be observed that the less defective copper-based nanocatalyst (DeCu-3WO) of gained presents surface roughness , Large particles (approximately 300 nm) with small particles attached. Fig. 5 is the TEM figure of the less defective copper-based nano-catalyst (DeCu-3WO) of comparative example 1 gained, as can be seen from the figure, the surface of catalyst has one deck amorphous thin layer, contains a small amount of crystal in this thin layer Domain, the Fourier transform diffraction pattern of this crystal domain shows that it contains 211 crystal plane (see the mark in the upper left corner of b in Figure 5), and there are lattice defects such as vacancies and dislocations in these crystal domains (see the upper right corner of b in Figure 5 corners, vacancies are circled, and dislocations are framed by boxes).

The 200-300 mesh Verde alloy particles (P-AlCuZn) obtained above, the defect-rich copper-based nanocatalyst (DeCu-3W) obtained in Example 1 and the less defective copper-based nanocatalyst (DeCu-3W) obtained in Comparative Example 1 -3WO) X-ray diffraction (XRD) characterization results are shown in Figure 6. The main phase structure of P-AlCuZn is Al ₂ Cu, and the second is Al _4.2 Cu _3.2 Zn _0.7 . Both DeCu-3W and DeCu-3WO obtained by etching have basically lost their original phase structure, indicating that the composition and structure of the Deweed alloy have completely changed.

The defect-rich copper-based nanocatalyst (DeCu-3W) prepared in Example 1 was used to electrocatalyze the carbon dioxide reduction reaction.

The electrocatalytic carbon dioxide reduction reaction is carried out in an H-type electrolytic cell of a three-electrode system, and the electrolytic cell is separated from the cathode and the anode by a proton exchange membrane. Catalyst, isopropanol and Nafion solution are mixed ultrasonically to form a uniform slurry, and the slurry is dropped onto a glassy carbon electrode to form a working electrode. The reference electrode is a silver-silver chloride electrode, the counter electrode is a platinum sheet, and the electrolyte is CO ₂ saturated 0.1 M potassium bicarbonate solution. Carbon dioxide undergoes an electrolytic reduction reaction at a constant voltage, and CO ₂ gas is continuously fed during the electrolytic reaction.

The defect-rich copper-based nanocatalyst (DeCu-3W) prepared in Example 1 was tested at different voltages (respectively-1.0Vvs RHE,-1.1V vs RHE,-1.2V vs RHE,-1.3V vs RHE,-1.4V vs RHE) The product distribution of the electrocatalytic CO2 reduction is shown in Fig. 7. It can be seen from Figure 7 that in the voltage range of -1.0V to -1.3V, the faradaic efficiency of hydrogen is about 20%, which shows that the copper-based nanocatalyst rich in defects has good hydrogen suppression performance, and has a certain effect on the reduction path of carbon dioxide. stronger tendencies. At -1.0V, the Faradaic efficiency of CO is 30%. As the voltage increases, the yield of CO decreases significantly, and the generation of C2 products (ethylene and ethanol) continues to increase. It reaches the optimum at -1.3V, that is, Faradaic The excellent selectivity with an efficiency higher than 60% indicates that the defect-rich copper-based nanocatalysts can strongly adsorb *CO intermediates, and can effectively reduce the activation energy of C-C coupling reactions and promote C-C coupling at a suitable voltage. reaction, resulting in a large number of high-carbon compounds.

Finally, it should be noted that: the detailed descriptions of the above embodiments and associated drawings are only used to illustrate the technical solutions of the present invention and not to limit them, and the present invention is not limited to the above-mentioned specific implementation methods. Under the enlightenment of the present invention, any modification or equivalent replacement without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims (7)

1. A method for preparing a copper-based nano catalyst rich in defects, which is characterized by comprising the following steps:

(1) Crushing the purchased Wildd alloy by a crusher, and screening the Wildd alloy particles with uniform granularity; the mesh number of the Wide alloy particles is 200-300 meshes;

(2) Placing the screened Wide alloy particles with uniform granularity into an acid solution containing a corrosion inhibitor, and heating for reaction; the mass fraction of the acid solution is 5% -20%; the corrosion inhibitor is more than one of benzotriazole and methylbenzotriazole; the mass percentage of the corrosion inhibitor in the acid solution containing the corrosion inhibitor is 0.1% -1%; the temperature of the heating reaction is 30-80 ℃, and the time of the heating reaction is 1-12 hours;

(3) Washing the reacted particles, filtering, and drying in a vacuum environment to obtain the copper-based nano catalyst rich in defects.

2. The method of claim 1, wherein the first wid alloy in step (1) is an aluminum-copper-zinc alloy.

3. The method for preparing the defect-rich copper-based nano catalyst according to claim 1, wherein the acid solution in the step (2) is one or more of hydrochloric acid solution, sulfuric acid solution, phosphoric acid solution and perchloric acid solution.

4. The method for preparing a defect-rich copper-based nanocatalyst according to claim 1, wherein the washing of the reacted particles in step (3) is performed 3 to 6 times with water and ethanol, respectively; and (3) drying in the step (3) in a vacuum drying oven at 20-80 ℃ to dry 6-12h.

5. A defect-rich copper-based nanocatalyst prepared by the method of any of claims 1-4.

6. Use of a defect-rich copper-based nanocatalyst according to claim 5 for electrocatalytic reduction of carbon dioxide to higher carbon compounds.

7. The use of a defect-rich copper-based nano-catalyst according to claim 6 for electrocatalytic reduction of carbon dioxide to high carbon compounds, wherein the defect-rich copper-based nano-catalyst is dripped on a glassy carbon electrode as a working electrode, silver-silver chloride as a reference electrode, a platinum sheet as a counter electrode, and a potassium bicarbonate solution as an electrolyte, and electrocatalytic reaction is performed in an H-cell.

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