Preparation method and application of flaky Cu electrode material

Abstract

The invention discloses a preparation method and application of a flaky Cu electrode material, and the preparation method comprises the following steps: S1, dispersing a CuO catalyst into a mixed solution containing isopropanol, perfluorosulfonic acid, tetrahydrofuran and carbon nanotubes, and finally preparing CuO catalyst slurry; and S2, dispensing the slurry on a gas diffusion layer, and carrying out reduction pretreatment to obtain the Cu electrode material. The method has the following beneficial effects that eNO3-RR is carried out in a flowing electrolytic cell by using prepared flaky Cu and commercial blocky Cu as catalysts, a stable fluid field is constructed by using two-dimensional flaky Cu as an electrocatalyst and removing carrier gas in a microfluid flowing electrolytic cell, and the catalytic performance of eNO3-RR can be remarkably improved. In one embodiment of the invention, the eNO3-RR system has relatively high NH3 selectivity and yield of 0.93 mmol cm <-2 > h <-1 > under the potential condition of a relative reversible hydrogen electrode of-0.68 V; when the current density is 900 mAcm <-2 >, the yield of NH3 can reach 3.14 mmol cm <-2 > h <-1 >.

Description

Technical Field

[0001] This invention belongs to the field of energy conversion materials, specifically a method for preparing sheet-like Cu electrode materials and their applications. Background Technology

[0002] Ammonia (NH3) is both an important chemical in agricultural production and an emerging carbon-free liquid fuel. Currently, NH3 is mainly synthesized via the Haber-Bosch process, but this traditional process is energy-intensive and highly polluting. Therefore, researchers are focusing on developing green methods for ammonia synthesis. In recent years, nitrogen reduction reaction (NRR) powered by renewable energy has shown promise for ammonia production. However, due to the low solubility of N2 and the difficulty in breaking the N≡N bond (dissociation energy: 941 kJ·mol⁻¹),... -1 This severely limits the efficient synthesis of NH3. Furthermore, nitrates (NO3)... - NO3- is considered a nitrogen-containing pollutant in nature. The widespread use of artificial fertilizers, the combustion of fossil fuels, and industrial activities all contribute to the formation of NO3-. - It accumulates in groundwater, surface water, animals, and plants. Humans ingest NO3. - It may lead to diseases such as non-Hodgkin's lymphoma and methemoglobinemia. Therefore, using the pollutant nitrate as a nitrogen source to produce eNO3... - RR synthesis of ammonia is a green and environmentally friendly feasible strategy.

[0003] Therefore, this invention aims to investigate the morphology of Cu-based materials and the influence of carrier gas on the stability of the fluid field in a flowing electrolytic cell, and to develop a highly active electrochemical reduction system for nitrates. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide a method for preparing sheet-like Cu electrode materials and their applications.

[0005] The technical solution adopted in this invention is as follows: The first invention provides a method for preparing a sheet-like Cu electrode material, comprising the following steps: S1. Disperse CuO catalyst in a mixture containing isopropanol, perfluorosulfonic acid, tetrahydrofuran and carbon nanotubes to finally prepare CuO catalyst slurry; S2. The slurry is drop-coated onto the gas diffusion layer and subjected to reduction pretreatment to obtain Cu electrode material.

[0006] In another aspect, the present invention provides an electrolytic cell system for generating NH3, wherein the cathode is prepared using the Cu electrode material as described in claim 1.

[0007] Furthermore, there is no carrier gas in the electrolytic cell system.

[0008] Furthermore, it is applied to the electrochemical reduction of nitrates.

[0009] The beneficial effects of this invention are as follows: The prepared 2D plate-like Cu, utilizing the advantages of its 2D plate-like structure—namely, its large specific surface area and robust layered structure—provides abundant stable reaction sites, resulting in excellent electrochemical performance. Furthermore, the stable fluid field constructed using plate-like Cu and the removal of the carrier gas significantly improves the performance of the electrochemical reduction of nitrate, demonstrating the importance of constructing a stable fluid field and enabling it to react with NO3. - The field of transformation has enormous application potential and industrialization prospects. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0011] Figure 1 This is a scanning electron microscope image of the sheet-like Cu used in this invention; Figure 2 This is a scanning electron microscope image of the bulk Cu selected in this invention; Figure 3 This is a figure showing the results of the COMSOL multiphysics simulation of the effect of different morphologies on the stability of the catalyst interface fluid field. Figure 4 This is a figure showing the results of the simulation of the effect of carrier gas in the gas chamber of a flow electrolyzer on the stability of the fluid field at the catalyst interface using COMSOL multiphysics. Figure 5 eNO3 under the action of a stable fluid field - RR performance graph. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. However, the uses and purposes of these exemplary embodiments are only for illustrating the present invention and do not constitute any limitation on the actual scope of protection of the present invention, nor are they intended to limit the scope of protection of the present invention to these embodiments.

[0013] Example 1: Method for preparing sheet-like Cu catalyst S1: Dissolve 1 g Cu(NO3)2 in 100 mL of aqueous solution, then add 30 mL of ammonia water (0.15 mol∙L⁻¹) to the solution. -1 ) and 30 mL NaOH solution (1 mol∙L -1 Stir well and let stand for 30 minutes, then transfer to a hydrothermal reactor and heat at 130°C. o The reaction was carried out at C for 15 h. The liquid after the hydrothermal reaction was removed, washed several times with deionized water, and then subjected to a process at 50 °C. o Dry in a C oven overnight to obtain flake-shaped CuO powder. Disperse the flake-shaped CuO powder into a powder containing... n In a mixture of PrOH, THF and CNTs, Nafion is physically mixed, and the mixture is then sonicated for 30-60 min to prepare a flake-like CuO slurry.

[0014] S2: The prepared sheet-like CuO slurry is drop-coated onto GDL and subjected to a reduction treatment for 10 min to obtain a sheet-like Cu electrode.

[0015] Example 2: Method for preparing bulk Cu catalyst S1: Select commercially available bulk CuO powder and disperse it into a solution containing... n In a mixture of PrOH, THF and CNTs, Nafion is physically mixed, and the mixture is then sonicated for 30-60 min to prepare a blocky CuO slurry.

[0016] S2: The prepared bulk CuO slurry is drop-coated onto GDL and subjected to a reduction treatment for 10 min to obtain a bulk Cu electrode.

[0017] Example 3: Simulation of the effect of catalyst morphology and carrier gas presence on the stability of the fluid field at the catalyst interface using COMSOL multiphysics simulation: A two-dimensional finite element model was established to study eNO3. - The study investigated the difference in liquid flow velocity distribution between lamellar Cu and bulk micron-sized Cu during the RR process, as well as the effect of gas disturbance on the surface of lamellar Cu. The surface of the lamellar Cu electrode was assumed to be planar, while the surface of the bulk micron-sized Cu electrode was assumed to be a stacked cube. The geometric model was simulated in the micron range, including the main channel and the inlet. Both fluids (fluid 1: electrolyte, fluid 2: Ar) were considered incompressible and immiscible laminar fluids. This method was used to simulate the influence of catalyst morphology and the presence of a carrier gas on the stability of the fluid field at the catalytic interface.

[0018] Example 4: eNO3 reaction under stable fluid field conditions at the catalytic interface - RR performance test: Electrolysis was performed using a three-electrode system, with 0.3 mg∙cm⁻¹ drop-coated onto GDL. -2 The catalyst material was assembled into a flowing electrolyzer as the working electrode, with nickel foam as the anode and saturated Ag / AgCl as the reference electrode, using 1 mol∙L⁻¹. -1 KOH solution was used as the anolyte, and 1 mol∙L⁻¹ was used. -1 KOH and 0.5 mol∙L -1 A mixture of KNO3 was used as the cathode electrolyte. The content of NH3 produced was detected using a miniature ultraviolet Nessler (HANNA: HI 96715).

[0019] Characterization of the catalyst obtained in this invention, COMSOL multiphysics simulation, and eNO3 - The RR performance test results are as follows: 1. By Figure 1 As can be seen from the SEM image, the sheet-like Cu material has a uniform morphology and a novel structure, which is a micron-scale 2D sheet-like structure.

[0020] 2. By Figure 2 As can be seen from the SEM image, the morphology of the bulk Cu material is a micron-scale bulk structure.

[0021] 3. Figure 3 The figure shows the results of COMSOL multiphysics simulation of the effects of plate-shaped Cu and bulk Cu on the fluid field stability of the catalytic interface. Under the same initial flow rate and electric field, the electrolyte flow rate of plate-shaped Cu is nearly 200 times higher than that of bulk Cu. The uniform planar structure of plate-shaped Cu allows for continuous renewal of the electrolyte at the solid-liquid interface, thereby achieving the goal of reducing more electrolyte, which ensures the eNO3... - RR produces NH3 with long-term stability and high Faraday efficiency.

[0022] 4. Figure 4 The figure shows the effect of carrier gas in the gas chamber of a flow electrolyzer on the stability of the fluid field at the catalytic interface, as simulated by COMSOL multiphysics simulation. Once the carrier gas Ar enters the gas chamber, it easily covers the catalyst surface and forms a cavity within 1 ms, temporarily separating the electrolyte from the catalyst. Simultaneously, the bubbles also form fluid vortices, reducing the electrolyte flow rate and leading to increased eNO3 concentration. - RR activity decreased.

[0023] 5. Figure 5 This invention regulates the stable fluid field for eNO3. - Results of the study on the impact of RR performance.

[0024] The figure shows that the relatively localized static fluid field caused by the plate-like Cu structure and the absence of carrier gas contributes to the long-term stable operation of the flow electrolyzer at industrial current densities.- RR yields high NH3 Faradaic efficiency and yield, for example, achieving a Faradaic efficiency of up to 99% and a yield of 0.93 mmol∙cm⁻¹ at -0.68 V vs. RHE potential. -2 ∙h -1 The highest yield was at 900 mA∙cm⁻¹ -2 Under certain conditions, it can reach 3.14 mmol∙cm⁻¹ -2 ∙h -1 .

[0025] It should be understood that the above-disclosed embodiments are merely preferred embodiments of the present invention, and these embodiments are intended only to illustrate the present invention and not to limit the scope of protection of the present invention. Furthermore, it should be understood that after reading the technical content of the present invention, those skilled in the art can make various modifications or variations to the present invention, and all such equivalent forms also fall within the scope of protection defined by the appended claims.

Claims

1. A method for preparing a sheet-like Cu electrode material, characterized in that, Includes the following steps: S1. Disperse CuO catalyst in a mixture containing isopropanol, perfluorosulfonic acid, tetrahydrofuran and carbon nanotubes to finally prepare CuO catalyst slurry; S2. The slurry is drop-coated onto the gas diffusion layer and subjected to reduction pretreatment to obtain Cu electrode material.

2. An electrolytic cell system for generating NH3, characterized in that: The cathode is prepared using the Cu electrode material as described in claim 1.

3. The electrolytic cell system for generating NH3 according to claim 2, characterized in that: There is no carrier gas in the electrolytic cell system.

4. The electrolytic cell system for generating NH3 according to claim 2, characterized in that: It is used in the electrochemical reduction of nitrates.

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