Oxide cluster modified copper nano-whisker catalyst for electrochemical carbon dioxide reduction as well as preparation method and application of oxide cluster modified copper nano-whisker catalyst

Abstract

The invention discloses an oxide cluster modified copper nano whisker catalyst for electrochemical carbon dioxide reduction as well as a preparation method and application of the oxide cluster modified copper nano whisker catalyst, and aims to solve the problems of low activity selectivity and poor catalyst stability of a current copper-based product. According to the copper nano whisker catalyst, an oxide cluster MOx is deposited on the surface of a copper-based material to obtain a pre-catalyst, then negative voltage is applied to the pre-catalyst in a CO2 gas atmosphere for reduction treatment, so that the oxide cluster modified copper nano whisker catalyst is formed, and the chemical general formula of the oxide cluster modified copper nano whisker catalyst is MOx / Cu. The prepared oxide cluster modified copper nano whisker catalyst has outstanding stability, has high multi-carbon Faraday efficiency in the electrochemical carbon dioxide reduction process, FEC < 2 + > is larger than 80%, good stability is achieved, and the multi-carbon Faraday efficiency is still higher than 75% after continuous operation for 24 h.

Description

Technical Field

[0001] The present invention belongs to the field of catalytic technology, and particularly relates to an oxide cluster-modified copper nanowhisker and a preparation method thereof. The catalyst is used for electrochemical carbon dioxide reduction. Background Art

[0002] In the past few decades, with the excessive use of fossil fuels by people, the concentration of carbon dioxide in the air has risen sharply, and the global CO2 concentration has exceeded 424 ppm, leading to increasingly severe global climate change problems. In addition, in industrial production, the emissions of CO2 are huge, especially in energy-intensive industries such as chemical engineering, steel, and cement production, which have become the main emission sources. Therefore, it is crucial to capture and reuse CO2. At present, the methods for converting CO2 into value-added chemicals include thermal catalytic hydrogenation of CO2, photocatalytic reduction of CO2, and electrochemical conversion of CO2. Thermal catalytic hydrogenation of CO2 mainly converts CO2 into low-carbon chain products such as CO, CH4, and CH3OH under high temperature and high pressure conditions. Although it has a high conversion efficiency, it has high energy consumption and low calorific value of the products. Photocatalytic reduction of CO2 faces problems of low light utilization efficiency and low product yield. In contrast, electrochemical conversion of CO2 can convert CO2 into multi-carbon products such as ethylene, ethanol, acetic acid, and n-propanol under mild conditions, showing great application potential for converting CO2 into value-added chemicals. In addition, electrochemical conversion of CO2 into value-added chemicals can not only effectively reduce the concentration of carbon dioxide in the atmosphere but also promote the green transformation of the energy structure. By using renewable energy sources such as solar energy and wind energy to provide power for the electrochemical conversion process, sustainable conversion of CO2 can be achieved. Converting CO2 into value-added chemicals such as ethylene and ethanol not only provides a new solution for energy storage but also brings a more green and low-carbon approach for chemical production.

[0003] Electrochemical conversion of CO2 to multi-carbon (C 2+ ) products, such as ethylene, ethanol, n-propanol, etc., has received extensive attention in recent years. Due to its high added value and wide application potential, C 2+ products have become ideal targets in the CO2 reduction reaction. However, electrochemical conversion of CO2 to C 2+ still faces some challenges: (i) The product distribution is complex, increasing the separation cost. Due to the complex electrode / electrolyte interface environment, the selectivity of a single multi-carbon product in the electrochemical CO2 conversion process is low. The complex product distribution requires a large amount of energy to separate the product mixture in the outlet stream to meet the industrial purity standards of each hydrocarbon, alcohol, carboxylic acid, etc. (99% purity). In addition, when the electrochemical CO2 conversion product is used as a fuel, there is an even more urgent need for chemicals with higher carbon chains (representing high calorific value). Currently, in the electrochemical CO2 conversion products, C 4+The Faradaic efficiency (FE) of hydrocarbons remains below 5% currently, and the current density is also below 3 mA cm -2 . (ii) Insufficient stability. The reconstruction of catalyst active sites, the poisoning of active sites by carbonate deposits near the cathode, and the valence state imbalance lead to insufficient catalyst stability and reduce the efficient and directional conversion efficiency of CO2.

[0004] Therefore, developing an oxide cluster-modified copper nanowhisker catalyst and its preparation method to solve the above problems has important industrial application value for electrocatalytic reduction of carbon dioxide to prepare high-value chemicals and green fuels. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of low activity selectivity of current copper-based products and poor catalyst stability, and to provide an oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction, its preparation method and application, so as to improve the activity, stability and product selectivity of the catalyst and reduce energy consumption.

[0006] The oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction in the present invention is to deposit an oxide cluster MO on the surface of a copper-based material (lamellar copper oxide) x , to obtain a pre-catalyst, and then the pre-catalyst is subjected to reduction treatment by applying a negative voltage in a CO2 gas atmosphere, thereby forming an oxide cluster-modified copper nanowhisker catalyst. The chemical general formula of the oxide cluster-modified copper nanowhisker catalyst is MO x / Cu, and M in MO x represents one or more of metal zirconium, magnesium, calcium, titanium, aluminum, and gallium.

[0007] The preparation method of the oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction in the present invention is realized according to the following steps:

[0008] One, using copper powder, CuO or Cu2O as the copper-based material;

[0009] Two, dissolving ammonium hypophosphite in a solvent, then adding tartaric acid and sodium hydroxide, stirring and then adding the copper-based material to disperse evenly, adding the precursor material, stirring and reacting at a temperature of 40 °C to 110 °C, and subjecting the collected solid-phase reactant to calcination treatment in the air to obtain a pre-catalyst;

[0010] Three, mixing the pre-catalyst, Nafion solution and organic solvent evenly, and then coating them on the gas diffusion layer as the working electrode;

[0011] Four, placing the working electrode in an electrolyte solution, using a three-electrode system, and applying a negative voltage to the working electrode for reduction treatment in a CO2 gas atmosphere to obtain an oxide cluster-modified copper nanowhisker catalyst MO x / Cu;

[0012] Among them, the precursor materials are one, two or more of (soluble) zirconium salt precursor, magnesium salt precursor, calcium salt precursor, titanium salt precursor, aluminum salt precursor, and gallium salt precursor.

[0013] The application of the copper nanowhisker catalyst modified with oxide clusters of the present invention is to use the copper nanowhisker catalyst modified with oxide clusters for electrochemical carbon dioxide reduction.

[0014] The copper nanowhisker catalyst modified with oxide clusters of the present invention, its preparation method and application have the following beneficial effects:

[0015] The process for preparing the copper nanowhisker catalyst modified with oxide clusters of the present invention is convenient to operate and the preparation process is simple. Only need to form CuO nanosheets by alkali deposition of the corresponding copper salt, and then load the precursor of the corresponding oxide salt on its surface to form oxide clusters. In an atmosphere of 100% carbon dioxide, in one, two or more electrolyte solutions of 1M KCl / KBr / KHCO3 or 0.5M K2SO4, electrochemical carbon dioxide reduction can be carried out to obtain copper nanowhiskers modified with oxide clusters, which can be synthesized in large quantities; the conditions for the catalytic reaction using the catalyst are mild, and in one, two or more mixed electrolyte solutions of 1M KCl / KHCO3 / KBr / KOH or 0.5M K2SO4, multi-carbon products such as ethanol, ethylene, acetic acid, and n-propanol can be obtained with high selectivity, and the catalyst is stable during the long-term electrochemical reduction of carbon dioxide and is not easily deactivated.

[0016] Secondly, the copper nanowhisker catalyst modified with oxide clusters prepared by this method has outstanding stability. It has a high multi-carbon Faraday efficiency (FE C2+ greater than 80%) during the electrochemical carbon dioxide reduction process and has long-term stability (the multi-carbon Faraday efficiency is still higher than 75% after continuous operation for 24 hours), ensuring that there is no loss of the catalyst during use, further improving the product quality and reducing the process cost. Thirdly, the copper nanowhisker catalyst modified with oxide clusters prepared by this method has outstanding stability, low cost, environmental protection, and high conversion rate. Description of the Drawings

[0017] Figure 1 is the process flow chart of the preparation method of the copper nanowhisker catalyst modified with oxide clusters of the present invention;

[0018] Figure 2 is the test chart of the carbon dioxide reduction products and their selectivity of the ZrO2 modified copper-based catalyst compared with the unmodified ZrO2 copper-based catalyst in Test 1;

[0019] Figure 3It is the 1H NMR spectrum of the liquid for the electrochemical carbon dioxide reduction tandem thermal catalytic synthesis of ethylene glycol in Test 2;

[0020] Figure 4 It is the morphology and structure diagram taken by the aberration-corrected electron microscope of the pre-catalyst ZrO2 / CuO and CuO in the examples;

[0021] Figure 5 It is the XRD spectrum of the pre-catalyst ZrO2 / CuO and CuO in the examples;

[0022] Figure 6 It is the scanning electron microscope image of ZrO2 / Cu synthesized at different voltages obtained in the examples;

[0023] Figure 7 It is the linear sweep voltammetry test graph (b) and the Tafel slope test curve graph (a) of ZrO2 / Cu in Test 5;

[0024] Figure 8 It is the stability test curve graph of ZrO2 / Cu in Test 6. Detailed implementation manners

[0025] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0026] Detailed implementation manner 1: In this implementation manner, an oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction deposits an oxide cluster MO on the surface of a copper-based material (lamellar copper oxide) x , to obtain a pre-catalyst, and then the pre-catalyst is subjected to reduction treatment by applying a negative voltage in a CO2 gas atmosphere, thereby forming an oxide cluster-modified copper nanowhisker catalyst. The chemical general formula of the oxide cluster-modified copper nanowhisker catalyst is MO x / Cu, and M in MO x represents one or more of metals zirconium, magnesium, calcium, titanium, aluminum, and gallium.

[0027] This implementation manner finally forms an MO x / Cu oxide cluster-modified copper nanowhisker catalyst, where x = 1 or 2 or 3, where the valence of M is +1 or +2 or +3, and the valence of copper is greater than zero and less than +2.

[0028] Embodiment 2: The preparation method of the oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction is implemented according to the following steps:

[0029] 1. Use copper powder, CuO or Cu2O as the copper-based material;

[0030] 2. Dissolve ammonium hypophosphite in a solvent, then add tartaric acid and sodium hydroxide. After stirring, add the copper-based material to disperse it evenly. Add the precursor material and stir and react at a temperature of 40 °C to 110 °C. The collected solid-phase reactant is calcined in air to obtain a pre-catalyst;

[0031] 3. Mix the pre-catalyst, Nafion solution and organic solvent evenly, and then coat it on the gas diffusion layer as the working electrode;

[0032] 4. Place the working electrode in the electrolyte solution, adopt a three-electrode system, and apply a negative voltage to the working electrode in a CO2 gas atmosphere for reduction treatment to obtain the oxide cluster-modified copper nanowhisker catalyst MO x / Cu;

[0033] Wherein the precursor material is one, two or more of (soluble) zirconium salt precursor, magnesium salt precursor, calcium salt precursor, titanium salt precursor, aluminum salt precursor, gallium salt precursor.

[0034] In this embodiment, the copper-modifying oxide is the nanocluster MO x , with a size less than 5 nm. The final catalyst is obtained by reconstructing copper to obtain oxide-modified flaky copper nanowhiskers MO x / CuO in a 100% CO2 atmosphere in the electrolyte solution by applying a negative voltage. The preparation of the final catalyst and the electrochemical reduction of carbon dioxide are carried out simultaneously, thereby improving its selectivity and activity as the catalyst for reducing carbon dioxide to multi-carbon products. x / Cu.

[0035] Embodiment 3: The difference between this embodiment and Embodiment 2 is that the preparation method of the copper-based material in step 1 is as follows:

[0036] Disperse sodium hydroxide and cetyltrimethylammonium bromide (CTAB) in deionized water or absolute ethanol, add the copper precursor, and heat and stir the reaction at a temperature of 20 to 60 °C. The reactant is washed and dried to obtain the copper-based material.

[0037] The copper-based material prepared in this embodiment is ultrathin CuO nanosheets.

[0038] Embodiment 4: The difference between this embodiment and Embodiment 3 is that the copper precursor is copper nitrate, copper chloride, copper acetylacetonate or copper acetate.

[0039] Embodiment 5: The difference between this embodiment and Embodiment 3 is that the mass ratio of sodium hydroxide, cetyltrimethylammonium bromide and copper precursor is (28 - 60):(2.8 - 12):1.

[0040] Embodiment 6: The difference between this embodiment and Embodiment 2 is that in Step 2, 5 - 10.6 g of ammonium hypophosphite is dissolved in 30 - 50 mL of solvent, then 0.2 - 2 g of tartaric acid and 0.2 - 2 g of sodium hydroxide are added. After stirring, 100 mg of copper-based material is added and dispersed evenly.

[0041] The solvent described in this embodiment is water or ethanol.

[0042] Embodiment 7: The difference between this embodiment and Embodiment 2 is that the mass ratio of the precursor material and the copper-based material in Step 2 is 0.1 - 10:100.

[0043] Embodiment 8: The difference between this embodiment and Embodiment 2 is that in Step 2, it is calcined in air at a temperature of 200 - 500 °C for 1 - 3 h.

[0044] Embodiment 9: The difference between this embodiment and Embodiment 2 is that the electrolyte solution described in Step 4 is 1 mol / L KCl solution, 1 mol / L KBr solution, 1 mol / L KHCO3 solution or 0.5 mol / L K2SO4 solution.

[0045] Embodiment 10: The difference between this embodiment and Embodiment 2 is that the negative voltage applied in Step 4 is -0.6 - -1.6 V vs. RHE, and the reduction treatment time is 0.5 - 6 h.

[0046] Example: The preparation method of the oxide cluster-modified copper nanowire catalyst for electrochemical carbon dioxide reduction in this example is implemented according to the following steps:

[0047] 1. Disperse 20 g of sodium hydroxide and 4 g of cetyltrimethylammonium bromide (CTAB) in deionized water, add the copper nitrate precursor, and heat and stir the reaction at 60 °C for 4 h. After washing and drying the reactants, copper-based material is obtained;

[0048] II. Dissolve 8 g of ammonium hypophosphite in water, then add 1 g of tartaric acid and 1 g of sodium hydroxide. After stirring, add 100 mg of copper-based material and disperse it evenly. Then add the zirconium nitrate precursor material and stir and react at 70 °C for 6 h. The collected solid-phase reactant is calcined in air at 300 °C for 2 h to obtain the pre-catalyst;

[0049] III. Mix 10 mg of the pre-catalyst, 25 μL of Nafion (5 wt%) solution and 500 μL of absolute ethanol evenly. Take 50 μL and coat it on a 1 cm 2 gas diffusion layer as the working electrode;

[0050] IV. Place the working electrode in an electrolyte of 1 M KCl solution. Using a three-electrode system, the reference electrode is Ag / AgCl and the counter electrode is a platinum sheet. Apply a negative voltage of -0.6 V vs. RHE to the working electrode in a 100% CO2 gas atmosphere for 15 min for reduction treatment to obtain the copper nanowhisker catalyst MO x / Cu modified with different contents of oxide clusters.

[0051] Test 1

[0052] Weigh 10 mg of 0.5 wt% ZrO2 / CuO, 1 wt% ZrO2 / CuO, 2 wt% ZrO2 / CuO, 5 wt% ZrO2 / CuO, 10 wt% ZrO2 / CuO, 0.5 wt% ZrO2 / Cu2O, 1 wt% ZrO2 / Cu2O, 2 wt% ZrO2 / Cu2O, 5 wt% ZrO2 / Cu2O, and 10 wt% ZrO2 / Cu2O respectively, and name them Test Group 1, Test Group 2, Test Group 3, Test Group 4, Test Group 5, Test Group 6, Test Group 7, Test Group 8, Test Group 9, and Test Group 10 respectively. Then add 500 μL of absolute ethanol and 25 μL of Nafion (5 wt%) respectively, and ultrasonically disperse the solution evenly. Take 50 μL respectively and coat it evenly on a 1 cm 2 gas diffusion layer as the working electrode. The reference electrode is Ag / AgCl and the counter electrode is a platinum sheet. Before the electrochemical test, inject 20 mL of 1 mol / L KCl electrolyte and KOH electrolyte into the cathode and anode chambers respectively, and continuously introduce CO2 gas into the cathode chamber for 30 min to ensure that the cathode electrolyte is in a CO2-saturated state. During the electrocatalytic CO2 reduction process, introduce CO2 gas at a rate of 30 mL / min, and directly connect the outlet to a gas chromatography system for the detection of gas-phase products. After 2 h of electrolysis reaction, take the electrolyte for the detection of liquid-phase products. The specific situation is shown in Table 1.

[0053] As Figure 2a and 2b show in detail the CO2RR products and their selectivities of 5% ZrO2 / CuO at different voltages (vs. RHE) and different currents. In the voltage range of -1.2 to -1.4 V, the C 2+ product Faradaic efficiency (FE C2+ ) always remains above 75% and reaches a maximum of 80.1 ± 0.5% as the negative potential increases. In the current density range of 300 to 600 mA cm -2 , the C 2+ Faradaic efficiency (FE C2+ ) of 5% ZrO2 / CuO always remains above 70%, among which the partial Faradaic efficiency of C2H4 is maintained above 40%, showing significant potential for industrial applications. It is worth noting that at a current density of 400 mA cm -2 , the C 2+ Faradaic efficiency reaches a peak of 78%.

[0054] Table 1 Faradaic efficiencies of multi-carbon products for electroreduction of carbon dioxide by different catalysts at -1.2 V vs. RHE

[0055] Test group number Catalyst Faraday efficiency of multi-carbon products % Test group 1 <![CDATA[0.5% ZrO2 / CuO]]> 65.7 Test group 2 <![CDATA[1.0% ZrO2 / CuO]]> 66.7 Test group 3 <![CDATA[2.0% ZrO2 / CuO]]> 69.3 Test group 4 <![CDATA[5.0% ZrO2 / CuO]]> 80.1 Test group 5 <![CDATA[10.0%ZrO2 / CuO]]> 68.6 Test group 6 <![CDATA[0.5% ZrO2 / Cu2O]]> 67.1 Test group 7 <![CDATA[1.0% ZrO2 / Cu2O]]> 69.5 Test group 8 <![CDATA[2.0% ZrO2 / Cu2O]]> 70.7 Test group 9 <![CDATA[5.0%ZrO2 / Cu2O]]> 78.9 Test group 10 <![CDATA[10.0%ZrO2 / Cu2O]]> 72.6

[0056] Weigh 10 mg of CuO nanosheets and Cu2O cubes respectively, which are copper-based catalysts without ZrO2 modification, and name them as experimental group 11 and experimental group 12. Then add 500 μL of absolute ethanol and 25 μL of Nafion (5 wt%) respectively, and ultrasonically disperse the solution evenly. Take 50 μL respectively and coat it evenly on a 1 cm 2 gas diffusion layer as the working electrode, the reference electrode is Ag / AgCl, and the counter electrode is a platinum sheet. Before the electrochemical test, inject 20 mL of 1 mol / L KCl electrolyte and KOH electrolyte into the cathode and anode chambers respectively, and continuously introduce CO2 gas into the cathode chamber for 30 min to ensure that the cathode electrolyte is in a CO2-saturated state. During the electrocatalytic CO2 reduction process, CO2 gas is introduced at a rate of 30 mL / min, and the outlet is directly connected to a gas chromatography system for the detection of gas-phase products, and the electrolyte is taken for the detection of liquid-phase products after 2 h of electrolysis reaction. The specific situation is shown in Table 2.

[0057] The specific situation is as Figure 2 shown in Figure 2 c. C1 c shows in detail the CO2RR products and their selectivities of CuO at different voltages (vs. RHE). In the voltage range of -1.2 to -1.4 V, CuO shows a higher C1 product Faradaic efficiency (FE 2+ ) and a lower C C2+) In the same voltage range, the Faradaic efficiency of the C1 product decreased from 64.8 ± 1.5% to 29.1 ± 2.2%, while the FE C2+ increased from 20.3 ± 0.8% to 58.6 ± 1.3%.

[0058] Table 2 Faradaic efficiency of multi-carbon products for electroreduction of carbon dioxide by different catalysts at -1.2 V vs. RHE

[0059] Test group number Catalyst Faraday efficiency of multi-carbon products % Test group 11 CuO 51.0 Test group 12 <![CDATA[Copper(I) oxide]]> 53.1

[0060] The MgO / CuO and Al2O3 / CuO copper nanowhisker catalysts were prepared separately according to the method of the examples. Weigh 10 mg of 5 wt% MgO / CuO and 5 wt% Al2O3 / CuO, and name them as test group 13 and test group 14 respectively. Then add 500 μL of absolute ethanol and 25 μL of Nafion (5 wt%) respectively, and ultrasonically disperse the solution evenly. Take 50 μL respectively and coat it evenly on a 1 cm 2 gas diffusion layer as the working electrode, the reference electrode is Ag / AgCl, and the counter electrode is a platinum sheet. Before the electrochemical test, 20 mL of 1 mol / L KCl electrolyte and KOH electrolyte are injected into the cathode and anode chambers respectively, and CO2 gas is continuously introduced into the cathode chamber for 30 min to ensure that the cathode electrolyte is in a CO2-saturated state. During the electrocatalytic CO2 reduction process, CO2 gas is introduced at a rate of 30 mL / min, and the outlet gas is directly connected to a gas chromatography system for the detection of gas-phase products, and the electrolyte is taken for liquid-phase product detection after 2 h of electrolysis reaction. The specific situation is shown in Table 3.

[0061] Table 3 Faradaic efficiency of multi-carbon products for electroreduction of carbon dioxide by copper catalysts modified with different oxide clusters at -1.2 V vs. RHE

[0062] Test group number Catalyst Faraday efficiency of multi-carbon products % Test group 13 5.0% MgO / CuO 68 Test group 14 <![CDATA[5.0%Al2O3 / CuO]]> 65

[0063] Test 2

[0064] When using oxide-modified flaky copper nanowhiskers for the electrochemical reduction of carbon dioxide to produce multi-carbon products, the gas multi-carbon products are mainly ethylene. Connecting the ethylene product in series to the subsequent hot catalyst reaction can further convert ethylene. In Test 2 of the example part of the present invention, the mixed gas of ethylene and carbon dioxide generated by the electrochemical reduction of CO2 is directly introduced into an aqueous solution (the concentration of dilute sulfuric acid is 0.1% - 10%), using titanium silicalite molecular sieve and acid as the reaction catalyst, stirring and reacting for 0.5 - 5 hours, and then taking the reaction solution for 1 HNMR detection of the product. Please refer to Figure 3, ethylene glycol is the only product observed, which means that by coupling the electrochemical reduction of CO2 reaction with the oxidation of ethylene in series, a highly selective ethylene glycol product can be obtained to produce a product with higher added value. It should be noted that the test in this example focuses on the combination of electrochemical carbon dioxide reduction and thermal catalytic ethylene oxidation at normal temperature and pressure. As a tandem reaction to convert ethylene into ethylene glycol to produce higher value chemicals, this belongs to the application of this catalyst.

[0065] The acid can be a liquid acid or a solid acid. The liquid acid is sulfuric acid with a concentration of 0.1% - 10%; the mass of the titanium silicalite molecular sieve is 10 - 500 mg.

[0066] Test 3

[0067] Please refer to Figure 4 and Figure 5 , which are the aberration-corrected transmission electron microscopy images and XRD patterns after the pre-catalyst 5% ZrO2 / CuO was synthesized. The first product CuO synthesized by the above method has an ultrathin lamellar structure ( Figure 4 a and b). After depositing ZrO2 on the surface of the first product, aberration-corrected transmission electron microscopy shows that the ZrO2 on the surface of CuO is oxide clusters smaller than 5 nm (refer to Figure 4 c and d). The XRD pattern of Figure 5 shows that the diffraction peaks in the patterns before and after depositing ZrO2 are all those of CuO, and there are no obvious ZrO2 diffraction peaks, indicating that ZrO2 is evenly dispersed on the surface of CuO and has a very small size, which is consistent with the results of aberration-corrected transmission electron microscopy.

[0068] Test 4

[0069] Please refer to Figure 6 , the morphological change process of the catalyst during the electrochemical carbon dioxide reduction process. The initial catalyst is a two-dimensional nanosheet. It becomes a hollow columnar nanoflower cluster with a diameter of about 20 - 30 μm after 1 h of CO2RR at -1.2 V vs. RHE, and becomes a flower cluster-like two-dimensional copper nanowhisker with a diameter of about 20 - 30 μm after 2 h (refer to Figure 6 a), while CuO becomes irregular polycrystals without obvious lamellar copper nanowhiskers (refer to Figure 6 c). By changing the applied cathodic constant potential, sheet-like copper nanowhiskers appear at low potentials of -0.9 V to -1.3 V vs. RHE (refer to Figure 6 b), indicating that the oxide-modified copper nanowhiskers can be synthesized within a relatively wide potential range. In addition, by changing the mass ratio of different metals M to copper from 0.1 - 10:100, sheet-like copper nanowhiskers can be synthesized.

[0070] Test 5

[0071] Please refer to Figure 7, the final catalyst ZrO2 / Cu was subjected to linear sweep voltammetry tests in an electrolyte solution at a scan rate of 50 mV s -1 . These test results highlight the positive effect of ZrO2 on the catalytic performance of Cu. At -1.2 V vs. RHE, the peak local current density of the 5% ZrO2 / Cu catalyst reached 360 mA cm Figure 7 , while that of pure Cu was only 310 mA cm -2 under the same conditions. Please refer to -2 . Please refer to Figure 7 b, the Tafel slopes of 5% ZrO2 / Cu and Cu were 186 mV dec -1 and 232 mV dec -1 respectively. The smaller Tafel slope indicates better reaction kinetics, suggesting that the ZrO2-modified flaky copper nanowhiskers have stronger multi-carbon production ability.

[0072] Test 6

[0073] Please refer to Figure 8 . Under the above test conditions, at a high current density of 400 mA cm -2 , the 5% ZrO2 / Cu catalyst was subjected to a 24-hour high-activity and selectivity test. Its performance decay was negligible, and a stable C 2+ Faradaic efficiency of more than 75% was maintained.

[0074] The present invention not only provides the oxide cluster-modified copper nanowhiskers prepared by the described preparation method, but also provides the application of the oxide cluster-modified copper nanowhisker catalyst. The catalyst prepared by the present invention is mainly applied to the electrochemical reduction of carbon dioxide to produce multi-carbon products, and / or the further application of the ethylene gas produced by the electrochemical reduction of carbon dioxide through a tandem reaction. The reaction conditions can refer to the foregoing content and will not be elaborated here.

[0075] The technology for preparing the oxide cluster-modified copper nanowhisker catalyst by this method is simple and the operation is convenient. The preparation process is simple. Only the corresponding copper salt needs to be precipitated by an alkali to form the first product, and then one, two or more of the corresponding oxides are deposited, and then electrochemically reduced in an atmosphere of a carbon-containing gas (100% CO2) to obtain the catalyst, which can be synthesized in large quantities; the conditions for the catalytic reaction using the catalyst are mild, and multi-carbon products can be obtained with high selectivity at a lower voltage.

[0076] Secondly, the copper nanowhiskers modified with oxide M (M includes one, two or more of zirconium, magnesium, calcium, titanium, aluminum, and gallium) prepared by this method have outstanding stability, good mechanical strength, and still have good stability during long-term electrochemical carbon dioxide reduction, ensuring that there is no loss of the catalyst during use, further improving the product quality and reducing the process cost.

[0077] Thirdly, the copper nanowhiskers modified with oxide M (M includes one, two or more of zirconium, magnesium, calcium, titanium, aluminum, and gallium) prepared by this method have outstanding stability, low cost, environmental friendliness, and high selectivity for multi-carbon products. Using the catalyst for electrocatalytic reduction of carbon dioxide, the Faraday efficiency of multi-carbon products is as high as over 80%, reducing the generation of single-carbon products with low value and increasing the energy utilization efficiency.

[0078] In summary, the prepared copper nanowhisker catalyst modified with oxide M (M includes one, two or more of zirconium, magnesium, calcium, titanium, aluminum, and gallium) can solve the problems of insufficient catalyst stability, low efficiency of multi-carbon products, energy consumption, environmental protection, etc.

[0079] Obviously, the above are only the preferred embodiments of the present invention and the applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described here, and various obvious changes, re-adjustments, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. Oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction, characterized in that The described oxide cluster-modified copper nanowhisker catalyst is to deposit oxide clusters MO on the surface of a copper-based material x , obtaining a pre-catalyst, and then the pre-catalyst is subjected to reduction treatment by applying a negative voltage in a CO2 gas atmosphere, thereby forming an oxide cluster-modified copper nanowhisker catalyst. The chemical general formula of the oxide cluster-modified copper nanowhisker catalyst is MO x / Cu, and M in MO x represents one or more of metal zirconium, magnesium, calcium, titanium, aluminum, and gallium.

2. The preparation method of the oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction according to claim 1, characterized in that The described preparation method is realized according to the following steps:

1. Using copper powder, CuO or Cu2O as the copper-based material; 2. Dissolving ammonium hypophosphite in a solvent, then adding tartaric acid and sodium hydroxide, stirring and then adding the copper-based material to disperse evenly, adding the precursor material, stirring and reacting at a temperature of 40°C to 110°C, and subjecting the collected solid-phase reactant to calcination treatment in the air to obtain a pre-catalyst; 3. Mixing the pre-catalyst, Nafion solution and organic solvent evenly, and then coating them on the gas diffusion layer as the working electrode; IV. Place the working electrode in the electrolyte solution, adopt a three-electrode system, apply a negative voltage to the working electrode in a CO2 gas atmosphere for reduction treatment to obtain a copper nanowhisker catalyst MO x / Cu; Among them, the precursor material is one, two or more of zirconium salt precursor, magnesium salt precursor, calcium salt precursor, titanium salt precursor, aluminum salt precursor, gallium salt precursor.

3. The preparation method of the oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction according to claim 2, characterized in that The preparation method of the copper-based material in step 1 is as follows: Dispersing sodium hydroxide and cetyltrimethylammonium bromide in deionized water or absolute ethanol, adding a copper precursor, heating and stirring and reacting at a temperature of 20 to 60°C, and obtaining the copper-based material after the reactant is washed and dried.

4. The preparation method of the oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction according to claim 3, characterized in that The mass ratio of sodium hydroxide, cetyltrimethylammonium bromide and copper precursor is (28 to 60):(2.8 to 12):

1.

5. The preparation method of the oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction according to claim 2, wherein In step 2, 5 to 10.6 g of ammonium hypophosphite is dissolved in 30 to 50 mL of solvent, then 0.2 to 2 g of tartaric acid and 0.2 to 2 g of sodium hydroxide are added, and after stirring, 100 mg of the copper-based material is added to disperse evenly.

6. The preparation method of the oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction according to claim 2, wherein In step 2, the mass ratio of the precursor material to the copper-based material is 0.1 to 10:

100.

7. The preparation method of the oxide cluster modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction according to claim 2, characterized in that In step 2, it is calcined in the air at a temperature of 200 to 500°C for 1 to 3 h.

8. The preparation method of the oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction according to claim 2, characterized in that The electrolyte solution described in step 4 is 1 mol / L KCl solution, 1 mol / L KBr solution, 1 mol / L KHCO3 solution or 0.5 mol / L K2SO4 solution.

9. The preparation method of the oxide cluster-modified copper nanowhisker catalyst for electrochemical carbon dioxide reduction according to claim 2, wherein In step 4, a negative voltage of -0.6 to -1.6 V vs. RHE is applied, and the reduction treatment time is 0.5 to 6 h.

10. Use of the oxide cluster-modified copper nanowhisker catalyst prepared as claimed in claim 2 for electrochemical carbon dioxide reduction, characterized in that Using the copper nanowhisker catalyst modified by the oxide cluster for electrochemical carbon dioxide reduction.

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