A halogen-doped Bi2WO6 / Bi 3.84 W 0.16 O 6.24 Catalyst, process for its preparation and use

Abstract

This invention discloses a halogen-doped Bi2WO6 / Bi 3.84 W 0.16 O 6.24 This paper describes the catalyst, its preparation method, and its application, belonging to the field of photocatalysis technology. The catalyst is prepared by dispersing Bi(NO3)3·5H2O, Na2WO4·2H2O, and NaCl in water at a molar ratio of 2:1:1. The pH is adjusted to 11-12 with sodium hydroxide solution. The reaction is carried out in a stainless steel autoclave at 150-180℃ for 15-25 hours. After washing and drying, Cl-doped Bi2WO6 / Bi is obtained. 3.84 W 0.16 O 6.24 This material exhibits high photocatalytic selectivity, low production cost, and simple manufacturing process, and also possesses advantages over Bi2WO6 and Bi... 3.84 W 0.16 O 6.24 and Bi2WO6 / Bi 3.84 W 0.16 O 6.24 Photocatalysts exhibit higher photocatalytic CO2 reduction performance.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis technology, specifically to a halogen-doped Bi2WO6 / Bi 3.84 W 0.16 O 6.24 The catalyst also relates to its preparation method and application in photoreduction of CO2. Background Technology

[0002] For decades, modern society has relied heavily on fossil fuels to develop productivity. However, burning fossil fuels produces large amounts of carbon dioxide emissions into the atmosphere, leading to a series of environmental problems such as global warming, rising sea levels, increasing desertification, ocean acidification, and declining biodiversity. This will seriously affect human production and safety. Therefore, we urgently need to find green and sustainable methods to solve this problem. Photocatalysis technology, due to its mild reaction conditions and use of clean energy, is considered a promising approach.

[0003] Bi₂WO₆ is a promising photocatalyst, attracting widespread attention due to its suitable band gap, structural stability, non-toxicity, and low cost. Currently, the preparation of Bi₂WO₆ photocatalysts typically employs hydrothermal reactions. The hydrothermal method is not only a mild and simple process, but also yields products with high crystallinity and controllable particle size. Numerous studies have shown that the pH value of the hydrothermal reaction solution significantly affects the composition of the product. When the pH value of the precursor solution reaches a certain alkalinity, the crystalline product is Bi₂WO₆. 3.84 W 0.16 O 6.24 For Bi 3.84 W 0.16 O 6.24 Research and application of Bi₂WO₆ are still relatively limited. 3.84 W 0.16 O 6.24 Due to severe charge recombination and weak light absorption, the photoreduction activity of carbon dioxide is poor. Summary of the Invention

[0004] In view of this, one of the objectives of the present invention is to provide a halogen-doped Bi2WO6 / Bi 3.84 W 0.16 O 6.24 The method for preparing the catalyst; a second objective of this invention is to provide a halogen-doped Bi₂WO₆ / Bi₂ prepared by the method. 3.84 W 0.16 O 6.24 Catalyst; a third objective of this invention is to provide the halogen-doped Bi₂WO₆ / Bi 3.84 W 0.16 O6.24 Application of catalysts in photoreduction of CO2.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] 1. A halogen-doped Bi₂WO₆ / Bi 3.84 W 0.16 O 6.24 The catalyst preparation method includes the following preparation steps:

[0007] 1) Add Bi(NO3)3·5H2O and Na2WO4·2H2O to deionized water;

[0008] 2) Add NaCl, sonicate for a certain time, and then stir to obtain an opaque white dispersion;

[0009] 3) Adjust the pH with 1M sodium hydroxide solution and stir for a period of time;

[0010] 4) Transfer the solution obtained in step 3) to a stainless steel autoclave for reaction, wash and dry to obtain Cl-doped Bi₂WO₆ / Bi 3.84 W 0.16 O 6.24 Based on the weight ratio of NaCl to Bi2WO6, the obtained samples were named BWO / FBWO-Cl-1, BWO / FBWO-Cl-5, and BWO / FBWO-Cl-10, respectively.

[0011] Preferably, the molar ratio of Bi(NO3)3·5H2O and Na2WO4·2H2O is 2:1.

[0012] Preferably, in step 3), the pH is 11-12.

[0013] Preferably, in step 3), the stirring time is 20-30 minutes.

[0014] In a preferred embodiment of the present invention, in step 4), the reaction temperature is 150–180°C and the time is 15–25 h.

[0015] 2. Halogen-doped Bi₂WO₆ / Bi prepared by the method according to any one of claims 1 to 5 3.84 W 0.16 O 6.24 catalyst.

[0016] 3. The halogen-doped Bi₂WO₆ / Bi as described in claim 6 3.84 W 0.16 O 6.24 Application of catalysts in photoreduction of CO2.

[0017] The beneficial effects of this invention are as follows:

[0018] (1) This invention uses Cl-doped Bi2WO6 / Bi 3.84 W 0.16 O 6.24 The photocatalyst is used for photocatalytic CO2 reduction and has a high photocatalytic carbon dioxide reduction capacity. The prepared Cl-doped Bi2WO6 / Bi 3.84 W 0.16 O 6.24 The photocatalyst exhibits higher photocatalytic CO2 reduction performance than Bi2WO6 and Bi3.84W0.16O6.24 photocatalysts.

[0019] (2) This invention employs a simple hydrothermal method to prepare Cl-doped Bi₂WO₆ / Bi₂ in one step by adjusting the pH of the precursor. 3.84 W 0.16 O 6.24 Photocatalyst. This material exhibits high photocatalytic selectivity, low manufacturing cost, and simple production process. Attached Figure Description

[0020] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration:

[0021] Figure 1 XRD patterns of the prepared BWO, FBWO, BWO / FBWO, and BWO / FBWO-Cl;

[0022] Figure 2 TEM image of the prepared BWO / FBWO-Cl;

[0023] Figure 3 EDX images of the prepared BWO, FBWO, BWO / FBWO and BWO / FBWO-Cl catalysts;

[0024] Figure 4 The UV-Vis absorption spectra of the prepared BWO, FBWO, BWO / FBWO and BWO / FBWO-Cl catalysts are shown.

[0025] Figure 5 The photoluminescence spectrum of the prepared BWO / FBWO-Cl is shown below.

[0026] Figure 6 The yield of CO produced by reducing CO2 to CO was determined by simulating the effects of BWO, FBWO, BWO / FBWO and BWO / FBWO-Cl catalysts prepared under simulated sunlight irradiation. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0028] Example 1

[0029] Cl-doped Bi₂WO₆ / Bi 3.84 W 0.16 O 6.24 The specific method for preparing the catalyst is as follows:

[0030] (1) Weigh 2 mmol Bi(NO3)3·5H2O and 1 mmol Na2WO4·2H2O and add them to 75 ml of deionized water;

[0031] (2) Then add NaCl, sonicate for a certain time and stir to obtain an opaque white dispersion;

[0032] (3) Then adjust the pH to 11-12 with 1M sodium hydroxide solution and stir for 30 min;

[0033] The solution obtained in step 3) was transferred to a stainless steel autoclave and reacted at 160°C for 20 hours. After washing and drying, Cl-doped Bi₂WO₆ / Bi₂ was obtained. 3.84 W 0.16 O 6.24 Based on the weight ratio of NaCl added to the theoretical product Bi2WO6 from step 1 (1%, 5%, and 10%), the prepared samples were named BWO / FBWO-Cl-1, BWO / FBWO-Cl-5, and BWO / FBWO-Cl-10, respectively.

[0034] Example 2

[0035] The preparation method of Bi2WO6 catalyst is as follows:

[0036] (1) Weigh 2 mmol Bi(NO3)3·5H2O and 1 mmol Na2WO4·2H2O and add them to 75 ml of deionized water;

[0037] (2) After ultrasonication for a certain time, the mixture was stirred to obtain an opaque white dispersion;

[0038] (3) Then adjust the pH to 9-11 with 1M sodium hydroxide solution and stir for 30 min;

[0039] (4) The solution obtained in step 3) was transferred to a stainless steel autoclave and reacted at 160°C for 20 h. After washing and drying, Bi2WO6 was obtained and the product was named BWO.

[0040] Example 3

[0041] Bi 3.84 W 0.16 O 6.24 The specific method for preparing the catalyst is as follows:

[0042] (1) Weigh 2 mmol Bi(NO3)3·5H2O and 1 mmol Na2WO4·2H2O and add them to 75 ml of deionized water;

[0043] (2) Then, after sonication for a certain time, the mixture was stirred to obtain an opaque white dispersion.

[0044] (3) Then adjust the pH to 12-13 with 1M sodium hydroxide solution and stir for 30 min;

[0045] (4) Transfer the solution obtained in step 3) to a stainless steel autoclave, react at 160°C for 20 h, wash and dry to obtain Bi. 3.84 W 0.16 O 6.24 The resulting product was named FBWO.

[0046] Example 4

[0047] Bi2WO6 / Bi 3.84 W 0.16 O 6.24 The specific method for preparing the catalyst is as follows:

[0048] (1) Weigh 2 mmol Bi(NO3)3·5H2O and 1 mmol Na2WO4·2H2O and add them to 75 ml of deionized water;

[0049] (2) After ultrasonication for a certain time, the mixture was stirred to obtain an opaque white dispersion;

[0050] (3) Then adjust the pH to 11-12 with 1M sodium hydroxide solution and stir for 30 min;

[0051] (4) The solution obtained in step 3) is transferred to a stainless steel autoclave and reacted at 160°C for 20 h. After washing and drying, Bi2WO6 / Bi is obtained. 3.84 W 0.16 O 6.24 The resulting product is named BWO / FBWO.

[0052] Figure 1The images show the XRD patterns of the materials prepared in Examples 1-4 of this invention. It can be clearly seen that the XRD diffraction peaks of the BWO material prepared in Example 2 are consistent with the standard card JCPDS No. 73-2020, indicating that the prepared sample is pure Bi₂WO₆ material. The XRD diffraction peaks of the FBWO prepared in Example 3 are consistent with the standard card JCPDS No. 43-0447, indicating that the prepared sample is pure Bi₂WO₆ material. 3.84 W 0.16 O 6.24 Materials. Furthermore, in the XRD patterns of the catalysts prepared in Examples 1 and 4, both Bi₂WO₆ diffraction peaks and Bi₂WO₆ diffraction peaks were observed. 3.84 W 0.16 O 6.24 The diffraction peaks indicate the successful preparation of Bi2WO6 and Bi. 3.84 W 0.16 O 6.24 Composite catalyst.

[0053] Figure 2 It is a TEM of BWO / FBWO-Cl-5 ( Figure 2 (ab). Figure 2 The TEM image of b not only revealed the lattice fringes of Bi₂WO₆, but also Bi 3.84 W 0.16 O 6.24 The crystal lattice fringes were observed, and obvious interfacial contacts were also observed in the figure.

[0054] Figure 3 It is BWO / FBWO-Cl-5's EDX ( Figure 3 EDX results show that Cl is uniformly distributed in BWO / FBWO-Cl, confirming that Cl atoms have been successfully doped into the material. This further demonstrates the successful preparation of Cl-doped BWO / FBWO composite catalysts.

[0055] Figure 4 The photocatalysts prepared in Examples 1-4 of this invention were subjected to ultraviolet-vis light absorption (UV-vis) tests and analyses. The BWO / FBWO-Cl-5 photocatalyst prepared in Example 1 of this invention has better light absorption capacity and higher light utilization rate.

[0056] Figure 5 The images show the photoluminescence spectra of the photocatalysts prepared in Examples 1-4 of this invention. The BWO / FBWO-Cl-5 photocatalyst exhibits the weakest emission peak in the PL spectrum, indicating a low electron-hole recombination rate. This is due to the synergistic effect of the heterojunction and Cl doping, which suppresses the recombination of photogenerated electron-hole pairs, thereby improving the photocatalytic performance of the material.

[0057] Example 5

[0058] The photocatalytic performance of the material prepared in this invention was evaluated using a Labsolar-6A device (Beijing Perfectlight, China). The prepared material under simulated sunlight irradiation was used in a photocatalytic carbon dioxide reduction experiment. First, a test sample was prepared. 10 mg of the sample was weighed and placed in a glass bottle, and 1.0 mL of deionized water was added. The deionized water containing the sample was then evenly dropped onto a glass fiber filter membrane and dried at 60°C. The experiment was conducted in a 250 mL glass reactor using a 300 W Xe lamp (PLS-300, Beijing). (Perfectlight, China). During the experiment, circulating water was used to maintain the temperature at 20±0.03℃. Before turning on the lights, the reactor was sealed and then purged three times with high-purity carbon dioxide (≥99.999%) to remove O2 and other foreign gases. After purging, carbon dioxide was introduced into the reactor at a pressure of 91 kPa, followed by the injection of a small amount of water (100 μL). During the reaction, analysis was performed every hour using gas chromatography (GC2002, CeChuang) and a flame ionization detector (FID) and thermal conductivity detector (TCD).

[0059] Figure 6 The figures show the CO production yields of the photocatalysts prepared in Examples 1-4 of this invention after 5 hours of simulated sunlight irradiation. The images reveal that the synergistic effect of Cl doping and the heterojunction effectively improves the catalytic performance of the catalysts. Among them, BWO / FBWO-Cl-5 exhibits the best photocatalytic reduction CO2 conversion performance, with a CO yield of approximately 6.27 μmol·g⁻¹ after 5 hours of illumination. -1 .

[0060] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A Cl-doped Bi₂WO₆ / Bi 3.84 W 0.16 O 6.24 The application of catalysts in the photocatalytic reduction of CO2 to CO is characterized by, The catalyst preparation method includes the following preparation steps: 1) Add Bi(NO3)3·5H2O and Na2WO4·2H2O to deionized water, wherein the molar ratio of Bi(NO3)3·5H2O and Na2WO4·2H2O is 2:1; 2) Add NaCl, sonicate for a certain time, and then stir to obtain an opaque white dispersion. The amount of NaCl added is 1-10% of the weight of the theoretical product Bi2WO6 in step 1). 3) Adjust the pH to 11-12 with 1M sodium hydroxide solution and stir for 20-30 minutes; 4) Transfer the solution obtained in step 3) to a stainless steel autoclave and react at 160°C for 20 hours. Wash and dry to obtain Cl-doped Bi₂WO₆ / Bi 3.84 W 0.16 O 6.24 .

2. The application according to claim 1, characterized in that: In step 2), the amount of NaCl added is 5% of the weight of the theoretical product Bi2WO6 in step 1).

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