An in-situ regeneration method of a catalytic electrode for electrochemical reduction of carbon dioxide

Abstract

This invention belongs to the field of catalytic electrode preparation technology, specifically relating to an in-situ regeneration method for an electrochemical reduction carbon dioxide catalytic electrode. The method includes: dissolving a noble metal precursor in a solvent to obtain a noble metal precursor solution, wherein the noble metal is gold and / or silver; reacting the noble metal precursor solution with a carbon dioxide catalytic electrode that has lost its catalytic activity in the cathode chamber of an electrolyzer to obtain a carbon dioxide catalytic electrode with restored catalytic activity, thus completing the in-situ regeneration of the carbon dioxide catalytic electrode; and washing the electrode to obtain the final product. This invention extends the overall service life of the catalytic electrode and the electrolyzer. Compared with methods that require re-preparing the catalyst and disassembling the electrolyzer to replace the catalytic electrode, this method is simpler to operate and saves on the preparation costs of the catalyst and catalytic electrode, as well as the costs of disassembling and maintaining the electrolyzer, thus possessing significant industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of catalytic electrode preparation technology, specifically relating to an in-situ regeneration method for an electrochemical carbon dioxide reduction catalytic electrode. Background Technology

[0002] In the electrochemical reduction of carbon dioxide to produce syngas (carbon monoxide and hydrogen), formic acid, methanol, ethylene, and methane, the catalytic electrode plays a decisive role, and different catalytic electrodes exhibit different catalytic performance and service life.

[0003] For example, literature (Joule, 2019, 3, 265-278) reports the use of nickel-based catalysts for the electrochemical reduction of carbon dioxide to carbon monoxide. Literature (J. Phys. Chem. C, 2017, 121, 22637-22643) studies the performance of gold catalysts for the electrochemical reduction of carbon dioxide to carbon monoxide. Literature (ACS Energy Letters, 2018, 3, 1301-1306) studies the selectivity of silver catalysts for the electrochemical reduction of carbon dioxide to carbon monoxide. CN 112176360B discloses a gold-silver alloy catalyst for the electrochemical reduction of carbon dioxide to syngas, which can improve the Faradaic efficiency of the syngas product and can control the ratio of carbon monoxide to hydrogen in the syngas. CN 112251766 A discloses a carbon nanotube-supported gold-based bimetallic catalyst for the electrochemical reduction of carbon dioxide, which can improve the Faradaic efficiency of the carbon monoxide product. CN 112410803 B discloses a gold-copper alloy catalyst for the electrochemical reduction of carbon dioxide to carbon monoxide. CN 111013606 A discloses a gold-nickel catalyst exhibiting high selectivity and stability for carbon monoxide.

[0004] Although scientists have conducted extensive research in this field, focusing on modifying the composition and morphology of catalytic electrode materials to alter the carbon dioxide electroreduction activity, selectivity, stability, and lifespan of the electrodes, the lifespan of existing electrochemical carbon dioxide reduction catalytic electrodes still largely fails to meet industrial requirements. Often, after these electrodes lose their catalytic activity, it is necessary to re-prepare the catalyst and disassemble the electrolyzer to replace the electrode. This results in high costs for catalyst and electrode preparation, as well as high costs and complex operations for disassembling and maintaining the electrolyzer, hindering its large-scale commercial application and becoming a problem urgently needing to be solved. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the prior art by providing an in-situ regeneration method for an electrochemical carbon dioxide reduction catalytic electrode. This method can efficiently, conveniently, and cost-effectively extend the service life of the deactivated catalytic electrode, enabling it to meet the needs of industrial production.

[0006] To achieve the above-mentioned objectives of this invention, the following technical solution is adopted:

[0007] This invention provides an in-situ regeneration method for an electrochemical carbon dioxide reduction catalytic electrode, comprising the following steps:

[0008] S1. Solution preparation: Dissolve the noble metal precursor in a solvent to obtain a noble metal precursor solution, wherein the noble metal is gold and / or silver.

[0009] S2. In-situ regeneration: In the cathode chamber of the electrolytic cell, the noble metal precursor solution reacts with the carbon dioxide catalytic electrode that has lost its catalytic activity to obtain a carbon dioxide catalytic electrode with restored catalytic activity, thus completing the in-situ regeneration of the carbon dioxide catalytic electrode.

[0010] The carbon dioxide catalytic electrode that has lost its catalytic activity can be a catalytic electrode for the electrochemical reduction of carbon dioxide to syngas, formic acid, methanol, ethylene, methane, etc. The catalyst in this catalytic electrode includes one or more combinations of Ni, Au, Ag, Zn, Sn, Co, In, Pb, Bi, and Cu, such as NiAg, NiZn, NiAu, AgAu, ZnAg, AgSn, CuCo, CuZn, CuNi, etc. Correspondingly, the catalyst in the carbon dioxide catalytic electrode that has regained its catalytic activity is a composite metal catalyst composed of the above metals and gold, silver, or gold-silver alloys, such as AuNi, AuAg, AuZn, AgNi, AuAgNi, AuZnAg, AuZnAg, etc. The compositional changes of the catalyst in the catalytic electrode before and after in-situ regeneration are as follows: Figure 2 As shown, M is the catalyst in the catalytic electrode, which is deactivated after electrochemical reduction of carbon dioxide. The deactivated M undergoes a displacement reaction with the gold, silver or gold-silver active components in the noble metal precursor solution to generate an Au / Ag / AuAg-M composite catalyst containing gold, silver or gold-silver alloy active components, which regains its catalytic activity.

[0011] S3. Washing: The carbon dioxide catalytic electrode with restored catalytic activity is washed to obtain the final product.

[0012] According to the method of the present invention, in step S1, the gold precursor is chloroauric acid and / or chloroaurate; chloroaurate is preferably sodium chloroaurate or potassium chloroaurate; the silver precursor is silver nitrate and / or silver acetate, etc.

[0013] According to the method of the present invention, in step S1, the solvent is water; or, the solvent is a mixed solution of water and an organic solvent; preferably, water.

[0014] According to the method of the present invention, in step S1, the concentration of the noble metal precursor solution is 0.01 mmol / L-1.0 mol / L; preferably 0.01 mol / L-0.1 mol / L. When the concentration is too low, the reaction rate is slow; when the concentration is too high, the reaction is too fast, the catalyst particles on the surface of the catalytic electrode are too large, and the electrical performance of the catalytic electrode after regeneration cannot reach the optimal level.

[0015] According to the method of the present invention, step S1 further includes adding a complexing agent and / or a surfactant to the noble metal precursor solution, wherein the complexing agent includes, but is not limited to, any one of pyrophosphate, citrate, and thiosulfate, and the surfactant includes, but is not limited to, any one of polyethylene glycol, sodium dodecylbenzenesulfonate, and polyvinylpyrrolidone.

[0016] According to the method of the present invention, in step S2, the reaction temperature is 0℃-100℃, preferably 25℃-60℃; the reaction time is 5s-96h, preferably 10min-3h. When the temperature is too low, the reaction rate is too slow, and the regeneration time is long; when the temperature is too high, the reaction is too fast, difficult to control, and the performance cannot be regulated. When the reaction time is too short, the reaction is insufficient, and the regeneration performance is not fully restored in a short time.

[0017] According to the method of the present invention, in step S2, the noble metal precursor solution reacts with a deactivated carbon dioxide catalytic electrode under circulating or static conditions, preferably under circulating conditions to improve reaction efficiency. The circulating flow rate per unit area (per square centimeter) is 0.4 mL / min-50 mL / min, preferably 1 mL / min-5 mL / min. Specifically, a circulating pump can be used to inject the noble metal precursor solution into the cathode chamber of the electrolytic cell, allowing it to react with the deactivated carbon dioxide catalytic electrode under circulating conditions. Further, a pulse voltage can be applied across the electrodes of a single cell to promote the reaction between the noble metal precursor solution and the deactivated catalytic electrode. The magnitude of the pulse voltage is 0V-6V, preferably 1V-4V, and the pulse frequency is 1-2000 Hz, preferably 10-100 Hz.

[0018] The carbon dioxide catalytic electrode that has lost its catalytic activity refers to a catalytic electrode whose catalytic activity has decreased to the point that it can no longer meet the requirements for the electroreduction of carbon dioxide. Determining whether the requirements can be met is a basic skill possessed by those skilled in the art. The catalytic electrode includes: i) a catalytic electrode formed by adhering the catalyst to a conductive substrate such as titanium mesh, titanium felt, stainless steel mesh, carbon paper, carbon cloth, carbon felt, nickel mesh, or nickel foam using a binder; or ii) a catalytic electrode formed by in-situ growth of the catalyst on the surface of the aforementioned conductive substrate (such as in-situ electrochemical deposition or in-situ solvothermal synthesis); or iii) an integrated catalytic electrode formed by adhering the catalyst and polymer resin to an ion exchange membrane.

[0019] According to the method of the present invention, in step S3, the carbon dioxide catalytic electrode whose catalytic activity has been restored is washed in situ in the electrolyzer using deionized water. The purpose of washing is to remove impurity ions from the surface of the catalytic electrode.

[0020] The beneficial effects of this invention are as follows:

[0021] The in-situ regeneration method for electrochemical carbon dioxide reduction catalytic electrodes provided by this invention involves in-situ reintroducing gold, silver, or gold-silver alloy active components onto the catalyst surface of a deactivated catalytic electrode. This restores the catalytic activity of the electrode, resulting in a renewed high electrochemical carbon dioxide reduction catalytic activity and long-term stability. Compared to methods involving the re-preparation of catalysts and the disassembly and replacement of the catalytic electrode, this method extends the overall service life of the catalytic electrode and the electrolyzer. It is simpler to operate and saves on the preparation costs of catalysts and electrodes, as well as the costs of disassembling and maintaining the electrolyzer, thus possessing significant industrial application value. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the in-situ regeneration preparation process in this invention; wherein, 1-cathode catalytic electrode; 2-anodic catalytic electrode; 3-ion exchange membrane; 4-circulation pump; 5-noble metal precursor solution; 6-electrolytic cell;

[0023] Figure 2 This is a schematic diagram illustrating the compositional changes of the catalyst in the catalytic electrode before and after in-situ regeneration according to the present invention.

[0024] Figure 3 Photograph of the gold-nickel-silver-carbon catalytic electrode of Example 1;

[0025] Figure 4 This is a SEM image of the gold-nickel-silver-carbon catalytic electrode from Example 1.

[0026] Figure 5 The graph shows the total current density of the gold-nickel-silver-carbon catalytic electrode in Example 1 as a function of electrolysis voltage.

[0027] Figure 6 The graph shows the change in CO / H2 volume ratio of the product gas from the gold-nickel-silver carbon catalytic electrode in Example 1 as a function of electrolysis voltage.

[0028] Figure 7 The graph shows the total current density of the gold-nickel-silver-carbon catalytic electrode in Example 1 as a function of electrolysis temperature.

[0029] Figure 8 The graph shows the change in the CO / H2 volume ratio of the product gas with electrolysis temperature for the gold-nickel-silver carbon catalytic electrode of Example 1.

[0030] Figure 9The graph shows the change in the CO / H2 volume ratio of the product gas as a function of reaction time for Example 1 and Comparative Example 1.

[0031] Figure 10 Photograph of the gold-silver carbon catalytic electrode in Example 2;

[0032] Figure 11 This is a SEM image of the gold-silver carbon catalytic electrode from Example 2.

[0033] Figure 12 The graph shows the change in CO / H2 volume ratio over reaction time for Example 2 and Comparative Example 2.

[0034] Figure 13 Photograph of the gold-nickel-carbon catalytic electrode in Example 3;

[0035] Figure 14 This is a SEM image of the gold-nickel-carbon catalytic electrode from Example 3;

[0036] Figure 15 The graph shows the change in the CO / H2 volume ratio of the product gas as a function of reaction time for Example 3 and Comparative Example 3.

[0037] Figure 16 Photograph of the gold-silver-zinc-carbon catalytic electrode in Example 4;

[0038] Figure 17 This is a SEM image of the gold-silver-zinc-carbon catalytic electrode from Example 4.

[0039] Figure 18 The graph shows the change in the CO / H2 volume ratio of the product gas in Example 4 and Comparative Example 4 over reaction time. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0041] Example 1

[0042] At 25°C, 3 L of a 0.01 mol / L chloroauric acid aqueous solution was prepared and then injected into the deactivated nickel-silver-carbon catalytic electrode cathode chamber using a circulating pump. The nickel-silver-carbon catalytic electrode was formed by adhering the nickel-silver-carbon catalyst to a titanium mesh substrate using a binder. At 25°C, the circulating flow rate of the chloroauric acid aqueous solution was 1 mL / min, and the circulation displacement reaction was carried out for 3 hours. The reaction apparatus was as follows: Figure 1As shown, the inactive nickel-silver-carbon catalytic electrode was reacted with an aqueous solution of chloroauric acid to obtain a gold-nickel-silver-carbon catalytic electrode with restored catalytic activity. Then, it was washed three times with deionized water to remove impurity ions from the surface of the catalytic electrode, thus completing the in-situ regeneration of the inactive nickel-silver-carbon catalytic electrode. A photograph of the electrode after in-situ regeneration is shown below. Figure 3 As shown in the figure, the SEM image is as follows: Figure 4 As shown.

[0043] Performance testing:

[0044] Test method: The cathode was the gold-nickel-silver-carbon catalytic electrode prepared in Example 1 or a largely inactive nickel-silver-carbon catalytic electrode; the anode was an iridium oxide catalyst; the membrane was a cation exchange membrane; and the electrode working area of ​​both the anode and cathode was 200 cm². 2 During the test, a circulating pump was used to introduce electrolyte into the electrolytic cell. A 1.5 mol / L KHCO3 aqueous solution was introduced at a flow rate of 3000 mL / min at the cathode, while CO2 gas was introduced at a flow rate of 200 mL / min. A 1.5 mol / L KHCO3 aqueous solution was also introduced at a flow rate of 3000 mL / min at the anode. The test temperature ranged from 25℃ to 80℃, and the test voltage ranged from 2.6V to 3.6V.

[0045] Test results: such as Figures 5-8 As shown, when the cathode is a gold-nickel-silver-carbon catalytic electrode regenerated in situ (Example 1), the current density is 34 mA / cm². 2 -145mA / cm 2 The product gas CO / H2 (volume ratio) = 0.32-0.63; For example... Figure 9 As shown, when the cathode is a gold-nickel-silver-carbon catalytic electrode regenerated in situ (Example 1), it can maintain a stable CO / H2 (volume ratio) of 0.45-0.56 for over 3000 hours under an electrolysis voltage of 3.0V. However, when the cathode is a nickel-silver-carbon catalytic electrode that has largely lost its activity (Comparative Example 1), the CO / H2 (volume ratio) decreases from 0.06 to 0.02 after 240 hours of operation under an electrolysis voltage of 3.0V. The comparison shows that the catalytic electrode regenerated in situ of this invention exhibits high electrochemical carbon dioxide reduction catalytic activity and long-term stability, improving the service life of both the catalytic electrode and the electrolyzer. Figure 9 .

[0046] Example 2

[0047] At 50℃, 4 L of a 0.1 mol / L potassium chloroaurate aqueous solution was prepared and then injected into the cathode chamber of a deactivated silver-carbon catalytic electrode using a circulating pump. The silver-carbon catalytic electrode is an integrated catalytic electrode formed by adhering a silver-carbon catalyst to an ion exchange membrane using a polymer. At 50℃, the potassium chloroaurate aqueous solution was circulated at a flow rate of 5 mL / min per unit area for 10 min, allowing the deactivated silver-carbon catalytic electrode to react with the potassium chloroaurate, thus obtaining a gold-silver-carbon catalytic electrode with restored catalytic activity. The electrode was then washed three times with deionized water to remove impurity ions from its surface, completing the in-situ regeneration of the deactivated silver-carbon catalytic electrode. An image of the regenerated electrode is shown below. Figure 10 As shown in the figure, the SEM image is as follows: Figure 11 As shown.

[0048] Performance testing:

[0049] Test method: The cathode was the gold-silver-carbon catalytic electrode prepared in Example 2 or a silver-carbon catalytic electrode that had largely lost its activity; the anode was an iridium oxide catalyst; the membrane was a cation exchange membrane; and the working area of ​​both the anode and cathode was 200 cm². 2 During the test, a circulating pump was used to introduce electrolyte into the electrolytic cell. A 1 mol / L NaHCO3 aqueous solution was introduced at a flow rate of 3000 mL / min at the cathode, while CO2 gas was introduced at a flow rate of 100 mL / min. A 1 mol / L NaHCO3 aqueous solution was also introduced at a flow rate of 3000 mL / min at the anode.

[0050] Test results: such as Figure 12 As shown, when the cathode is a gold-silver-carbon catalytic electrode regenerated in situ (Example 2), it can maintain a stable CO / H2 (volume ratio) of 0.51-0.65 for 504 hours under an electrolysis voltage of 3.0V. However, when the cathode is a silver-carbon catalytic electrode that has largely lost its activity (Comparative Example 2), the CO / H2 (volume ratio) decreases from 0.08 to 0.02 after 240 hours of operation under an electrolysis voltage of 3.0V. The comparison shows that the catalytic electrode regenerated in situ of this invention exhibits high electrochemical catalytic activity for carbon dioxide reduction and long-term stability, thus improving the service life of both the catalytic electrode and the electrolyzer.

[0051] Example 3

[0052] At 40℃, 4 L of a 0.02 mol / L sodium chloroaurate aqueous solution was prepared and then injected into the cathode chamber of a deactivated nickel-carbon catalytic electrode using a circulating pump. The nickel-carbon catalytic electrode was formed by adhering a nickel-carbon catalyst to a polymer mesh using a binder. At 40℃, the sodium chloroaurate aqueous solution was circulated at a flow rate of 2.5 mL / min per unit area for 1 hour, allowing the deactivated nickel-carbon catalytic electrode to react with the sodium chloroaurate aqueous solution, thus obtaining a gold-nickel-carbon catalytic electrode with restored catalytic activity. The electrode was then washed three times with deionized water to remove impurity ions from its surface, completing the in-situ regeneration of the deactivated nickel-carbon catalytic electrode. A photograph of the regenerated electrode is shown below. Figure 13 As shown in the figure, the SEM image is as follows: Figure 14 As shown.

[0053] Performance testing:

[0054] Test method: The cathode was the gold-nickel-carbon catalytic electrode prepared in Example 3 or a largely inactive nickel-carbon catalytic electrode; the anode was an iridium oxide catalyst; the membrane was a cation exchange membrane; and the electrode working area of ​​both the anode and cathode was 200 cm². 2 During the test, a circulating pump was used to introduce electrolyte into the electrolytic cell. A 2 mol / L KHCO3 aqueous solution was introduced at a flow rate of 3000 mL / min at the cathode, while CO2 gas was introduced at a flow rate of 300 mL / min. A 2 mol / L KHCO3 aqueous solution was also introduced at a flow rate of 3000 mL / min at the anode.

[0055] Test results: such as Figure 15 As shown, when the cathode is a gold-nickel-carbon catalytic electrode regenerated in situ (Example 3), it can maintain a stable CO / H2 (volume ratio) of 0.36-0.42 for 504 hours under an electrolysis voltage of 3.0V. However, when the cathode is a nickel-carbon catalytic electrode that has largely lost its activity (Comparative Example 3), the CO / H2 (volume ratio) decreases from 0.05 to 0.01 after 240 hours of operation under an electrolysis voltage of 3.0V. The comparison shows that the catalytic electrode regenerated in situ of this invention exhibits high electrochemical carbon dioxide reduction catalytic activity and long-term stability, thus improving the service life of both the catalytic electrode and the electrolyzer.

[0056] Example 4

[0057] At 60℃, 4 L of a 0.05 mol / L chloroauric acid aqueous / ethanol solution was prepared, and 3 g of polyvinylpyrrolidone was added. The chloroauric acid aqueous / ethanol solution was then injected into the cathode chamber of a deactivated silver-zinc-carbon catalytic electrode using a circulating pump. The silver-zinc-carbon catalytic electrode was formed by adhering the silver-zinc-carbon catalyst to carbon cloth using a binder. At 60℃, the chloroauric acid aqueous / ethanol solution was circulated at a flow rate of 1.5 mL / min per unit area for 2 hours, allowing the deactivated silver-zinc-carbon catalytic electrode to react with chloroauric acid, thus obtaining a gold-silver-zinc-carbon catalytic electrode with restored catalytic activity. The electrode was then washed three times with deionized water to remove impurity ions from its surface, completing the in-situ regeneration of the deactivated silver-zinc-carbon catalytic electrode. A photograph of the regenerated electrode is shown below. Figure 16 As shown in the figure, the SEM image is as follows: Figure 17 As shown.

[0058] Performance testing:

[0059] Test method: The cathode was the gold-silver-zinc-carbon catalytic electrode prepared in Example 4 or a silver-zinc-carbon catalytic electrode that had largely lost its activity; the anode was an iridium oxide catalyst; the membrane was a cation exchange membrane; and the working area of ​​both the anode and cathode was 200 cm². 2 During the test, a circulating pump was used to introduce electrolyte into the electrolytic cell. A 3 mol / L KHCO3 aqueous solution was introduced at a flow rate of 3000 mL / min at the cathode, while CO2 gas was introduced at a flow rate of 200 mL / min. A 3 mol / L KHCO3 aqueous solution was also introduced at a flow rate of 3000 mL / min at the anode.

[0060] Test results: such as Figure 18 As shown, when the cathode is a gold-silver-zinc-carbon catalytic electrode regenerated in situ (Example 4), it can maintain a stable CO / H2 (volume ratio) of 0.41-0.46 for 504 hours under an electrolysis voltage of 3.0V. However, when the cathode is a silver-zinc-carbon catalytic electrode that has largely lost its activity (Comparative Example 4), the CO / H2 (volume ratio) decreases from 0.06 to 0.01 after 240 hours of operation under an electrolysis voltage of 3.0V. The comparison shows that the catalytic electrode regenerated in situ of this invention exhibits high electrochemical carbon dioxide reduction catalytic activity and long-term stability, thus improving the service life of both the catalytic electrode and the electrolyzer.

[0061] Example 5

[0062] At 30°C, 5 L of a 0.05 mol / L silver nitrate aqueous solution was prepared, and 2 g of potassium pyrophosphate was added. The silver nitrate aqueous solution was then injected into the cathode chamber of a deactivated nickel-nitrogen-carbon catalytic electrode using a circulating pump. The nickel-nitrogen-carbon catalytic electrode was formed by adhering the nickel-nitrogen-carbon catalyst to carbon cloth using a binder. At 30°C, the silver nitrate aqueous solution was circulated at a unit area flow rate of 1.5 mL / min for 16 h, allowing the deactivated nickel-nitrogen-carbon catalytic electrode to react with the silver nitrate, thus obtaining a silver-nickel-nitrogen-carbon catalytic electrode with restored catalytic activity. The electrode was then washed three times with deionized water to remove impurity ions from its surface, completing the in-situ regeneration of the deactivated nickel-nitrogen-carbon catalytic electrode.

[0063] Performance testing:

[0064] Test method: The cathode was the silver-nickel-nitrogen-carbon catalytic electrode prepared in Example 5 or a largely inactive nickel-nitrogen-carbon catalytic electrode; the anode was an iridium oxide catalyst; the membrane was a cation exchange membrane; and the electrode working area of ​​both the anode and cathode was 200 cm². 2 During the test, a circulating pump was used to introduce electrolyte into the electrolytic cell. A 3 mol / L KHCO3 aqueous solution was introduced at a flow rate of 3000 mL / min at the cathode, while CO2 gas was introduced at a flow rate of 200 mL / min. A 3 mol / L KHCO3 aqueous solution was also introduced at a flow rate of 3000 mL / min at the anode.

[0065] Test results: When the cathode is a silver-nickel-nitrogen-carbon catalytic electrode that has been regenerated in situ, it can maintain a stable CO / H2 (volume ratio) of 0.34-0.40 for 504 hours under an electrolysis voltage of 3.0V. However, when the cathode is a nickel-nitrogen-carbon catalytic electrode that has largely lost its activity, the CO / H2 (volume ratio) decreases from 0.04 to below 0.01 after 240 hours of operation under the same electrolysis voltage of 3.0V. This comparison shows that the catalytic electrode regenerated in situ in this invention exhibits high electrochemical catalytic activity for carbon dioxide reduction and long-term stability, thus improving the service life of both the catalytic electrode and the electrolyzer.

[0066] Example 6

[0067] At 50°C, 5 L of a 0.1 mol / L aqueous solution of chloroauric acid and silver nitrate was prepared, and 5 g of polyethylene glycol was added. The aqueous solution was then injected into the cathode chamber of a deactivated nickel-silver-carbon catalytic electrode using a circulating pump. The nickel-silver-carbon catalytic electrode was formed by adhering the nickel-silver-carbon catalyst to a titanium mesh substrate using a binder. At 50°C, the aqueous solution of chloroauric acid and silver nitrate was circulated at a flow rate of 1 mL / min per unit area for 12 h, allowing the deactivated nickel-silver-carbon catalytic electrode to react with the aqueous solution, thus obtaining a restored catalytically active nickel-silver-carbon catalytic electrode. The electrode was then washed three times with deionized water to remove impurity ions from its surface, completing the in-situ regeneration of the deactivated nickel-silver-carbon catalytic electrode.

[0068] Performance testing:

[0069] Test method: The cathode was the gold-silver-nickel-carbon catalytic electrode prepared in Example 6 or a largely inactive nickel-silver-carbon catalytic electrode; the anode was an iridium oxide catalyst; the membrane was a cation exchange membrane; and the electrode working area of ​​both the anode and cathode was 200 cm². 2 During the test, a circulating pump was used to introduce electrolyte into the electrolytic cell. A 1.5 mol / L KHCO3 aqueous solution was introduced at the cathode at a flow rate of 3000 mL / min, while CO2 gas was introduced at a flow rate of 200 mL / min. A 1.5 mol / L KHCO3 aqueous solution was also introduced at the anode at a flow rate of 3000 mL / min.

[0070] Test results: When the cathode is a gold-silver-nickel-carbon catalytic electrode regenerated in situ, it can maintain a stable CO / H2 (volume ratio) of 0.43-0.65 for over 504 hours under an electrolysis voltage of 3.0V. However, when the cathode is a nickel-silver-carbon catalytic electrode that has largely lost its activity, the CO / H2 (volume ratio) decreases from 0.06 to 0.02 after 240 hours of operation under the same electrolysis voltage of 3.0V. This comparison shows that the catalytic electrode regenerated in situ in this invention regains high electrochemical catalytic activity for carbon dioxide reduction and exhibits long-term stability, thus improving the service life of both the catalytic electrode and the electrolyzer.

[0071] Example 7

[0072] At 30°C, 5 L of a 0.1 mol / L aqueous solution of chloroauric acid and silver nitrate was prepared. This solution was then injected into the cathode chamber of a deactivated nickel-silver-carbon catalytic electrode using a circulating pump. The nickel-silver-carbon catalytic electrode was formed by adhering a nickel-silver-carbon catalyst to a titanium mesh substrate using a binder. At 30°C, the circulating flow rate of the aqueous solution was 1 mL / min per unit area. A 2V, 50Hz pulsed voltage was applied across the anode and cathode to promote the reaction between the aqueous solution and the deactivated nickel-silver-carbon catalytic electrode. The cyclic displacement reaction was carried out for 6 hours to obtain a restored catalytically active nickel-silver-carbon catalytic electrode. The electrode was then washed three times with deionized water to remove impurity ions from its surface, thus completing the in-situ regeneration of the deactivated nickel-silver-carbon catalytic electrode.

[0073] Performance testing:

[0074] Test method: The cathode was the gold-silver-nickel-carbon catalytic electrode prepared in Example 7 or a largely inactive nickel-silver-carbon catalytic electrode; the anode was an iridium oxide catalyst; the membrane was a cation exchange membrane; and the electrode working area of ​​both the anode and cathode was 200 cm². 2 During the test, a circulating pump was used to introduce electrolyte into the electrolytic cell. A 1.5 mol / L KHCO3 aqueous solution was introduced at the cathode at a flow rate of 3000 mL / min, while CO2 gas was introduced at a flow rate of 200 mL / min. A 1.5 mol / L KHCO3 aqueous solution was also introduced at the anode at a flow rate of 3000 mL / min.

[0075] Test results: When the cathode is a gold-silver-nickel-carbon catalytic electrode regenerated in situ, it can maintain a stable CO / H2 (volume ratio) of 0.51-0.64 for over 504 hours under an electrolysis voltage of 3.0V. However, when the cathode is a nickel-silver-carbon catalytic electrode that has largely lost its activity, the CO / H2 (volume ratio) decreases from 0.06 to 0.02 after 240 hours of operation under the same electrolysis voltage of 3.0V. This comparison shows that the catalytic electrode regenerated in situ in this invention exhibits high electrochemical catalytic activity for carbon dioxide reduction and long-term stability, thus improving the service life of both the catalytic electrode and the electrolyzer.

[0076] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for in-situ regeneration of an electrochemical carbon dioxide reduction catalytic electrode, characterized in that, Includes the following steps: S1. Solution preparation: Dissolve the noble metal precursor in a solvent to obtain a noble metal precursor solution. The noble metal precursor is chloroauric acid, chloroaurate, silver nitrate or silver acetate. The concentration of the noble metal precursor solution is 0.01 mmol / L to 1.0 mol / L; The solvent is water; or, the solvent is a mixture of water and an organic solvent. S2. In-situ regeneration: In the cathode chamber of the electrolytic cell, the noble metal precursor solution reacts with the carbon dioxide catalytic electrode that has lost its catalytic activity to obtain a carbon dioxide catalytic electrode with restored catalytic activity, thus completing the in-situ regeneration of the carbon dioxide catalytic electrode. The catalyst in the carbon dioxide catalytic electrode that has lost its catalytic activity includes one or more of the following: Ni, Au, Ag, Zn, Sn, Co, In, Pb, Bi, and Cu. In step S2, the reaction temperature is 25℃-60℃, and the reaction time is 10min-3h; S3. Washing: The carbon dioxide catalytic electrode with restored catalytic activity is washed to obtain the final product.

2. The in-situ regeneration method for the electrochemical carbon dioxide reduction catalytic electrode according to claim 1, characterized in that, In step S1, the concentration of the noble metal precursor solution is 0.01 mol / L to 0.1 mol / L.

3. The in-situ regeneration method for the electrochemical carbon dioxide reduction catalytic electrode according to claim 1, characterized in that, Step S2 also includes applying a pulse voltage across the electrodes, wherein the magnitude of the pulse voltage is 0V-6V and the corresponding pulse frequency is 1-2000HZ.

4. The in-situ regeneration method for the electrochemical carbon dioxide reduction catalytic electrode according to claim 3, characterized in that, The pulse voltage is 1-4V, the pulse frequency is 10-100Hz, and the pulse duration is less than or equal to the above-mentioned reaction time.

5. The in-situ regeneration method for the electrochemical carbon dioxide reduction catalytic electrode according to claim 1, characterized in that, In step S3, the carbon dioxide catalytic electrode with restored catalytic activity is washed in situ in the electrolyzer using deionized water.

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