A method for preparing an atomic dispersion metal (Cu, Ag)-Bi2O2SO4 catalyst for CO2 photoreduction and application thereof

Abstract

The application discloses a preparation method of a photocatalyst for CO2 reduction and application thereof. The photocatalyst is prepared through the following steps: first, preparation of the photocatalyst bismuth oxysulfate; second, metal loading modification of the photocatalyst bismuth oxysulfate. Thiocyanic acid and bismuth nitrate are used as raw materials to synthesize the photocatalyst bismuth oxysulfate, and copper chloride or silver nitrate reagent is selected as a material for metal loading modification of the bismuth oxysulfate, and the selected materials are inexpensive and easy to purchase, and the economic cost is low. The photocatalyst prepared by the method has the advantages of high selectivity, can accelerate electron movement under light conditions, promotes CO2 reduction degradation, and has high stability, and is an ideal photocatalyst. Compared with existing photocatalyst materials, the material has high catalytic degradation reducibility and selectivity, high stability, and when used as a CO2 photocatalyst, can efficiently reduce and convert CO2 into multi-carbon products.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation, specifically to a method for preparing and applying an atomically dispersed metal (Cu,Ag)-Bi2O2SO4 catalyst for CO2 photoreduction. Background Technology

[0002] In recent years, the concentration of CO2 in the atmosphere has shown a gradual upward trend, increasing by about 40% compared to the mid-20th century. However, CO2 capture and storage technologies are costly to implement, consume a lot of energy, and are prone to leakage. Therefore, developing a new low-energy-consumption CO2 conversion method is imperative. Inspired by natural photosynthesis, photocatalytic reduction technology, which utilizes sunlight for CO2 hydrogenation, has attracted widespread interest. However, due to the various intermediate products and complex pathways in the CO2 conversion process, the reactivity and product selectivity of photocatalytic carbon dioxide reduction remain limited. Therefore, to improve the reactivity and product selectivity of carbon dioxide reduction, the photocatalyst needs to be rationally designed and integrated.

[0003] As a wide-bandgap semiconductor material, bismuth oxysulfate (Bi₂O₂SO₄) has a typical Sillén structure, in which alternating (Bi₂O₂) atoms are formed. 2+ and (SO4) 2- Metal-supported photocatalysts hold great promise for applications in photocatalysis. However, the controllable synthesis of Bi₂O₂SO₄ still faces certain challenges. Furthermore, the wide band gap and rapid recombination of charge carriers in single Bi₂O₂SO₄ limit its widespread application. Metal-supported strategies, which enhance local electric field density through the plasmon resonance effect (LSPR) and photocatalytic activity through hot electron injection, are effective modification strategies. Therefore, developing metal-supported photocatalysts for CO₂ reduction has significant practical implications. Among numerous metals, silver (Ag) and copper (Cu) are highly efficient CO₂ reduction metals and have been extensively studied in the field of electrocatalysis. Copper (Cu), due to its optimal binding ability with CO₂ and reaction intermediates, has been identified as one of the most promising co-catalysts for converting CO₂ into various hydrocarbons. Further research has shown that atomically dispersed metals can maximize the utilization of each metal atom and significantly increase the surface area of ​​the active metal, thereby maximizing specific activities and breaking traditional ratio relationships to generate new catalytic behaviors. Atomically dispersed catalysts have become a reasonable choice for designing and preparing cost-effective and efficient photocatalysts. This not only maximizes metal utilization but also provides catalytic centers that promote charge separation / transfer and reactant adsorption / activation. However, there are currently no reports on the controllable preparation of atomically dispersed metal-Bi₂O₂SO₄ photocatalysts. Summary of the Invention

[0004] To address the problems existing in the aforementioned background technology, this invention provides an atomically dispersed (Cu,Ag)-Bi₂O₂SO₄ catalyst for CO₂ photoreduction. Bismuth oxysulfate is used as the photocatalytic semiconductor material, and Cu or Ag is used as the supported metal. Cu or Ag ions are reduced to Cu or Ag elemental form under light irradiation, respectively, to obtain the atomically dispersed metal-Bi₂O₂SO₄ catalytic material. This photocatalyst is stable, reusable, and exhibits strong reducing properties.

[0005] The present invention is achieved through the following technical solution: a method for preparing an atomically dispersed metal-Bi2O2SO4 catalytic material, using bismuth nitrate, thiourea, CuCl2 or AgNO3 as raw materials, and forming an atomically dispersed metal Cu or Ag on the surface of the material after photoreduction.

[0006] The preparation method includes the following steps:

[0007] Step 1: Preparation of bismuth oxysulfate:

[0008] Step 1.1 Place thiourea in a container, add ethanol solution, sonicate for 15-30 min, add ground Bi(NO3)3·5H2O, continue sonicating for 15-30 min, let stand at 20-30℃ for 30-40 min, precipitate and filter to obtain a bright yellow precipitate;

[0009] Step 1.2 Place the bright yellow precipitate obtained in Step 1.1 into a porcelain jar, place it in a muffle furnace, and heat it to 500℃ at 2℃ / min under atmospheric conditions, and maintain the temperature for 3-5 hours to obtain pure phase bismuth oxysulfate powder.

[0010] Step 2: Metal ion-supported modified bismuth oxysulfate:

[0011] Step 2.1 Place the pure phase bismuth oxysulfate powder obtained in Step 1.2 into a container, add ethanol solution, sonicate for 15-30 min, then transfer it to a jacketed photoreactor, purge with argon gas for 30-40 min, stir under xenon lamp illumination for 6-8 h, then add metal compound solution dropwise, continue stirring for 30-40 min, precipitate and filter, wash three times with 99% ethanol, and dry in a 60℃ oven for 30 min to obtain a mixed product;

[0012] Step 2.2 Place the mixed product obtained in Step 2.1 in a container, add ethanol solution, sonicate for 15-30 min, then transfer it to a jacketed photoreactor, introduce argon gas for 30-40 min, stir under xenon lamp illumination for 60-90 min, filter the precipitate, wash three times with 99% ethanol, place it in a 60℃ oven, and dry for 10 h to obtain metal ion-supported modified bismuth oxysulfate.

[0013] Furthermore, in step 1.1, the mass ratio of thiourea and Bi(NO3)3·5H2O is 1:2 to 5.

[0014] Furthermore, the ethanol solution used in the preparation method has a mass fraction of 99%.

[0015] Furthermore, the metal compound solution in step 2.1 is a metal compound solution containing Cu ions or a metal compound solution containing Ag ions.

[0016] Furthermore, the Cu-containing metal compound solution uses CuCl2 as the Cu ion source, and the CuCl2 solution is added dropwise during the reaction.

[0017] Furthermore, the mass ratio of CuCl2 to Bi2O2SO4 is 1:200-300.

[0018] Furthermore, the Ag-containing metal compound solution uses AgNO3 as the Ag ion source, and the AgNO3 solution is added dropwise during the reaction.

[0019] Furthermore, the mass ratio of AgNO3 to Bi2O2SO4 is 1:200-300.

[0020] Furthermore, the atomically dispersed metal (Cu,Ag)-Bi2O2SO4 catalyst is applied in CO2 photoreduction.

[0021] This invention uses bismuth nitrate, thiourea, copper chloride, or silver nitrate as raw materials. Through photo-irradiation reaction, the materials are gradually reduced to form atomically dispersed metal Cu or Ag on the surface of the material, thereby modifying the bismuth oxysulfate material.

[0022] Compared with existing technologies, the beneficial effects of this invention are as follows: The metal Cu or Ag supported Bi₂O₂SO₄ photocatalyst prepared by this invention has a broad-spectrum reducing ability, can accelerate electron transfer under light irradiation, enhance the reducing ability, and has a certain directionality in the reduction and degradation of CO₂, making it effective for CO₂ reduction. This invention uses thiourea and bismuth nitrate as raw materials to synthesize the photocatalyst bismuth oxysulfate, and selects copper chloride or silver nitrate reagents as materials for metal-supported modification of bismuth oxysulfate. All selected materials are inexpensive and readily available, resulting in low economic cost. The photoreduction catalyst prepared by this method has the advantage of high selectivity, can accelerate electron movement under light irradiation, promote CO₂ reduction and degradation, and also has high stability, making it a relatively ideal photocatalyst. Compared with existing photocatalyst materials, the material of this invention has strong catalytic degradation and reducing properties, high selectivity, and high stability. When used as a CO₂ photoreduction catalyst, it can efficiently reduce CO₂ into multi-carbon products. Attached Figure Description

[0023] Figure 1 The XRD pattern of bismuth oxysulfate is shown.

[0024] Figure 2 The XRD pattern of atomically dispersed Cu-Bi2O2SO4;

[0025] Figure 3 The XRD pattern of atomically dispersed Ag-Bi2O2SO4;

[0026] Figure 4 This is a SEM image of bismuth oxysulfate.

[0027] Figure 5 SEM image of atomically dispersed Cu-Bi2O2SO4;

[0028] Figure 6 SEM image of atomically dispersed Ag-Bi2O2SO4;

[0029] Figure 7 EDS diagram of atomically dispersed Cu-Bi2O2SO4.

[0030] Figure 8 EDS diagram of atomically dispersed Ag-Bi2O2SO4. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1: Metal ion Cu-supported modified bismuth oxysulfate

[0032] Step 1: Preparation of Bismuth Oxysulfate

[0033] Step 1.1 First, weigh 2.0g of thiourea and place it in a beaker. Add 60mL of 99% ethanol solution and sonicate in an ultrasonic instrument for 20min until completely dissolved. Then, add 4.0g of ground Bi(NO3)3·5H2O to the above solution and continue sonicating for 20min. Remove the beaker and let it stand at 25℃ for 30min. After the precipitation is complete, filter and wash three times with 99% ethanol solution to obtain a bright yellow precipitate.

[0034] Step 1.2 Weigh 2.0g of the bright yellow precipitate prepared in Step 1.1, spread it evenly in a porcelain cup, place it in a muffle furnace, heat it to 500℃ at a rate of 2℃ / min under atmospheric conditions, and keep it at that temperature for 3h to obtain bismuth oxysulfate powder.

[0035] Step 2: Photodeposition metal modification of bismuth oxysulfate

[0036] Step 2.1 Weigh 1.0 g of the bismuth oxysulfate powder prepared in Step 1.2, place it in a beaker, add 150 mL of 99% ethanol solution, sonicate for 20 min until uniformly dispersed, then transfer it to a jacketed photoreactor. Purge with argon gas for 30 min to ensure air removal from the apparatus, then irradiate with a xenon lamp and stir magnetically for 6 h. Add 3 mL of 0.1 g / L CuCl2 ethanol solution dropwise, continue stirring magnetically for 30 min, precipitate, filter, and obtain the mixed product. Wash three times with 99% ethanol and dry in a 60℃ oven for 30 min.

[0037] Step 2.2: Place the mixed product prepared in Step 2.1 in a beaker, add 150 mL of 99% ethanol solution, and sonicate in an ultrasonicator for 20 min until uniformly dispersed. Then transfer it to a jacketed photoreactor, purge with argon gas for 30 min to ensure air removal from the apparatus, and then irradiate with a xenon lamp and stir magnetically for 1 h. Wash the product three times with 99% ethanol and dry it in a 60℃ oven for 10 h to obtain modified bismuth oxysulfate.

[0038] Figure 1 The crystal structure diagram of bismuth oxysulfate is shown separately, and it matches perfectly with the standard card for bismuth oxysulfate, demonstrating the high purity and high crystallinity of the product. The obtained product was tested, and the results are as follows... Figure 2 As shown, the crystal form of the material did not change before and after modification with bismuth oxysulfate, indicating that the loading of Cu did not destroy the physical and crystal structure of bismuth oxysulfate. At the same time, the absence of Cu peaks indicates that it is not a long-range ordered structure, indirectly indicating its atomic-level dispersion characteristics.

[0039] Figure 4 The SEM image of bismuth oxysulfate shows that its microstructure is a granular morphology of approximately 100 nm. Figure 5 As shown, the morphology of the modified bismuth oxysulfate material is all nanoparticles of about 100 nm, indicating that the microstructure of bismuth oxysulfate was not destroyed by Cu loading.

[0040] like Figure 7 As shown, (a) shows the distribution of Cu element in atomically dispersed Cu-Bi2O2SO4, and (b) shows the distribution of Bi element in atomically dispersed Cu-Bi2O2SO4. The Cu element content: Bi element content is approximately 1:100, indicating that bismuth oxysulfate was successfully modified by CuCl2 under light irradiation, so that the bismuth oxysulfate material was successfully loaded with atomically dispersed Cu metal.

[0041] Example 2: Metal ion Cu-supported modified bismuth oxysulfate

[0042] Step 1: Preparation of Bismuth Oxysulfate

[0043] Step 1.1 First, weigh 2.0g of thiourea and place it in a beaker. Add 60mL of 99% ethanol solution and sonicate in an ultrasonic instrument for 30min until completely dissolved. Then, add 4.0g of ground Bi(NO3)3·5H2O to the above solution and continue sonicating for 30min. Remove the beaker and let it stand at 30℃ for 30min. After the precipitation is complete, filter and wash three times with 99% ethanol solution to obtain a bright yellow precipitate.

[0044] Step 1.2 Weigh 2.0g of the bright yellow precipitate prepared in Step 1.1, spread it evenly in a porcelain cup, place it in a muffle furnace, heat it to 500℃ at a rate of 2℃ / min under atmospheric conditions, and keep it at that temperature for 5h to obtain bismuth oxysulfate powder.

[0045] Step 2: Photodeposition metal modification of bismuth oxysulfate

[0046] Step 2.1 Weigh 1.0 g of the bismuth oxysulfate powder prepared in Step 1.2, place it in a beaker, add 150 mL of 99% ethanol solution, sonicate for 30 min until uniformly dispersed, then transfer it to a jacketed photoreactor. Purge with argon gas for 40 min to ensure air removal from the apparatus, then irradiate with a xenon lamp and stir magnetically for 8 h. Add 3 mL of 0.1 g / L CuCl2 ethanol solution dropwise, continue stirring magnetically for 30 min, precipitate, filter, and obtain the mixed product. Wash three times with 99% ethanol and dry in a 60℃ oven for 30 min.

[0047] Step 2.2: Place the mixed product prepared in Step 2.1 in a beaker, add 150 mL of 99% ethanol solution, and sonicate in an ultrasonicator for 30 min until uniformly dispersed. Then transfer it to a jacketed photoreactor, purge with argon gas for 35 min to ensure air removal from the apparatus, and then magnetically stir under xenon lamp illumination for 90 min. Wash the product three times with 99% ethanol and dry it in a 60℃ oven for 10 h to obtain modified bismuth oxysulfate.

[0048] Example 3: Metal ion Ag-supported modified bismuth oxysulfate

[0049] Step 1: Preparation of Bismuth Oxysulfate

[0050] Step 1.1 First, weigh 2.0g of thiourea and place it in a beaker. Add 60mL of 99% ethanol solution and sonicate in an ultrasonic instrument for 20min until completely dissolved. Then, add 4.0g of ground Bi(NO3)3·5H2O to the above solution and continue sonicating for 20min. Remove the beaker and let it stand at 25℃ for 30min. After the precipitation is complete, filter and wash three times with 99% ethanol solution to obtain a bright yellow precipitate.

[0051] Step 1.2 Weigh 2.0g of the product prepared in Step 1.1, spread it evenly in a porcelain pot, place it in a muffle furnace, heat it to 500℃ at a rate of 2℃ / min under atmospheric conditions, and keep it at that temperature for 3h to obtain bismuth oxysulfate product.

[0052] Step 2: Metal-supported modification of bismuth oxysulfate

[0053] Step 2.1 Weigh 1.0 g of the bismuth oxysulfate powder prepared in Step 1.2, place it in a beaker, add 150 mL of 99% ethanol solution, sonicate for 20 min until uniformly dispersed, then transfer it to a jacketed photoreactor. Purge with argon gas for 30 min to ensure air removal from the apparatus, then irradiate with a xenon lamp and stir magnetically for 6 h. Add 3 mL of 0.1 g / L AgNO3 ethanol solution dropwise, continue stirring magnetically for 30 min, precipitate, filter, and obtain the mixed product. Wash three times with 99% ethanol and dry in a 60℃ oven for 30 min.

[0054] Step 2.2: Place the mixed product prepared in Step 2.1 in a beaker, add 150 mL of 99% ethanol solution, and sonicate in an ultrasonicator for 20 min until uniformly dispersed. Then transfer it to a jacketed photoreactor, purge with argon gas for 30 min to ensure air removal from the apparatus, and then irradiate with a xenon lamp and stir magnetically for 1 h. Wash the product three times with 99% ethanol and dry it in a 60℃ oven for 10 h to obtain modified bismuth oxysulfate.

[0055] The obtained product was then tested. Figure 1 The crystal structure diagram of bismuth oxysulfate alone is shown below, and the detection results are as follows. Figure 3 As shown, the crystal form of the material did not change after modification with bismuth oxysulfate, indicating that the loading of Ag did not destroy the physical and crystal structure of bismuth oxysulfate. At the same time, the absence of Ag peaks indicates that it is not a long-range ordered structure, indirectly indicating its atomic-level dispersion characteristics.

[0056] Figure 4 The SEM image of bismuth oxysulfate shows that its microstructure is a granular morphology of approximately 100 nm. Figure 6 As shown, the morphology of the modified bismuth oxysulfate material is all nanoparticle, indicating that the loading of Ag did not destroy the microstructure of bismuth oxysulfate.

[0057] like Figure 8 As shown, (a) shows the distribution of Ag elements in Ag-Bi2O2SO4, and (b) shows the distribution of Bi elements in Ag-Bi2O2SO4. The ratio of Ag element content to Bi element content is approximately 1:100, indicating that the bismuth oxysulfate material was successfully modified by loading with AgNO3 under light irradiation, resulting in the successful loading of atomically dispersed Ag metal.

[0058] Example 4: Metal ion Ag-supported modified bismuth oxysulfate

[0059] Step 1: Preparation of Bismuth Oxysulfate

[0060] Step 1.1 First, weigh 2.0g of thiourea and place it in a beaker. Add 60mL of 99% ethanol solution and sonicate in an ultrasonic instrument for 30min until completely dissolved. Then, add 4.0g of ground Bi(NO3)3·5H2O to the above solution and continue sonicating for 30min. Remove the beaker and let it stand at 20℃ for 30min. After the precipitation is complete, filter and wash three times with 99% ethanol solution to obtain a bright yellow precipitate.

[0061] Step 1.2 Weigh 2.0g of the product prepared in Step 1.1, spread it evenly in a porcelain pot, place it in a muffle furnace, heat it to 500℃ at a rate of 2℃ / min under atmospheric conditions, and keep it at that temperature for 4h to obtain bismuth oxysulfate product.

[0062] Step 2: Metal-supported modification of bismuth oxysulfate

[0063] Step 2.1 Weigh 1.0 g of the bismuth oxysulfate powder prepared in Step 1.2, place it in a beaker, add 150 mL of 99% ethanol solution, sonicate for 30 min until uniformly dispersed, then transfer it to a jacketed photoreactor, purge with argon gas for 40 min to ensure air removal from the apparatus, irradiate with a xenon lamp and stir magnetically for 7 h, then add 3 mL of 0.1 g / L AgNO3 ethanol solution dropwise, continue stirring magnetically for 35 min, precipitate and filter to obtain a mixed product. Wash three times with 99% ethanol and dry in a 60℃ oven for 40 min;

[0064] Step 2.2: Place the mixed product prepared in Step 2.1 in a beaker, add 150 mL of 99% ethanol solution, and sonicate in an ultrasonicator for 30 min until uniformly dispersed. Then transfer it to a jacketed photoreactor, purge with argon gas for 40 min to ensure air removal from the apparatus, and then magnetically stir under xenon lamp illumination for 75 min. Wash the product three times with 99% ethanol and dry it in a 60℃ oven for 10 h to obtain modified bismuth oxysulfate.

[0065] Test Example 1

[0066] Weigh 10 mg of modified bismuth oxysulfate, add an appropriate amount of deionized water, and sonicate for 30 min until completely and uniformly dispersed. Then, evenly disperse the mixture on a filter membrane. Transfer the mixture to a photocatalytic system, charge with sufficient CO2, and react for 6 h under xenon lamp irradiation. Record the CO2 gas catalytic conversion effect every 1 h. The test results showed that the modified catalyst exhibited highly efficient CO2 to methane production performance, with a methane production rate of 240 μmol / g. -1 h -1 .

[0067] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an atomically dispersed metal Cu, Ag-Bi2O2SO4 catalyst for CO2 photoreduction, characterized in that: Step 1: Preparation of bismuth oxysulfate: Step 1.1 Place thiourea in a container, add ethanol solution, sonicate for 15-30 min, add ground Bi(NO3)3·5H2O, continue sonicating for 15-30 min, let stand at 20-30℃ for 30-40 min, precipitate and filter to obtain a bright yellow precipitate; Step 1.2 Place the bright yellow precipitate obtained in Step 1.1 into a porcelain pot, place it in a muffle furnace, and heat it to 500℃ at 2℃ / min under atmospheric conditions, and maintain it for 3-5 hours to obtain pure phase bismuth oxysulfate powder. Step 2: Metal ion-supported modified bismuth oxysulfate: Step 2.1 Place the pure phase bismuth oxysulfate powder obtained in Step 1.2 into a container, add ethanol solution, sonicate for 15-30 min, then transfer it to a jacketed photoreactor, purge with argon gas for 30-40 min, stir under xenon lamp illumination for 6-8 h, then add a metal compound solution dropwise, the metal compound solution being either a Cu ion-containing metal compound solution or an Ag ion-containing metal compound solution, continue stirring for 30-40 min, precipitate and filter, wash three times with 99% ethanol, and dry in a 60℃ oven for 30 min to obtain a mixed product; Step 2.2 Place the mixed product obtained in Step 2.1 in a container, add ethanol solution, sonicate for 15-30 min, then transfer it to a jacketed photoreactor, introduce argon gas for 30-40 min, stir under xenon lamp illumination for 60-90 min, filter the precipitate, wash three times with 99% ethanol, place it in a 60℃ oven, and dry for 10 h to obtain metal ion-supported modified bismuth oxysulfate.

2. The method for preparing atomic dispersed metal Cu, Ag-Bi2O2SO4 catalysts for CO2 photoreduction according to claim 1, characterized in that: In step 1.1, the mass ratio of thiourea and Bi(NO3)3·5H2O is 1:2~5.

3. The method for preparing atomic dispersion metal Cu, Ag-Bi2O2SO4 catalyst for CO2 photoreduction according to claim 1, characterized in that: The ethanol solution used in the preparation method has a mass fraction of 99%.

4. The method for preparing an atomically dispersed metal Cu, Ag-Bi2O2SO4 catalyst for CO2 photoreduction according to claim 1, characterized in that: The Cu-containing metal compound solution uses CuCl2 as the Cu ion source, and CuCl2 solution is added dropwise during the reaction.

5. The method for preparing an atomically dispersed metal Cu, Ag-Bi2O2SO4 catalyst for CO2 photoreduction according to claim 4, characterized in that: The mass ratio of CuCl2 to Bi2O2SO4 is 1:200~300.

6. The method for preparing an atomically dispersed metal Cu, Ag-Bi2O2SO4 catalyst for CO2 photoreduction according to claim 1, characterized in that: The metal compound solution containing Ag ions uses AgNO3 as the Ag ion source, and the AgNO3 solution is added dropwise during the reaction.

7. The method for preparing an atomically dispersed metal Cu, Ag-Bi2O2SO4 catalyst for CO2 photoreduction according to claim 6, characterized in that: The mass ratio of AgNO3 to Bi2O2SO4 is 1:200~300.

8. The application of the atomically dispersed metal Cu, Ag-Bi2O2SO4 catalyst prepared by the method according to claim 1, characterized in that: The atomically dispersed metal Cu, Ag-Bi2O2SO4 catalyst is used in CO2 photoreduction.

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