A carbon-coated electrode with controllable interface microenvironment, its preparation method and application

Abstract

This invention relates to a carbon-coated electrode with controllable interface microenvironment, its preparation method, and its application. The carbon-coated electrode comprises a gas diffusion electrode substrate, a copper catalyst layer, and a carbon coating. The copper catalyst layer coats the outside of the gas diffusion electrode substrate, and the carbon coating coats the outside of the copper catalyst layer. The carbon coating forms a dense porous structure on the outside of the copper catalyst layer. The carbon particles in the carbon coating are 15–25 nm in size, and the copper catalyst layer contains several copper nanoparticles with a size of 60–100 nm. During fabrication, copper nanoparticles, a dispersant, and a binder are mixed to form a mixture containing copper nanoparticles, which is then uniformly sprayed onto the surface of the gas diffusion electrode to form the copper catalyst layer. Finally, a mixture of carbon-based nanomaterials and a dispersant is sprayed onto the surface of the copper catalyst layer to form the carbon coating. This invention uses a carbon coating to create hydrophobicity at the electrode interface, improving the interface microenvironment and enhancing the activity of CO electroreduction for ethylene production.

Description

Technical Field

[0001] This invention relates to the field of electrochemical catalysis, specifically to a carbon-coated electrode with controllable interface microenvironment, its preparation method, and its application. Background Technology

[0002] Global climate change is intensifying. Excessive emissions are one of the main contributing factors, achieving The utilization of resources is of great significance to the "dual carbon" goal. Electrochemical reduction ( ) can Converting CO into high-value chemicals is a sustainable and promising transformation pathway. CO electroreduction (CORR) is... Preparation of multi-carbon products ( This is a key intermediate step and the core reaction currently used for high current density and high ethylene / ethanol selectivity. It is extremely sensitive to the local environment and highly dependent on the regulation of the interfacial microenvironment, including microenvironmental factors such as local pH, local CO concentration, interfacial water content, ion concentration, and electric field distribution.

[0003] Interfacial coating strategies are a key technology for the industrialization of CO electroreduction catalysts. Current technologies focus on precise design of coating structures, interfacial electronic regulation, stability enhancement, and high current density adaptation. The core value lies in breaking through the bottlenecks of selectivity and lifetime of traditional catalysts, but there is a lack of research on the scale of interfacial analysis.

[0004] In existing technologies, the uncontrollable interfacial microenvironment, limited local CO mass transfer, and large local pH fluctuations in CO electroreduction catalysts lead to low CC coupling efficiency. The technical problems include poor product selectivity, severe HER side reactions, insufficient catalyst stability, and difficulty in adapting to the extremely high current density operation requirements of gas diffusion electrodes. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a carbon-coated electrode with controllable interface microenvironment, its preparation method, and its application. The carbon coating enables the electrode interface to become hydrophobic, thereby improving the interface microenvironment and enhancing the activity of CO electroreduction in the preparation of ethylene.

[0006] The technical objective of this invention is achieved through the following technical solution: A carbon-coated electrode with controllable interface microenvironment includes: a gas diffusion electrode substrate, a copper catalyst layer, and a carbon coating. The copper catalyst layer coats the outside of the gas diffusion electrode substrate, and the carbon coating coats the outside of the copper catalyst layer. The carbon coating forms a dense porous structure on the outside of the copper catalyst layer. The carbon particles in the carbon coating are 15–25 nm in size, and the copper catalyst layer contains several copper nanoparticles with a size of 60–100 nm. The dense porous structure formed by the carbon coating ensures the mass transfer of ions and water. Although there is close contact between the carbon layer and the copper catalyst layer, the 15–25 nm carbon particle size ensures the exposure of copper sites on the surface of the copper catalyst layer, providing sufficient space for reactant adsorption.

[0007] Furthermore, the loading of copper nanoparticles on the surface of the gas diffusion electrode is 0.6–1.5 mg / cm², and the loading of carbon coating particles on the surface of the copper catalyst layer is 0.1–0.5 mg / cm².

[0008] Furthermore, the thickness of the carbon coating is 200–1000 nm, and the thickness of the copper catalyst layer is 0.5–1.5 μm.

[0009] This invention also provides a method for preparing a carbon-coated electrode with controllable interface microenvironment, the method comprising: S1. Mix copper nanoparticles, dispersant and binder to form a mixture containing copper nanoparticles; S2. The mixture obtained in step S1 is uniformly sprayed onto the surface of the gas diffusion electrode to form a copper catalyst layer; S3. After mixing carbon-based nanomaterials and dispersants, spray them onto the surface of the copper catalyst layer to form a carbon coating.

[0010] Furthermore, the dispersant is an alcohol-based dispersant.

[0011] Furthermore, the dispersant is isopropanol, ethanol, or n-propanol.

[0012] Furthermore, the adhesive is Sustainion XA-9 solution.

[0013] Furthermore, the carbon-based nanomaterial is carbon black ink.

[0014] This invention also provides an application of a carbon-coated electrode with controllable interface microenvironment, which is used as a cathode in a membrane electrode electrolyzer for CO electrochemical reduction.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The interface microenvironment controllable carbon-coated electrode of the present invention can effectively improve the hydrophobicity of the electrode interface and improve the interface microenvironment through the surface carbon coating, which is beneficial to improving the activity of CO electroreduction to prepare ethylene.

[0016] 2. The preparation method of the controllable interface microenvironment carbon coating electrode of the present invention is simple, and the properties of the carbon layer can be adjusted by controlling the carbon layer spraying load.

[0017] 3. The interfacial carbon layer can rebuild the interfacial hydrogen bond network and enhance its orderliness, thereby inducing a hydrogenation step in the intermediate that is more favorable than hydrogen evolution in the CORR process.

[0018] 4. The Cu-C interface can modulate the vibrational dynamics of CO linear adsorption, enhance Cu-CO interaction, and reduce C / C coupling to CO. Energy barrier of the product. Attached Figure Description

[0019] Figure 1 This is a structural diagram of the carbon-coated electrode with controllable interface microenvironment according to the present invention.

[0020] Figure 2 This is a potential-total current density curve of the carbon-coated electrode in Embodiments 2-4 of the present invention in a flow cell.

[0021] Figure 3 This is the attenuated total reflectance infrared spectrum of the carbon-coated electrode in Examples 2-4 of this invention.

[0022] Figure 4 This is a CO depletion analysis graph obtained by DEMS measurement of the carbon-coated electrode and Cu electrode of the present invention.

[0023] Figure 5 This is a comparison diagram of the hydrogen evolution reaction during the operation of the carbon-coated electrode and the Cu electrode in the embodiments of the present invention.

[0024] Figure 6 This is a proton current diagram on the carbon-coated electrode and the Cu electrode in the embodiments of the present invention.

[0025] Figure 7 In this embodiment of the invention, the carbon-coated electrode and the Cu electrode are used in the preparation of CO reduction. Mass spectrometry ion current graph during the process.

[0026] Figure 8 On the carbon-coated electrode and Cu electrode in the embodiments of the present invention Comparison of logarithmic ion currents.

[0027] Figure 9 The carbon-coated electrode and Cu electrode in the embodiments of the present invention Feature diagram.

[0028] Figure 10 The carbon-coated electrode and the Cu electrode at different potentials in the embodiments of the present invention / Schematic diagram of the changes.

[0029] Figure 11 This is a schematic diagram of the application of the interface microenvironment controllable carbon coating electrode of the present invention in a membrane electrode electrolyzer.

[0030] In the picture: 1. Gas diffusion electrode substrate; 2. Copper catalyst layer; 3. Carbon coating; 4. Anode current collector; 5. Anode side gasket; 6. Anode diffusion electrode; 7. Anion exchange membrane; 8. Cathode diffusion electrode; 9. Cathode side gasket; 10. Cathode current collector. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to specific embodiments: Example 1 A method for preparing a carbon-coated electrode with controllable interface microenvironment, the method comprising: S1. Mix copper nanoparticles with a particle size of 60-100 nm, a dispersant, and a binder to form a mixture containing copper nanoparticles; the dispersant is an alcoholic dispersant, for example, isopropanol, ethanol, or n-propanol is used as the dispersant, and Sustainion XA-9 solution (5 wt.%, Dioxide Materials) is used as the binder. In one implementation, a commercial gas diffusion electrode (GDE, YLS-30T, Toray) was selected as the gas diffusion electrode substrate, with a thickness of approximately 240 μm.

[0032] S2. The mixture obtained in step S1 is uniformly sprayed onto the surface of the gas diffusion electrode to form a copper catalyst layer, wherein the thickness of the copper catalyst layer is 0.5-1.5 μm and the loading of copper nanoparticles on the surface of the gas diffusion electrode is 0.6-1.5 mg / cm². S3. After mixing the carbon-based nanomaterials and the dispersant, the mixture is sprayed onto the surface of the copper catalyst layer to form a carbon coating. The carbon particles in the carbon coating are 15-25 nm in size, the carbon coating particle loading on the surface of the copper catalyst layer is 0.1-0.5 mg / cm², and the thickness is 200-1000 nm. In step S3, the dispersant is an alcohol-based dispersant, such as isopropanol, ethanol, or n-propanol. The carbon-based nanomaterials are carbon black ink, such as XC-72R carbon black.

[0033] Example 2 A carbon-coated electrode with controllable interface microenvironment, such as Figure 1As shown, the electrode comprises: a gas diffusion electrode substrate 1, a copper catalyst layer 2, and a carbon coating layer 3. The copper catalyst layer 2 covers the exterior of the gas diffusion electrode substrate 1, and the carbon coating layer 3 covers the exterior of the copper catalyst layer 2. The carbon coating layer 3 forms a dense porous structure on the exterior of the copper catalyst layer 2. The carbon particles in the carbon coating layer 3 have a size of 15–25 nm, and the copper catalyst layer 2 contains several copper nanoparticles with a size of 60–100 nm. The loading of copper nanoparticles on the surface of the gas diffusion electrode is 1.0 mg / cm², and the loading of carbon coating particles on the surface of the copper catalyst layer is 0.1 mg / cm². The thickness of the carbon coating layer is 600 nm, and the thickness of the copper catalyst layer is 1.5 μm.

[0034] Example 3 A carbon-coated electrode with controllable interface microenvironment, such as Figure 1 As shown, the electrode comprises: a gas diffusion electrode substrate 1, a copper catalyst layer 2, and a carbon coating layer 3. The copper catalyst layer 2 coats the exterior of the gas diffusion electrode substrate 1, and the carbon coating layer 3 coats the exterior of the copper catalyst layer 2. The carbon coating layer 3 forms a dense porous structure on the exterior of the copper catalyst layer 2. The carbon particles in the carbon coating layer 3 have a size of 15–25 nm, and the copper catalyst layer 2 contains several copper nanoparticles with a size of 60–100 nm. The loading of copper nanoparticles on the surface of the gas diffusion electrode is 1.0 mg / cm², and the loading of carbon coating particles on the surface of the copper catalyst layer is 0.2 mg / cm². The thickness of the carbon coating layer is 600 nm, and the thickness of the copper catalyst layer is 1.5 μm.

[0035] Example 4 A carbon-coated electrode with controllable interface microenvironment, such as Figure 1 As shown, the electrode comprises: a gas diffusion electrode substrate 1, a copper catalyst layer 2, and a carbon coating layer 3. The copper catalyst layer 2 coats the exterior of the gas diffusion electrode substrate 1, and the carbon coating layer 3 coats the exterior of the copper catalyst layer 2. The carbon coating layer 3 forms a dense porous structure on the exterior of the copper catalyst layer 2. The carbon particles in the carbon coating layer 3 have a size of 15–25 nm, and the copper catalyst layer 2 contains several copper nanoparticles with a size of 60–100 nm. The loading of copper nanoparticles on the surface of the gas diffusion electrode is 1.0 mg / cm², and the loading of carbon coating particles on the surface of the copper catalyst layer is 0.5 mg / cm². The thickness of the carbon coating layer is 600 nm, and the thickness of the copper catalyst layer is 1.5 μm.

[0036] For the carbon-coated electrodes and Cu electrodes in Examples 2, 3, and 4, BPM was used to minimize the diffusion transport of heavy liquid-phase multi-carbon products from the cathode to the anode at an industrial-scale current density of 0.1 M KOH to test CO generation. The electroconversion properties of the product are determined by... Figure 2 As can be seen, the introduction of the interfacial carbon layer significantly reduced the reaction overpotential at a current density of 1.0 A. At that time, the cathode potential decreased from -0.96V on the Cu electrode vs. RHE to that on the carbon-coated electrode in Example 2 ( The voltage dropped from -0.90V on the carbon-coated electrode in Example 3 to -0.90V. The voltage drops further from -0.84V on the carbon-coated electrode in Example 4 to -0.84V on the carbon-coated electrode in Example 4. The -0.8V on the surface was confirmed by contact angle analysis to be due to improved hydrophobicity leading to a decrease in CO / This is due to an increase in concentration.

[0037] The changes in surface functional groups of the carbon layer before and after the CORR reaction were characterized using attenuated total reflectance infrared spectroscopy (ATR-IR), such as... Figure 3 As shown, the characteristic absorption bands corresponding to different functional groups are different: free water has a band at 3665. OH stretching vibration at 2800-3000 CH stretching vibration at 1596 The CO stretching vibration at the point. Even with a low loading of carbon-coated particles as in Example 2, its infrared signal is not affected by the trace amount of anion exchange resin in the copper catalyst layer. Before the CORR reaction, the carbon-coated electrode surfaces in Examples 2, 3, and 4 all exhibited obvious free water and CO signals, as well as a weak C-OH signal; after the CORR reaction, the free water and CO signals, as well as the weak C-OH signal, almost completely disappeared, indicating that these signals originated from water molecules adsorbed in the air; after the reaction, obvious C=O and C-OH signals appeared on the carbon-coated electrodes in Examples 2, 3, and 4, which is due to the interaction between the interfacial carbon layer and the hydroxyl groups generated by water decomposition during the reduction process, leading to the oxidation of the carbon layer, which indicates that the interfacial carbon layer participated in the regulation of mass transfer in the aqueous electrolyte during the CORR process and reconstructed the interfacial hydrogen bond network.

[0038] In the carbon-coated electrode flow electrolyzers of Examples 2, 3, and 4, using the carbon-coated electrode as the working electrode in 0.1 M CO-saturated KOH, measurements revealed a faster CO depletion rate observed on the carbon-coated electrode. Figure 4 As shown; furthermore, the deposition of the carbon layer inhibits the hydrogen evolution reaction, such as Figure 5 As shown; this, in turn, promotes the hydrogenation step of carbon-containing intermediates, such as Figure 6 , Figure 7 and Figure 8 As shown.

[0039] Through detailed spectra Analysis of the cathode potential scan results showed that the Cu electrode and the carbon-coated electrode... The features all exhibit volcanic characteristics, such as Figure 9 As shown, The signal appears at approximately -0.1V vs. RHE, reaches its maximum strength at -0.4V vs. RHE, and then weakens with increasing overpotential. The signal intensity decay and the redshift of the peak position indicate a weakening of the CO bonds in the adsorbed CO, thus making the *CO state more active at the heterojunction of the carbon-coated electrode. Furthermore, on the Cu electrode... Deconvolve into two vibrational modes: 2072 High frequency band ( ) and 2036 low frequency band ( ),in More conducive to CORR; such as Figure 10 As shown, in the carbon-coated electrode The ratio gradually increases from -0.3V vs. RHE to -0.5V vs. RHE, and across all potential ranges, / The intensity ratio on the carbon-coated electrode is consistently higher than that on the Cu electrode; at high overpotentials, the carbon-coated electrode... / The ratio remained basically stable, while the Cu electrode... The proportion of CO increases rapidly. Therefore, the carbon coating alters the local adsorption environment of CO and stabilizes a CO population more conducive to CORR at the carbon coating interface.

[0040] Example 5 An application of a carbon-coated electrode with controllable interface microenvironment is described, in which the carbon-coated electrode is used as the cathode of a membrane electrode electrolyzer in the electrochemical reduction of CO. For example... Figure 11 As shown, the membrane electrode electrolyzer includes an anode current collector 4, an anode side gasket 5, an anode diffusion electrode 6, an anion exchange membrane 7, a cathode diffusion electrode 8, a cathode side gasket 9, and a cathode current collector 10 arranged sequentially. Equal-sized square windows are respectively set at the center of the anode side gasket 5 and the cathode side gasket 9. The anode diffusion electrode 6 is positioned opposite the square window of the anode side gasket 5, and the cathode diffusion electrode 8 is positioned opposite the square window of the cathode side gasket 9. The area of ​​the anode diffusion electrode 6 is larger than the area of ​​the square window on the anode side gasket 5, and the area of ​​the cathode diffusion electrode 8 is larger than the area of ​​the square window on the cathode side gasket 9. The area of ​​the square window is 1 cm² to 10 cm². The anode current collector 4 and the cathode current collector 10 are connected as a single unit by bolts. For example, if the area of ​​the anode diffusion electrode 6 is 1.5 cm * 1.5 cm and the working area is 1 cm², then the size of the square window on the anode side gasket 5 is 1.5 cm * 1.5 cm. The usable area of ​​the electrode is adjusted by the size of the window.

[0041] The cathode current collector 10 is provided with a gas diffusion channel, which adopts a serpentine flow field. The cathode gas inlet is connected to one end of the gas diffusion channel, and the cathode gas outlet is connected to the other end of the gas diffusion channel. The anode current collector 4 is provided with a serpentine electrolyte diffusion channel. The anode electrolyte inlet is connected to one end of the electrolyte diffusion channel, and the anode electrolyte outlet is connected to the other end of the electrolyte diffusion channel.

[0042] The anode current collector 4 and the cathode current collector 10 are made of titanium plates, the anode side gasket 5 and the cathode side gasket 9 are made of polytetrafluoroethylene, the anode diffusion electrode 6 is made of commercially available iridium-plated titanium felt, and the cathode diffusion electrode 8 is the interface microenvironment controllable carbon coating electrode of this application.

[0043] For example, 0.1M KOH was used as the anolyte, and CO was humidified with an acid solution before entering the cathode. Tests showed that for both the anolyte and cathode diffusion electrodes with a working area of ​​1 cm², the operating voltage at 400-1000 mA was [data missing]. CO generation within the current density range The selectivity remains above 47% within a battery voltage range of 3.9-4.7V. Over 53%. By increasing the electrode area tenfold, using an anode diffusion electrode and cathode diffusion electrode with a working area of ​​10 cm², only a 4.5V battery voltage is required to drive a current of 30A, and... It reached 53.4% ​​at 20A.

[0044] The carbon-coated electrode from Example 2 was used for catalytic CO production. During the process, in 15A During 24 hours of continuous electrolysis under current conditions It has consistently remained above 40%, of which It only increased slightly from 23.2% to 28.5%. Electrosynthesis remains stable.

[0045] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. Those skilled in the art can make non-inventive modifications to this embodiment as needed after reading this specification, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A carbon-coated electrode with controllable interface microenvironment, characterized in that, include: The gas diffusion electrode substrate, the copper catalyst layer, and the carbon coating are provided. The copper catalyst layer covers the outside of the gas diffusion electrode substrate, and the carbon coating covers the outside of the copper catalyst layer. The carbon coating forms a dense porous structure on the outside of the copper catalyst layer. The carbon particles in the carbon coating are 15-25 nm in size, and the copper catalyst layer contains several copper nanoparticles with a size of 60-100 nm.

2. The carbon-coated electrode with controllable interface microenvironment according to claim 1, characterized in that, The loading of copper nanoparticles on the surface of the gas diffusion electrode is 0.6–1.5 mg / cm², and the loading of carbon coating particles on the surface of the copper catalyst layer is 0.1–0.5 mg / cm².

3. The carbon-coated electrode with controllable interface microenvironment according to claim 2, characterized in that, The thickness of the carbon coating is 200–1000 nm, and the thickness of the copper catalyst layer is 0.5–1.5 μm.

4. A method for preparing a carbon-coated electrode with controllable interface microenvironment as described in claim 1, characterized in that, The method includes: S1. Mix copper nanoparticles, dispersant and binder to form a mixture containing copper nanoparticles; S2. The mixture obtained in step S1 is uniformly sprayed onto the surface of the gas diffusion electrode to form a copper catalyst layer; S3. After mixing carbon-based nanomaterials and dispersants, spray them onto the surface of the copper catalyst layer to form a carbon coating.

5. The method for preparing a carbon-coated electrode with controllable interface microenvironment according to claim 4, characterized in that, The dispersant is an alcohol-based dispersant.

6. The method for preparing a carbon-coated electrode with controllable interface microenvironment according to claim 5, characterized in that, The dispersant is isopropanol, ethanol, or n-propanol.

7. The method for preparing a carbon-coated electrode with controllable interface microenvironment according to claim 4, characterized in that, The adhesive is Sustainion XA-9 solution.

8. The method for preparing a carbon-coated electrode with controllable interface microenvironment according to claim 4, characterized in that, The carbon-based nanomaterial is carbon black ink.

9. An application of a carbon-coated electrode with controllable interface microenvironment as described in any one of claims 1 to 3, characterized in that, The carbon-coated electrode is used as the cathode of a membrane electrode electrolyzer in the electrochemical reduction of CO.

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