A nano gold-palladium alloy catalyst, a preparation method and application thereof

Abstract

The application discloses a kind of nano gold palladium alloy catalyst and its preparation method and application.In protective atmosphere, the mixed solution comprising gold precursor, palladium precursor, reducing agent and stabilizer is reduced and coprecipitation reaction, the reaction product obtained is calcined, and the nano gold palladium alloy catalyst is obtained.The catalyst is based on gold palladium mutual solution and causes electron structure reconstruction principle, adjusts gold palladium alloy peripheral electron cloud density, so as to change the adsorption of gold palladium alloy, and greatly improves the selectivity and catalytic activity of catalyst.The catalyst is used for electrocatalytic reduction CO2, and the selectivity of CO can reach more than 90%, which is much higher than that of commercial CO2 reduction catalyst, and has a wide application prospect in the field of "carbon neutralization".

Description

Technical Field

[0001] This invention relates to a nano-gold-palladium alloy catalyst, specifically to a nano-gold-palladium alloy catalyst, its preparation method, and its application, belonging to the field of renewable energy recycling. Background Technology

[0002] Currently, fossil fuels such as coal, oil, and natural gas account for over 80% of the global energy mix. The massive combustion of fossil fuels has led to excessive carbon dioxide (CO2) emissions into the atmosphere, exacerbating the greenhouse effect and subsequently triggering and intensifying problems such as climate anomalies, sea-level rise, and biodiversity loss. Converting carbon dioxide into storable renewable energy sources or chemical feedstocks through appropriate methods can not only alleviate current energy and environmental problems but also has significant economic value.

[0003] The main methods for carbon dioxide conversion include thermocatalysis, photocatalysis, and electrocatalysis. Electrocatalysis offers several advantages: the electrical energy used in the reaction can be generated from renewable and clean energy sources; the reaction products exhibit better selectivity; the electrolyte solution can be recycled multiple times; and the electrical energy can be stored as chemical energy. Furthermore, with the increasing proportion of renewable electricity and the decreasing cost of electricity, the pathway of converting CO2 into fuels or chemicals with higher industrial added value through electrocatalytic reduction has attracted widespread attention from researchers. The products of electrocatalytic CO2 reduction include C1 products (such as carbon monoxide, formic acid, and formate) and C2 products. 2+ Products (such as ethylene, ethanol, etc.). Studies have shown that, due to their simple mechanical structure, C1 products are more efficient than C2 products. 2+ The product has higher energy efficiency. Carbon monoxide (CO) in the C1 product is one of the important raw materials for Fischer-Tropsch synthesis and alcohol synthesis in the chemical industry. Through further reaction, CO can be efficiently synthesized into a variety of high-value-added fuels or chemicals, and CO also plays a key role in the metallurgical industry. Therefore, the electrocatalytic reduction of CO2 to CO has great application potential. However, there are currently many bottlenecks. On the one hand, the reaction involves multiple electron transfer processes, resulting in complex intermediates, numerous reduction products, poor selectivity, and serious interference from hydrogen evolution side reactions. On the other hand, the CO current density is low, and the reaction rate is slow and inefficient. Therefore, developing efficient catalysts is key to improving CO selectivity, inhibiting hydrogen evolution, and increasing CO current density. Summary of the Invention

[0004] To address the problems existing in the prior art, the first objective of this invention is to provide a nano-gold-palladium alloy catalyst, which is a supported palladium-gold bimetallic nano-alloy catalyst. This catalyst, based on the synergistic effect between gold and palladium, alters the outer electron density through electron migration between gold and palladium, thereby lowering the energy barrier of the catalytic reaction and significantly improving the catalyst activity and selectivity.

[0005] The second objective of this invention is to provide a method for preparing a nano-gold-palladium alloy catalyst. This method utilizes the infinite miscibility of gold and palladium and improves the dispersibility and uniformity of the gold-palladium alloy through co-precipitation combined with calcination treatment. Furthermore, this preparation method is simple, environmentally friendly, and suitable for continuous production.

[0006] The third objective of this invention is to provide an application of a nano-gold-palladium alloy catalyst, using a palladium-gold bimetallic nanocatalyst as an electrocatalytic reduction catalyst in the preparation of an electrocatalytic cathode to catalyze the reduction of CO2 to CO. Testing has shown that this catalyst exhibits excellent catalytic activity and selectivity, with a CO catalytic selectivity exceeding 90%, and its overall performance far surpasses that of commercial CO2 reduction catalysts.

[0007] To achieve the above-mentioned technical objectives, the present invention provides a method for preparing a nano-gold-palladium alloy catalyst. Under a protective atmosphere, a mixture containing a gold precursor, a palladium precursor, a reducing agent, and a stabilizer is subjected to a reduction and co-precipitation reaction. The reaction product is washed, dried, and then calcined to obtain the catalyst.

[0008] This invention employs a co-precipitation-co-reduction preparation method, enabling the simultaneous precipitation of palladium and gold. The resulting nano-gold-palladium alloy exhibits higher dispersibility and uniformity. Furthermore, a high-temperature calcination process is used to induce atomic rearrangement of palladium and gold, resulting in a more ordered structure for the palladium-gold alloy catalyst. This structure contains numerous Au-Pd centers, which can stabilize more *HOCO through O··Au-Pd··CO, weakening the C=O adsorption capacity, improving the *CO desorption capacity, and significantly enhancing the catalyst's selectivity for CO.

[0009] As a preferred embodiment, the protective atmosphere is at least one of nitrogen, argon, and helium.

[0010] As a preferred embodiment, the molar ratio of the gold precursor to the palladium precursor is 1:0.9 to 1.1.

[0011] As a preferred embodiment, the molar ratio of the gold precursor to the reducing agent is 1:19000-20000.

[0012] As a preferred embodiment, the molar ratio of the gold precursor to the stabilizer is 1:5 to 10.

[0013] As a preferred embodiment, the mixture further comprises a carrier, wherein the molar ratio of the carrier to the gold precursor is 30-40:1.

[0014] As a preferred embodiment, the gold precursor is at least one of chloroauric acid, sodium chloroaurate, gold trichloride, and gold thiosulfate.

[0015] As a preferred embodiment, the palladium precursor is at least one of palladium chloropalladium, palladium acetylacetonate, sodium palladium chloropalladium, and palladium chloride.

[0016] As a preferred embodiment, the reducing agent is at least one selected from ethylene glycol, 1,2-propanediol, and mercaptoethanol. This invention employs a relatively mild reducing agent to simultaneously reduce gold and palladium from gold and palladium precursor solutions to generate gold and palladium nanoparticles.

[0017] As a preferred embodiment, the stabilizer is at least one of oleic acid and oleylamine. The stabilizer can effectively limit the size of the nanoparticles and prevent their aggregation.

[0018] As a preferred embodiment, the carrier is at least one of carbon powder, metal nitride, metal sulfide, metal phosphide and metal oxide.

[0019] The support selected in this invention is based on the Pd site-support interface stress effect. Through interfacial lattice mismatch, the interaction force between CO and Pd is weakened, promoting CO desorption and generation. Furthermore, by utilizing the synergistic effect between the support and palladium nanoparticles, not only is it helpful for the uniform dispersion of palladium nanoparticles, but it can also effectively reduce the shedding and migration of palladium nanoparticles, thereby effectively protecting the electrochemical active sites of the catalyst and improving the activity and stability of the catalyst.

[0020] As a preferred embodiment, the reduction and coprecipitation reaction conditions are as follows: heating to 110–180°C at a heating rate of 1–10°C / min, and maintaining the temperature at this point for 0.5–3 hours. By changing the reaction conditions, the nucleation and growth rate of palladium can be quantitatively controlled, thereby obtaining palladium nanoparticles with superior electrocatalytic reduction performance of carbon dioxide to carbon monoxide.

[0021] As a preferred embodiment, the calcination conditions are as follows: under a protective atmosphere, the temperature is increased to 200–600°C at a heating rate of 3–8°C / min, and held at this temperature for 1–3 hours. By changing the calcination conditions, the degree of palladium lattice distortion can be altered, optimizing the catalyst's lattice and electronic structure, thereby improving the catalyst's electrocatalytic reduction of carbon dioxide to carbon monoxide. A further preferred calcination temperature is 400–600°C.

[0022] Furthermore, the detailed preparation process of the nano-gold-palladium alloy catalyst is as follows: 1) Add the gold precursor, palladium precursor, support, reducing agent and stabilizer to a three-necked flask, and under a protective atmosphere, heat to 110-180℃ at a heating rate of 1-10℃ / min, and maintain the temperature for 0.5-3h. After the temperature is maintained, the nano-gold-palladium alloy precursor is obtained; 2) After washing and drying, the nano-gold-palladium alloy precursor is calcined under a protective atmosphere, and heated to 200-600℃ at a heating rate of 3-8℃ / min, and maintained for 1-3h.

[0023] The present invention also provides a method for preparing a nano-gold-palladium alloy catalyst, which is obtained by any of the preparation methods described above.

[0024] As a preferred embodiment, the average particle size of the nano-gold-palladium alloy catalyst is 2–10 nm. Smaller and more uniform nano-gold-palladium alloy catalysts exhibit higher catalytic activity.

[0025] This invention also provides an application of a nano-gold-palladium alloy catalyst as a catalyst for the electrocatalytic reduction of carbon dioxide.

[0026] As a preferred embodiment, the nano-gold-palladium alloy catalyst is used to prepare the cathode of an H-type electrolytic cell.

[0027] The main mechanism of action of the nano-gold-palladium alloy catalyst described in this invention is as follows: Palladium is a common noble metal catalyst with high activity for various catalytic reactions and strong adsorption for various reducing gases. Based on this, elemental palladium exhibits strong adsorption for CO, and under a CO atmosphere, its active sites are easily enriched and occupied by CO, leading to catalyst deactivation. This invention uses palladium as a base material and utilizes the infinite miscibility between palladium and gold to introduce elemental gold to form a continuous solid solution, thereby regulating the electronic structure of palladium. Because the crystal lattices of palladium and gold are mismatched, the combination of palladium and gold causes a shift in the 3d electron orbitals of palladium, thus affecting the outer electron cloud density of palladium and altering the surface energy density of the alloy. Changes in the surface energy density of an alloy directly affect its desorption energy barrier. As mentioned earlier, palladium has a strong adsorption capacity for CO, and its desorption energy barrier is very high, making it difficult for CO to be removed from palladium. However, with the addition of gold, the surface energy barrier of the alloyed palladium is significantly reduced, greatly decreasing its adsorption capacity for CO. Furthermore, with the change in the outer electron cloud density, the adsorption capacity of the alloy surface for *HOCO is further enhanced. This effect is most obvious when the palladium-to-gold ratio is close to 1:1. Since *HOCO is an intermediate in the conversion of CO2 to CO, the palladium with the introduction of gold not only accelerates the desorption of CO but also significantly improves the catalytic activity and selectivity for CO.

[0028] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are as follows:

[0029] 1) The nano-gold-palladium alloy catalyst provided by the present invention is based on the synergistic effect between gold and palladium. Through the electron migration between gold and palladium, the outer electron density is changed, the energy barrier of the catalytic reaction is reduced, thereby significantly improving the catalyst activity and selectivity.

[0030] 2) In the technical solution provided by the present invention, the gold and palladium are infinitely miscible, and the co-reduction-co-precipitation method is adopted to improve the dispersibility and uniformity of the gold-palladium alloy. Moreover, the preparation method is simple, environmentally friendly, and easy to carry out continuous production.

[0031] 3) In the technical solution provided by this invention, palladium-gold bimetallic nanocatalysts are used as the negative electrode material of an electrolytic cell to catalyze the reduction of CO2 to CO. Testing has shown that this catalyst exhibits excellent catalytic activity and selectivity, with a CO catalytic selectivity exceeding 90%. Its overall performance far surpasses that of commercial CO2 reduction catalysts, demonstrating broad application prospects in the field of carbon neutrality. Attached Figure Description

[0032] Figure 1 The CO Faradaic efficiency of carbon-supported PdAu alloy catalysts at different calcination temperatures is given.

[0033] Figure 2 The CO current density is given for carbon-supported PdAu alloy catalysts at different calcination temperatures.

[0034] Figure 3 a is a low-magnification TEM image of the carbon-supported PdAu alloy catalyst in Example 2. Figure 3 b is a high-magnification TEM image.

[0035] Figure 4 a is the HAADF-STEM image of the carbon-supported PdAu alloy catalyst in Example 2. Figure 4 b represents the distribution of Pd in ​​the PdAu alloy. Figure 4 c represents the distribution of Au in the PdAu alloy. Figure 4 d represents the overall distribution of the PdAu alloy and the corresponding HAADF-STEM line scan palladium atom distribution fraction. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the following embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] (1) Add 2.5 mL of 9.4 mmol / L HAuCl4 solution, 2.5 mL of 9.4 mmol / L PdCl2 solution, 0.141 mmol of oleylamine, 0.141 mmol of oleic acid, and 25 mL of ethylene glycol to a three-necked flask. Connect the three-necked flask to a vacuum / inert gas manifold system, evacuate the flask, and fill it with nitrogen. Set the heating rate to 5 °C / min and react at 160 °C for 2 hours. After the reaction is completed, wash the sample three times by centrifugation with distilled water and anhydrous ethanol, and dry it under vacuum at 80 °C for 12 hours. Place the dried sample in a tube furnace, use nitrogen as the calcination atmosphere, and calcine it at 500 °C for 2 hours at a heating rate of 5 °C / min to obtain the PdAu alloy catalyst.

[0039] (2) Add 2 mg of PdAu alloy catalyst to a mixture of 1980 μL of 1:1 isopropanol aqueous solution and 20 μL of 5% naphthol solution. After ultrasonic treatment, take 50 μL and coat it evenly on the cut hydrophobic carbon paper in 5 portions. After drying, the catalyst-modified electrode is obtained.

[0040] (3) The H-type closed electrolytic cell is separated by a proton exchange membrane to obtain an anode chamber and a cathode chamber. The electrolyte of the cell is 0.5 mol / L K2CO3. Before the reaction, the electrolyte in the cathode chamber is stirred with a magnetic stirrer, and CO2 is pre-introduced into the electrolyte in the cathode chamber until saturation. A three-electrode system is adopted (working electrode: the catalyst-modified electrode obtained in step (2); reference electrode: saturated calomel electrode; counter electrode: graphite rod electrode). The working electrode is placed in the cathode chamber. The reference electrode is corrected and the surface of the working electrode is pretreated before the reactor is sealed. The electrocatalytic reaction is carried out by passing electricity. The performance of PdAu alloy catalyst for electrocatalytic reduction of carbon dioxide to CO is studied.

[0041] Experimental results show that the PdAu alloy catalyst exhibits a CO selectivity of up to 83.7% and a maximum CO current density of 10.3 mA / cm². 2 .

[0042] This embodiment also investigated the electrocatalytic reduction activity of PdAu alloy catalysts obtained at different calcination temperatures for the conversion of carbon dioxide to carbon monoxide. The specific operation was carried out according to the steps described above, with calcination temperatures of 200℃, 300℃, 400℃, 500℃, and 600℃. The CO Faradaic efficiency and CO current density of the carbon-supported PdAu alloy catalysts at different calcination temperatures were also investigated.

[0043] Example 2

[0044] (1) Add 2.5 mL of 9.4 mmol / L HAuCl4 solution, 2.5 mL of 9.4 mmol / L PdCl2 solution, 0.141 mmol of oleylamine, 0.141 mmol of oleic acid, 25 mL of ethylene glycol and 45 mg of carbon powder to a three-necked flask. Connect the three-necked flask to a vacuum / inert gas manifold system to evacuate and fill it with nitrogen. Set the heating rate to 5 °C / min and react at 160 °C for 2 hours. After the reaction is completed, wash the sample three times by centrifugation with distilled water and anhydrous ethanol, and dry it under vacuum at 80 °C for 12 hours. Place the dried sample in a tube furnace, use nitrogen as the calcination atmosphere, and calcine it at 500 °C for 2 hours at a heating rate of 5 °C / min to obtain carbon-supported PdAu alloy catalyst.

[0045] (2) Add 2 mg of carbon-supported PdAu alloy catalyst to a mixture of 1980 μL of 1:1 isopropanol aqueous solution and 20 μL of 5% naphthol solution. After ultrasonic treatment, take 50 μL and coat it evenly on the cut hydrophobic carbon paper in 5 portions. After drying, the catalyst-modified electrode is obtained.

[0046] (3) The H-type closed electrolytic cell is separated by a proton exchange membrane to obtain an anode chamber and a cathode chamber. The electrolyte of the cell is 0.5 mol / L K2CO3. Before the reaction, the electrolyte in the cathode chamber is stirred with a magnetic stirrer, and CO2 is pre-introduced into the electrolyte in the cathode chamber until saturation. A three-electrode system is adopted (working electrode: the catalyst-modified electrode obtained in step (2); reference electrode: saturated calomel electrode; counter electrode: graphite rod electrode). The working electrode is placed in the cathode chamber. The reference electrode is corrected and the surface of the working electrode is pretreated before the reactor is sealed. The electrocatalytic reaction is carried out by passing electricity. The performance of PdAu alloy catalyst for electrocatalytic reduction of carbon dioxide to CO is studied.

[0047] Experimental results show that the carbon-supported PdAu alloy catalyst can achieve a CO selectivity of up to 90.5% and a maximum CO current density of 13.2 mA / cm². 2 .

[0048] Example 3

[0049] (1) Add 2.5 mL of 9.4 mmol / L HAuCl4 solution, 2.5 mL of 9.4 mmol / L PdCl2 solution, 0.141 mmol of oleylamine, 0.141 mmol of oleic acid, 25 mL of ethylene glycol and 45 mg of niobium nitride (NbN) to a three-necked flask. Connect the three-necked flask to a vacuum / inert gas manifold system, evacuate and fill with nitrogen. Set the heating rate to 5 °C / min and react at 160 °C for 2 hours. After the reaction is completed, wash the sample three times by centrifugation with distilled water and anhydrous ethanol, and dry it under vacuum at 80 °C for 12 hours. Place the dried sample in a tube furnace, use nitrogen as the calcination atmosphere, and calcine it at 600 °C for 2 hours at a heating rate of 5 °C / min to obtain the niobium nitride supported PdAu alloy catalyst.

[0050] (2) Add 2 mg of niobium nitride-supported PdAu alloy catalyst to a mixture of 1980 μL of 1:1 isopropanol aqueous solution and 20 μL of 5% naphthol solution. After ultrasonic treatment, take 50 μL and coat it evenly on the cut hydrophobic carbon paper in 5 portions. After drying, the catalyst-modified electrode is obtained.

[0051] (3) The H-type closed electrolytic cell is separated by a proton exchange membrane to obtain an anode chamber and a cathode chamber. The electrolyte of the cell is 0.5 mol / L K2CO3. Before the reaction, the electrolyte in the cathode chamber is stirred with a magnetic stirrer, and CO2 is pre-introduced into the electrolyte in the cathode chamber until saturation. A three-electrode system is adopted (working electrode: the catalyst-modified electrode obtained in step (2); reference electrode: saturated calomel electrode; counter electrode: graphite rod electrode). The working electrode is placed in the cathode chamber. The reference electrode is corrected and the surface of the working electrode is pretreated before the reactor is sealed. The electrocatalytic reaction is carried out by passing electricity. The performance of PdAu alloy catalyst for electrocatalytic reduction of carbon dioxide to CO is studied.

[0052] Experimental results show that the niobium nitride-supported PdAu alloy catalyst exhibits a CO selectivity of up to 90.1% and a maximum CO current density of 13.7 mA / cm². 2 .

[0053] Example 4

[0054] (1) Add 2.5 mL of 9.4 mmol / L HAuCl4 solution, 2.5 mL of 9.4 mmol / L PdCl2 solution, 0.141 mmol of oleylamine, 0.141 mmol of oleic acid, 25 mL of ethylene glycol and 45 mg of molybdenum sulfide (MoS2) to a three-necked flask. Connect the three-necked flask to a vacuum / inert gas manifold system, evacuate and fill with nitrogen. Set the heating rate to 5 °C / min and react at 160 °C for 2 hours. After the reaction is completed, wash the sample three times by centrifugation with distilled water and anhydrous ethanol, and dry it under vacuum at 80 °C for 12 hours. Place the dried sample in a tube furnace, use nitrogen as the calcination atmosphere, and calcine at 5 °C / min to 500 °C for 2 hours to obtain the molybdenum sulfide supported PdAu alloy catalyst.

[0055] (2) Add 2 mg of molybdenum sulfide-supported PdAu alloy catalyst to a mixture of 1980 μL of 1:1 isopropanol aqueous solution and 20 μL of 5% naphthol solution. After ultrasonic treatment, take 50 μL and coat it evenly on the cut hydrophobic carbon paper in 5 portions. After drying, the catalyst-modified electrode is obtained.

[0056] (3) The H-type closed electrolytic cell is separated by a proton exchange membrane to obtain an anode chamber and a cathode chamber. The electrolyte of the cell is 0.5 mol / L K2CO3. Before the reaction, the electrolyte in the cathode chamber is stirred with a magnetic stirrer, and CO2 is pre-introduced into the electrolyte in the cathode chamber until saturation. A three-electrode system is adopted (working electrode: the catalyst-modified electrode obtained in step (2); reference electrode: saturated calomel electrode; counter electrode: graphite rod electrode). The working electrode is placed in the cathode chamber. The reference electrode is corrected and the surface of the working electrode is pretreated before the reactor is sealed. The electrocatalytic reaction is carried out by passing electricity. The performance of PdAu alloy catalyst for electrocatalytic reduction of carbon dioxide to CO is studied.

[0057] Experimental results show that the PdAu alloy catalyst supported on molybdenum sulfide exhibits a CO selectivity of up to 87.4% and a maximum CO current density of 11.8 mA / cm². 2 .

[0058] Example 5

[0059] (1) Add 2.5 mL of 9.4 mmol / L HAuCl4 solution, 2.5 mL of 9.4 mmol / L PdCl2 solution, 0.141 mmol of oleylamine, 0.141 mmol of oleic acid, 25 mL of ethylene glycol and 45 mg of nickel phosphide (Ni2P) to a three-necked flask. Connect the three-necked flask to a vacuum / inert gas manifold system, evacuate and fill with nitrogen. Set the heating rate to 5 °C / min and react at 160 °C for 2 hours. After the reaction is completed, wash the sample three times by centrifugation with distilled water and anhydrous ethanol, and dry it under vacuum at 80 °C for 12 hours. Place the dried sample in a tube furnace, use nitrogen as the calcination atmosphere, and calcine it at 500 °C for 2 hours at a heating rate of 5 °C / min to obtain the nickel phosphide supported PdAu alloy catalyst.

[0060] (2) Add 2 mg of nickel phosphide-supported PdAu alloy catalyst to a mixture of 1980 μL of 1:1 isopropanol aqueous solution and 20 μL of 5% naphthol solution. After ultrasonic treatment, take 50 μL and coat it evenly on the cut hydrophobic carbon paper in 5 portions. After drying, the catalyst-modified electrode is obtained.

[0061] (3) The H-type closed electrolytic cell is separated by a proton exchange membrane to obtain an anode chamber and a cathode chamber. The electrolyte of the cell is 0.5 mol / L K2CO3. Before the reaction, the electrolyte in the cathode chamber is stirred with a magnetic stirrer, and CO2 is pre-introduced into the electrolyte in the cathode chamber until saturation. A three-electrode system is adopted (working electrode: the catalyst-modified electrode obtained in step (2); reference electrode: saturated calomel electrode; counter electrode: graphite rod electrode). The working electrode is placed in the cathode chamber. The reference electrode is corrected and the surface of the working electrode is pretreated before the reactor is sealed. The electrocatalytic reaction is carried out by passing electricity. The performance of PdAu alloy catalyst for electrocatalytic reduction of carbon dioxide to CO is studied.

[0062] Experimental results show that the nickel phosphide-supported PdAu alloy catalyst exhibits a CO selectivity of up to 88.6% and a maximum CO current density of 12.5 mA / cm². 2 .

[0063] Example 6

[0064] (1) Add 2.5 mL of 9.4 mmol / L HAuCl4 solution, 2.5 mL of 9.4 mmol / L PdCl2 solution, 0.141 mmol of oleylamine, 0.141 mmol of oleic acid, 25 mL of ethylene glycol and 45 mg of bismuth oxide (Bi2O3) to a three-necked flask. Connect the three-necked flask to a vacuum / inert gas manifold system, evacuate and fill with nitrogen. Set the heating rate to 5 °C / min and react at 160 °C for 2 hours. After the reaction is completed, wash the sample three times by centrifugation with distilled water and anhydrous ethanol, and dry it under vacuum at 80 °C for 12 hours. Place the dried sample in a tube furnace, use nitrogen as the calcination atmosphere, and calcine at 5 °C / min to 500 °C for 2 hours to obtain the bismuth oxide-supported PdAu alloy catalyst.

[0065] (2) Add 2 mg of bismuth oxide-supported PdAu alloy catalyst to a mixture of 1980 μL of 1:1 isopropanol aqueous solution and 20 μL of 5% naphthol solution. After ultrasonic treatment, take 50 μL and coat it evenly on the cut hydrophobic carbon paper in 5 portions. After drying, the catalyst-modified electrode is obtained.

[0066] (3) The H-type closed electrolytic cell is separated by a proton exchange membrane to obtain an anode chamber and a cathode chamber. The electrolyte of the cell is 0.5 mol / L K2CO3. Before the reaction, the electrolyte in the cathode chamber is stirred with a magnetic stirrer, and CO2 is pre-introduced into the electrolyte in the cathode chamber until saturation. A three-electrode system is adopted (working electrode: the catalyst-modified electrode obtained in step (2); reference electrode: saturated calomel electrode; counter electrode: graphite rod electrode). The working electrode is placed in the cathode chamber. The reference electrode is corrected and the surface of the working electrode is pretreated before the reactor is sealed. The electrocatalytic reaction is carried out by passing electricity. The performance of PdAu alloy catalyst for electrocatalytic reduction of carbon dioxide to CO is studied.

[0067] Experimental results show that the bismuth oxide-supported PdAu alloy catalyst exhibits a CO selectivity of up to 86.8% and a maximum CO current density of 12.7 mA / cm². 2 .

[0068] Comparative Example 1

[0069] The reagents and steps were exactly the same as in Example 1, using 3.5 mL of 9.4 mmol / L HAuCl4 solution and 1.5 mL of 9.4 mmol / L PdCl2 solution.

[0070] The results show that the PdAu alloy catalyst obtained in this comparative example exhibits a CO selectivity of up to 66.3% and a maximum CO current density of 6.6 mA / cm². 2 .

[0071] Comparative Example 2

[0072] The reagents and steps were exactly the same as in Example 1, using 1.5 mL of 9.4 mmol / L HAuCl4 solution and 3.5 mL of 9.4 mmol / L PdCl2 solution.

[0073] Experimental results show that the PdAu alloy catalyst obtained in this comparative example exhibits a CO selectivity of up to 64.5% and a maximum CO current density of 6.1 mA / cm². 2 .

Claims

1. A method for preparing a nano-gold-palladium alloy catalyst, characterized in that: Under a protective atmosphere, a mixture containing a gold precursor, a palladium precursor, a reducing agent, and a stabilizer is subjected to a reduction and co-precipitation reaction. The resulting reaction product is then calcined to obtain the final product. The protective atmosphere is at least one of nitrogen, argon and helium; The molar ratio of the gold precursor to the palladium precursor is 1:0.9~1.1; The molar ratio of the gold precursor to the reducing agent is 1:19000~20000; The molar ratio of the gold precursor to the stabilizer is 1:5~10; The mixture also contains a carrier, and the mass ratio of the carrier to the gold precursor is 30-40:

1. The gold precursor is at least one of chloroauric acid, sodium chloroaurate, gold trichloride, and gold thiosulfate. The palladium precursor is at least one of chloropalladium acid, palladium acetylacetonate, sodium chloropalladium, and palladium chloride; The reducing agent is at least one of ethylene glycol, 1,2-propanediol and mercaptoethanol; The stabilizer is at least one of oleylamine and oleic acid; The conditions for the reduction and coprecipitation reaction are as follows: heating to 110-180℃ at a heating rate of 1-10℃ / min, and maintaining the temperature at a constant temperature for 0.5-3h.

2. The method for preparing a nano-gold-palladium alloy catalyst according to claim 1, characterized in that: The calcination conditions are as follows: under a protective atmosphere, the temperature is increased to 200-600℃ at a heating rate of 3-8℃ / min, and held at a constant temperature for 1-3 hours.

3. A nano-gold-palladium alloy catalyst, characterized in that: Obtained by the preparation method described in claim 1 or 2.

4. The nano-gold-palladium alloy catalyst according to claim 3, characterized in that: The particle size distribution of the nano-gold-palladium alloy catalyst is 2~10 nm.

5. The application of the nano-gold-palladium alloy catalyst according to claim 3, characterized in that: It is used as a catalyst for the electrocatalytic reduction of carbon dioxide.

6. The application of the nano-gold-palladium alloy catalyst according to claim 5, characterized in that: Used to prepare H-type electrolytic cell cathodes.

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